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Diffstat (limited to 'src/backend/access/transam/xlog.c')
| -rw-r--r-- | src/backend/access/transam/xlog.c | 13209 |
1 files changed, 13209 insertions, 0 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c new file mode 100644 index 0000000..ef72bde --- /dev/null +++ b/src/backend/access/transam/xlog.c @@ -0,0 +1,13209 @@ +/*------------------------------------------------------------------------- + * + * xlog.c + * PostgreSQL write-ahead log manager + * + * + * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/backend/access/transam/xlog.c + * + *------------------------------------------------------------------------- + */ + +#include "postgres.h" + +#include <ctype.h> +#include <math.h> +#include <time.h> +#include <fcntl.h> +#include <sys/stat.h> +#include <sys/time.h> +#include <unistd.h> + +#include "access/clog.h" +#include "access/commit_ts.h" +#include "access/heaptoast.h" +#include "access/multixact.h" +#include "access/rewriteheap.h" +#include "access/subtrans.h" +#include "access/timeline.h" +#include "access/transam.h" +#include "access/twophase.h" +#include "access/xact.h" +#include "access/xlog_internal.h" +#include "access/xlogarchive.h" +#include "access/xloginsert.h" +#include "access/xlogreader.h" +#include "access/xlogutils.h" +#include "catalog/catversion.h" +#include "catalog/pg_control.h" +#include "catalog/pg_database.h" +#include "commands/progress.h" +#include "commands/tablespace.h" +#include "common/controldata_utils.h" +#include "common/file_utils.h" +#include "executor/instrument.h" +#include "miscadmin.h" +#include "pg_trace.h" +#include "pgstat.h" +#include "port/atomics.h" +#include "port/pg_iovec.h" +#include "postmaster/bgwriter.h" +#include "postmaster/startup.h" +#include "postmaster/walwriter.h" +#include "replication/basebackup.h" +#include "replication/logical.h" +#include "replication/origin.h" +#include "replication/slot.h" +#include "replication/snapbuild.h" +#include "replication/walreceiver.h" +#include "replication/walsender.h" +#include "storage/bufmgr.h" +#include "storage/fd.h" +#include "storage/ipc.h" +#include "storage/large_object.h" +#include "storage/latch.h" +#include "storage/pmsignal.h" +#include "storage/predicate.h" +#include "storage/proc.h" +#include "storage/procarray.h" +#include "storage/reinit.h" +#include "storage/smgr.h" +#include "storage/spin.h" +#include "storage/sync.h" +#include "utils/builtins.h" +#include "utils/guc.h" +#include "utils/memutils.h" +#include "utils/ps_status.h" +#include "utils/relmapper.h" +#include "utils/pg_rusage.h" +#include "utils/snapmgr.h" +#include "utils/timestamp.h" + +extern uint32 bootstrap_data_checksum_version; + +/* Unsupported old recovery command file names (relative to $PGDATA) */ +#define RECOVERY_COMMAND_FILE "recovery.conf" +#define RECOVERY_COMMAND_DONE "recovery.done" + +/* User-settable parameters */ +int max_wal_size_mb = 1024; /* 1 GB */ +int min_wal_size_mb = 80; /* 80 MB */ +int wal_keep_size_mb = 0; +int XLOGbuffers = -1; +int XLogArchiveTimeout = 0; +int XLogArchiveMode = ARCHIVE_MODE_OFF; +char *XLogArchiveCommand = NULL; +bool EnableHotStandby = false; +bool fullPageWrites = true; +bool wal_log_hints = false; +bool wal_compression = false; +char *wal_consistency_checking_string = NULL; +bool *wal_consistency_checking = NULL; +bool wal_init_zero = true; +bool wal_recycle = true; +bool log_checkpoints = false; +int sync_method = DEFAULT_SYNC_METHOD; +int wal_level = WAL_LEVEL_MINIMAL; +int CommitDelay = 0; /* precommit delay in microseconds */ +int CommitSiblings = 5; /* # concurrent xacts needed to sleep */ +int wal_retrieve_retry_interval = 5000; +int max_slot_wal_keep_size_mb = -1; +bool track_wal_io_timing = false; + +#ifdef WAL_DEBUG +bool XLOG_DEBUG = false; +#endif + +int wal_segment_size = DEFAULT_XLOG_SEG_SIZE; + +/* + * Number of WAL insertion locks to use. A higher value allows more insertions + * to happen concurrently, but adds some CPU overhead to flushing the WAL, + * which needs to iterate all the locks. + */ +#define NUM_XLOGINSERT_LOCKS 8 + +/* + * Max distance from last checkpoint, before triggering a new xlog-based + * checkpoint. + */ +int CheckPointSegments; + +/* Estimated distance between checkpoints, in bytes */ +static double CheckPointDistanceEstimate = 0; +static double PrevCheckPointDistance = 0; + +/* + * GUC support + */ +const struct config_enum_entry sync_method_options[] = { + {"fsync", SYNC_METHOD_FSYNC, false}, +#ifdef HAVE_FSYNC_WRITETHROUGH + {"fsync_writethrough", SYNC_METHOD_FSYNC_WRITETHROUGH, false}, +#endif +#ifdef HAVE_FDATASYNC + {"fdatasync", SYNC_METHOD_FDATASYNC, false}, +#endif +#ifdef OPEN_SYNC_FLAG + {"open_sync", SYNC_METHOD_OPEN, false}, +#endif +#ifdef OPEN_DATASYNC_FLAG + {"open_datasync", SYNC_METHOD_OPEN_DSYNC, false}, +#endif + {NULL, 0, false} +}; + + +/* + * Although only "on", "off", and "always" are documented, + * we accept all the likely variants of "on" and "off". + */ +const struct config_enum_entry archive_mode_options[] = { + {"always", ARCHIVE_MODE_ALWAYS, false}, + {"on", ARCHIVE_MODE_ON, false}, + {"off", ARCHIVE_MODE_OFF, false}, + {"true", ARCHIVE_MODE_ON, true}, + {"false", ARCHIVE_MODE_OFF, true}, + {"yes", ARCHIVE_MODE_ON, true}, + {"no", ARCHIVE_MODE_OFF, true}, + {"1", ARCHIVE_MODE_ON, true}, + {"0", ARCHIVE_MODE_OFF, true}, + {NULL, 0, false} +}; + +const struct config_enum_entry recovery_target_action_options[] = { + {"pause", RECOVERY_TARGET_ACTION_PAUSE, false}, + {"promote", RECOVERY_TARGET_ACTION_PROMOTE, false}, + {"shutdown", RECOVERY_TARGET_ACTION_SHUTDOWN, false}, + {NULL, 0, false} +}; + +/* + * Statistics for current checkpoint are collected in this global struct. + * Because only the checkpointer or a stand-alone backend can perform + * checkpoints, this will be unused in normal backends. + */ +CheckpointStatsData CheckpointStats; + +/* + * ThisTimeLineID will be same in all backends --- it identifies current + * WAL timeline for the database system. + */ +TimeLineID ThisTimeLineID = 0; + +/* + * Are we doing recovery from XLOG? + * + * This is only ever true in the startup process; it should be read as meaning + * "this process is replaying WAL records", rather than "the system is in + * recovery mode". It should be examined primarily by functions that need + * to act differently when called from a WAL redo function (e.g., to skip WAL + * logging). To check whether the system is in recovery regardless of which + * process you're running in, use RecoveryInProgress() but only after shared + * memory startup and lock initialization. + */ +bool InRecovery = false; + +/* Are we in Hot Standby mode? Only valid in startup process, see xlog.h */ +HotStandbyState standbyState = STANDBY_DISABLED; + +static XLogRecPtr LastRec; + +/* Local copy of WalRcv->flushedUpto */ +static XLogRecPtr flushedUpto = 0; +static TimeLineID receiveTLI = 0; + +/* + * abortedRecPtr is the start pointer of a broken record at end of WAL when + * recovery completes; missingContrecPtr is the location of the first + * contrecord that went missing. See CreateOverwriteContrecordRecord for + * details. + */ +static XLogRecPtr abortedRecPtr; +static XLogRecPtr missingContrecPtr; + +/* + * During recovery, lastFullPageWrites keeps track of full_page_writes that + * the replayed WAL records indicate. It's initialized with full_page_writes + * that the recovery starting checkpoint record indicates, and then updated + * each time XLOG_FPW_CHANGE record is replayed. + */ +static bool lastFullPageWrites; + +/* + * Local copy of the state tracked by SharedRecoveryState in shared memory, + * It is false if SharedRecoveryState is RECOVERY_STATE_DONE. True actually + * means "not known, need to check the shared state". + */ +static bool LocalRecoveryInProgress = true; + +/* + * Local copy of SharedHotStandbyActive variable. False actually means "not + * known, need to check the shared state". + */ +static bool LocalHotStandbyActive = false; + +/* + * Local copy of SharedPromoteIsTriggered variable. False actually means "not + * known, need to check the shared state". + */ +static bool LocalPromoteIsTriggered = false; + +/* + * Local state for XLogInsertAllowed(): + * 1: unconditionally allowed to insert XLOG + * 0: unconditionally not allowed to insert XLOG + * -1: must check RecoveryInProgress(); disallow until it is false + * Most processes start with -1 and transition to 1 after seeing that recovery + * is not in progress. But we can also force the value for special cases. + * The coding in XLogInsertAllowed() depends on the first two of these states + * being numerically the same as bool true and false. + */ +static int LocalXLogInsertAllowed = -1; + +/* + * When ArchiveRecoveryRequested is set, archive recovery was requested, + * ie. signal files were present. When InArchiveRecovery is set, we are + * currently recovering using offline XLOG archives. These variables are only + * valid in the startup process. + * + * When ArchiveRecoveryRequested is true, but InArchiveRecovery is false, we're + * currently performing crash recovery using only XLOG files in pg_wal, but + * will switch to using offline XLOG archives as soon as we reach the end of + * WAL in pg_wal. +*/ +bool ArchiveRecoveryRequested = false; +bool InArchiveRecovery = false; + +static bool standby_signal_file_found = false; +static bool recovery_signal_file_found = false; + +/* Was the last xlog file restored from archive, or local? */ +static bool restoredFromArchive = false; + +/* Buffers dedicated to consistency checks of size BLCKSZ */ +static char *replay_image_masked = NULL; +static char *primary_image_masked = NULL; + +/* options formerly taken from recovery.conf for archive recovery */ +char *recoveryRestoreCommand = NULL; +char *recoveryEndCommand = NULL; +char *archiveCleanupCommand = NULL; +RecoveryTargetType recoveryTarget = RECOVERY_TARGET_UNSET; +bool recoveryTargetInclusive = true; +int recoveryTargetAction = RECOVERY_TARGET_ACTION_PAUSE; +TransactionId recoveryTargetXid; +char *recovery_target_time_string; +static TimestampTz recoveryTargetTime; +const char *recoveryTargetName; +XLogRecPtr recoveryTargetLSN; +int recovery_min_apply_delay = 0; + +/* options formerly taken from recovery.conf for XLOG streaming */ +bool StandbyModeRequested = false; +char *PrimaryConnInfo = NULL; +char *PrimarySlotName = NULL; +char *PromoteTriggerFile = NULL; +bool wal_receiver_create_temp_slot = false; + +/* are we currently in standby mode? */ +bool StandbyMode = false; + +/* + * if recoveryStopsBefore/After returns true, it saves information of the stop + * point here + */ +static TransactionId recoveryStopXid; +static TimestampTz recoveryStopTime; +static XLogRecPtr recoveryStopLSN; +static char recoveryStopName[MAXFNAMELEN]; +static bool recoveryStopAfter; + +/* + * During normal operation, the only timeline we care about is ThisTimeLineID. + * During recovery, however, things are more complicated. To simplify life + * for rmgr code, we keep ThisTimeLineID set to the "current" timeline as we + * scan through the WAL history (that is, it is the line that was active when + * the currently-scanned WAL record was generated). We also need these + * timeline values: + * + * recoveryTargetTimeLineGoal: what the user requested, if any + * + * recoveryTargetTLIRequested: numeric value of requested timeline, if constant + * + * recoveryTargetTLI: the currently understood target timeline; changes + * + * expectedTLEs: a list of TimeLineHistoryEntries for recoveryTargetTLI and the timelines of + * its known parents, newest first (so recoveryTargetTLI is always the + * first list member). Only these TLIs are expected to be seen in the WAL + * segments we read, and indeed only these TLIs will be considered as + * candidate WAL files to open at all. + * + * curFileTLI: the TLI appearing in the name of the current input WAL file. + * (This is not necessarily the same as ThisTimeLineID, because we could + * be scanning data that was copied from an ancestor timeline when the current + * file was created.) During a sequential scan we do not allow this value + * to decrease. + */ +RecoveryTargetTimeLineGoal recoveryTargetTimeLineGoal = RECOVERY_TARGET_TIMELINE_LATEST; +TimeLineID recoveryTargetTLIRequested = 0; +TimeLineID recoveryTargetTLI = 0; +static List *expectedTLEs; +static TimeLineID curFileTLI; + +/* + * ProcLastRecPtr points to the start of the last XLOG record inserted by the + * current backend. It is updated for all inserts. XactLastRecEnd points to + * end+1 of the last record, and is reset when we end a top-level transaction, + * or start a new one; so it can be used to tell if the current transaction has + * created any XLOG records. + * + * While in parallel mode, this may not be fully up to date. When committing, + * a transaction can assume this covers all xlog records written either by the + * user backend or by any parallel worker which was present at any point during + * the transaction. But when aborting, or when still in parallel mode, other + * parallel backends may have written WAL records at later LSNs than the value + * stored here. The parallel leader advances its own copy, when necessary, + * in WaitForParallelWorkersToFinish. + */ +XLogRecPtr ProcLastRecPtr = InvalidXLogRecPtr; +XLogRecPtr XactLastRecEnd = InvalidXLogRecPtr; +XLogRecPtr XactLastCommitEnd = InvalidXLogRecPtr; + +/* + * RedoRecPtr is this backend's local copy of the REDO record pointer + * (which is almost but not quite the same as a pointer to the most recent + * CHECKPOINT record). We update this from the shared-memory copy, + * XLogCtl->Insert.RedoRecPtr, whenever we can safely do so (ie, when we + * hold an insertion lock). See XLogInsertRecord for details. We are also + * allowed to update from XLogCtl->RedoRecPtr if we hold the info_lck; + * see GetRedoRecPtr. A freshly spawned backend obtains the value during + * InitXLOGAccess. + */ +static XLogRecPtr RedoRecPtr; + +/* + * doPageWrites is this backend's local copy of (forcePageWrites || + * fullPageWrites). It is used together with RedoRecPtr to decide whether + * a full-page image of a page need to be taken. + */ +static bool doPageWrites; + +/* Has the recovery code requested a walreceiver wakeup? */ +static bool doRequestWalReceiverReply; + +/* + * RedoStartLSN points to the checkpoint's REDO location which is specified + * in a backup label file, backup history file or control file. In standby + * mode, XLOG streaming usually starts from the position where an invalid + * record was found. But if we fail to read even the initial checkpoint + * record, we use the REDO location instead of the checkpoint location as + * the start position of XLOG streaming. Otherwise we would have to jump + * backwards to the REDO location after reading the checkpoint record, + * because the REDO record can precede the checkpoint record. + */ +static XLogRecPtr RedoStartLSN = InvalidXLogRecPtr; + +/*---------- + * Shared-memory data structures for XLOG control + * + * LogwrtRqst indicates a byte position that we need to write and/or fsync + * the log up to (all records before that point must be written or fsynced). + * LogwrtResult indicates the byte positions we have already written/fsynced. + * These structs are identical but are declared separately to indicate their + * slightly different functions. + * + * To read XLogCtl->LogwrtResult, you must hold either info_lck or + * WALWriteLock. To update it, you need to hold both locks. The point of + * this arrangement is that the value can be examined by code that already + * holds WALWriteLock without needing to grab info_lck as well. In addition + * to the shared variable, each backend has a private copy of LogwrtResult, + * which is updated when convenient. + * + * The request bookkeeping is simpler: there is a shared XLogCtl->LogwrtRqst + * (protected by info_lck), but we don't need to cache any copies of it. + * + * info_lck is only held long enough to read/update the protected variables, + * so it's a plain spinlock. The other locks are held longer (potentially + * over I/O operations), so we use LWLocks for them. These locks are: + * + * WALBufMappingLock: must be held to replace a page in the WAL buffer cache. + * It is only held while initializing and changing the mapping. If the + * contents of the buffer being replaced haven't been written yet, the mapping + * lock is released while the write is done, and reacquired afterwards. + * + * WALWriteLock: must be held to write WAL buffers to disk (XLogWrite or + * XLogFlush). + * + * ControlFileLock: must be held to read/update control file or create + * new log file. + * + *---------- + */ + +typedef struct XLogwrtRqst +{ + XLogRecPtr Write; /* last byte + 1 to write out */ + XLogRecPtr Flush; /* last byte + 1 to flush */ +} XLogwrtRqst; + +typedef struct XLogwrtResult +{ + XLogRecPtr Write; /* last byte + 1 written out */ + XLogRecPtr Flush; /* last byte + 1 flushed */ +} XLogwrtResult; + +/* + * Inserting to WAL is protected by a small fixed number of WAL insertion + * locks. To insert to the WAL, you must hold one of the locks - it doesn't + * matter which one. To lock out other concurrent insertions, you must hold + * of them. Each WAL insertion lock consists of a lightweight lock, plus an + * indicator of how far the insertion has progressed (insertingAt). + * + * The insertingAt values are read when a process wants to flush WAL from + * the in-memory buffers to disk, to check that all the insertions to the + * region the process is about to write out have finished. You could simply + * wait for all currently in-progress insertions to finish, but the + * insertingAt indicator allows you to ignore insertions to later in the WAL, + * so that you only wait for the insertions that are modifying the buffers + * you're about to write out. + * + * This isn't just an optimization. If all the WAL buffers are dirty, an + * inserter that's holding a WAL insert lock might need to evict an old WAL + * buffer, which requires flushing the WAL. If it's possible for an inserter + * to block on another inserter unnecessarily, deadlock can arise when two + * inserters holding a WAL insert lock wait for each other to finish their + * insertion. + * + * Small WAL records that don't cross a page boundary never update the value, + * the WAL record is just copied to the page and the lock is released. But + * to avoid the deadlock-scenario explained above, the indicator is always + * updated before sleeping while holding an insertion lock. + * + * lastImportantAt contains the LSN of the last important WAL record inserted + * using a given lock. This value is used to detect if there has been + * important WAL activity since the last time some action, like a checkpoint, + * was performed - allowing to not repeat the action if not. The LSN is + * updated for all insertions, unless the XLOG_MARK_UNIMPORTANT flag was + * set. lastImportantAt is never cleared, only overwritten by the LSN of newer + * records. Tracking the WAL activity directly in WALInsertLock has the + * advantage of not needing any additional locks to update the value. + */ +typedef struct +{ + LWLock lock; + XLogRecPtr insertingAt; + XLogRecPtr lastImportantAt; +} WALInsertLock; + +/* + * All the WAL insertion locks are allocated as an array in shared memory. We + * force the array stride to be a power of 2, which saves a few cycles in + * indexing, but more importantly also ensures that individual slots don't + * cross cache line boundaries. (Of course, we have to also ensure that the + * array start address is suitably aligned.) + */ +typedef union WALInsertLockPadded +{ + WALInsertLock l; + char pad[PG_CACHE_LINE_SIZE]; +} WALInsertLockPadded; + +/* + * State of an exclusive backup, necessary to control concurrent activities + * across sessions when working on exclusive backups. + * + * EXCLUSIVE_BACKUP_NONE means that there is no exclusive backup actually + * running, to be more precise pg_start_backup() is not being executed for + * an exclusive backup and there is no exclusive backup in progress. + * EXCLUSIVE_BACKUP_STARTING means that pg_start_backup() is starting an + * exclusive backup. + * EXCLUSIVE_BACKUP_IN_PROGRESS means that pg_start_backup() has finished + * running and an exclusive backup is in progress. pg_stop_backup() is + * needed to finish it. + * EXCLUSIVE_BACKUP_STOPPING means that pg_stop_backup() is stopping an + * exclusive backup. + */ +typedef enum ExclusiveBackupState +{ + EXCLUSIVE_BACKUP_NONE = 0, + EXCLUSIVE_BACKUP_STARTING, + EXCLUSIVE_BACKUP_IN_PROGRESS, + EXCLUSIVE_BACKUP_STOPPING +} ExclusiveBackupState; + +/* + * Session status of running backup, used for sanity checks in SQL-callable + * functions to start and stop backups. + */ +static SessionBackupState sessionBackupState = SESSION_BACKUP_NONE; + +/* + * Shared state data for WAL insertion. + */ +typedef struct XLogCtlInsert +{ + slock_t insertpos_lck; /* protects CurrBytePos and PrevBytePos */ + + /* + * CurrBytePos is the end of reserved WAL. The next record will be + * inserted at that position. PrevBytePos is the start position of the + * previously inserted (or rather, reserved) record - it is copied to the + * prev-link of the next record. These are stored as "usable byte + * positions" rather than XLogRecPtrs (see XLogBytePosToRecPtr()). + */ + uint64 CurrBytePos; + uint64 PrevBytePos; + + /* + * Make sure the above heavily-contended spinlock and byte positions are + * on their own cache line. In particular, the RedoRecPtr and full page + * write variables below should be on a different cache line. They are + * read on every WAL insertion, but updated rarely, and we don't want + * those reads to steal the cache line containing Curr/PrevBytePos. + */ + char pad[PG_CACHE_LINE_SIZE]; + + /* + * fullPageWrites is the authoritative value used by all backends to + * determine whether to write full-page image to WAL. This shared value, + * instead of the process-local fullPageWrites, is required because, when + * full_page_writes is changed by SIGHUP, we must WAL-log it before it + * actually affects WAL-logging by backends. Checkpointer sets at startup + * or after SIGHUP. + * + * To read these fields, you must hold an insertion lock. To modify them, + * you must hold ALL the locks. + */ + XLogRecPtr RedoRecPtr; /* current redo point for insertions */ + bool forcePageWrites; /* forcing full-page writes for PITR? */ + bool fullPageWrites; + + /* + * exclusiveBackupState indicates the state of an exclusive backup (see + * comments of ExclusiveBackupState for more details). nonExclusiveBackups + * is a counter indicating the number of streaming base backups currently + * in progress. forcePageWrites is set to true when either of these is + * non-zero. lastBackupStart is the latest checkpoint redo location used + * as a starting point for an online backup. + */ + ExclusiveBackupState exclusiveBackupState; + int nonExclusiveBackups; + XLogRecPtr lastBackupStart; + + /* + * WAL insertion locks. + */ + WALInsertLockPadded *WALInsertLocks; +} XLogCtlInsert; + +/* + * Total shared-memory state for XLOG. + */ +typedef struct XLogCtlData +{ + XLogCtlInsert Insert; + + /* Protected by info_lck: */ + XLogwrtRqst LogwrtRqst; + XLogRecPtr RedoRecPtr; /* a recent copy of Insert->RedoRecPtr */ + FullTransactionId ckptFullXid; /* nextXid of latest checkpoint */ + XLogRecPtr asyncXactLSN; /* LSN of newest async commit/abort */ + XLogRecPtr replicationSlotMinLSN; /* oldest LSN needed by any slot */ + + XLogSegNo lastRemovedSegNo; /* latest removed/recycled XLOG segment */ + + /* Fake LSN counter, for unlogged relations. Protected by ulsn_lck. */ + XLogRecPtr unloggedLSN; + slock_t ulsn_lck; + + /* Time and LSN of last xlog segment switch. Protected by WALWriteLock. */ + pg_time_t lastSegSwitchTime; + XLogRecPtr lastSegSwitchLSN; + + /* + * Protected by info_lck and WALWriteLock (you must hold either lock to + * read it, but both to update) + */ + XLogwrtResult LogwrtResult; + + /* + * Latest initialized page in the cache (last byte position + 1). + * + * To change the identity of a buffer (and InitializedUpTo), you need to + * hold WALBufMappingLock. To change the identity of a buffer that's + * still dirty, the old page needs to be written out first, and for that + * you need WALWriteLock, and you need to ensure that there are no + * in-progress insertions to the page by calling + * WaitXLogInsertionsToFinish(). + */ + XLogRecPtr InitializedUpTo; + + /* + * These values do not change after startup, although the pointed-to pages + * and xlblocks values certainly do. xlblocks values are protected by + * WALBufMappingLock. + */ + char *pages; /* buffers for unwritten XLOG pages */ + XLogRecPtr *xlblocks; /* 1st byte ptr-s + XLOG_BLCKSZ */ + int XLogCacheBlck; /* highest allocated xlog buffer index */ + + /* + * Shared copy of ThisTimeLineID. Does not change after end-of-recovery. + * If we created a new timeline when the system was started up, + * PrevTimeLineID is the old timeline's ID that we forked off from. + * Otherwise it's equal to ThisTimeLineID. + */ + TimeLineID ThisTimeLineID; + TimeLineID PrevTimeLineID; + + /* + * SharedRecoveryState indicates if we're still in crash or archive + * recovery. Protected by info_lck. + */ + RecoveryState SharedRecoveryState; + + /* + * SharedHotStandbyActive indicates if we allow hot standby queries to be + * run. Protected by info_lck. + */ + bool SharedHotStandbyActive; + + /* + * SharedPromoteIsTriggered indicates if a standby promotion has been + * triggered. Protected by info_lck. + */ + bool SharedPromoteIsTriggered; + + /* + * WalWriterSleeping indicates whether the WAL writer is currently in + * low-power mode (and hence should be nudged if an async commit occurs). + * Protected by info_lck. + */ + bool WalWriterSleeping; + + /* + * recoveryWakeupLatch is used to wake up the startup process to continue + * WAL replay, if it is waiting for WAL to arrive or failover trigger file + * to appear. + * + * Note that the startup process also uses another latch, its procLatch, + * to wait for recovery conflict. If we get rid of recoveryWakeupLatch for + * signaling the startup process in favor of using its procLatch, which + * comports better with possible generic signal handlers using that latch. + * But we should not do that because the startup process doesn't assume + * that it's waken up by walreceiver process or SIGHUP signal handler + * while it's waiting for recovery conflict. The separate latches, + * recoveryWakeupLatch and procLatch, should be used for inter-process + * communication for WAL replay and recovery conflict, respectively. + */ + Latch recoveryWakeupLatch; + + /* + * During recovery, we keep a copy of the latest checkpoint record here. + * lastCheckPointRecPtr points to start of checkpoint record and + * lastCheckPointEndPtr points to end+1 of checkpoint record. Used by the + * checkpointer when it wants to create a restartpoint. + * + * Protected by info_lck. + */ + XLogRecPtr lastCheckPointRecPtr; + XLogRecPtr lastCheckPointEndPtr; + CheckPoint lastCheckPoint; + + /* + * lastReplayedEndRecPtr points to end+1 of the last record successfully + * replayed. When we're currently replaying a record, ie. in a redo + * function, replayEndRecPtr points to the end+1 of the record being + * replayed, otherwise it's equal to lastReplayedEndRecPtr. + */ + XLogRecPtr lastReplayedEndRecPtr; + TimeLineID lastReplayedTLI; + XLogRecPtr replayEndRecPtr; + TimeLineID replayEndTLI; + /* timestamp of last COMMIT/ABORT record replayed (or being replayed) */ + TimestampTz recoveryLastXTime; + + /* + * timestamp of when we started replaying the current chunk of WAL data, + * only relevant for replication or archive recovery + */ + TimestampTz currentChunkStartTime; + /* Recovery pause state */ + RecoveryPauseState recoveryPauseState; + ConditionVariable recoveryNotPausedCV; + + /* + * lastFpwDisableRecPtr points to the start of the last replayed + * XLOG_FPW_CHANGE record that instructs full_page_writes is disabled. + */ + XLogRecPtr lastFpwDisableRecPtr; + + slock_t info_lck; /* locks shared variables shown above */ +} XLogCtlData; + +static XLogCtlData *XLogCtl = NULL; + +/* a private copy of XLogCtl->Insert.WALInsertLocks, for convenience */ +static WALInsertLockPadded *WALInsertLocks = NULL; + +/* + * We maintain an image of pg_control in shared memory. + */ +static ControlFileData *ControlFile = NULL; + +/* + * Calculate the amount of space left on the page after 'endptr'. Beware + * multiple evaluation! + */ +#define INSERT_FREESPACE(endptr) \ + (((endptr) % XLOG_BLCKSZ == 0) ? 0 : (XLOG_BLCKSZ - (endptr) % XLOG_BLCKSZ)) + +/* Macro to advance to next buffer index. */ +#define NextBufIdx(idx) \ + (((idx) == XLogCtl->XLogCacheBlck) ? 0 : ((idx) + 1)) + +/* + * XLogRecPtrToBufIdx returns the index of the WAL buffer that holds, or + * would hold if it was in cache, the page containing 'recptr'. + */ +#define XLogRecPtrToBufIdx(recptr) \ + (((recptr) / XLOG_BLCKSZ) % (XLogCtl->XLogCacheBlck + 1)) + +/* + * These are the number of bytes in a WAL page usable for WAL data. + */ +#define UsableBytesInPage (XLOG_BLCKSZ - SizeOfXLogShortPHD) + +/* + * Convert values of GUCs measured in megabytes to equiv. segment count. + * Rounds down. + */ +#define ConvertToXSegs(x, segsize) XLogMBVarToSegs((x), (segsize)) + +/* The number of bytes in a WAL segment usable for WAL data. */ +static int UsableBytesInSegment; + +/* + * Private, possibly out-of-date copy of shared LogwrtResult. + * See discussion above. + */ +static XLogwrtResult LogwrtResult = {0, 0}; + +/* + * Codes indicating where we got a WAL file from during recovery, or where + * to attempt to get one. + */ +typedef enum +{ + XLOG_FROM_ANY = 0, /* request to read WAL from any source */ + XLOG_FROM_ARCHIVE, /* restored using restore_command */ + XLOG_FROM_PG_WAL, /* existing file in pg_wal */ + XLOG_FROM_STREAM /* streamed from primary */ +} XLogSource; + +/* human-readable names for XLogSources, for debugging output */ +static const char *const xlogSourceNames[] = {"any", "archive", "pg_wal", "stream"}; + +/* + * openLogFile is -1 or a kernel FD for an open log file segment. + * openLogSegNo identifies the segment. These variables are only used to + * write the XLOG, and so will normally refer to the active segment. + * Note: call Reserve/ReleaseExternalFD to track consumption of this FD. + */ +static int openLogFile = -1; +static XLogSegNo openLogSegNo = 0; + +/* + * These variables are used similarly to the ones above, but for reading + * the XLOG. readOff is the offset of the page just read, readLen + * indicates how much of it has been read into readBuf, and readSource + * indicates where we got the currently open file from. + * Note: we could use Reserve/ReleaseExternalFD to track consumption of + * this FD too; but it doesn't currently seem worthwhile, since the XLOG is + * not read by general-purpose sessions. + */ +static int readFile = -1; +static XLogSegNo readSegNo = 0; +static uint32 readOff = 0; +static uint32 readLen = 0; +static XLogSource readSource = XLOG_FROM_ANY; + +/* + * Keeps track of which source we're currently reading from. This is + * different from readSource in that this is always set, even when we don't + * currently have a WAL file open. If lastSourceFailed is set, our last + * attempt to read from currentSource failed, and we should try another source + * next. + * + * pendingWalRcvRestart is set when a config change occurs that requires a + * walreceiver restart. This is only valid in XLOG_FROM_STREAM state. + */ +static XLogSource currentSource = XLOG_FROM_ANY; +static bool lastSourceFailed = false; +static bool pendingWalRcvRestart = false; + +typedef struct XLogPageReadPrivate +{ + int emode; + bool fetching_ckpt; /* are we fetching a checkpoint record? */ + bool randAccess; +} XLogPageReadPrivate; + +/* + * These variables track when we last obtained some WAL data to process, + * and where we got it from. (XLogReceiptSource is initially the same as + * readSource, but readSource gets reset to zero when we don't have data + * to process right now. It is also different from currentSource, which + * also changes when we try to read from a source and fail, while + * XLogReceiptSource tracks where we last successfully read some WAL.) + */ +static TimestampTz XLogReceiptTime = 0; +static XLogSource XLogReceiptSource = XLOG_FROM_ANY; + +/* State information for XLOG reading */ +static XLogRecPtr ReadRecPtr; /* start of last record read */ +static XLogRecPtr EndRecPtr; /* end+1 of last record read */ + +/* + * Local copies of equivalent fields in the control file. When running + * crash recovery, minRecoveryPoint is set to InvalidXLogRecPtr as we + * expect to replay all the WAL available, and updateMinRecoveryPoint is + * switched to false to prevent any updates while replaying records. + * Those values are kept consistent as long as crash recovery runs. + */ +static XLogRecPtr minRecoveryPoint; +static TimeLineID minRecoveryPointTLI; +static bool updateMinRecoveryPoint = true; + +/* + * Have we reached a consistent database state? In crash recovery, we have + * to replay all the WAL, so reachedConsistency is never set. During archive + * recovery, the database is consistent once minRecoveryPoint is reached. + */ +bool reachedConsistency = false; + +static bool InRedo = false; + +/* Have we launched bgwriter during recovery? */ +static bool bgwriterLaunched = false; + +/* For WALInsertLockAcquire/Release functions */ +static int MyLockNo = 0; +static bool holdingAllLocks = false; + +#ifdef WAL_DEBUG +static MemoryContext walDebugCxt = NULL; +#endif + +static void readRecoverySignalFile(void); +static void validateRecoveryParameters(void); +static void exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog); +static bool recoveryStopsBefore(XLogReaderState *record); +static bool recoveryStopsAfter(XLogReaderState *record); +static void ConfirmRecoveryPaused(void); +static void recoveryPausesHere(bool endOfRecovery); +static bool recoveryApplyDelay(XLogReaderState *record); +static void SetLatestXTime(TimestampTz xtime); +static void SetCurrentChunkStartTime(TimestampTz xtime); +static void CheckRequiredParameterValues(void); +static void XLogReportParameters(void); +static void checkTimeLineSwitch(XLogRecPtr lsn, TimeLineID newTLI, + TimeLineID prevTLI); +static void VerifyOverwriteContrecord(xl_overwrite_contrecord *xlrec, + XLogReaderState *state); +static void LocalSetXLogInsertAllowed(void); +static void CreateEndOfRecoveryRecord(void); +static XLogRecPtr CreateOverwriteContrecordRecord(XLogRecPtr aborted_lsn); +static void CheckPointGuts(XLogRecPtr checkPointRedo, int flags); +static void KeepLogSeg(XLogRecPtr recptr, XLogSegNo *logSegNo); +static XLogRecPtr XLogGetReplicationSlotMinimumLSN(void); + +static void AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic); +static bool XLogCheckpointNeeded(XLogSegNo new_segno); +static void XLogWrite(XLogwrtRqst WriteRqst, bool flexible); +static bool InstallXLogFileSegment(XLogSegNo *segno, char *tmppath, + bool find_free, XLogSegNo max_segno, + bool use_lock); +static int XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli, + XLogSource source, bool notfoundOk); +static int XLogFileReadAnyTLI(XLogSegNo segno, int emode, XLogSource source); +static int XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr, + int reqLen, XLogRecPtr targetRecPtr, char *readBuf); +static bool WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess, + bool fetching_ckpt, XLogRecPtr tliRecPtr); +static int emode_for_corrupt_record(int emode, XLogRecPtr RecPtr); +static void XLogFileClose(void); +static void PreallocXlogFiles(XLogRecPtr endptr); +static void RemoveTempXlogFiles(void); +static void RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr lastredoptr, XLogRecPtr endptr); +static void RemoveXlogFile(const char *segname, XLogSegNo recycleSegNo, + XLogSegNo *endlogSegNo); +static void UpdateLastRemovedPtr(char *filename); +static void ValidateXLOGDirectoryStructure(void); +static void CleanupBackupHistory(void); +static void UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force); +static XLogRecord *ReadRecord(XLogReaderState *xlogreader, + int emode, bool fetching_ckpt); +static void CheckRecoveryConsistency(void); +static XLogRecord *ReadCheckpointRecord(XLogReaderState *xlogreader, + XLogRecPtr RecPtr, int whichChkpt, bool report); +static bool rescanLatestTimeLine(void); +static void InitControlFile(uint64 sysidentifier); +static void WriteControlFile(void); +static void ReadControlFile(void); +static char *str_time(pg_time_t tnow); +static void SetPromoteIsTriggered(void); +static bool CheckForStandbyTrigger(void); + +#ifdef WAL_DEBUG +static void xlog_outrec(StringInfo buf, XLogReaderState *record); +#endif +static void xlog_block_info(StringInfo buf, XLogReaderState *record); +static void xlog_outdesc(StringInfo buf, XLogReaderState *record); +static void pg_start_backup_callback(int code, Datum arg); +static void pg_stop_backup_callback(int code, Datum arg); +static bool read_backup_label(XLogRecPtr *checkPointLoc, + bool *backupEndRequired, bool *backupFromStandby); +static bool read_tablespace_map(List **tablespaces); + +static void rm_redo_error_callback(void *arg); +static int get_sync_bit(int method); + +static void CopyXLogRecordToWAL(int write_len, bool isLogSwitch, + XLogRecData *rdata, + XLogRecPtr StartPos, XLogRecPtr EndPos); +static void ReserveXLogInsertLocation(int size, XLogRecPtr *StartPos, + XLogRecPtr *EndPos, XLogRecPtr *PrevPtr); +static bool ReserveXLogSwitch(XLogRecPtr *StartPos, XLogRecPtr *EndPos, + XLogRecPtr *PrevPtr); +static XLogRecPtr WaitXLogInsertionsToFinish(XLogRecPtr upto); +static char *GetXLogBuffer(XLogRecPtr ptr); +static XLogRecPtr XLogBytePosToRecPtr(uint64 bytepos); +static XLogRecPtr XLogBytePosToEndRecPtr(uint64 bytepos); +static uint64 XLogRecPtrToBytePos(XLogRecPtr ptr); +static void checkXLogConsistency(XLogReaderState *record); + +static void WALInsertLockAcquire(void); +static void WALInsertLockAcquireExclusive(void); +static void WALInsertLockRelease(void); +static void WALInsertLockUpdateInsertingAt(XLogRecPtr insertingAt); + +/* + * Insert an XLOG record represented by an already-constructed chain of data + * chunks. This is a low-level routine; to construct the WAL record header + * and data, use the higher-level routines in xloginsert.c. + * + * If 'fpw_lsn' is valid, it is the oldest LSN among the pages that this + * WAL record applies to, that were not included in the record as full page + * images. If fpw_lsn <= RedoRecPtr, the function does not perform the + * insertion and returns InvalidXLogRecPtr. The caller can then recalculate + * which pages need a full-page image, and retry. If fpw_lsn is invalid, the + * record is always inserted. + * + * 'flags' gives more in-depth control on the record being inserted. See + * XLogSetRecordFlags() for details. + * + * The first XLogRecData in the chain must be for the record header, and its + * data must be MAXALIGNed. XLogInsertRecord fills in the xl_prev and + * xl_crc fields in the header, the rest of the header must already be filled + * by the caller. + * + * Returns XLOG pointer to end of record (beginning of next record). + * This can be used as LSN for data pages affected by the logged action. + * (LSN is the XLOG point up to which the XLOG must be flushed to disk + * before the data page can be written out. This implements the basic + * WAL rule "write the log before the data".) + */ +XLogRecPtr +XLogInsertRecord(XLogRecData *rdata, + XLogRecPtr fpw_lsn, + uint8 flags, + int num_fpi) +{ + XLogCtlInsert *Insert = &XLogCtl->Insert; + pg_crc32c rdata_crc; + bool inserted; + XLogRecord *rechdr = (XLogRecord *) rdata->data; + uint8 info = rechdr->xl_info & ~XLR_INFO_MASK; + bool isLogSwitch = (rechdr->xl_rmid == RM_XLOG_ID && + info == XLOG_SWITCH); + XLogRecPtr StartPos; + XLogRecPtr EndPos; + bool prevDoPageWrites = doPageWrites; + + /* we assume that all of the record header is in the first chunk */ + Assert(rdata->len >= SizeOfXLogRecord); + + /* cross-check on whether we should be here or not */ + if (!XLogInsertAllowed()) + elog(ERROR, "cannot make new WAL entries during recovery"); + + /*---------- + * + * We have now done all the preparatory work we can without holding a + * lock or modifying shared state. From here on, inserting the new WAL + * record to the shared WAL buffer cache is a two-step process: + * + * 1. Reserve the right amount of space from the WAL. The current head of + * reserved space is kept in Insert->CurrBytePos, and is protected by + * insertpos_lck. + * + * 2. Copy the record to the reserved WAL space. This involves finding the + * correct WAL buffer containing the reserved space, and copying the + * record in place. This can be done concurrently in multiple processes. + * + * To keep track of which insertions are still in-progress, each concurrent + * inserter acquires an insertion lock. In addition to just indicating that + * an insertion is in progress, the lock tells others how far the inserter + * has progressed. There is a small fixed number of insertion locks, + * determined by NUM_XLOGINSERT_LOCKS. When an inserter crosses a page + * boundary, it updates the value stored in the lock to the how far it has + * inserted, to allow the previous buffer to be flushed. + * + * Holding onto an insertion lock also protects RedoRecPtr and + * fullPageWrites from changing until the insertion is finished. + * + * Step 2 can usually be done completely in parallel. If the required WAL + * page is not initialized yet, you have to grab WALBufMappingLock to + * initialize it, but the WAL writer tries to do that ahead of insertions + * to avoid that from happening in the critical path. + * + *---------- + */ + START_CRIT_SECTION(); + if (isLogSwitch) + WALInsertLockAcquireExclusive(); + else + WALInsertLockAcquire(); + + /* + * Check to see if my copy of RedoRecPtr is out of date. If so, may have + * to go back and have the caller recompute everything. This can only + * happen just after a checkpoint, so it's better to be slow in this case + * and fast otherwise. + * + * Also check to see if fullPageWrites or forcePageWrites was just turned + * on; if we weren't already doing full-page writes then go back and + * recompute. + * + * If we aren't doing full-page writes then RedoRecPtr doesn't actually + * affect the contents of the XLOG record, so we'll update our local copy + * but not force a recomputation. (If doPageWrites was just turned off, + * we could recompute the record without full pages, but we choose not to + * bother.) + */ + if (RedoRecPtr != Insert->RedoRecPtr) + { + Assert(RedoRecPtr < Insert->RedoRecPtr); + RedoRecPtr = Insert->RedoRecPtr; + } + doPageWrites = (Insert->fullPageWrites || Insert->forcePageWrites); + + if (doPageWrites && + (!prevDoPageWrites || + (fpw_lsn != InvalidXLogRecPtr && fpw_lsn <= RedoRecPtr))) + { + /* + * Oops, some buffer now needs to be backed up that the caller didn't + * back up. Start over. + */ + WALInsertLockRelease(); + END_CRIT_SECTION(); + return InvalidXLogRecPtr; + } + + /* + * Reserve space for the record in the WAL. This also sets the xl_prev + * pointer. + */ + if (isLogSwitch) + inserted = ReserveXLogSwitch(&StartPos, &EndPos, &rechdr->xl_prev); + else + { + ReserveXLogInsertLocation(rechdr->xl_tot_len, &StartPos, &EndPos, + &rechdr->xl_prev); + inserted = true; + } + + if (inserted) + { + /* + * Now that xl_prev has been filled in, calculate CRC of the record + * header. + */ + rdata_crc = rechdr->xl_crc; + COMP_CRC32C(rdata_crc, rechdr, offsetof(XLogRecord, xl_crc)); + FIN_CRC32C(rdata_crc); + rechdr->xl_crc = rdata_crc; + + /* + * All the record data, including the header, is now ready to be + * inserted. Copy the record in the space reserved. + */ + CopyXLogRecordToWAL(rechdr->xl_tot_len, isLogSwitch, rdata, + StartPos, EndPos); + + /* + * Unless record is flagged as not important, update LSN of last + * important record in the current slot. When holding all locks, just + * update the first one. + */ + if ((flags & XLOG_MARK_UNIMPORTANT) == 0) + { + int lockno = holdingAllLocks ? 0 : MyLockNo; + + WALInsertLocks[lockno].l.lastImportantAt = StartPos; + } + } + else + { + /* + * This was an xlog-switch record, but the current insert location was + * already exactly at the beginning of a segment, so there was no need + * to do anything. + */ + } + + /* + * Done! Let others know that we're finished. + */ + WALInsertLockRelease(); + + MarkCurrentTransactionIdLoggedIfAny(); + + END_CRIT_SECTION(); + + /* + * Update shared LogwrtRqst.Write, if we crossed page boundary. + */ + if (StartPos / XLOG_BLCKSZ != EndPos / XLOG_BLCKSZ) + { + SpinLockAcquire(&XLogCtl->info_lck); + /* advance global request to include new block(s) */ + if (XLogCtl->LogwrtRqst.Write < EndPos) + XLogCtl->LogwrtRqst.Write = EndPos; + /* update local result copy while I have the chance */ + LogwrtResult = XLogCtl->LogwrtResult; + SpinLockRelease(&XLogCtl->info_lck); + } + + /* + * If this was an XLOG_SWITCH record, flush the record and the empty + * padding space that fills the rest of the segment, and perform + * end-of-segment actions (eg, notifying archiver). + */ + if (isLogSwitch) + { + TRACE_POSTGRESQL_WAL_SWITCH(); + XLogFlush(EndPos); + + /* + * Even though we reserved the rest of the segment for us, which is + * reflected in EndPos, we return a pointer to just the end of the + * xlog-switch record. + */ + if (inserted) + { + EndPos = StartPos + SizeOfXLogRecord; + if (StartPos / XLOG_BLCKSZ != EndPos / XLOG_BLCKSZ) + { + uint64 offset = XLogSegmentOffset(EndPos, wal_segment_size); + + if (offset == EndPos % XLOG_BLCKSZ) + EndPos += SizeOfXLogLongPHD; + else + EndPos += SizeOfXLogShortPHD; + } + } + } + +#ifdef WAL_DEBUG + if (XLOG_DEBUG) + { + static XLogReaderState *debug_reader = NULL; + StringInfoData buf; + StringInfoData recordBuf; + char *errormsg = NULL; + MemoryContext oldCxt; + + oldCxt = MemoryContextSwitchTo(walDebugCxt); + + initStringInfo(&buf); + appendStringInfo(&buf, "INSERT @ %X/%X: ", LSN_FORMAT_ARGS(EndPos)); + + /* + * We have to piece together the WAL record data from the XLogRecData + * entries, so that we can pass it to the rm_desc function as one + * contiguous chunk. + */ + initStringInfo(&recordBuf); + for (; rdata != NULL; rdata = rdata->next) + appendBinaryStringInfo(&recordBuf, rdata->data, rdata->len); + + if (!debug_reader) + debug_reader = XLogReaderAllocate(wal_segment_size, NULL, + XL_ROUTINE(), NULL); + + if (!debug_reader) + { + appendStringInfoString(&buf, "error decoding record: out of memory"); + } + else if (!DecodeXLogRecord(debug_reader, (XLogRecord *) recordBuf.data, + &errormsg)) + { + appendStringInfo(&buf, "error decoding record: %s", + errormsg ? errormsg : "no error message"); + } + else + { + appendStringInfoString(&buf, " - "); + xlog_outdesc(&buf, debug_reader); + } + elog(LOG, "%s", buf.data); + + pfree(buf.data); + pfree(recordBuf.data); + MemoryContextSwitchTo(oldCxt); + } +#endif + + /* + * Update our global variables + */ + ProcLastRecPtr = StartPos; + XactLastRecEnd = EndPos; + + /* Report WAL traffic to the instrumentation. */ + if (inserted) + { + pgWalUsage.wal_bytes += rechdr->xl_tot_len; + pgWalUsage.wal_records++; + pgWalUsage.wal_fpi += num_fpi; + } + + return EndPos; +} + +/* + * Reserves the right amount of space for a record of given size from the WAL. + * *StartPos is set to the beginning of the reserved section, *EndPos to + * its end+1. *PrevPtr is set to the beginning of the previous record; it is + * used to set the xl_prev of this record. + * + * This is the performance critical part of XLogInsert that must be serialized + * across backends. The rest can happen mostly in parallel. Try to keep this + * section as short as possible, insertpos_lck can be heavily contended on a + * busy system. + * + * NB: The space calculation here must match the code in CopyXLogRecordToWAL, + * where we actually copy the record to the reserved space. + */ +static void +ReserveXLogInsertLocation(int size, XLogRecPtr *StartPos, XLogRecPtr *EndPos, + XLogRecPtr *PrevPtr) +{ + XLogCtlInsert *Insert = &XLogCtl->Insert; + uint64 startbytepos; + uint64 endbytepos; + uint64 prevbytepos; + + size = MAXALIGN(size); + + /* All (non xlog-switch) records should contain data. */ + Assert(size > SizeOfXLogRecord); + + /* + * The duration the spinlock needs to be held is minimized by minimizing + * the calculations that have to be done while holding the lock. The + * current tip of reserved WAL is kept in CurrBytePos, as a byte position + * that only counts "usable" bytes in WAL, that is, it excludes all WAL + * page headers. The mapping between "usable" byte positions and physical + * positions (XLogRecPtrs) can be done outside the locked region, and + * because the usable byte position doesn't include any headers, reserving + * X bytes from WAL is almost as simple as "CurrBytePos += X". + */ + SpinLockAcquire(&Insert->insertpos_lck); + + startbytepos = Insert->CurrBytePos; + endbytepos = startbytepos + size; + prevbytepos = Insert->PrevBytePos; + Insert->CurrBytePos = endbytepos; + Insert->PrevBytePos = startbytepos; + + SpinLockRelease(&Insert->insertpos_lck); + + *StartPos = XLogBytePosToRecPtr(startbytepos); + *EndPos = XLogBytePosToEndRecPtr(endbytepos); + *PrevPtr = XLogBytePosToRecPtr(prevbytepos); + + /* + * Check that the conversions between "usable byte positions" and + * XLogRecPtrs work consistently in both directions. + */ + Assert(XLogRecPtrToBytePos(*StartPos) == startbytepos); + Assert(XLogRecPtrToBytePos(*EndPos) == endbytepos); + Assert(XLogRecPtrToBytePos(*PrevPtr) == prevbytepos); +} + +/* + * Like ReserveXLogInsertLocation(), but for an xlog-switch record. + * + * A log-switch record is handled slightly differently. The rest of the + * segment will be reserved for this insertion, as indicated by the returned + * *EndPos value. However, if we are already at the beginning of the current + * segment, *StartPos and *EndPos are set to the current location without + * reserving any space, and the function returns false. +*/ +static bool +ReserveXLogSwitch(XLogRecPtr *StartPos, XLogRecPtr *EndPos, XLogRecPtr *PrevPtr) +{ + XLogCtlInsert *Insert = &XLogCtl->Insert; + uint64 startbytepos; + uint64 endbytepos; + uint64 prevbytepos; + uint32 size = MAXALIGN(SizeOfXLogRecord); + XLogRecPtr ptr; + uint32 segleft; + + /* + * These calculations are a bit heavy-weight to be done while holding a + * spinlock, but since we're holding all the WAL insertion locks, there + * are no other inserters competing for it. GetXLogInsertRecPtr() does + * compete for it, but that's not called very frequently. + */ + SpinLockAcquire(&Insert->insertpos_lck); + + startbytepos = Insert->CurrBytePos; + + ptr = XLogBytePosToEndRecPtr(startbytepos); + if (XLogSegmentOffset(ptr, wal_segment_size) == 0) + { + SpinLockRelease(&Insert->insertpos_lck); + *EndPos = *StartPos = ptr; + return false; + } + + endbytepos = startbytepos + size; + prevbytepos = Insert->PrevBytePos; + + *StartPos = XLogBytePosToRecPtr(startbytepos); + *EndPos = XLogBytePosToEndRecPtr(endbytepos); + + segleft = wal_segment_size - XLogSegmentOffset(*EndPos, wal_segment_size); + if (segleft != wal_segment_size) + { + /* consume the rest of the segment */ + *EndPos += segleft; + endbytepos = XLogRecPtrToBytePos(*EndPos); + } + Insert->CurrBytePos = endbytepos; + Insert->PrevBytePos = startbytepos; + + SpinLockRelease(&Insert->insertpos_lck); + + *PrevPtr = XLogBytePosToRecPtr(prevbytepos); + + Assert(XLogSegmentOffset(*EndPos, wal_segment_size) == 0); + Assert(XLogRecPtrToBytePos(*EndPos) == endbytepos); + Assert(XLogRecPtrToBytePos(*StartPos) == startbytepos); + Assert(XLogRecPtrToBytePos(*PrevPtr) == prevbytepos); + + return true; +} + +/* + * Checks whether the current buffer page and backup page stored in the + * WAL record are consistent or not. Before comparing the two pages, a + * masking can be applied to the pages to ignore certain areas like hint bits, + * unused space between pd_lower and pd_upper among other things. This + * function should be called once WAL replay has been completed for a + * given record. + */ +static void +checkXLogConsistency(XLogReaderState *record) +{ + RmgrId rmid = XLogRecGetRmid(record); + RelFileNode rnode; + ForkNumber forknum; + BlockNumber blkno; + int block_id; + + /* Records with no backup blocks have no need for consistency checks. */ + if (!XLogRecHasAnyBlockRefs(record)) + return; + + Assert((XLogRecGetInfo(record) & XLR_CHECK_CONSISTENCY) != 0); + + for (block_id = 0; block_id <= record->max_block_id; block_id++) + { + Buffer buf; + Page page; + + if (!XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blkno)) + { + /* + * WAL record doesn't contain a block reference with the given id. + * Do nothing. + */ + continue; + } + + Assert(XLogRecHasBlockImage(record, block_id)); + + if (XLogRecBlockImageApply(record, block_id)) + { + /* + * WAL record has already applied the page, so bypass the + * consistency check as that would result in comparing the full + * page stored in the record with itself. + */ + continue; + } + + /* + * Read the contents from the current buffer and store it in a + * temporary page. + */ + buf = XLogReadBufferExtended(rnode, forknum, blkno, + RBM_NORMAL_NO_LOG); + if (!BufferIsValid(buf)) + continue; + + LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE); + page = BufferGetPage(buf); + + /* + * Take a copy of the local page where WAL has been applied to have a + * comparison base before masking it... + */ + memcpy(replay_image_masked, page, BLCKSZ); + + /* No need for this page anymore now that a copy is in. */ + UnlockReleaseBuffer(buf); + + /* + * If the block LSN is already ahead of this WAL record, we can't + * expect contents to match. This can happen if recovery is + * restarted. + */ + if (PageGetLSN(replay_image_masked) > record->EndRecPtr) + continue; + + /* + * Read the contents from the backup copy, stored in WAL record and + * store it in a temporary page. There is no need to allocate a new + * page here, a local buffer is fine to hold its contents and a mask + * can be directly applied on it. + */ + if (!RestoreBlockImage(record, block_id, primary_image_masked)) + elog(ERROR, "failed to restore block image"); + + /* + * If masking function is defined, mask both the primary and replay + * images + */ + if (RmgrTable[rmid].rm_mask != NULL) + { + RmgrTable[rmid].rm_mask(replay_image_masked, blkno); + RmgrTable[rmid].rm_mask(primary_image_masked, blkno); + } + + /* Time to compare the primary and replay images. */ + if (memcmp(replay_image_masked, primary_image_masked, BLCKSZ) != 0) + { + elog(FATAL, + "inconsistent page found, rel %u/%u/%u, forknum %u, blkno %u", + rnode.spcNode, rnode.dbNode, rnode.relNode, + forknum, blkno); + } + } +} + +/* + * Subroutine of XLogInsertRecord. Copies a WAL record to an already-reserved + * area in the WAL. + */ +static void +CopyXLogRecordToWAL(int write_len, bool isLogSwitch, XLogRecData *rdata, + XLogRecPtr StartPos, XLogRecPtr EndPos) +{ + char *currpos; + int freespace; + int written; + XLogRecPtr CurrPos; + XLogPageHeader pagehdr; + + /* + * Get a pointer to the right place in the right WAL buffer to start + * inserting to. + */ + CurrPos = StartPos; + currpos = GetXLogBuffer(CurrPos); + freespace = INSERT_FREESPACE(CurrPos); + + /* + * there should be enough space for at least the first field (xl_tot_len) + * on this page. + */ + Assert(freespace >= sizeof(uint32)); + + /* Copy record data */ + written = 0; + while (rdata != NULL) + { + char *rdata_data = rdata->data; + int rdata_len = rdata->len; + + while (rdata_len > freespace) + { + /* + * Write what fits on this page, and continue on the next page. + */ + Assert(CurrPos % XLOG_BLCKSZ >= SizeOfXLogShortPHD || freespace == 0); + memcpy(currpos, rdata_data, freespace); + rdata_data += freespace; + rdata_len -= freespace; + written += freespace; + CurrPos += freespace; + + /* + * Get pointer to beginning of next page, and set the xlp_rem_len + * in the page header. Set XLP_FIRST_IS_CONTRECORD. + * + * It's safe to set the contrecord flag and xlp_rem_len without a + * lock on the page. All the other flags were already set when the + * page was initialized, in AdvanceXLInsertBuffer, and we're the + * only backend that needs to set the contrecord flag. + */ + currpos = GetXLogBuffer(CurrPos); + pagehdr = (XLogPageHeader) currpos; + pagehdr->xlp_rem_len = write_len - written; + pagehdr->xlp_info |= XLP_FIRST_IS_CONTRECORD; + + /* skip over the page header */ + if (XLogSegmentOffset(CurrPos, wal_segment_size) == 0) + { + CurrPos += SizeOfXLogLongPHD; + currpos += SizeOfXLogLongPHD; + } + else + { + CurrPos += SizeOfXLogShortPHD; + currpos += SizeOfXLogShortPHD; + } + freespace = INSERT_FREESPACE(CurrPos); + } + + Assert(CurrPos % XLOG_BLCKSZ >= SizeOfXLogShortPHD || rdata_len == 0); + memcpy(currpos, rdata_data, rdata_len); + currpos += rdata_len; + CurrPos += rdata_len; + freespace -= rdata_len; + written += rdata_len; + + rdata = rdata->next; + } + Assert(written == write_len); + + /* + * If this was an xlog-switch, it's not enough to write the switch record, + * we also have to consume all the remaining space in the WAL segment. We + * have already reserved that space, but we need to actually fill it. + */ + if (isLogSwitch && XLogSegmentOffset(CurrPos, wal_segment_size) != 0) + { + /* An xlog-switch record doesn't contain any data besides the header */ + Assert(write_len == SizeOfXLogRecord); + + /* Assert that we did reserve the right amount of space */ + Assert(XLogSegmentOffset(EndPos, wal_segment_size) == 0); + + /* Use up all the remaining space on the current page */ + CurrPos += freespace; + + /* + * Cause all remaining pages in the segment to be flushed, leaving the + * XLog position where it should be, at the start of the next segment. + * We do this one page at a time, to make sure we don't deadlock + * against ourselves if wal_buffers < wal_segment_size. + */ + while (CurrPos < EndPos) + { + /* + * The minimal action to flush the page would be to call + * WALInsertLockUpdateInsertingAt(CurrPos) followed by + * AdvanceXLInsertBuffer(...). The page would be left initialized + * mostly to zeros, except for the page header (always the short + * variant, as this is never a segment's first page). + * + * The large vistas of zeros are good for compressibility, but the + * headers interrupting them every XLOG_BLCKSZ (with values that + * differ from page to page) are not. The effect varies with + * compression tool, but bzip2 for instance compresses about an + * order of magnitude worse if those headers are left in place. + * + * Rather than complicating AdvanceXLInsertBuffer itself (which is + * called in heavily-loaded circumstances as well as this lightly- + * loaded one) with variant behavior, we just use GetXLogBuffer + * (which itself calls the two methods we need) to get the pointer + * and zero most of the page. Then we just zero the page header. + */ + currpos = GetXLogBuffer(CurrPos); + MemSet(currpos, 0, SizeOfXLogShortPHD); + + CurrPos += XLOG_BLCKSZ; + } + } + else + { + /* Align the end position, so that the next record starts aligned */ + CurrPos = MAXALIGN64(CurrPos); + } + + if (CurrPos != EndPos) + elog(PANIC, "space reserved for WAL record does not match what was written"); +} + +/* + * Acquire a WAL insertion lock, for inserting to WAL. + */ +static void +WALInsertLockAcquire(void) +{ + bool immed; + + /* + * It doesn't matter which of the WAL insertion locks we acquire, so try + * the one we used last time. If the system isn't particularly busy, it's + * a good bet that it's still available, and it's good to have some + * affinity to a particular lock so that you don't unnecessarily bounce + * cache lines between processes when there's no contention. + * + * If this is the first time through in this backend, pick a lock + * (semi-)randomly. This allows the locks to be used evenly if you have a + * lot of very short connections. + */ + static int lockToTry = -1; + + if (lockToTry == -1) + lockToTry = MyProc->pgprocno % NUM_XLOGINSERT_LOCKS; + MyLockNo = lockToTry; + + /* + * The insertingAt value is initially set to 0, as we don't know our + * insert location yet. + */ + immed = LWLockAcquire(&WALInsertLocks[MyLockNo].l.lock, LW_EXCLUSIVE); + if (!immed) + { + /* + * If we couldn't get the lock immediately, try another lock next + * time. On a system with more insertion locks than concurrent + * inserters, this causes all the inserters to eventually migrate to a + * lock that no-one else is using. On a system with more inserters + * than locks, it still helps to distribute the inserters evenly + * across the locks. + */ + lockToTry = (lockToTry + 1) % NUM_XLOGINSERT_LOCKS; + } +} + +/* + * Acquire all WAL insertion locks, to prevent other backends from inserting + * to WAL. + */ +static void +WALInsertLockAcquireExclusive(void) +{ + int i; + + /* + * When holding all the locks, all but the last lock's insertingAt + * indicator is set to 0xFFFFFFFFFFFFFFFF, which is higher than any real + * XLogRecPtr value, to make sure that no-one blocks waiting on those. + */ + for (i = 0; i < NUM_XLOGINSERT_LOCKS - 1; i++) + { + LWLockAcquire(&WALInsertLocks[i].l.lock, LW_EXCLUSIVE); + LWLockUpdateVar(&WALInsertLocks[i].l.lock, + &WALInsertLocks[i].l.insertingAt, + PG_UINT64_MAX); + } + /* Variable value reset to 0 at release */ + LWLockAcquire(&WALInsertLocks[i].l.lock, LW_EXCLUSIVE); + + holdingAllLocks = true; +} + +/* + * Release our insertion lock (or locks, if we're holding them all). + * + * NB: Reset all variables to 0, so they cause LWLockWaitForVar to block the + * next time the lock is acquired. + */ +static void +WALInsertLockRelease(void) +{ + if (holdingAllLocks) + { + int i; + + for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++) + LWLockReleaseClearVar(&WALInsertLocks[i].l.lock, + &WALInsertLocks[i].l.insertingAt, + 0); + + holdingAllLocks = false; + } + else + { + LWLockReleaseClearVar(&WALInsertLocks[MyLockNo].l.lock, + &WALInsertLocks[MyLockNo].l.insertingAt, + 0); + } +} + +/* + * Update our insertingAt value, to let others know that we've finished + * inserting up to that point. + */ +static void +WALInsertLockUpdateInsertingAt(XLogRecPtr insertingAt) +{ + if (holdingAllLocks) + { + /* + * We use the last lock to mark our actual position, see comments in + * WALInsertLockAcquireExclusive. + */ + LWLockUpdateVar(&WALInsertLocks[NUM_XLOGINSERT_LOCKS - 1].l.lock, + &WALInsertLocks[NUM_XLOGINSERT_LOCKS - 1].l.insertingAt, + insertingAt); + } + else + LWLockUpdateVar(&WALInsertLocks[MyLockNo].l.lock, + &WALInsertLocks[MyLockNo].l.insertingAt, + insertingAt); +} + +/* + * Wait for any WAL insertions < upto to finish. + * + * Returns the location of the oldest insertion that is still in-progress. + * Any WAL prior to that point has been fully copied into WAL buffers, and + * can be flushed out to disk. Because this waits for any insertions older + * than 'upto' to finish, the return value is always >= 'upto'. + * + * Note: When you are about to write out WAL, you must call this function + * *before* acquiring WALWriteLock, to avoid deadlocks. This function might + * need to wait for an insertion to finish (or at least advance to next + * uninitialized page), and the inserter might need to evict an old WAL buffer + * to make room for a new one, which in turn requires WALWriteLock. + */ +static XLogRecPtr +WaitXLogInsertionsToFinish(XLogRecPtr upto) +{ + uint64 bytepos; + XLogRecPtr reservedUpto; + XLogRecPtr finishedUpto; + XLogCtlInsert *Insert = &XLogCtl->Insert; + int i; + + if (MyProc == NULL) + elog(PANIC, "cannot wait without a PGPROC structure"); + + /* Read the current insert position */ + SpinLockAcquire(&Insert->insertpos_lck); + bytepos = Insert->CurrBytePos; + SpinLockRelease(&Insert->insertpos_lck); + reservedUpto = XLogBytePosToEndRecPtr(bytepos); + + /* + * No-one should request to flush a piece of WAL that hasn't even been + * reserved yet. However, it can happen if there is a block with a bogus + * LSN on disk, for example. XLogFlush checks for that situation and + * complains, but only after the flush. Here we just assume that to mean + * that all WAL that has been reserved needs to be finished. In this + * corner-case, the return value can be smaller than 'upto' argument. + */ + if (upto > reservedUpto) + { + ereport(LOG, + (errmsg("request to flush past end of generated WAL; request %X/%X, current position %X/%X", + LSN_FORMAT_ARGS(upto), LSN_FORMAT_ARGS(reservedUpto)))); + upto = reservedUpto; + } + + /* + * Loop through all the locks, sleeping on any in-progress insert older + * than 'upto'. + * + * finishedUpto is our return value, indicating the point upto which all + * the WAL insertions have been finished. Initialize it to the head of + * reserved WAL, and as we iterate through the insertion locks, back it + * out for any insertion that's still in progress. + */ + finishedUpto = reservedUpto; + for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++) + { + XLogRecPtr insertingat = InvalidXLogRecPtr; + + do + { + /* + * See if this insertion is in progress. LWLockWaitForVar will + * wait for the lock to be released, or for the 'value' to be set + * by a LWLockUpdateVar call. When a lock is initially acquired, + * its value is 0 (InvalidXLogRecPtr), which means that we don't + * know where it's inserting yet. We will have to wait for it. If + * it's a small insertion, the record will most likely fit on the + * same page and the inserter will release the lock without ever + * calling LWLockUpdateVar. But if it has to sleep, it will + * advertise the insertion point with LWLockUpdateVar before + * sleeping. + */ + if (LWLockWaitForVar(&WALInsertLocks[i].l.lock, + &WALInsertLocks[i].l.insertingAt, + insertingat, &insertingat)) + { + /* the lock was free, so no insertion in progress */ + insertingat = InvalidXLogRecPtr; + break; + } + + /* + * This insertion is still in progress. Have to wait, unless the + * inserter has proceeded past 'upto'. + */ + } while (insertingat < upto); + + if (insertingat != InvalidXLogRecPtr && insertingat < finishedUpto) + finishedUpto = insertingat; + } + return finishedUpto; +} + +/* + * Get a pointer to the right location in the WAL buffer containing the + * given XLogRecPtr. + * + * If the page is not initialized yet, it is initialized. That might require + * evicting an old dirty buffer from the buffer cache, which means I/O. + * + * The caller must ensure that the page containing the requested location + * isn't evicted yet, and won't be evicted. The way to ensure that is to + * hold onto a WAL insertion lock with the insertingAt position set to + * something <= ptr. GetXLogBuffer() will update insertingAt if it needs + * to evict an old page from the buffer. (This means that once you call + * GetXLogBuffer() with a given 'ptr', you must not access anything before + * that point anymore, and must not call GetXLogBuffer() with an older 'ptr' + * later, because older buffers might be recycled already) + */ +static char * +GetXLogBuffer(XLogRecPtr ptr) +{ + int idx; + XLogRecPtr endptr; + static uint64 cachedPage = 0; + static char *cachedPos = NULL; + XLogRecPtr expectedEndPtr; + + /* + * Fast path for the common case that we need to access again the same + * page as last time. + */ + if (ptr / XLOG_BLCKSZ == cachedPage) + { + Assert(((XLogPageHeader) cachedPos)->xlp_magic == XLOG_PAGE_MAGIC); + Assert(((XLogPageHeader) cachedPos)->xlp_pageaddr == ptr - (ptr % XLOG_BLCKSZ)); + return cachedPos + ptr % XLOG_BLCKSZ; + } + + /* + * The XLog buffer cache is organized so that a page is always loaded to a + * particular buffer. That way we can easily calculate the buffer a given + * page must be loaded into, from the XLogRecPtr alone. + */ + idx = XLogRecPtrToBufIdx(ptr); + + /* + * See what page is loaded in the buffer at the moment. It could be the + * page we're looking for, or something older. It can't be anything newer + * - that would imply the page we're looking for has already been written + * out to disk and evicted, and the caller is responsible for making sure + * that doesn't happen. + * + * However, we don't hold a lock while we read the value. If someone has + * just initialized the page, it's possible that we get a "torn read" of + * the XLogRecPtr if 64-bit fetches are not atomic on this platform. In + * that case we will see a bogus value. That's ok, we'll grab the mapping + * lock (in AdvanceXLInsertBuffer) and retry if we see anything else than + * the page we're looking for. But it means that when we do this unlocked + * read, we might see a value that appears to be ahead of the page we're + * looking for. Don't PANIC on that, until we've verified the value while + * holding the lock. + */ + expectedEndPtr = ptr; + expectedEndPtr += XLOG_BLCKSZ - ptr % XLOG_BLCKSZ; + + endptr = XLogCtl->xlblocks[idx]; + if (expectedEndPtr != endptr) + { + XLogRecPtr initializedUpto; + + /* + * Before calling AdvanceXLInsertBuffer(), which can block, let others + * know how far we're finished with inserting the record. + * + * NB: If 'ptr' points to just after the page header, advertise a + * position at the beginning of the page rather than 'ptr' itself. If + * there are no other insertions running, someone might try to flush + * up to our advertised location. If we advertised a position after + * the page header, someone might try to flush the page header, even + * though page might actually not be initialized yet. As the first + * inserter on the page, we are effectively responsible for making + * sure that it's initialized, before we let insertingAt to move past + * the page header. + */ + if (ptr % XLOG_BLCKSZ == SizeOfXLogShortPHD && + XLogSegmentOffset(ptr, wal_segment_size) > XLOG_BLCKSZ) + initializedUpto = ptr - SizeOfXLogShortPHD; + else if (ptr % XLOG_BLCKSZ == SizeOfXLogLongPHD && + XLogSegmentOffset(ptr, wal_segment_size) < XLOG_BLCKSZ) + initializedUpto = ptr - SizeOfXLogLongPHD; + else + initializedUpto = ptr; + + WALInsertLockUpdateInsertingAt(initializedUpto); + + AdvanceXLInsertBuffer(ptr, false); + endptr = XLogCtl->xlblocks[idx]; + + if (expectedEndPtr != endptr) + elog(PANIC, "could not find WAL buffer for %X/%X", + LSN_FORMAT_ARGS(ptr)); + } + else + { + /* + * Make sure the initialization of the page is visible to us, and + * won't arrive later to overwrite the WAL data we write on the page. + */ + pg_memory_barrier(); + } + + /* + * Found the buffer holding this page. Return a pointer to the right + * offset within the page. + */ + cachedPage = ptr / XLOG_BLCKSZ; + cachedPos = XLogCtl->pages + idx * (Size) XLOG_BLCKSZ; + + Assert(((XLogPageHeader) cachedPos)->xlp_magic == XLOG_PAGE_MAGIC); + Assert(((XLogPageHeader) cachedPos)->xlp_pageaddr == ptr - (ptr % XLOG_BLCKSZ)); + + return cachedPos + ptr % XLOG_BLCKSZ; +} + +/* + * Converts a "usable byte position" to XLogRecPtr. A usable byte position + * is the position starting from the beginning of WAL, excluding all WAL + * page headers. + */ +static XLogRecPtr +XLogBytePosToRecPtr(uint64 bytepos) +{ + uint64 fullsegs; + uint64 fullpages; + uint64 bytesleft; + uint32 seg_offset; + XLogRecPtr result; + + fullsegs = bytepos / UsableBytesInSegment; + bytesleft = bytepos % UsableBytesInSegment; + + if (bytesleft < XLOG_BLCKSZ - SizeOfXLogLongPHD) + { + /* fits on first page of segment */ + seg_offset = bytesleft + SizeOfXLogLongPHD; + } + else + { + /* account for the first page on segment with long header */ + seg_offset = XLOG_BLCKSZ; + bytesleft -= XLOG_BLCKSZ - SizeOfXLogLongPHD; + + fullpages = bytesleft / UsableBytesInPage; + bytesleft = bytesleft % UsableBytesInPage; + + seg_offset += fullpages * XLOG_BLCKSZ + bytesleft + SizeOfXLogShortPHD; + } + + XLogSegNoOffsetToRecPtr(fullsegs, seg_offset, wal_segment_size, result); + + return result; +} + +/* + * Like XLogBytePosToRecPtr, but if the position is at a page boundary, + * returns a pointer to the beginning of the page (ie. before page header), + * not to where the first xlog record on that page would go to. This is used + * when converting a pointer to the end of a record. + */ +static XLogRecPtr +XLogBytePosToEndRecPtr(uint64 bytepos) +{ + uint64 fullsegs; + uint64 fullpages; + uint64 bytesleft; + uint32 seg_offset; + XLogRecPtr result; + + fullsegs = bytepos / UsableBytesInSegment; + bytesleft = bytepos % UsableBytesInSegment; + + if (bytesleft < XLOG_BLCKSZ - SizeOfXLogLongPHD) + { + /* fits on first page of segment */ + if (bytesleft == 0) + seg_offset = 0; + else + seg_offset = bytesleft + SizeOfXLogLongPHD; + } + else + { + /* account for the first page on segment with long header */ + seg_offset = XLOG_BLCKSZ; + bytesleft -= XLOG_BLCKSZ - SizeOfXLogLongPHD; + + fullpages = bytesleft / UsableBytesInPage; + bytesleft = bytesleft % UsableBytesInPage; + + if (bytesleft == 0) + seg_offset += fullpages * XLOG_BLCKSZ + bytesleft; + else + seg_offset += fullpages * XLOG_BLCKSZ + bytesleft + SizeOfXLogShortPHD; + } + + XLogSegNoOffsetToRecPtr(fullsegs, seg_offset, wal_segment_size, result); + + return result; +} + +/* + * Convert an XLogRecPtr to a "usable byte position". + */ +static uint64 +XLogRecPtrToBytePos(XLogRecPtr ptr) +{ + uint64 fullsegs; + uint32 fullpages; + uint32 offset; + uint64 result; + + XLByteToSeg(ptr, fullsegs, wal_segment_size); + + fullpages = (XLogSegmentOffset(ptr, wal_segment_size)) / XLOG_BLCKSZ; + offset = ptr % XLOG_BLCKSZ; + + if (fullpages == 0) + { + result = fullsegs * UsableBytesInSegment; + if (offset > 0) + { + Assert(offset >= SizeOfXLogLongPHD); + result += offset - SizeOfXLogLongPHD; + } + } + else + { + result = fullsegs * UsableBytesInSegment + + (XLOG_BLCKSZ - SizeOfXLogLongPHD) + /* account for first page */ + (fullpages - 1) * UsableBytesInPage; /* full pages */ + if (offset > 0) + { + Assert(offset >= SizeOfXLogShortPHD); + result += offset - SizeOfXLogShortPHD; + } + } + + return result; +} + +/* + * Initialize XLOG buffers, writing out old buffers if they still contain + * unwritten data, upto the page containing 'upto'. Or if 'opportunistic' is + * true, initialize as many pages as we can without having to write out + * unwritten data. Any new pages are initialized to zeros, with pages headers + * initialized properly. + */ +static void +AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic) +{ + XLogCtlInsert *Insert = &XLogCtl->Insert; + int nextidx; + XLogRecPtr OldPageRqstPtr; + XLogwrtRqst WriteRqst; + XLogRecPtr NewPageEndPtr = InvalidXLogRecPtr; + XLogRecPtr NewPageBeginPtr; + XLogPageHeader NewPage; + int npages = 0; + + LWLockAcquire(WALBufMappingLock, LW_EXCLUSIVE); + + /* + * Now that we have the lock, check if someone initialized the page + * already. + */ + while (upto >= XLogCtl->InitializedUpTo || opportunistic) + { + nextidx = XLogRecPtrToBufIdx(XLogCtl->InitializedUpTo); + + /* + * Get ending-offset of the buffer page we need to replace (this may + * be zero if the buffer hasn't been used yet). Fall through if it's + * already written out. + */ + OldPageRqstPtr = XLogCtl->xlblocks[nextidx]; + if (LogwrtResult.Write < OldPageRqstPtr) + { + /* + * Nope, got work to do. If we just want to pre-initialize as much + * as we can without flushing, give up now. + */ + if (opportunistic) + break; + + /* Before waiting, get info_lck and update LogwrtResult */ + SpinLockAcquire(&XLogCtl->info_lck); + if (XLogCtl->LogwrtRqst.Write < OldPageRqstPtr) + XLogCtl->LogwrtRqst.Write = OldPageRqstPtr; + LogwrtResult = XLogCtl->LogwrtResult; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * Now that we have an up-to-date LogwrtResult value, see if we + * still need to write it or if someone else already did. + */ + if (LogwrtResult.Write < OldPageRqstPtr) + { + /* + * Must acquire write lock. Release WALBufMappingLock first, + * to make sure that all insertions that we need to wait for + * can finish (up to this same position). Otherwise we risk + * deadlock. + */ + LWLockRelease(WALBufMappingLock); + + WaitXLogInsertionsToFinish(OldPageRqstPtr); + + LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); + + LogwrtResult = XLogCtl->LogwrtResult; + if (LogwrtResult.Write >= OldPageRqstPtr) + { + /* OK, someone wrote it already */ + LWLockRelease(WALWriteLock); + } + else + { + /* Have to write it ourselves */ + TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_START(); + WriteRqst.Write = OldPageRqstPtr; + WriteRqst.Flush = 0; + XLogWrite(WriteRqst, false); + LWLockRelease(WALWriteLock); + WalStats.m_wal_buffers_full++; + TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_DONE(); + } + /* Re-acquire WALBufMappingLock and retry */ + LWLockAcquire(WALBufMappingLock, LW_EXCLUSIVE); + continue; + } + } + + /* + * Now the next buffer slot is free and we can set it up to be the + * next output page. + */ + NewPageBeginPtr = XLogCtl->InitializedUpTo; + NewPageEndPtr = NewPageBeginPtr + XLOG_BLCKSZ; + + Assert(XLogRecPtrToBufIdx(NewPageBeginPtr) == nextidx); + + NewPage = (XLogPageHeader) (XLogCtl->pages + nextidx * (Size) XLOG_BLCKSZ); + + /* + * Be sure to re-zero the buffer so that bytes beyond what we've + * written will look like zeroes and not valid XLOG records... + */ + MemSet((char *) NewPage, 0, XLOG_BLCKSZ); + + /* + * Fill the new page's header + */ + NewPage->xlp_magic = XLOG_PAGE_MAGIC; + + /* NewPage->xlp_info = 0; */ /* done by memset */ + NewPage->xlp_tli = ThisTimeLineID; + NewPage->xlp_pageaddr = NewPageBeginPtr; + + /* NewPage->xlp_rem_len = 0; */ /* done by memset */ + + /* + * If online backup is not in progress, mark the header to indicate + * that WAL records beginning in this page have removable backup + * blocks. This allows the WAL archiver to know whether it is safe to + * compress archived WAL data by transforming full-block records into + * the non-full-block format. It is sufficient to record this at the + * page level because we force a page switch (in fact a segment + * switch) when starting a backup, so the flag will be off before any + * records can be written during the backup. At the end of a backup, + * the last page will be marked as all unsafe when perhaps only part + * is unsafe, but at worst the archiver would miss the opportunity to + * compress a few records. + */ + if (!Insert->forcePageWrites) + NewPage->xlp_info |= XLP_BKP_REMOVABLE; + + /* + * If a record was found to be broken at the end of recovery, and + * we're going to write on the page where its first contrecord was + * lost, set the XLP_FIRST_IS_OVERWRITE_CONTRECORD flag on the page + * header. See CreateOverwriteContrecordRecord(). + */ + if (missingContrecPtr == NewPageBeginPtr) + { + NewPage->xlp_info |= XLP_FIRST_IS_OVERWRITE_CONTRECORD; + missingContrecPtr = InvalidXLogRecPtr; + } + + /* + * If first page of an XLOG segment file, make it a long header. + */ + if ((XLogSegmentOffset(NewPage->xlp_pageaddr, wal_segment_size)) == 0) + { + XLogLongPageHeader NewLongPage = (XLogLongPageHeader) NewPage; + + NewLongPage->xlp_sysid = ControlFile->system_identifier; + NewLongPage->xlp_seg_size = wal_segment_size; + NewLongPage->xlp_xlog_blcksz = XLOG_BLCKSZ; + NewPage->xlp_info |= XLP_LONG_HEADER; + } + + /* + * Make sure the initialization of the page becomes visible to others + * before the xlblocks update. GetXLogBuffer() reads xlblocks without + * holding a lock. + */ + pg_write_barrier(); + + *((volatile XLogRecPtr *) &XLogCtl->xlblocks[nextidx]) = NewPageEndPtr; + + XLogCtl->InitializedUpTo = NewPageEndPtr; + + npages++; + } + LWLockRelease(WALBufMappingLock); + +#ifdef WAL_DEBUG + if (XLOG_DEBUG && npages > 0) + { + elog(DEBUG1, "initialized %d pages, up to %X/%X", + npages, LSN_FORMAT_ARGS(NewPageEndPtr)); + } +#endif +} + +/* + * Calculate CheckPointSegments based on max_wal_size_mb and + * checkpoint_completion_target. + */ +static void +CalculateCheckpointSegments(void) +{ + double target; + + /*------- + * Calculate the distance at which to trigger a checkpoint, to avoid + * exceeding max_wal_size_mb. This is based on two assumptions: + * + * a) we keep WAL for only one checkpoint cycle (prior to PG11 we kept + * WAL for two checkpoint cycles to allow us to recover from the + * secondary checkpoint if the first checkpoint failed, though we + * only did this on the primary anyway, not on standby. Keeping just + * one checkpoint simplifies processing and reduces disk space in + * many smaller databases.) + * b) during checkpoint, we consume checkpoint_completion_target * + * number of segments consumed between checkpoints. + *------- + */ + target = (double) ConvertToXSegs(max_wal_size_mb, wal_segment_size) / + (1.0 + CheckPointCompletionTarget); + + /* round down */ + CheckPointSegments = (int) target; + + if (CheckPointSegments < 1) + CheckPointSegments = 1; +} + +void +assign_max_wal_size(int newval, void *extra) +{ + max_wal_size_mb = newval; + CalculateCheckpointSegments(); +} + +void +assign_checkpoint_completion_target(double newval, void *extra) +{ + CheckPointCompletionTarget = newval; + CalculateCheckpointSegments(); +} + +/* + * At a checkpoint, how many WAL segments to recycle as preallocated future + * XLOG segments? Returns the highest segment that should be preallocated. + */ +static XLogSegNo +XLOGfileslop(XLogRecPtr lastredoptr) +{ + XLogSegNo minSegNo; + XLogSegNo maxSegNo; + double distance; + XLogSegNo recycleSegNo; + + /* + * Calculate the segment numbers that min_wal_size_mb and max_wal_size_mb + * correspond to. Always recycle enough segments to meet the minimum, and + * remove enough segments to stay below the maximum. + */ + minSegNo = lastredoptr / wal_segment_size + + ConvertToXSegs(min_wal_size_mb, wal_segment_size) - 1; + maxSegNo = lastredoptr / wal_segment_size + + ConvertToXSegs(max_wal_size_mb, wal_segment_size) - 1; + + /* + * Between those limits, recycle enough segments to get us through to the + * estimated end of next checkpoint. + * + * To estimate where the next checkpoint will finish, assume that the + * system runs steadily consuming CheckPointDistanceEstimate bytes between + * every checkpoint. + */ + distance = (1.0 + CheckPointCompletionTarget) * CheckPointDistanceEstimate; + /* add 10% for good measure. */ + distance *= 1.10; + + recycleSegNo = (XLogSegNo) ceil(((double) lastredoptr + distance) / + wal_segment_size); + + if (recycleSegNo < minSegNo) + recycleSegNo = minSegNo; + if (recycleSegNo > maxSegNo) + recycleSegNo = maxSegNo; + + return recycleSegNo; +} + +/* + * Check whether we've consumed enough xlog space that a checkpoint is needed. + * + * new_segno indicates a log file that has just been filled up (or read + * during recovery). We measure the distance from RedoRecPtr to new_segno + * and see if that exceeds CheckPointSegments. + * + * Note: it is caller's responsibility that RedoRecPtr is up-to-date. + */ +static bool +XLogCheckpointNeeded(XLogSegNo new_segno) +{ + XLogSegNo old_segno; + + XLByteToSeg(RedoRecPtr, old_segno, wal_segment_size); + + if (new_segno >= old_segno + (uint64) (CheckPointSegments - 1)) + return true; + return false; +} + +/* + * Write and/or fsync the log at least as far as WriteRqst indicates. + * + * If flexible == true, we don't have to write as far as WriteRqst, but + * may stop at any convenient boundary (such as a cache or logfile boundary). + * This option allows us to avoid uselessly issuing multiple writes when a + * single one would do. + * + * Must be called with WALWriteLock held. WaitXLogInsertionsToFinish(WriteRqst) + * must be called before grabbing the lock, to make sure the data is ready to + * write. + */ +static void +XLogWrite(XLogwrtRqst WriteRqst, bool flexible) +{ + bool ispartialpage; + bool last_iteration; + bool finishing_seg; + bool use_existent; + int curridx; + int npages; + int startidx; + uint32 startoffset; + + /* We should always be inside a critical section here */ + Assert(CritSectionCount > 0); + + /* + * Update local LogwrtResult (caller probably did this already, but...) + */ + LogwrtResult = XLogCtl->LogwrtResult; + + /* + * Since successive pages in the xlog cache are consecutively allocated, + * we can usually gather multiple pages together and issue just one + * write() call. npages is the number of pages we have determined can be + * written together; startidx is the cache block index of the first one, + * and startoffset is the file offset at which it should go. The latter + * two variables are only valid when npages > 0, but we must initialize + * all of them to keep the compiler quiet. + */ + npages = 0; + startidx = 0; + startoffset = 0; + + /* + * Within the loop, curridx is the cache block index of the page to + * consider writing. Begin at the buffer containing the next unwritten + * page, or last partially written page. + */ + curridx = XLogRecPtrToBufIdx(LogwrtResult.Write); + + while (LogwrtResult.Write < WriteRqst.Write) + { + /* + * Make sure we're not ahead of the insert process. This could happen + * if we're passed a bogus WriteRqst.Write that is past the end of the + * last page that's been initialized by AdvanceXLInsertBuffer. + */ + XLogRecPtr EndPtr = XLogCtl->xlblocks[curridx]; + + if (LogwrtResult.Write >= EndPtr) + elog(PANIC, "xlog write request %X/%X is past end of log %X/%X", + LSN_FORMAT_ARGS(LogwrtResult.Write), + LSN_FORMAT_ARGS(EndPtr)); + + /* Advance LogwrtResult.Write to end of current buffer page */ + LogwrtResult.Write = EndPtr; + ispartialpage = WriteRqst.Write < LogwrtResult.Write; + + if (!XLByteInPrevSeg(LogwrtResult.Write, openLogSegNo, + wal_segment_size)) + { + /* + * Switch to new logfile segment. We cannot have any pending + * pages here (since we dump what we have at segment end). + */ + Assert(npages == 0); + if (openLogFile >= 0) + XLogFileClose(); + XLByteToPrevSeg(LogwrtResult.Write, openLogSegNo, + wal_segment_size); + + /* create/use new log file */ + use_existent = true; + openLogFile = XLogFileInit(openLogSegNo, &use_existent, true); + ReserveExternalFD(); + } + + /* Make sure we have the current logfile open */ + if (openLogFile < 0) + { + XLByteToPrevSeg(LogwrtResult.Write, openLogSegNo, + wal_segment_size); + openLogFile = XLogFileOpen(openLogSegNo); + ReserveExternalFD(); + } + + /* Add current page to the set of pending pages-to-dump */ + if (npages == 0) + { + /* first of group */ + startidx = curridx; + startoffset = XLogSegmentOffset(LogwrtResult.Write - XLOG_BLCKSZ, + wal_segment_size); + } + npages++; + + /* + * Dump the set if this will be the last loop iteration, or if we are + * at the last page of the cache area (since the next page won't be + * contiguous in memory), or if we are at the end of the logfile + * segment. + */ + last_iteration = WriteRqst.Write <= LogwrtResult.Write; + + finishing_seg = !ispartialpage && + (startoffset + npages * XLOG_BLCKSZ) >= wal_segment_size; + + if (last_iteration || + curridx == XLogCtl->XLogCacheBlck || + finishing_seg) + { + char *from; + Size nbytes; + Size nleft; + int written; + instr_time start; + + /* OK to write the page(s) */ + from = XLogCtl->pages + startidx * (Size) XLOG_BLCKSZ; + nbytes = npages * (Size) XLOG_BLCKSZ; + nleft = nbytes; + do + { + errno = 0; + + /* Measure I/O timing to write WAL data */ + if (track_wal_io_timing) + INSTR_TIME_SET_CURRENT(start); + + pgstat_report_wait_start(WAIT_EVENT_WAL_WRITE); + written = pg_pwrite(openLogFile, from, nleft, startoffset); + pgstat_report_wait_end(); + + /* + * Increment the I/O timing and the number of times WAL data + * were written out to disk. + */ + if (track_wal_io_timing) + { + instr_time duration; + + INSTR_TIME_SET_CURRENT(duration); + INSTR_TIME_SUBTRACT(duration, start); + WalStats.m_wal_write_time += INSTR_TIME_GET_MICROSEC(duration); + } + + WalStats.m_wal_write++; + + if (written <= 0) + { + char xlogfname[MAXFNAMELEN]; + int save_errno; + + if (errno == EINTR) + continue; + + save_errno = errno; + XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo, + wal_segment_size); + errno = save_errno; + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not write to log file %s " + "at offset %u, length %zu: %m", + xlogfname, startoffset, nleft))); + } + nleft -= written; + from += written; + startoffset += written; + } while (nleft > 0); + + npages = 0; + + /* + * If we just wrote the whole last page of a logfile segment, + * fsync the segment immediately. This avoids having to go back + * and re-open prior segments when an fsync request comes along + * later. Doing it here ensures that one and only one backend will + * perform this fsync. + * + * This is also the right place to notify the Archiver that the + * segment is ready to copy to archival storage, and to update the + * timer for archive_timeout, and to signal for a checkpoint if + * too many logfile segments have been used since the last + * checkpoint. + */ + if (finishing_seg) + { + issue_xlog_fsync(openLogFile, openLogSegNo); + + /* signal that we need to wakeup walsenders later */ + WalSndWakeupRequest(); + + LogwrtResult.Flush = LogwrtResult.Write; /* end of page */ + + if (XLogArchivingActive()) + XLogArchiveNotifySeg(openLogSegNo); + + XLogCtl->lastSegSwitchTime = (pg_time_t) time(NULL); + XLogCtl->lastSegSwitchLSN = LogwrtResult.Flush; + + /* + * Request a checkpoint if we've consumed too much xlog since + * the last one. For speed, we first check using the local + * copy of RedoRecPtr, which might be out of date; if it looks + * like a checkpoint is needed, forcibly update RedoRecPtr and + * recheck. + */ + if (IsUnderPostmaster && XLogCheckpointNeeded(openLogSegNo)) + { + (void) GetRedoRecPtr(); + if (XLogCheckpointNeeded(openLogSegNo)) + RequestCheckpoint(CHECKPOINT_CAUSE_XLOG); + } + } + } + + if (ispartialpage) + { + /* Only asked to write a partial page */ + LogwrtResult.Write = WriteRqst.Write; + break; + } + curridx = NextBufIdx(curridx); + + /* If flexible, break out of loop as soon as we wrote something */ + if (flexible && npages == 0) + break; + } + + Assert(npages == 0); + + /* + * If asked to flush, do so + */ + if (LogwrtResult.Flush < WriteRqst.Flush && + LogwrtResult.Flush < LogwrtResult.Write) + + { + /* + * Could get here without iterating above loop, in which case we might + * have no open file or the wrong one. However, we do not need to + * fsync more than one file. + */ + if (sync_method != SYNC_METHOD_OPEN && + sync_method != SYNC_METHOD_OPEN_DSYNC) + { + if (openLogFile >= 0 && + !XLByteInPrevSeg(LogwrtResult.Write, openLogSegNo, + wal_segment_size)) + XLogFileClose(); + if (openLogFile < 0) + { + XLByteToPrevSeg(LogwrtResult.Write, openLogSegNo, + wal_segment_size); + openLogFile = XLogFileOpen(openLogSegNo); + ReserveExternalFD(); + } + + issue_xlog_fsync(openLogFile, openLogSegNo); + } + + /* signal that we need to wakeup walsenders later */ + WalSndWakeupRequest(); + + LogwrtResult.Flush = LogwrtResult.Write; + } + + /* + * Update shared-memory status + * + * We make sure that the shared 'request' values do not fall behind the + * 'result' values. This is not absolutely essential, but it saves some + * code in a couple of places. + */ + { + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->LogwrtResult = LogwrtResult; + if (XLogCtl->LogwrtRqst.Write < LogwrtResult.Write) + XLogCtl->LogwrtRqst.Write = LogwrtResult.Write; + if (XLogCtl->LogwrtRqst.Flush < LogwrtResult.Flush) + XLogCtl->LogwrtRqst.Flush = LogwrtResult.Flush; + SpinLockRelease(&XLogCtl->info_lck); + } +} + +/* + * Record the LSN for an asynchronous transaction commit/abort + * and nudge the WALWriter if there is work for it to do. + * (This should not be called for synchronous commits.) + */ +void +XLogSetAsyncXactLSN(XLogRecPtr asyncXactLSN) +{ + XLogRecPtr WriteRqstPtr = asyncXactLSN; + bool sleeping; + + SpinLockAcquire(&XLogCtl->info_lck); + LogwrtResult = XLogCtl->LogwrtResult; + sleeping = XLogCtl->WalWriterSleeping; + if (XLogCtl->asyncXactLSN < asyncXactLSN) + XLogCtl->asyncXactLSN = asyncXactLSN; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * If the WALWriter is sleeping, we should kick it to make it come out of + * low-power mode. Otherwise, determine whether there's a full page of + * WAL available to write. + */ + if (!sleeping) + { + /* back off to last completed page boundary */ + WriteRqstPtr -= WriteRqstPtr % XLOG_BLCKSZ; + + /* if we have already flushed that far, we're done */ + if (WriteRqstPtr <= LogwrtResult.Flush) + return; + } + + /* + * Nudge the WALWriter: it has a full page of WAL to write, or we want it + * to come out of low-power mode so that this async commit will reach disk + * within the expected amount of time. + */ + if (ProcGlobal->walwriterLatch) + SetLatch(ProcGlobal->walwriterLatch); +} + +/* + * Record the LSN up to which we can remove WAL because it's not required by + * any replication slot. + */ +void +XLogSetReplicationSlotMinimumLSN(XLogRecPtr lsn) +{ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->replicationSlotMinLSN = lsn; + SpinLockRelease(&XLogCtl->info_lck); +} + + +/* + * Return the oldest LSN we must retain to satisfy the needs of some + * replication slot. + */ +static XLogRecPtr +XLogGetReplicationSlotMinimumLSN(void) +{ + XLogRecPtr retval; + + SpinLockAcquire(&XLogCtl->info_lck); + retval = XLogCtl->replicationSlotMinLSN; + SpinLockRelease(&XLogCtl->info_lck); + + return retval; +} + +/* + * Advance minRecoveryPoint in control file. + * + * If we crash during recovery, we must reach this point again before the + * database is consistent. + * + * If 'force' is true, 'lsn' argument is ignored. Otherwise, minRecoveryPoint + * is only updated if it's not already greater than or equal to 'lsn'. + */ +static void +UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force) +{ + /* Quick check using our local copy of the variable */ + if (!updateMinRecoveryPoint || (!force && lsn <= minRecoveryPoint)) + return; + + /* + * An invalid minRecoveryPoint means that we need to recover all the WAL, + * i.e., we're doing crash recovery. We never modify the control file's + * value in that case, so we can short-circuit future checks here too. The + * local values of minRecoveryPoint and minRecoveryPointTLI should not be + * updated until crash recovery finishes. We only do this for the startup + * process as it should not update its own reference of minRecoveryPoint + * until it has finished crash recovery to make sure that all WAL + * available is replayed in this case. This also saves from extra locks + * taken on the control file from the startup process. + */ + if (XLogRecPtrIsInvalid(minRecoveryPoint) && InRecovery) + { + updateMinRecoveryPoint = false; + return; + } + + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + + /* update local copy */ + minRecoveryPoint = ControlFile->minRecoveryPoint; + minRecoveryPointTLI = ControlFile->minRecoveryPointTLI; + + if (XLogRecPtrIsInvalid(minRecoveryPoint)) + updateMinRecoveryPoint = false; + else if (force || minRecoveryPoint < lsn) + { + XLogRecPtr newMinRecoveryPoint; + TimeLineID newMinRecoveryPointTLI; + + /* + * To avoid having to update the control file too often, we update it + * all the way to the last record being replayed, even though 'lsn' + * would suffice for correctness. This also allows the 'force' case + * to not need a valid 'lsn' value. + * + * Another important reason for doing it this way is that the passed + * 'lsn' value could be bogus, i.e., past the end of available WAL, if + * the caller got it from a corrupted heap page. Accepting such a + * value as the min recovery point would prevent us from coming up at + * all. Instead, we just log a warning and continue with recovery. + * (See also the comments about corrupt LSNs in XLogFlush.) + */ + SpinLockAcquire(&XLogCtl->info_lck); + newMinRecoveryPoint = XLogCtl->replayEndRecPtr; + newMinRecoveryPointTLI = XLogCtl->replayEndTLI; + SpinLockRelease(&XLogCtl->info_lck); + + if (!force && newMinRecoveryPoint < lsn) + elog(WARNING, + "xlog min recovery request %X/%X is past current point %X/%X", + LSN_FORMAT_ARGS(lsn), LSN_FORMAT_ARGS(newMinRecoveryPoint)); + + /* update control file */ + if (ControlFile->minRecoveryPoint < newMinRecoveryPoint) + { + ControlFile->minRecoveryPoint = newMinRecoveryPoint; + ControlFile->minRecoveryPointTLI = newMinRecoveryPointTLI; + UpdateControlFile(); + minRecoveryPoint = newMinRecoveryPoint; + minRecoveryPointTLI = newMinRecoveryPointTLI; + + ereport(DEBUG2, + (errmsg_internal("updated min recovery point to %X/%X on timeline %u", + LSN_FORMAT_ARGS(minRecoveryPoint), + newMinRecoveryPointTLI))); + } + } + LWLockRelease(ControlFileLock); +} + +/* + * Ensure that all XLOG data through the given position is flushed to disk. + * + * NOTE: this differs from XLogWrite mainly in that the WALWriteLock is not + * already held, and we try to avoid acquiring it if possible. + */ +void +XLogFlush(XLogRecPtr record) +{ + XLogRecPtr WriteRqstPtr; + XLogwrtRqst WriteRqst; + + /* + * During REDO, we are reading not writing WAL. Therefore, instead of + * trying to flush the WAL, we should update minRecoveryPoint instead. We + * test XLogInsertAllowed(), not InRecovery, because we need checkpointer + * to act this way too, and because when it tries to write the + * end-of-recovery checkpoint, it should indeed flush. + */ + if (!XLogInsertAllowed()) + { + UpdateMinRecoveryPoint(record, false); + return; + } + + /* Quick exit if already known flushed */ + if (record <= LogwrtResult.Flush) + return; + +#ifdef WAL_DEBUG + if (XLOG_DEBUG) + elog(LOG, "xlog flush request %X/%X; write %X/%X; flush %X/%X", + LSN_FORMAT_ARGS(record), + LSN_FORMAT_ARGS(LogwrtResult.Write), + LSN_FORMAT_ARGS(LogwrtResult.Flush)); +#endif + + START_CRIT_SECTION(); + + /* + * Since fsync is usually a horribly expensive operation, we try to + * piggyback as much data as we can on each fsync: if we see any more data + * entered into the xlog buffer, we'll write and fsync that too, so that + * the final value of LogwrtResult.Flush is as large as possible. This + * gives us some chance of avoiding another fsync immediately after. + */ + + /* initialize to given target; may increase below */ + WriteRqstPtr = record; + + /* + * Now wait until we get the write lock, or someone else does the flush + * for us. + */ + for (;;) + { + XLogRecPtr insertpos; + + /* read LogwrtResult and update local state */ + SpinLockAcquire(&XLogCtl->info_lck); + if (WriteRqstPtr < XLogCtl->LogwrtRqst.Write) + WriteRqstPtr = XLogCtl->LogwrtRqst.Write; + LogwrtResult = XLogCtl->LogwrtResult; + SpinLockRelease(&XLogCtl->info_lck); + + /* done already? */ + if (record <= LogwrtResult.Flush) + break; + + /* + * Before actually performing the write, wait for all in-flight + * insertions to the pages we're about to write to finish. + */ + insertpos = WaitXLogInsertionsToFinish(WriteRqstPtr); + + /* + * Try to get the write lock. If we can't get it immediately, wait + * until it's released, and recheck if we still need to do the flush + * or if the backend that held the lock did it for us already. This + * helps to maintain a good rate of group committing when the system + * is bottlenecked by the speed of fsyncing. + */ + if (!LWLockAcquireOrWait(WALWriteLock, LW_EXCLUSIVE)) + { + /* + * The lock is now free, but we didn't acquire it yet. Before we + * do, loop back to check if someone else flushed the record for + * us already. + */ + continue; + } + + /* Got the lock; recheck whether request is satisfied */ + LogwrtResult = XLogCtl->LogwrtResult; + if (record <= LogwrtResult.Flush) + { + LWLockRelease(WALWriteLock); + break; + } + + /* + * Sleep before flush! By adding a delay here, we may give further + * backends the opportunity to join the backlog of group commit + * followers; this can significantly improve transaction throughput, + * at the risk of increasing transaction latency. + * + * We do not sleep if enableFsync is not turned on, nor if there are + * fewer than CommitSiblings other backends with active transactions. + */ + if (CommitDelay > 0 && enableFsync && + MinimumActiveBackends(CommitSiblings)) + { + pg_usleep(CommitDelay); + + /* + * Re-check how far we can now flush the WAL. It's generally not + * safe to call WaitXLogInsertionsToFinish while holding + * WALWriteLock, because an in-progress insertion might need to + * also grab WALWriteLock to make progress. But we know that all + * the insertions up to insertpos have already finished, because + * that's what the earlier WaitXLogInsertionsToFinish() returned. + * We're only calling it again to allow insertpos to be moved + * further forward, not to actually wait for anyone. + */ + insertpos = WaitXLogInsertionsToFinish(insertpos); + } + + /* try to write/flush later additions to XLOG as well */ + WriteRqst.Write = insertpos; + WriteRqst.Flush = insertpos; + + XLogWrite(WriteRqst, false); + + LWLockRelease(WALWriteLock); + /* done */ + break; + } + + END_CRIT_SECTION(); + + /* wake up walsenders now that we've released heavily contended locks */ + WalSndWakeupProcessRequests(); + + /* + * If we still haven't flushed to the request point then we have a + * problem; most likely, the requested flush point is past end of XLOG. + * This has been seen to occur when a disk page has a corrupted LSN. + * + * Formerly we treated this as a PANIC condition, but that hurts the + * system's robustness rather than helping it: we do not want to take down + * the whole system due to corruption on one data page. In particular, if + * the bad page is encountered again during recovery then we would be + * unable to restart the database at all! (This scenario actually + * happened in the field several times with 7.1 releases.) As of 8.4, bad + * LSNs encountered during recovery are UpdateMinRecoveryPoint's problem; + * the only time we can reach here during recovery is while flushing the + * end-of-recovery checkpoint record, and we don't expect that to have a + * bad LSN. + * + * Note that for calls from xact.c, the ERROR will be promoted to PANIC + * since xact.c calls this routine inside a critical section. However, + * calls from bufmgr.c are not within critical sections and so we will not + * force a restart for a bad LSN on a data page. + */ + if (LogwrtResult.Flush < record) + elog(ERROR, + "xlog flush request %X/%X is not satisfied --- flushed only to %X/%X", + LSN_FORMAT_ARGS(record), + LSN_FORMAT_ARGS(LogwrtResult.Flush)); +} + +/* + * Write & flush xlog, but without specifying exactly where to. + * + * We normally write only completed blocks; but if there is nothing to do on + * that basis, we check for unwritten async commits in the current incomplete + * block, and write through the latest one of those. Thus, if async commits + * are not being used, we will write complete blocks only. + * + * If, based on the above, there's anything to write we do so immediately. But + * to avoid calling fsync, fdatasync et. al. at a rate that'd impact + * concurrent IO, we only flush WAL every wal_writer_delay ms, or if there's + * more than wal_writer_flush_after unflushed blocks. + * + * We can guarantee that async commits reach disk after at most three + * wal_writer_delay cycles. (When flushing complete blocks, we allow XLogWrite + * to write "flexibly", meaning it can stop at the end of the buffer ring; + * this makes a difference only with very high load or long wal_writer_delay, + * but imposes one extra cycle for the worst case for async commits.) + * + * This routine is invoked periodically by the background walwriter process. + * + * Returns true if there was any work to do, even if we skipped flushing due + * to wal_writer_delay/wal_writer_flush_after. + */ +bool +XLogBackgroundFlush(void) +{ + XLogwrtRqst WriteRqst; + bool flexible = true; + static TimestampTz lastflush; + TimestampTz now; + int flushbytes; + + /* XLOG doesn't need flushing during recovery */ + if (RecoveryInProgress()) + return false; + + /* read LogwrtResult and update local state */ + SpinLockAcquire(&XLogCtl->info_lck); + LogwrtResult = XLogCtl->LogwrtResult; + WriteRqst = XLogCtl->LogwrtRqst; + SpinLockRelease(&XLogCtl->info_lck); + + /* back off to last completed page boundary */ + WriteRqst.Write -= WriteRqst.Write % XLOG_BLCKSZ; + + /* if we have already flushed that far, consider async commit records */ + if (WriteRqst.Write <= LogwrtResult.Flush) + { + SpinLockAcquire(&XLogCtl->info_lck); + WriteRqst.Write = XLogCtl->asyncXactLSN; + SpinLockRelease(&XLogCtl->info_lck); + flexible = false; /* ensure it all gets written */ + } + + /* + * If already known flushed, we're done. Just need to check if we are + * holding an open file handle to a logfile that's no longer in use, + * preventing the file from being deleted. + */ + if (WriteRqst.Write <= LogwrtResult.Flush) + { + if (openLogFile >= 0) + { + if (!XLByteInPrevSeg(LogwrtResult.Write, openLogSegNo, + wal_segment_size)) + { + XLogFileClose(); + } + } + return false; + } + + /* + * Determine how far to flush WAL, based on the wal_writer_delay and + * wal_writer_flush_after GUCs. + */ + now = GetCurrentTimestamp(); + flushbytes = + WriteRqst.Write / XLOG_BLCKSZ - LogwrtResult.Flush / XLOG_BLCKSZ; + + if (WalWriterFlushAfter == 0 || lastflush == 0) + { + /* first call, or block based limits disabled */ + WriteRqst.Flush = WriteRqst.Write; + lastflush = now; + } + else if (TimestampDifferenceExceeds(lastflush, now, WalWriterDelay)) + { + /* + * Flush the writes at least every WalWriterDelay ms. This is + * important to bound the amount of time it takes for an asynchronous + * commit to hit disk. + */ + WriteRqst.Flush = WriteRqst.Write; + lastflush = now; + } + else if (flushbytes >= WalWriterFlushAfter) + { + /* exceeded wal_writer_flush_after blocks, flush */ + WriteRqst.Flush = WriteRqst.Write; + lastflush = now; + } + else + { + /* no flushing, this time round */ + WriteRqst.Flush = 0; + } + +#ifdef WAL_DEBUG + if (XLOG_DEBUG) + elog(LOG, "xlog bg flush request write %X/%X; flush: %X/%X, current is write %X/%X; flush %X/%X", + LSN_FORMAT_ARGS(WriteRqst.Write), + LSN_FORMAT_ARGS(WriteRqst.Flush), + LSN_FORMAT_ARGS(LogwrtResult.Write), + LSN_FORMAT_ARGS(LogwrtResult.Flush)); +#endif + + START_CRIT_SECTION(); + + /* now wait for any in-progress insertions to finish and get write lock */ + WaitXLogInsertionsToFinish(WriteRqst.Write); + LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); + LogwrtResult = XLogCtl->LogwrtResult; + if (WriteRqst.Write > LogwrtResult.Write || + WriteRqst.Flush > LogwrtResult.Flush) + { + XLogWrite(WriteRqst, flexible); + } + LWLockRelease(WALWriteLock); + + END_CRIT_SECTION(); + + /* wake up walsenders now that we've released heavily contended locks */ + WalSndWakeupProcessRequests(); + + /* + * Great, done. To take some work off the critical path, try to initialize + * as many of the no-longer-needed WAL buffers for future use as we can. + */ + AdvanceXLInsertBuffer(InvalidXLogRecPtr, true); + + /* + * If we determined that we need to write data, but somebody else + * wrote/flushed already, it should be considered as being active, to + * avoid hibernating too early. + */ + return true; +} + +/* + * Test whether XLOG data has been flushed up to (at least) the given position. + * + * Returns true if a flush is still needed. (It may be that someone else + * is already in process of flushing that far, however.) + */ +bool +XLogNeedsFlush(XLogRecPtr record) +{ + /* + * During recovery, we don't flush WAL but update minRecoveryPoint + * instead. So "needs flush" is taken to mean whether minRecoveryPoint + * would need to be updated. + */ + if (RecoveryInProgress()) + { + /* + * An invalid minRecoveryPoint means that we need to recover all the + * WAL, i.e., we're doing crash recovery. We never modify the control + * file's value in that case, so we can short-circuit future checks + * here too. This triggers a quick exit path for the startup process, + * which cannot update its local copy of minRecoveryPoint as long as + * it has not replayed all WAL available when doing crash recovery. + */ + if (XLogRecPtrIsInvalid(minRecoveryPoint) && InRecovery) + updateMinRecoveryPoint = false; + + /* Quick exit if already known to be updated or cannot be updated */ + if (record <= minRecoveryPoint || !updateMinRecoveryPoint) + return false; + + /* + * Update local copy of minRecoveryPoint. But if the lock is busy, + * just return a conservative guess. + */ + if (!LWLockConditionalAcquire(ControlFileLock, LW_SHARED)) + return true; + minRecoveryPoint = ControlFile->minRecoveryPoint; + minRecoveryPointTLI = ControlFile->minRecoveryPointTLI; + LWLockRelease(ControlFileLock); + + /* + * Check minRecoveryPoint for any other process than the startup + * process doing crash recovery, which should not update the control + * file value if crash recovery is still running. + */ + if (XLogRecPtrIsInvalid(minRecoveryPoint)) + updateMinRecoveryPoint = false; + + /* check again */ + if (record <= minRecoveryPoint || !updateMinRecoveryPoint) + return false; + else + return true; + } + + /* Quick exit if already known flushed */ + if (record <= LogwrtResult.Flush) + return false; + + /* read LogwrtResult and update local state */ + SpinLockAcquire(&XLogCtl->info_lck); + LogwrtResult = XLogCtl->LogwrtResult; + SpinLockRelease(&XLogCtl->info_lck); + + /* check again */ + if (record <= LogwrtResult.Flush) + return false; + + return true; +} + +/* + * Create a new XLOG file segment, or open a pre-existing one. + * + * logsegno: identify segment to be created/opened. + * + * *use_existent: if true, OK to use a pre-existing file (else, any + * pre-existing file will be deleted). On return, true if a pre-existing + * file was used. + * + * use_lock: if true, acquire ControlFileLock while moving file into + * place. This should be true except during bootstrap log creation. The + * caller must *not* hold the lock at call. + * + * Returns FD of opened file. + * + * Note: errors here are ERROR not PANIC because we might or might not be + * inside a critical section (eg, during checkpoint there is no reason to + * take down the system on failure). They will promote to PANIC if we are + * in a critical section. + */ +int +XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock) +{ + char path[MAXPGPATH]; + char tmppath[MAXPGPATH]; + PGAlignedXLogBlock zbuffer; + XLogSegNo installed_segno; + XLogSegNo max_segno; + int fd; + int save_errno; + + XLogFilePath(path, ThisTimeLineID, logsegno, wal_segment_size); + + /* + * Try to use existent file (checkpoint maker may have created it already) + */ + if (*use_existent) + { + fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method)); + if (fd < 0) + { + if (errno != ENOENT) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", path))); + } + else + return fd; + } + + /* + * Initialize an empty (all zeroes) segment. NOTE: it is possible that + * another process is doing the same thing. If so, we will end up + * pre-creating an extra log segment. That seems OK, and better than + * holding the lock throughout this lengthy process. + */ + elog(DEBUG2, "creating and filling new WAL file"); + + snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid()); + + unlink(tmppath); + + /* do not use get_sync_bit() here --- want to fsync only at end of fill */ + fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY); + if (fd < 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", tmppath))); + + memset(zbuffer.data, 0, XLOG_BLCKSZ); + + pgstat_report_wait_start(WAIT_EVENT_WAL_INIT_WRITE); + save_errno = 0; + if (wal_init_zero) + { + struct iovec iov[PG_IOV_MAX]; + int blocks; + + /* + * Zero-fill the file. With this setting, we do this the hard way to + * ensure that all the file space has really been allocated. On + * platforms that allow "holes" in files, just seeking to the end + * doesn't allocate intermediate space. This way, we know that we + * have all the space and (after the fsync below) that all the + * indirect blocks are down on disk. Therefore, fdatasync(2) or + * O_DSYNC will be sufficient to sync future writes to the log file. + */ + + /* Prepare to write out a lot of copies of our zero buffer at once. */ + for (int i = 0; i < lengthof(iov); ++i) + { + iov[i].iov_base = zbuffer.data; + iov[i].iov_len = XLOG_BLCKSZ; + } + + /* Loop, writing as many blocks as we can for each system call. */ + blocks = wal_segment_size / XLOG_BLCKSZ; + for (int i = 0; i < blocks;) + { + int iovcnt = Min(blocks - i, lengthof(iov)); + off_t offset = i * XLOG_BLCKSZ; + + if (pg_pwritev_with_retry(fd, iov, iovcnt, offset) < 0) + { + save_errno = errno; + break; + } + + i += iovcnt; + } + } + else + { + /* + * Otherwise, seeking to the end and writing a solitary byte is + * enough. + */ + errno = 0; + if (pg_pwrite(fd, zbuffer.data, 1, wal_segment_size - 1) != 1) + { + /* if write didn't set errno, assume no disk space */ + save_errno = errno ? errno : ENOSPC; + } + } + pgstat_report_wait_end(); + + if (save_errno) + { + /* + * If we fail to make the file, delete it to release disk space + */ + unlink(tmppath); + + close(fd); + + errno = save_errno; + + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not write to file \"%s\": %m", tmppath))); + } + + pgstat_report_wait_start(WAIT_EVENT_WAL_INIT_SYNC); + if (pg_fsync(fd) != 0) + { + int save_errno = errno; + + close(fd); + errno = save_errno; + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not fsync file \"%s\": %m", tmppath))); + } + pgstat_report_wait_end(); + + if (close(fd) != 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not close file \"%s\": %m", tmppath))); + + /* + * Now move the segment into place with its final name. + * + * If caller didn't want to use a pre-existing file, get rid of any + * pre-existing file. Otherwise, cope with possibility that someone else + * has created the file while we were filling ours: if so, use ours to + * pre-create a future log segment. + */ + installed_segno = logsegno; + + /* + * XXX: What should we use as max_segno? We used to use XLOGfileslop when + * that was a constant, but that was always a bit dubious: normally, at a + * checkpoint, XLOGfileslop was the offset from the checkpoint record, but + * here, it was the offset from the insert location. We can't do the + * normal XLOGfileslop calculation here because we don't have access to + * the prior checkpoint's redo location. So somewhat arbitrarily, just use + * CheckPointSegments. + */ + max_segno = logsegno + CheckPointSegments; + if (!InstallXLogFileSegment(&installed_segno, tmppath, + *use_existent, max_segno, + use_lock)) + { + /* + * No need for any more future segments, or InstallXLogFileSegment() + * failed to rename the file into place. If the rename failed, opening + * the file below will fail. + */ + unlink(tmppath); + } + + /* Set flag to tell caller there was no existent file */ + *use_existent = false; + + /* Now open original target segment (might not be file I just made) */ + fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method)); + if (fd < 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", path), + (AmCheckpointerProcess() ? + errhint("This is known to fail occasionally during archive recovery, where it is harmless.") : + 0))); + + elog(DEBUG2, "done creating and filling new WAL file"); + + return fd; +} + +/* + * Create a new XLOG file segment by copying a pre-existing one. + * + * destsegno: identify segment to be created. + * + * srcTLI, srcsegno: identify segment to be copied (could be from + * a different timeline) + * + * upto: how much of the source file to copy (the rest is filled with + * zeros) + * + * Currently this is only used during recovery, and so there are no locking + * considerations. But we should be just as tense as XLogFileInit to avoid + * emplacing a bogus file. + */ +static void +XLogFileCopy(XLogSegNo destsegno, TimeLineID srcTLI, XLogSegNo srcsegno, + int upto) +{ + char path[MAXPGPATH]; + char tmppath[MAXPGPATH]; + PGAlignedXLogBlock buffer; + int srcfd; + int fd; + int nbytes; + + /* + * Open the source file + */ + XLogFilePath(path, srcTLI, srcsegno, wal_segment_size); + srcfd = OpenTransientFile(path, O_RDONLY | PG_BINARY); + if (srcfd < 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", path))); + + /* + * Copy into a temp file name. + */ + snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid()); + + unlink(tmppath); + + /* do not use get_sync_bit() here --- want to fsync only at end of fill */ + fd = OpenTransientFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY); + if (fd < 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", tmppath))); + + /* + * Do the data copying. + */ + for (nbytes = 0; nbytes < wal_segment_size; nbytes += sizeof(buffer)) + { + int nread; + + nread = upto - nbytes; + + /* + * The part that is not read from the source file is filled with + * zeros. + */ + if (nread < sizeof(buffer)) + memset(buffer.data, 0, sizeof(buffer)); + + if (nread > 0) + { + int r; + + if (nread > sizeof(buffer)) + nread = sizeof(buffer); + pgstat_report_wait_start(WAIT_EVENT_WAL_COPY_READ); + r = read(srcfd, buffer.data, nread); + if (r != nread) + { + if (r < 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + path))); + else + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg("could not read file \"%s\": read %d of %zu", + path, r, (Size) nread))); + } + pgstat_report_wait_end(); + } + errno = 0; + pgstat_report_wait_start(WAIT_EVENT_WAL_COPY_WRITE); + if ((int) write(fd, buffer.data, sizeof(buffer)) != (int) sizeof(buffer)) + { + int save_errno = errno; + + /* + * If we fail to make the file, delete it to release disk space + */ + unlink(tmppath); + /* if write didn't set errno, assume problem is no disk space */ + errno = save_errno ? save_errno : ENOSPC; + + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not write to file \"%s\": %m", tmppath))); + } + pgstat_report_wait_end(); + } + + pgstat_report_wait_start(WAIT_EVENT_WAL_COPY_SYNC); + if (pg_fsync(fd) != 0) + ereport(data_sync_elevel(ERROR), + (errcode_for_file_access(), + errmsg("could not fsync file \"%s\": %m", tmppath))); + pgstat_report_wait_end(); + + if (CloseTransientFile(fd) != 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not close file \"%s\": %m", tmppath))); + + if (CloseTransientFile(srcfd) != 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not close file \"%s\": %m", path))); + + /* + * Now move the segment into place with its final name. + */ + if (!InstallXLogFileSegment(&destsegno, tmppath, false, 0, false)) + elog(ERROR, "InstallXLogFileSegment should not have failed"); +} + +/* + * Install a new XLOG segment file as a current or future log segment. + * + * This is used both to install a newly-created segment (which has a temp + * filename while it's being created) and to recycle an old segment. + * + * *segno: identify segment to install as (or first possible target). + * When find_free is true, this is modified on return to indicate the + * actual installation location or last segment searched. + * + * tmppath: initial name of file to install. It will be renamed into place. + * + * find_free: if true, install the new segment at the first empty segno + * number at or after the passed numbers. If false, install the new segment + * exactly where specified, deleting any existing segment file there. + * + * max_segno: maximum segment number to install the new file as. Fail if no + * free slot is found between *segno and max_segno. (Ignored when find_free + * is false.) + * + * use_lock: if true, acquire ControlFileLock while moving file into + * place. This should be true except during bootstrap log creation. The + * caller must *not* hold the lock at call. + * + * Returns true if the file was installed successfully. false indicates that + * max_segno limit was exceeded, or an error occurred while renaming the + * file into place. + */ +static bool +InstallXLogFileSegment(XLogSegNo *segno, char *tmppath, + bool find_free, XLogSegNo max_segno, + bool use_lock) +{ + char path[MAXPGPATH]; + struct stat stat_buf; + + XLogFilePath(path, ThisTimeLineID, *segno, wal_segment_size); + + /* + * We want to be sure that only one process does this at a time. + */ + if (use_lock) + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + + if (!find_free) + { + /* Force installation: get rid of any pre-existing segment file */ + durable_unlink(path, DEBUG1); + } + else + { + /* Find a free slot to put it in */ + while (stat(path, &stat_buf) == 0) + { + if ((*segno) >= max_segno) + { + /* Failed to find a free slot within specified range */ + if (use_lock) + LWLockRelease(ControlFileLock); + return false; + } + (*segno)++; + XLogFilePath(path, ThisTimeLineID, *segno, wal_segment_size); + } + } + + /* + * Perform the rename using link if available, paranoidly trying to avoid + * overwriting an existing file (there shouldn't be one). + */ + if (durable_rename_excl(tmppath, path, LOG) != 0) + { + if (use_lock) + LWLockRelease(ControlFileLock); + /* durable_rename_excl already emitted log message */ + return false; + } + + if (use_lock) + LWLockRelease(ControlFileLock); + + return true; +} + +/* + * Open a pre-existing logfile segment for writing. + */ +int +XLogFileOpen(XLogSegNo segno) +{ + char path[MAXPGPATH]; + int fd; + + XLogFilePath(path, ThisTimeLineID, segno, wal_segment_size); + + fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method)); + if (fd < 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", path))); + + return fd; +} + +/* + * Open a logfile segment for reading (during recovery). + * + * If source == XLOG_FROM_ARCHIVE, the segment is retrieved from archive. + * Otherwise, it's assumed to be already available in pg_wal. + */ +static int +XLogFileRead(XLogSegNo segno, int emode, TimeLineID tli, + XLogSource source, bool notfoundOk) +{ + char xlogfname[MAXFNAMELEN]; + char activitymsg[MAXFNAMELEN + 16]; + char path[MAXPGPATH]; + int fd; + + XLogFileName(xlogfname, tli, segno, wal_segment_size); + + switch (source) + { + case XLOG_FROM_ARCHIVE: + /* Report recovery progress in PS display */ + snprintf(activitymsg, sizeof(activitymsg), "waiting for %s", + xlogfname); + set_ps_display(activitymsg); + + restoredFromArchive = RestoreArchivedFile(path, xlogfname, + "RECOVERYXLOG", + wal_segment_size, + InRedo); + if (!restoredFromArchive) + return -1; + break; + + case XLOG_FROM_PG_WAL: + case XLOG_FROM_STREAM: + XLogFilePath(path, tli, segno, wal_segment_size); + restoredFromArchive = false; + break; + + default: + elog(ERROR, "invalid XLogFileRead source %d", source); + } + + /* + * If the segment was fetched from archival storage, replace the existing + * xlog segment (if any) with the archival version. + */ + if (source == XLOG_FROM_ARCHIVE) + { + KeepFileRestoredFromArchive(path, xlogfname); + + /* + * Set path to point at the new file in pg_wal. + */ + snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlogfname); + } + + fd = BasicOpenFile(path, O_RDONLY | PG_BINARY); + if (fd >= 0) + { + /* Success! */ + curFileTLI = tli; + + /* Report recovery progress in PS display */ + snprintf(activitymsg, sizeof(activitymsg), "recovering %s", + xlogfname); + set_ps_display(activitymsg); + + /* Track source of data in assorted state variables */ + readSource = source; + XLogReceiptSource = source; + /* In FROM_STREAM case, caller tracks receipt time, not me */ + if (source != XLOG_FROM_STREAM) + XLogReceiptTime = GetCurrentTimestamp(); + + return fd; + } + if (errno != ENOENT || !notfoundOk) /* unexpected failure? */ + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", path))); + return -1; +} + +/* + * Open a logfile segment for reading (during recovery). + * + * This version searches for the segment with any TLI listed in expectedTLEs. + */ +static int +XLogFileReadAnyTLI(XLogSegNo segno, int emode, XLogSource source) +{ + char path[MAXPGPATH]; + ListCell *cell; + int fd; + List *tles; + + /* + * Loop looking for a suitable timeline ID: we might need to read any of + * the timelines listed in expectedTLEs. + * + * We expect curFileTLI on entry to be the TLI of the preceding file in + * sequence, or 0 if there was no predecessor. We do not allow curFileTLI + * to go backwards; this prevents us from picking up the wrong file when a + * parent timeline extends to higher segment numbers than the child we + * want to read. + * + * If we haven't read the timeline history file yet, read it now, so that + * we know which TLIs to scan. We don't save the list in expectedTLEs, + * however, unless we actually find a valid segment. That way if there is + * neither a timeline history file nor a WAL segment in the archive, and + * streaming replication is set up, we'll read the timeline history file + * streamed from the primary when we start streaming, instead of + * recovering with a dummy history generated here. + */ + if (expectedTLEs) + tles = expectedTLEs; + else + tles = readTimeLineHistory(recoveryTargetTLI); + + foreach(cell, tles) + { + TimeLineHistoryEntry *hent = (TimeLineHistoryEntry *) lfirst(cell); + TimeLineID tli = hent->tli; + + if (tli < curFileTLI) + break; /* don't bother looking at too-old TLIs */ + + /* + * Skip scanning the timeline ID that the logfile segment to read + * doesn't belong to + */ + if (hent->begin != InvalidXLogRecPtr) + { + XLogSegNo beginseg = 0; + + XLByteToSeg(hent->begin, beginseg, wal_segment_size); + + /* + * The logfile segment that doesn't belong to the timeline is + * older or newer than the segment that the timeline started or + * ended at, respectively. It's sufficient to check only the + * starting segment of the timeline here. Since the timelines are + * scanned in descending order in this loop, any segments newer + * than the ending segment should belong to newer timeline and + * have already been read before. So it's not necessary to check + * the ending segment of the timeline here. + */ + if (segno < beginseg) + continue; + } + + if (source == XLOG_FROM_ANY || source == XLOG_FROM_ARCHIVE) + { + fd = XLogFileRead(segno, emode, tli, + XLOG_FROM_ARCHIVE, true); + if (fd != -1) + { + elog(DEBUG1, "got WAL segment from archive"); + if (!expectedTLEs) + expectedTLEs = tles; + return fd; + } + } + + if (source == XLOG_FROM_ANY || source == XLOG_FROM_PG_WAL) + { + fd = XLogFileRead(segno, emode, tli, + XLOG_FROM_PG_WAL, true); + if (fd != -1) + { + if (!expectedTLEs) + expectedTLEs = tles; + return fd; + } + } + } + + /* Couldn't find it. For simplicity, complain about front timeline */ + XLogFilePath(path, recoveryTargetTLI, segno, wal_segment_size); + errno = ENOENT; + ereport(emode, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", path))); + return -1; +} + +/* + * Close the current logfile segment for writing. + */ +static void +XLogFileClose(void) +{ + Assert(openLogFile >= 0); + + /* + * WAL segment files will not be re-read in normal operation, so we advise + * the OS to release any cached pages. But do not do so if WAL archiving + * or streaming is active, because archiver and walsender process could + * use the cache to read the WAL segment. + */ +#if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED) + if (!XLogIsNeeded()) + (void) posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED); +#endif + + if (close(openLogFile) != 0) + { + char xlogfname[MAXFNAMELEN]; + int save_errno = errno; + + XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo, wal_segment_size); + errno = save_errno; + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not close file \"%s\": %m", xlogfname))); + } + + openLogFile = -1; + ReleaseExternalFD(); +} + +/* + * Preallocate log files beyond the specified log endpoint. + * + * XXX this is currently extremely conservative, since it forces only one + * future log segment to exist, and even that only if we are 75% done with + * the current one. This is only appropriate for very low-WAL-volume systems. + * High-volume systems will be OK once they've built up a sufficient set of + * recycled log segments, but the startup transient is likely to include + * a lot of segment creations by foreground processes, which is not so good. + */ +static void +PreallocXlogFiles(XLogRecPtr endptr) +{ + XLogSegNo _logSegNo; + int lf; + bool use_existent; + uint64 offset; + + XLByteToPrevSeg(endptr, _logSegNo, wal_segment_size); + offset = XLogSegmentOffset(endptr - 1, wal_segment_size); + if (offset >= (uint32) (0.75 * wal_segment_size)) + { + _logSegNo++; + use_existent = true; + lf = XLogFileInit(_logSegNo, &use_existent, true); + close(lf); + if (!use_existent) + CheckpointStats.ckpt_segs_added++; + } +} + +/* + * Throws an error if the given log segment has already been removed or + * recycled. The caller should only pass a segment that it knows to have + * existed while the server has been running, as this function always + * succeeds if no WAL segments have been removed since startup. + * 'tli' is only used in the error message. + * + * Note: this function guarantees to keep errno unchanged on return. + * This supports callers that use this to possibly deliver a better + * error message about a missing file, while still being able to throw + * a normal file-access error afterwards, if this does return. + */ +void +CheckXLogRemoved(XLogSegNo segno, TimeLineID tli) +{ + int save_errno = errno; + XLogSegNo lastRemovedSegNo; + + SpinLockAcquire(&XLogCtl->info_lck); + lastRemovedSegNo = XLogCtl->lastRemovedSegNo; + SpinLockRelease(&XLogCtl->info_lck); + + if (segno <= lastRemovedSegNo) + { + char filename[MAXFNAMELEN]; + + XLogFileName(filename, tli, segno, wal_segment_size); + errno = save_errno; + ereport(ERROR, + (errcode_for_file_access(), + errmsg("requested WAL segment %s has already been removed", + filename))); + } + errno = save_errno; +} + +/* + * Return the last WAL segment removed, or 0 if no segment has been removed + * since startup. + * + * NB: the result can be out of date arbitrarily fast, the caller has to deal + * with that. + */ +XLogSegNo +XLogGetLastRemovedSegno(void) +{ + XLogSegNo lastRemovedSegNo; + + SpinLockAcquire(&XLogCtl->info_lck); + lastRemovedSegNo = XLogCtl->lastRemovedSegNo; + SpinLockRelease(&XLogCtl->info_lck); + + return lastRemovedSegNo; +} + + +/* + * Update the last removed segno pointer in shared memory, to reflect that the + * given XLOG file has been removed. + */ +static void +UpdateLastRemovedPtr(char *filename) +{ + uint32 tli; + XLogSegNo segno; + + XLogFromFileName(filename, &tli, &segno, wal_segment_size); + + SpinLockAcquire(&XLogCtl->info_lck); + if (segno > XLogCtl->lastRemovedSegNo) + XLogCtl->lastRemovedSegNo = segno; + SpinLockRelease(&XLogCtl->info_lck); +} + +/* + * Remove all temporary log files in pg_wal + * + * This is called at the beginning of recovery after a previous crash, + * at a point where no other processes write fresh WAL data. + */ +static void +RemoveTempXlogFiles(void) +{ + DIR *xldir; + struct dirent *xlde; + + elog(DEBUG2, "removing all temporary WAL segments"); + + xldir = AllocateDir(XLOGDIR); + while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL) + { + char path[MAXPGPATH]; + + if (strncmp(xlde->d_name, "xlogtemp.", 9) != 0) + continue; + + snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name); + unlink(path); + elog(DEBUG2, "removed temporary WAL segment \"%s\"", path); + } + FreeDir(xldir); +} + +/* + * Recycle or remove all log files older or equal to passed segno. + * + * endptr is current (or recent) end of xlog, and lastredoptr is the + * redo pointer of the last checkpoint. These are used to determine + * whether we want to recycle rather than delete no-longer-wanted log files. + */ +static void +RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr lastredoptr, XLogRecPtr endptr) +{ + DIR *xldir; + struct dirent *xlde; + char lastoff[MAXFNAMELEN]; + XLogSegNo endlogSegNo; + XLogSegNo recycleSegNo; + + /* Initialize info about where to try to recycle to */ + XLByteToSeg(endptr, endlogSegNo, wal_segment_size); + recycleSegNo = XLOGfileslop(lastredoptr); + + /* + * Construct a filename of the last segment to be kept. The timeline ID + * doesn't matter, we ignore that in the comparison. (During recovery, + * ThisTimeLineID isn't set, so we can't use that.) + */ + XLogFileName(lastoff, 0, segno, wal_segment_size); + + elog(DEBUG2, "attempting to remove WAL segments older than log file %s", + lastoff); + + xldir = AllocateDir(XLOGDIR); + + while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL) + { + /* Ignore files that are not XLOG segments */ + if (!IsXLogFileName(xlde->d_name) && + !IsPartialXLogFileName(xlde->d_name)) + continue; + + /* + * We ignore the timeline part of the XLOG segment identifiers in + * deciding whether a segment is still needed. This ensures that we + * won't prematurely remove a segment from a parent timeline. We could + * probably be a little more proactive about removing segments of + * non-parent timelines, but that would be a whole lot more + * complicated. + * + * We use the alphanumeric sorting property of the filenames to decide + * which ones are earlier than the lastoff segment. + */ + if (strcmp(xlde->d_name + 8, lastoff + 8) <= 0) + { + if (XLogArchiveCheckDone(xlde->d_name)) + { + /* Update the last removed location in shared memory first */ + UpdateLastRemovedPtr(xlde->d_name); + + RemoveXlogFile(xlde->d_name, recycleSegNo, &endlogSegNo); + } + } + } + + FreeDir(xldir); +} + +/* + * Remove WAL files that are not part of the given timeline's history. + * + * This is called during recovery, whenever we switch to follow a new + * timeline, and at the end of recovery when we create a new timeline. We + * wouldn't otherwise care about extra WAL files lying in pg_wal, but they + * might be leftover pre-allocated or recycled WAL segments on the old timeline + * that we haven't used yet, and contain garbage. If we just leave them in + * pg_wal, they will eventually be archived, and we can't let that happen. + * Files that belong to our timeline history are valid, because we have + * successfully replayed them, but from others we can't be sure. + * + * 'switchpoint' is the current point in WAL where we switch to new timeline, + * and 'newTLI' is the new timeline we switch to. + */ +static void +RemoveNonParentXlogFiles(XLogRecPtr switchpoint, TimeLineID newTLI) +{ + DIR *xldir; + struct dirent *xlde; + char switchseg[MAXFNAMELEN]; + XLogSegNo endLogSegNo; + XLogSegNo switchLogSegNo; + XLogSegNo recycleSegNo; + + /* + * Initialize info about where to begin the work. This will recycle, + * somewhat arbitrarily, 10 future segments. + */ + XLByteToPrevSeg(switchpoint, switchLogSegNo, wal_segment_size); + XLByteToSeg(switchpoint, endLogSegNo, wal_segment_size); + recycleSegNo = endLogSegNo + 10; + + /* + * Construct a filename of the last segment to be kept. + */ + XLogFileName(switchseg, newTLI, switchLogSegNo, wal_segment_size); + + elog(DEBUG2, "attempting to remove WAL segments newer than log file %s", + switchseg); + + xldir = AllocateDir(XLOGDIR); + + while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL) + { + /* Ignore files that are not XLOG segments */ + if (!IsXLogFileName(xlde->d_name)) + continue; + + /* + * Remove files that are on a timeline older than the new one we're + * switching to, but with a segment number >= the first segment on the + * new timeline. + */ + if (strncmp(xlde->d_name, switchseg, 8) < 0 && + strcmp(xlde->d_name + 8, switchseg + 8) > 0) + { + /* + * If the file has already been marked as .ready, however, don't + * remove it yet. It should be OK to remove it - files that are + * not part of our timeline history are not required for recovery + * - but seems safer to let them be archived and removed later. + */ + if (!XLogArchiveIsReady(xlde->d_name)) + RemoveXlogFile(xlde->d_name, recycleSegNo, &endLogSegNo); + } + } + + FreeDir(xldir); +} + +/* + * Recycle or remove a log file that's no longer needed. + * + * segname is the name of the segment to recycle or remove. recycleSegNo + * is the segment number to recycle up to. endlogSegNo is the segment + * number of the current (or recent) end of WAL. + * + * endlogSegNo gets incremented if the segment is recycled so as it is not + * checked again with future callers of this function. + */ +static void +RemoveXlogFile(const char *segname, XLogSegNo recycleSegNo, + XLogSegNo *endlogSegNo) +{ + char path[MAXPGPATH]; +#ifdef WIN32 + char newpath[MAXPGPATH]; +#endif + struct stat statbuf; + + snprintf(path, MAXPGPATH, XLOGDIR "/%s", segname); + + /* + * Before deleting the file, see if it can be recycled as a future log + * segment. Only recycle normal files, because we don't want to recycle + * symbolic links pointing to a separate archive directory. + */ + if (wal_recycle && + *endlogSegNo <= recycleSegNo && + lstat(path, &statbuf) == 0 && S_ISREG(statbuf.st_mode) && + InstallXLogFileSegment(endlogSegNo, path, + true, recycleSegNo, true)) + { + ereport(DEBUG2, + (errmsg_internal("recycled write-ahead log file \"%s\"", + segname))); + CheckpointStats.ckpt_segs_recycled++; + /* Needn't recheck that slot on future iterations */ + (*endlogSegNo)++; + } + else + { + /* No need for any more future segments... */ + int rc; + + ereport(DEBUG2, + (errmsg_internal("removing write-ahead log file \"%s\"", + segname))); + +#ifdef WIN32 + + /* + * On Windows, if another process (e.g another backend) holds the file + * open in FILE_SHARE_DELETE mode, unlink will succeed, but the file + * will still show up in directory listing until the last handle is + * closed. To avoid confusing the lingering deleted file for a live + * WAL file that needs to be archived, rename it before deleting it. + * + * If another process holds the file open without FILE_SHARE_DELETE + * flag, rename will fail. We'll try again at the next checkpoint. + */ + snprintf(newpath, MAXPGPATH, "%s.deleted", path); + if (rename(path, newpath) != 0) + { + ereport(LOG, + (errcode_for_file_access(), + errmsg("could not rename file \"%s\": %m", + path))); + return; + } + rc = durable_unlink(newpath, LOG); +#else + rc = durable_unlink(path, LOG); +#endif + if (rc != 0) + { + /* Message already logged by durable_unlink() */ + return; + } + CheckpointStats.ckpt_segs_removed++; + } + + XLogArchiveCleanup(segname); +} + +/* + * Verify whether pg_wal and pg_wal/archive_status exist. + * If the latter does not exist, recreate it. + * + * It is not the goal of this function to verify the contents of these + * directories, but to help in cases where someone has performed a cluster + * copy for PITR purposes but omitted pg_wal from the copy. + * + * We could also recreate pg_wal if it doesn't exist, but a deliberate + * policy decision was made not to. It is fairly common for pg_wal to be + * a symlink, and if that was the DBA's intent then automatically making a + * plain directory would result in degraded performance with no notice. + */ +static void +ValidateXLOGDirectoryStructure(void) +{ + char path[MAXPGPATH]; + struct stat stat_buf; + + /* Check for pg_wal; if it doesn't exist, error out */ + if (stat(XLOGDIR, &stat_buf) != 0 || + !S_ISDIR(stat_buf.st_mode)) + ereport(FATAL, + (errmsg("required WAL directory \"%s\" does not exist", + XLOGDIR))); + + /* Check for archive_status */ + snprintf(path, MAXPGPATH, XLOGDIR "/archive_status"); + if (stat(path, &stat_buf) == 0) + { + /* Check for weird cases where it exists but isn't a directory */ + if (!S_ISDIR(stat_buf.st_mode)) + ereport(FATAL, + (errmsg("required WAL directory \"%s\" does not exist", + path))); + } + else + { + ereport(LOG, + (errmsg("creating missing WAL directory \"%s\"", path))); + if (MakePGDirectory(path) < 0) + ereport(FATAL, + (errmsg("could not create missing directory \"%s\": %m", + path))); + } +} + +/* + * Remove previous backup history files. This also retries creation of + * .ready files for any backup history files for which XLogArchiveNotify + * failed earlier. + */ +static void +CleanupBackupHistory(void) +{ + DIR *xldir; + struct dirent *xlde; + char path[MAXPGPATH + sizeof(XLOGDIR)]; + + xldir = AllocateDir(XLOGDIR); + + while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL) + { + if (IsBackupHistoryFileName(xlde->d_name)) + { + if (XLogArchiveCheckDone(xlde->d_name)) + { + elog(DEBUG2, "removing WAL backup history file \"%s\"", + xlde->d_name); + snprintf(path, sizeof(path), XLOGDIR "/%s", xlde->d_name); + unlink(path); + XLogArchiveCleanup(xlde->d_name); + } + } + } + + FreeDir(xldir); +} + +/* + * Attempt to read the next XLOG record. + * + * Before first call, the reader needs to be positioned to the first record + * by calling XLogBeginRead(). + * + * If no valid record is available, returns NULL, or fails if emode is PANIC. + * (emode must be either PANIC, LOG). In standby mode, retries until a valid + * record is available. + */ +static XLogRecord * +ReadRecord(XLogReaderState *xlogreader, int emode, + bool fetching_ckpt) +{ + XLogRecord *record; + XLogPageReadPrivate *private = (XLogPageReadPrivate *) xlogreader->private_data; + + /* Pass through parameters to XLogPageRead */ + private->fetching_ckpt = fetching_ckpt; + private->emode = emode; + private->randAccess = (xlogreader->ReadRecPtr == InvalidXLogRecPtr); + + /* This is the first attempt to read this page. */ + lastSourceFailed = false; + + for (;;) + { + char *errormsg; + + record = XLogReadRecord(xlogreader, &errormsg); + ReadRecPtr = xlogreader->ReadRecPtr; + EndRecPtr = xlogreader->EndRecPtr; + if (record == NULL) + { + /* + * When not in standby mode we find that WAL ends in an incomplete + * record, keep track of that record. After recovery is done, + * we'll write a record to indicate downstream WAL readers that + * that portion is to be ignored. + */ + if (!StandbyMode && + !XLogRecPtrIsInvalid(xlogreader->abortedRecPtr)) + { + abortedRecPtr = xlogreader->abortedRecPtr; + missingContrecPtr = xlogreader->missingContrecPtr; + } + + if (readFile >= 0) + { + close(readFile); + readFile = -1; + } + + /* + * We only end up here without a message when XLogPageRead() + * failed - in that case we already logged something. In + * StandbyMode that only happens if we have been triggered, so we + * shouldn't loop anymore in that case. + */ + if (errormsg) + ereport(emode_for_corrupt_record(emode, EndRecPtr), + (errmsg_internal("%s", errormsg) /* already translated */ )); + } + + /* + * Check page TLI is one of the expected values. + */ + else if (!tliInHistory(xlogreader->latestPageTLI, expectedTLEs)) + { + char fname[MAXFNAMELEN]; + XLogSegNo segno; + int32 offset; + + XLByteToSeg(xlogreader->latestPagePtr, segno, wal_segment_size); + offset = XLogSegmentOffset(xlogreader->latestPagePtr, + wal_segment_size); + XLogFileName(fname, xlogreader->seg.ws_tli, segno, + wal_segment_size); + ereport(emode_for_corrupt_record(emode, EndRecPtr), + (errmsg("unexpected timeline ID %u in log segment %s, offset %u", + xlogreader->latestPageTLI, + fname, + offset))); + record = NULL; + } + + if (record) + { + /* Great, got a record */ + return record; + } + else + { + /* No valid record available from this source */ + lastSourceFailed = true; + + /* + * If archive recovery was requested, but we were still doing + * crash recovery, switch to archive recovery and retry using the + * offline archive. We have now replayed all the valid WAL in + * pg_wal, so we are presumably now consistent. + * + * We require that there's at least some valid WAL present in + * pg_wal, however (!fetching_ckpt). We could recover using the + * WAL from the archive, even if pg_wal is completely empty, but + * we'd have no idea how far we'd have to replay to reach + * consistency. So err on the safe side and give up. + */ + if (!InArchiveRecovery && ArchiveRecoveryRequested && + !fetching_ckpt) + { + ereport(DEBUG1, + (errmsg_internal("reached end of WAL in pg_wal, entering archive recovery"))); + InArchiveRecovery = true; + if (StandbyModeRequested) + StandbyMode = true; + + /* initialize minRecoveryPoint to this record */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->state = DB_IN_ARCHIVE_RECOVERY; + if (ControlFile->minRecoveryPoint < EndRecPtr) + { + ControlFile->minRecoveryPoint = EndRecPtr; + ControlFile->minRecoveryPointTLI = ThisTimeLineID; + } + /* update local copy */ + minRecoveryPoint = ControlFile->minRecoveryPoint; + minRecoveryPointTLI = ControlFile->minRecoveryPointTLI; + + /* + * The startup process can update its local copy of + * minRecoveryPoint from this point. + */ + updateMinRecoveryPoint = true; + + UpdateControlFile(); + + /* + * We update SharedRecoveryState while holding the lock on + * ControlFileLock so both states are consistent in shared + * memory. + */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->SharedRecoveryState = RECOVERY_STATE_ARCHIVE; + SpinLockRelease(&XLogCtl->info_lck); + + LWLockRelease(ControlFileLock); + + CheckRecoveryConsistency(); + + /* + * Before we retry, reset lastSourceFailed and currentSource + * so that we will check the archive next. + */ + lastSourceFailed = false; + currentSource = XLOG_FROM_ANY; + + continue; + } + + /* In standby mode, loop back to retry. Otherwise, give up. */ + if (StandbyMode && !CheckForStandbyTrigger()) + continue; + else + return NULL; + } + } +} + +/* + * Scan for new timelines that might have appeared in the archive since we + * started recovery. + * + * If there are any, the function changes recovery target TLI to the latest + * one and returns 'true'. + */ +static bool +rescanLatestTimeLine(void) +{ + List *newExpectedTLEs; + bool found; + ListCell *cell; + TimeLineID newtarget; + TimeLineID oldtarget = recoveryTargetTLI; + TimeLineHistoryEntry *currentTle = NULL; + + newtarget = findNewestTimeLine(recoveryTargetTLI); + if (newtarget == recoveryTargetTLI) + { + /* No new timelines found */ + return false; + } + + /* + * Determine the list of expected TLIs for the new TLI + */ + + newExpectedTLEs = readTimeLineHistory(newtarget); + + /* + * If the current timeline is not part of the history of the new timeline, + * we cannot proceed to it. + */ + found = false; + foreach(cell, newExpectedTLEs) + { + currentTle = (TimeLineHistoryEntry *) lfirst(cell); + + if (currentTle->tli == recoveryTargetTLI) + { + found = true; + break; + } + } + if (!found) + { + ereport(LOG, + (errmsg("new timeline %u is not a child of database system timeline %u", + newtarget, + ThisTimeLineID))); + return false; + } + + /* + * The current timeline was found in the history file, but check that the + * next timeline was forked off from it *after* the current recovery + * location. + */ + if (currentTle->end < EndRecPtr) + { + ereport(LOG, + (errmsg("new timeline %u forked off current database system timeline %u before current recovery point %X/%X", + newtarget, + ThisTimeLineID, + LSN_FORMAT_ARGS(EndRecPtr)))); + return false; + } + + /* The new timeline history seems valid. Switch target */ + recoveryTargetTLI = newtarget; + list_free_deep(expectedTLEs); + expectedTLEs = newExpectedTLEs; + + /* + * As in StartupXLOG(), try to ensure we have all the history files + * between the old target and new target in pg_wal. + */ + restoreTimeLineHistoryFiles(oldtarget + 1, newtarget); + + ereport(LOG, + (errmsg("new target timeline is %u", + recoveryTargetTLI))); + + return true; +} + +/* + * I/O routines for pg_control + * + * *ControlFile is a buffer in shared memory that holds an image of the + * contents of pg_control. WriteControlFile() initializes pg_control + * given a preloaded buffer, ReadControlFile() loads the buffer from + * the pg_control file (during postmaster or standalone-backend startup), + * and UpdateControlFile() rewrites pg_control after we modify xlog state. + * InitControlFile() fills the buffer with initial values. + * + * For simplicity, WriteControlFile() initializes the fields of pg_control + * that are related to checking backend/database compatibility, and + * ReadControlFile() verifies they are correct. We could split out the + * I/O and compatibility-check functions, but there seems no need currently. + */ + +static void +InitControlFile(uint64 sysidentifier) +{ + char mock_auth_nonce[MOCK_AUTH_NONCE_LEN]; + + /* + * Generate a random nonce. This is used for authentication requests that + * will fail because the user does not exist. The nonce is used to create + * a genuine-looking password challenge for the non-existent user, in lieu + * of an actual stored password. + */ + if (!pg_strong_random(mock_auth_nonce, MOCK_AUTH_NONCE_LEN)) + ereport(PANIC, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg("could not generate secret authorization token"))); + + memset(ControlFile, 0, sizeof(ControlFileData)); + /* Initialize pg_control status fields */ + ControlFile->system_identifier = sysidentifier; + memcpy(ControlFile->mock_authentication_nonce, mock_auth_nonce, MOCK_AUTH_NONCE_LEN); + ControlFile->state = DB_SHUTDOWNED; + ControlFile->unloggedLSN = FirstNormalUnloggedLSN; + + /* Set important parameter values for use when replaying WAL */ + ControlFile->MaxConnections = MaxConnections; + ControlFile->max_worker_processes = max_worker_processes; + ControlFile->max_wal_senders = max_wal_senders; + ControlFile->max_prepared_xacts = max_prepared_xacts; + ControlFile->max_locks_per_xact = max_locks_per_xact; + ControlFile->wal_level = wal_level; + ControlFile->wal_log_hints = wal_log_hints; + ControlFile->track_commit_timestamp = track_commit_timestamp; + ControlFile->data_checksum_version = bootstrap_data_checksum_version; +} + +static void +WriteControlFile(void) +{ + int fd; + char buffer[PG_CONTROL_FILE_SIZE]; /* need not be aligned */ + + /* + * Ensure that the size of the pg_control data structure is sane. See the + * comments for these symbols in pg_control.h. + */ + StaticAssertStmt(sizeof(ControlFileData) <= PG_CONTROL_MAX_SAFE_SIZE, + "pg_control is too large for atomic disk writes"); + StaticAssertStmt(sizeof(ControlFileData) <= PG_CONTROL_FILE_SIZE, + "sizeof(ControlFileData) exceeds PG_CONTROL_FILE_SIZE"); + + /* + * Initialize version and compatibility-check fields + */ + ControlFile->pg_control_version = PG_CONTROL_VERSION; + ControlFile->catalog_version_no = CATALOG_VERSION_NO; + + ControlFile->maxAlign = MAXIMUM_ALIGNOF; + ControlFile->floatFormat = FLOATFORMAT_VALUE; + + ControlFile->blcksz = BLCKSZ; + ControlFile->relseg_size = RELSEG_SIZE; + ControlFile->xlog_blcksz = XLOG_BLCKSZ; + ControlFile->xlog_seg_size = wal_segment_size; + + ControlFile->nameDataLen = NAMEDATALEN; + ControlFile->indexMaxKeys = INDEX_MAX_KEYS; + + ControlFile->toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE; + ControlFile->loblksize = LOBLKSIZE; + + ControlFile->float8ByVal = FLOAT8PASSBYVAL; + + /* Contents are protected with a CRC */ + INIT_CRC32C(ControlFile->crc); + COMP_CRC32C(ControlFile->crc, + (char *) ControlFile, + offsetof(ControlFileData, crc)); + FIN_CRC32C(ControlFile->crc); + + /* + * We write out PG_CONTROL_FILE_SIZE bytes into pg_control, zero-padding + * the excess over sizeof(ControlFileData). This reduces the odds of + * premature-EOF errors when reading pg_control. We'll still fail when we + * check the contents of the file, but hopefully with a more specific + * error than "couldn't read pg_control". + */ + memset(buffer, 0, PG_CONTROL_FILE_SIZE); + memcpy(buffer, ControlFile, sizeof(ControlFileData)); + + fd = BasicOpenFile(XLOG_CONTROL_FILE, + O_RDWR | O_CREAT | O_EXCL | PG_BINARY); + if (fd < 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", + XLOG_CONTROL_FILE))); + + errno = 0; + pgstat_report_wait_start(WAIT_EVENT_CONTROL_FILE_WRITE); + if (write(fd, buffer, PG_CONTROL_FILE_SIZE) != PG_CONTROL_FILE_SIZE) + { + /* if write didn't set errno, assume problem is no disk space */ + if (errno == 0) + errno = ENOSPC; + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not write to file \"%s\": %m", + XLOG_CONTROL_FILE))); + } + pgstat_report_wait_end(); + + pgstat_report_wait_start(WAIT_EVENT_CONTROL_FILE_SYNC); + if (pg_fsync(fd) != 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not fsync file \"%s\": %m", + XLOG_CONTROL_FILE))); + pgstat_report_wait_end(); + + if (close(fd) != 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not close file \"%s\": %m", + XLOG_CONTROL_FILE))); +} + +static void +ReadControlFile(void) +{ + pg_crc32c crc; + int fd; + static char wal_segsz_str[20]; + int r; + + /* + * Read data... + */ + fd = BasicOpenFile(XLOG_CONTROL_FILE, + O_RDWR | PG_BINARY); + if (fd < 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", + XLOG_CONTROL_FILE))); + + pgstat_report_wait_start(WAIT_EVENT_CONTROL_FILE_READ); + r = read(fd, ControlFile, sizeof(ControlFileData)); + if (r != sizeof(ControlFileData)) + { + if (r < 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + XLOG_CONTROL_FILE))); + else + ereport(PANIC, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg("could not read file \"%s\": read %d of %zu", + XLOG_CONTROL_FILE, r, sizeof(ControlFileData)))); + } + pgstat_report_wait_end(); + + close(fd); + + /* + * Check for expected pg_control format version. If this is wrong, the + * CRC check will likely fail because we'll be checking the wrong number + * of bytes. Complaining about wrong version will probably be more + * enlightening than complaining about wrong CRC. + */ + + if (ControlFile->pg_control_version != PG_CONTROL_VERSION && ControlFile->pg_control_version % 65536 == 0 && ControlFile->pg_control_version / 65536 != 0) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with PG_CONTROL_VERSION %d (0x%08x)," + " but the server was compiled with PG_CONTROL_VERSION %d (0x%08x).", + ControlFile->pg_control_version, ControlFile->pg_control_version, + PG_CONTROL_VERSION, PG_CONTROL_VERSION), + errhint("This could be a problem of mismatched byte ordering. It looks like you need to initdb."))); + + if (ControlFile->pg_control_version != PG_CONTROL_VERSION) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with PG_CONTROL_VERSION %d," + " but the server was compiled with PG_CONTROL_VERSION %d.", + ControlFile->pg_control_version, PG_CONTROL_VERSION), + errhint("It looks like you need to initdb."))); + + /* Now check the CRC. */ + INIT_CRC32C(crc); + COMP_CRC32C(crc, + (char *) ControlFile, + offsetof(ControlFileData, crc)); + FIN_CRC32C(crc); + + if (!EQ_CRC32C(crc, ControlFile->crc)) + ereport(FATAL, + (errmsg("incorrect checksum in control file"))); + + /* + * Do compatibility checking immediately. If the database isn't + * compatible with the backend executable, we want to abort before we can + * possibly do any damage. + */ + if (ControlFile->catalog_version_no != CATALOG_VERSION_NO) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with CATALOG_VERSION_NO %d," + " but the server was compiled with CATALOG_VERSION_NO %d.", + ControlFile->catalog_version_no, CATALOG_VERSION_NO), + errhint("It looks like you need to initdb."))); + if (ControlFile->maxAlign != MAXIMUM_ALIGNOF) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with MAXALIGN %d," + " but the server was compiled with MAXALIGN %d.", + ControlFile->maxAlign, MAXIMUM_ALIGNOF), + errhint("It looks like you need to initdb."))); + if (ControlFile->floatFormat != FLOATFORMAT_VALUE) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster appears to use a different floating-point number format than the server executable."), + errhint("It looks like you need to initdb."))); + if (ControlFile->blcksz != BLCKSZ) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with BLCKSZ %d," + " but the server was compiled with BLCKSZ %d.", + ControlFile->blcksz, BLCKSZ), + errhint("It looks like you need to recompile or initdb."))); + if (ControlFile->relseg_size != RELSEG_SIZE) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with RELSEG_SIZE %d," + " but the server was compiled with RELSEG_SIZE %d.", + ControlFile->relseg_size, RELSEG_SIZE), + errhint("It looks like you need to recompile or initdb."))); + if (ControlFile->xlog_blcksz != XLOG_BLCKSZ) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with XLOG_BLCKSZ %d," + " but the server was compiled with XLOG_BLCKSZ %d.", + ControlFile->xlog_blcksz, XLOG_BLCKSZ), + errhint("It looks like you need to recompile or initdb."))); + if (ControlFile->nameDataLen != NAMEDATALEN) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with NAMEDATALEN %d," + " but the server was compiled with NAMEDATALEN %d.", + ControlFile->nameDataLen, NAMEDATALEN), + errhint("It looks like you need to recompile or initdb."))); + if (ControlFile->indexMaxKeys != INDEX_MAX_KEYS) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with INDEX_MAX_KEYS %d," + " but the server was compiled with INDEX_MAX_KEYS %d.", + ControlFile->indexMaxKeys, INDEX_MAX_KEYS), + errhint("It looks like you need to recompile or initdb."))); + if (ControlFile->toast_max_chunk_size != TOAST_MAX_CHUNK_SIZE) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with TOAST_MAX_CHUNK_SIZE %d," + " but the server was compiled with TOAST_MAX_CHUNK_SIZE %d.", + ControlFile->toast_max_chunk_size, (int) TOAST_MAX_CHUNK_SIZE), + errhint("It looks like you need to recompile or initdb."))); + if (ControlFile->loblksize != LOBLKSIZE) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with LOBLKSIZE %d," + " but the server was compiled with LOBLKSIZE %d.", + ControlFile->loblksize, (int) LOBLKSIZE), + errhint("It looks like you need to recompile or initdb."))); + +#ifdef USE_FLOAT8_BYVAL + if (ControlFile->float8ByVal != true) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized without USE_FLOAT8_BYVAL" + " but the server was compiled with USE_FLOAT8_BYVAL."), + errhint("It looks like you need to recompile or initdb."))); +#else + if (ControlFile->float8ByVal != false) + ereport(FATAL, + (errmsg("database files are incompatible with server"), + errdetail("The database cluster was initialized with USE_FLOAT8_BYVAL" + " but the server was compiled without USE_FLOAT8_BYVAL."), + errhint("It looks like you need to recompile or initdb."))); +#endif + + wal_segment_size = ControlFile->xlog_seg_size; + + if (!IsValidWalSegSize(wal_segment_size)) + ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg_plural("WAL segment size must be a power of two between 1 MB and 1 GB, but the control file specifies %d byte", + "WAL segment size must be a power of two between 1 MB and 1 GB, but the control file specifies %d bytes", + wal_segment_size, + wal_segment_size))); + + snprintf(wal_segsz_str, sizeof(wal_segsz_str), "%d", wal_segment_size); + SetConfigOption("wal_segment_size", wal_segsz_str, PGC_INTERNAL, + PGC_S_OVERRIDE); + + /* check and update variables dependent on wal_segment_size */ + if (ConvertToXSegs(min_wal_size_mb, wal_segment_size) < 2) + ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("\"min_wal_size\" must be at least twice \"wal_segment_size\""))); + + if (ConvertToXSegs(max_wal_size_mb, wal_segment_size) < 2) + ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("\"max_wal_size\" must be at least twice \"wal_segment_size\""))); + + UsableBytesInSegment = + (wal_segment_size / XLOG_BLCKSZ * UsableBytesInPage) - + (SizeOfXLogLongPHD - SizeOfXLogShortPHD); + + CalculateCheckpointSegments(); + + /* Make the initdb settings visible as GUC variables, too */ + SetConfigOption("data_checksums", DataChecksumsEnabled() ? "yes" : "no", + PGC_INTERNAL, PGC_S_OVERRIDE); +} + +/* + * Utility wrapper to update the control file. Note that the control + * file gets flushed. + */ +void +UpdateControlFile(void) +{ + update_controlfile(DataDir, ControlFile, true); +} + +/* + * Returns the unique system identifier from control file. + */ +uint64 +GetSystemIdentifier(void) +{ + Assert(ControlFile != NULL); + return ControlFile->system_identifier; +} + +/* + * Returns the random nonce from control file. + */ +char * +GetMockAuthenticationNonce(void) +{ + Assert(ControlFile != NULL); + return ControlFile->mock_authentication_nonce; +} + +/* + * Are checksums enabled for data pages? + */ +bool +DataChecksumsEnabled(void) +{ + Assert(ControlFile != NULL); + return (ControlFile->data_checksum_version > 0); +} + +/* + * Returns a fake LSN for unlogged relations. + * + * Each call generates an LSN that is greater than any previous value + * returned. The current counter value is saved and restored across clean + * shutdowns, but like unlogged relations, does not survive a crash. This can + * be used in lieu of real LSN values returned by XLogInsert, if you need an + * LSN-like increasing sequence of numbers without writing any WAL. + */ +XLogRecPtr +GetFakeLSNForUnloggedRel(void) +{ + XLogRecPtr nextUnloggedLSN; + + /* increment the unloggedLSN counter, need SpinLock */ + SpinLockAcquire(&XLogCtl->ulsn_lck); + nextUnloggedLSN = XLogCtl->unloggedLSN++; + SpinLockRelease(&XLogCtl->ulsn_lck); + + return nextUnloggedLSN; +} + +/* + * Auto-tune the number of XLOG buffers. + * + * The preferred setting for wal_buffers is about 3% of shared_buffers, with + * a maximum of one XLOG segment (there is little reason to think that more + * is helpful, at least so long as we force an fsync when switching log files) + * and a minimum of 8 blocks (which was the default value prior to PostgreSQL + * 9.1, when auto-tuning was added). + * + * This should not be called until NBuffers has received its final value. + */ +static int +XLOGChooseNumBuffers(void) +{ + int xbuffers; + + xbuffers = NBuffers / 32; + if (xbuffers > (wal_segment_size / XLOG_BLCKSZ)) + xbuffers = (wal_segment_size / XLOG_BLCKSZ); + if (xbuffers < 8) + xbuffers = 8; + return xbuffers; +} + +/* + * GUC check_hook for wal_buffers + */ +bool +check_wal_buffers(int *newval, void **extra, GucSource source) +{ + /* + * -1 indicates a request for auto-tune. + */ + if (*newval == -1) + { + /* + * If we haven't yet changed the boot_val default of -1, just let it + * be. We'll fix it when XLOGShmemSize is called. + */ + if (XLOGbuffers == -1) + return true; + + /* Otherwise, substitute the auto-tune value */ + *newval = XLOGChooseNumBuffers(); + } + + /* + * We clamp manually-set values to at least 4 blocks. Prior to PostgreSQL + * 9.1, a minimum of 4 was enforced by guc.c, but since that is no longer + * the case, we just silently treat such values as a request for the + * minimum. (We could throw an error instead, but that doesn't seem very + * helpful.) + */ + if (*newval < 4) + *newval = 4; + + return true; +} + +/* + * Read the control file, set respective GUCs. + * + * This is to be called during startup, including a crash recovery cycle, + * unless in bootstrap mode, where no control file yet exists. As there's no + * usable shared memory yet (its sizing can depend on the contents of the + * control file!), first store the contents in local memory. XLOGShmemInit() + * will then copy it to shared memory later. + * + * reset just controls whether previous contents are to be expected (in the + * reset case, there's a dangling pointer into old shared memory), or not. + */ +void +LocalProcessControlFile(bool reset) +{ + Assert(reset || ControlFile == NULL); + ControlFile = palloc(sizeof(ControlFileData)); + ReadControlFile(); +} + +/* + * Initialization of shared memory for XLOG + */ +Size +XLOGShmemSize(void) +{ + Size size; + + /* + * If the value of wal_buffers is -1, use the preferred auto-tune value. + * This isn't an amazingly clean place to do this, but we must wait till + * NBuffers has received its final value, and must do it before using the + * value of XLOGbuffers to do anything important. + */ + if (XLOGbuffers == -1) + { + char buf[32]; + + snprintf(buf, sizeof(buf), "%d", XLOGChooseNumBuffers()); + SetConfigOption("wal_buffers", buf, PGC_POSTMASTER, PGC_S_OVERRIDE); + } + Assert(XLOGbuffers > 0); + + /* XLogCtl */ + size = sizeof(XLogCtlData); + + /* WAL insertion locks, plus alignment */ + size = add_size(size, mul_size(sizeof(WALInsertLockPadded), NUM_XLOGINSERT_LOCKS + 1)); + /* xlblocks array */ + size = add_size(size, mul_size(sizeof(XLogRecPtr), XLOGbuffers)); + /* extra alignment padding for XLOG I/O buffers */ + size = add_size(size, XLOG_BLCKSZ); + /* and the buffers themselves */ + size = add_size(size, mul_size(XLOG_BLCKSZ, XLOGbuffers)); + + /* + * Note: we don't count ControlFileData, it comes out of the "slop factor" + * added by CreateSharedMemoryAndSemaphores. This lets us use this + * routine again below to compute the actual allocation size. + */ + + return size; +} + +void +XLOGShmemInit(void) +{ + bool foundCFile, + foundXLog; + char *allocptr; + int i; + ControlFileData *localControlFile; + +#ifdef WAL_DEBUG + + /* + * Create a memory context for WAL debugging that's exempt from the normal + * "no pallocs in critical section" rule. Yes, that can lead to a PANIC if + * an allocation fails, but wal_debug is not for production use anyway. + */ + if (walDebugCxt == NULL) + { + walDebugCxt = AllocSetContextCreate(TopMemoryContext, + "WAL Debug", + ALLOCSET_DEFAULT_SIZES); + MemoryContextAllowInCriticalSection(walDebugCxt, true); + } +#endif + + + XLogCtl = (XLogCtlData *) + ShmemInitStruct("XLOG Ctl", XLOGShmemSize(), &foundXLog); + + localControlFile = ControlFile; + ControlFile = (ControlFileData *) + ShmemInitStruct("Control File", sizeof(ControlFileData), &foundCFile); + + if (foundCFile || foundXLog) + { + /* both should be present or neither */ + Assert(foundCFile && foundXLog); + + /* Initialize local copy of WALInsertLocks */ + WALInsertLocks = XLogCtl->Insert.WALInsertLocks; + + if (localControlFile) + pfree(localControlFile); + return; + } + memset(XLogCtl, 0, sizeof(XLogCtlData)); + + /* + * Already have read control file locally, unless in bootstrap mode. Move + * contents into shared memory. + */ + if (localControlFile) + { + memcpy(ControlFile, localControlFile, sizeof(ControlFileData)); + pfree(localControlFile); + } + + /* + * Since XLogCtlData contains XLogRecPtr fields, its sizeof should be a + * multiple of the alignment for same, so no extra alignment padding is + * needed here. + */ + allocptr = ((char *) XLogCtl) + sizeof(XLogCtlData); + XLogCtl->xlblocks = (XLogRecPtr *) allocptr; + memset(XLogCtl->xlblocks, 0, sizeof(XLogRecPtr) * XLOGbuffers); + allocptr += sizeof(XLogRecPtr) * XLOGbuffers; + + + /* WAL insertion locks. Ensure they're aligned to the full padded size */ + allocptr += sizeof(WALInsertLockPadded) - + ((uintptr_t) allocptr) % sizeof(WALInsertLockPadded); + WALInsertLocks = XLogCtl->Insert.WALInsertLocks = + (WALInsertLockPadded *) allocptr; + allocptr += sizeof(WALInsertLockPadded) * NUM_XLOGINSERT_LOCKS; + + for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++) + { + LWLockInitialize(&WALInsertLocks[i].l.lock, LWTRANCHE_WAL_INSERT); + WALInsertLocks[i].l.insertingAt = InvalidXLogRecPtr; + WALInsertLocks[i].l.lastImportantAt = InvalidXLogRecPtr; + } + + /* + * Align the start of the page buffers to a full xlog block size boundary. + * This simplifies some calculations in XLOG insertion. It is also + * required for O_DIRECT. + */ + allocptr = (char *) TYPEALIGN(XLOG_BLCKSZ, allocptr); + XLogCtl->pages = allocptr; + memset(XLogCtl->pages, 0, (Size) XLOG_BLCKSZ * XLOGbuffers); + + /* + * Do basic initialization of XLogCtl shared data. (StartupXLOG will fill + * in additional info.) + */ + XLogCtl->XLogCacheBlck = XLOGbuffers - 1; + XLogCtl->SharedRecoveryState = RECOVERY_STATE_CRASH; + XLogCtl->SharedHotStandbyActive = false; + XLogCtl->SharedPromoteIsTriggered = false; + XLogCtl->WalWriterSleeping = false; + + SpinLockInit(&XLogCtl->Insert.insertpos_lck); + SpinLockInit(&XLogCtl->info_lck); + SpinLockInit(&XLogCtl->ulsn_lck); + InitSharedLatch(&XLogCtl->recoveryWakeupLatch); + ConditionVariableInit(&XLogCtl->recoveryNotPausedCV); +} + +/* + * This func must be called ONCE on system install. It creates pg_control + * and the initial XLOG segment. + */ +void +BootStrapXLOG(void) +{ + CheckPoint checkPoint; + char *buffer; + XLogPageHeader page; + XLogLongPageHeader longpage; + XLogRecord *record; + char *recptr; + bool use_existent; + uint64 sysidentifier; + struct timeval tv; + pg_crc32c crc; + + /* + * Select a hopefully-unique system identifier code for this installation. + * We use the result of gettimeofday(), including the fractional seconds + * field, as being about as unique as we can easily get. (Think not to + * use random(), since it hasn't been seeded and there's no portable way + * to seed it other than the system clock value...) The upper half of the + * uint64 value is just the tv_sec part, while the lower half contains the + * tv_usec part (which must fit in 20 bits), plus 12 bits from our current + * PID for a little extra uniqueness. A person knowing this encoding can + * determine the initialization time of the installation, which could + * perhaps be useful sometimes. + */ + gettimeofday(&tv, NULL); + sysidentifier = ((uint64) tv.tv_sec) << 32; + sysidentifier |= ((uint64) tv.tv_usec) << 12; + sysidentifier |= getpid() & 0xFFF; + + /* First timeline ID is always 1 */ + ThisTimeLineID = 1; + + /* page buffer must be aligned suitably for O_DIRECT */ + buffer = (char *) palloc(XLOG_BLCKSZ + XLOG_BLCKSZ); + page = (XLogPageHeader) TYPEALIGN(XLOG_BLCKSZ, buffer); + memset(page, 0, XLOG_BLCKSZ); + + /* + * Set up information for the initial checkpoint record + * + * The initial checkpoint record is written to the beginning of the WAL + * segment with logid=0 logseg=1. The very first WAL segment, 0/0, is not + * used, so that we can use 0/0 to mean "before any valid WAL segment". + */ + checkPoint.redo = wal_segment_size + SizeOfXLogLongPHD; + checkPoint.ThisTimeLineID = ThisTimeLineID; + checkPoint.PrevTimeLineID = ThisTimeLineID; + checkPoint.fullPageWrites = fullPageWrites; + checkPoint.nextXid = + FullTransactionIdFromEpochAndXid(0, FirstNormalTransactionId); + checkPoint.nextOid = FirstBootstrapObjectId; + checkPoint.nextMulti = FirstMultiXactId; + checkPoint.nextMultiOffset = 0; + checkPoint.oldestXid = FirstNormalTransactionId; + checkPoint.oldestXidDB = TemplateDbOid; + checkPoint.oldestMulti = FirstMultiXactId; + checkPoint.oldestMultiDB = TemplateDbOid; + checkPoint.oldestCommitTsXid = InvalidTransactionId; + checkPoint.newestCommitTsXid = InvalidTransactionId; + checkPoint.time = (pg_time_t) time(NULL); + checkPoint.oldestActiveXid = InvalidTransactionId; + + ShmemVariableCache->nextXid = checkPoint.nextXid; + ShmemVariableCache->nextOid = checkPoint.nextOid; + ShmemVariableCache->oidCount = 0; + MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); + AdvanceOldestClogXid(checkPoint.oldestXid); + SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); + SetMultiXactIdLimit(checkPoint.oldestMulti, checkPoint.oldestMultiDB, true); + SetCommitTsLimit(InvalidTransactionId, InvalidTransactionId); + + /* Set up the XLOG page header */ + page->xlp_magic = XLOG_PAGE_MAGIC; + page->xlp_info = XLP_LONG_HEADER; + page->xlp_tli = ThisTimeLineID; + page->xlp_pageaddr = wal_segment_size; + longpage = (XLogLongPageHeader) page; + longpage->xlp_sysid = sysidentifier; + longpage->xlp_seg_size = wal_segment_size; + longpage->xlp_xlog_blcksz = XLOG_BLCKSZ; + + /* Insert the initial checkpoint record */ + recptr = ((char *) page + SizeOfXLogLongPHD); + record = (XLogRecord *) recptr; + record->xl_prev = 0; + record->xl_xid = InvalidTransactionId; + record->xl_tot_len = SizeOfXLogRecord + SizeOfXLogRecordDataHeaderShort + sizeof(checkPoint); + record->xl_info = XLOG_CHECKPOINT_SHUTDOWN; + record->xl_rmid = RM_XLOG_ID; + recptr += SizeOfXLogRecord; + /* fill the XLogRecordDataHeaderShort struct */ + *(recptr++) = (char) XLR_BLOCK_ID_DATA_SHORT; + *(recptr++) = sizeof(checkPoint); + memcpy(recptr, &checkPoint, sizeof(checkPoint)); + recptr += sizeof(checkPoint); + Assert(recptr - (char *) record == record->xl_tot_len); + + INIT_CRC32C(crc); + COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord); + COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc)); + FIN_CRC32C(crc); + record->xl_crc = crc; + + /* Create first XLOG segment file */ + use_existent = false; + openLogFile = XLogFileInit(1, &use_existent, false); + + /* + * We needn't bother with Reserve/ReleaseExternalFD here, since we'll + * close the file again in a moment. + */ + + /* Write the first page with the initial record */ + errno = 0; + pgstat_report_wait_start(WAIT_EVENT_WAL_BOOTSTRAP_WRITE); + if (write(openLogFile, page, XLOG_BLCKSZ) != XLOG_BLCKSZ) + { + /* if write didn't set errno, assume problem is no disk space */ + if (errno == 0) + errno = ENOSPC; + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not write bootstrap write-ahead log file: %m"))); + } + pgstat_report_wait_end(); + + pgstat_report_wait_start(WAIT_EVENT_WAL_BOOTSTRAP_SYNC); + if (pg_fsync(openLogFile) != 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not fsync bootstrap write-ahead log file: %m"))); + pgstat_report_wait_end(); + + if (close(openLogFile) != 0) + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not close bootstrap write-ahead log file: %m"))); + + openLogFile = -1; + + /* Now create pg_control */ + InitControlFile(sysidentifier); + ControlFile->time = checkPoint.time; + ControlFile->checkPoint = checkPoint.redo; + ControlFile->checkPointCopy = checkPoint; + + /* some additional ControlFile fields are set in WriteControlFile() */ + WriteControlFile(); + + /* Bootstrap the commit log, too */ + BootStrapCLOG(); + BootStrapCommitTs(); + BootStrapSUBTRANS(); + BootStrapMultiXact(); + + pfree(buffer); + + /* + * Force control file to be read - in contrast to normal processing we'd + * otherwise never run the checks and GUC related initializations therein. + */ + ReadControlFile(); +} + +static char * +str_time(pg_time_t tnow) +{ + static char buf[128]; + + pg_strftime(buf, sizeof(buf), + "%Y-%m-%d %H:%M:%S %Z", + pg_localtime(&tnow, log_timezone)); + + return buf; +} + +/* + * See if there are any recovery signal files and if so, set state for + * recovery. + * + * See if there is a recovery command file (recovery.conf), and if so + * throw an ERROR since as of PG12 we no longer recognize that. + */ +static void +readRecoverySignalFile(void) +{ + struct stat stat_buf; + + if (IsBootstrapProcessingMode()) + return; + + /* + * Check for old recovery API file: recovery.conf + */ + if (stat(RECOVERY_COMMAND_FILE, &stat_buf) == 0) + ereport(FATAL, + (errcode_for_file_access(), + errmsg("using recovery command file \"%s\" is not supported", + RECOVERY_COMMAND_FILE))); + + /* + * Remove unused .done file, if present. Ignore if absent. + */ + unlink(RECOVERY_COMMAND_DONE); + + /* + * Check for recovery signal files and if found, fsync them since they + * represent server state information. We don't sweat too much about the + * possibility of fsync failure, however. + * + * If present, standby signal file takes precedence. If neither is present + * then we won't enter archive recovery. + */ + if (stat(STANDBY_SIGNAL_FILE, &stat_buf) == 0) + { + int fd; + + fd = BasicOpenFilePerm(STANDBY_SIGNAL_FILE, O_RDWR | PG_BINARY | get_sync_bit(sync_method), + S_IRUSR | S_IWUSR); + if (fd >= 0) + { + (void) pg_fsync(fd); + close(fd); + } + standby_signal_file_found = true; + } + else if (stat(RECOVERY_SIGNAL_FILE, &stat_buf) == 0) + { + int fd; + + fd = BasicOpenFilePerm(RECOVERY_SIGNAL_FILE, O_RDWR | PG_BINARY | get_sync_bit(sync_method), + S_IRUSR | S_IWUSR); + if (fd >= 0) + { + (void) pg_fsync(fd); + close(fd); + } + recovery_signal_file_found = true; + } + + StandbyModeRequested = false; + ArchiveRecoveryRequested = false; + if (standby_signal_file_found) + { + StandbyModeRequested = true; + ArchiveRecoveryRequested = true; + } + else if (recovery_signal_file_found) + { + StandbyModeRequested = false; + ArchiveRecoveryRequested = true; + } + else + return; + + /* + * We don't support standby mode in standalone backends; that requires + * other processes such as the WAL receiver to be alive. + */ + if (StandbyModeRequested && !IsUnderPostmaster) + ereport(FATAL, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("standby mode is not supported by single-user servers"))); +} + +static void +validateRecoveryParameters(void) +{ + if (!ArchiveRecoveryRequested) + return; + + /* + * Check for compulsory parameters + */ + if (StandbyModeRequested) + { + if ((PrimaryConnInfo == NULL || strcmp(PrimaryConnInfo, "") == 0) && + (recoveryRestoreCommand == NULL || strcmp(recoveryRestoreCommand, "") == 0)) + ereport(WARNING, + (errmsg("specified neither primary_conninfo nor restore_command"), + errhint("The database server will regularly poll the pg_wal subdirectory to check for files placed there."))); + } + else + { + if (recoveryRestoreCommand == NULL || + strcmp(recoveryRestoreCommand, "") == 0) + ereport(FATAL, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("must specify restore_command when standby mode is not enabled"))); + } + + /* + * Override any inconsistent requests. Note that this is a change of + * behaviour in 9.5; prior to this we simply ignored a request to pause if + * hot_standby = off, which was surprising behaviour. + */ + if (recoveryTargetAction == RECOVERY_TARGET_ACTION_PAUSE && + !EnableHotStandby) + recoveryTargetAction = RECOVERY_TARGET_ACTION_SHUTDOWN; + + /* + * Final parsing of recovery_target_time string; see also + * check_recovery_target_time(). + */ + if (recoveryTarget == RECOVERY_TARGET_TIME) + { + recoveryTargetTime = DatumGetTimestampTz(DirectFunctionCall3(timestamptz_in, + CStringGetDatum(recovery_target_time_string), + ObjectIdGetDatum(InvalidOid), + Int32GetDatum(-1))); + } + + /* + * If user specified recovery_target_timeline, validate it or compute the + * "latest" value. We can't do this until after we've gotten the restore + * command and set InArchiveRecovery, because we need to fetch timeline + * history files from the archive. + */ + if (recoveryTargetTimeLineGoal == RECOVERY_TARGET_TIMELINE_NUMERIC) + { + TimeLineID rtli = recoveryTargetTLIRequested; + + /* Timeline 1 does not have a history file, all else should */ + if (rtli != 1 && !existsTimeLineHistory(rtli)) + ereport(FATAL, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("recovery target timeline %u does not exist", + rtli))); + recoveryTargetTLI = rtli; + } + else if (recoveryTargetTimeLineGoal == RECOVERY_TARGET_TIMELINE_LATEST) + { + /* We start the "latest" search from pg_control's timeline */ + recoveryTargetTLI = findNewestTimeLine(recoveryTargetTLI); + } + else + { + /* + * else we just use the recoveryTargetTLI as already read from + * ControlFile + */ + Assert(recoveryTargetTimeLineGoal == RECOVERY_TARGET_TIMELINE_CONTROLFILE); + } +} + +/* + * Exit archive-recovery state + */ +static void +exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog) +{ + char xlogfname[MAXFNAMELEN]; + XLogSegNo endLogSegNo; + XLogSegNo startLogSegNo; + + /* we always switch to a new timeline after archive recovery */ + Assert(endTLI != ThisTimeLineID); + + /* + * We are no longer in archive recovery state. + */ + InArchiveRecovery = false; + + /* + * Update min recovery point one last time. + */ + UpdateMinRecoveryPoint(InvalidXLogRecPtr, true); + + /* + * If the ending log segment is still open, close it (to avoid problems on + * Windows with trying to rename or delete an open file). + */ + if (readFile >= 0) + { + close(readFile); + readFile = -1; + } + + /* + * Calculate the last segment on the old timeline, and the first segment + * on the new timeline. If the switch happens in the middle of a segment, + * they are the same, but if the switch happens exactly at a segment + * boundary, startLogSegNo will be endLogSegNo + 1. + */ + XLByteToPrevSeg(endOfLog, endLogSegNo, wal_segment_size); + XLByteToSeg(endOfLog, startLogSegNo, wal_segment_size); + + /* + * Initialize the starting WAL segment for the new timeline. If the switch + * happens in the middle of a segment, copy data from the last WAL segment + * of the old timeline up to the switch point, to the starting WAL segment + * on the new timeline. + */ + if (endLogSegNo == startLogSegNo) + { + /* + * Make a copy of the file on the new timeline. + * + * Writing WAL isn't allowed yet, so there are no locking + * considerations. But we should be just as tense as XLogFileInit to + * avoid emplacing a bogus file. + */ + XLogFileCopy(endLogSegNo, endTLI, endLogSegNo, + XLogSegmentOffset(endOfLog, wal_segment_size)); + } + else + { + /* + * The switch happened at a segment boundary, so just create the next + * segment on the new timeline. + */ + bool use_existent = true; + int fd; + + fd = XLogFileInit(startLogSegNo, &use_existent, true); + + if (close(fd) != 0) + { + char xlogfname[MAXFNAMELEN]; + int save_errno = errno; + + XLogFileName(xlogfname, ThisTimeLineID, startLogSegNo, + wal_segment_size); + errno = save_errno; + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not close file \"%s\": %m", xlogfname))); + } + } + + /* + * Let's just make real sure there are not .ready or .done flags posted + * for the new segment. + */ + XLogFileName(xlogfname, ThisTimeLineID, startLogSegNo, wal_segment_size); + XLogArchiveCleanup(xlogfname); + + /* + * Remove the signal files out of the way, so that we don't accidentally + * re-enter archive recovery mode in a subsequent crash. + */ + if (standby_signal_file_found) + durable_unlink(STANDBY_SIGNAL_FILE, FATAL); + + if (recovery_signal_file_found) + durable_unlink(RECOVERY_SIGNAL_FILE, FATAL); + + ereport(LOG, + (errmsg("archive recovery complete"))); +} + +/* + * Extract timestamp from WAL record. + * + * If the record contains a timestamp, returns true, and saves the timestamp + * in *recordXtime. If the record type has no timestamp, returns false. + * Currently, only transaction commit/abort records and restore points contain + * timestamps. + */ +static bool +getRecordTimestamp(XLogReaderState *record, TimestampTz *recordXtime) +{ + uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK; + uint8 xact_info = info & XLOG_XACT_OPMASK; + uint8 rmid = XLogRecGetRmid(record); + + if (rmid == RM_XLOG_ID && info == XLOG_RESTORE_POINT) + { + *recordXtime = ((xl_restore_point *) XLogRecGetData(record))->rp_time; + return true; + } + if (rmid == RM_XACT_ID && (xact_info == XLOG_XACT_COMMIT || + xact_info == XLOG_XACT_COMMIT_PREPARED)) + { + *recordXtime = ((xl_xact_commit *) XLogRecGetData(record))->xact_time; + return true; + } + if (rmid == RM_XACT_ID && (xact_info == XLOG_XACT_ABORT || + xact_info == XLOG_XACT_ABORT_PREPARED)) + { + *recordXtime = ((xl_xact_abort *) XLogRecGetData(record))->xact_time; + return true; + } + return false; +} + +/* + * For point-in-time recovery, this function decides whether we want to + * stop applying the XLOG before the current record. + * + * Returns true if we are stopping, false otherwise. If stopping, some + * information is saved in recoveryStopXid et al for use in annotating the + * new timeline's history file. + */ +static bool +recoveryStopsBefore(XLogReaderState *record) +{ + bool stopsHere = false; + uint8 xact_info; + bool isCommit; + TimestampTz recordXtime = 0; + TransactionId recordXid; + + /* + * Ignore recovery target settings when not in archive recovery (meaning + * we are in crash recovery). + */ + if (!ArchiveRecoveryRequested) + return false; + + /* Check if we should stop as soon as reaching consistency */ + if (recoveryTarget == RECOVERY_TARGET_IMMEDIATE && reachedConsistency) + { + ereport(LOG, + (errmsg("recovery stopping after reaching consistency"))); + + recoveryStopAfter = false; + recoveryStopXid = InvalidTransactionId; + recoveryStopLSN = InvalidXLogRecPtr; + recoveryStopTime = 0; + recoveryStopName[0] = '\0'; + return true; + } + + /* Check if target LSN has been reached */ + if (recoveryTarget == RECOVERY_TARGET_LSN && + !recoveryTargetInclusive && + record->ReadRecPtr >= recoveryTargetLSN) + { + recoveryStopAfter = false; + recoveryStopXid = InvalidTransactionId; + recoveryStopLSN = record->ReadRecPtr; + recoveryStopTime = 0; + recoveryStopName[0] = '\0'; + ereport(LOG, + (errmsg("recovery stopping before WAL location (LSN) \"%X/%X\"", + LSN_FORMAT_ARGS(recoveryStopLSN)))); + return true; + } + + /* Otherwise we only consider stopping before COMMIT or ABORT records. */ + if (XLogRecGetRmid(record) != RM_XACT_ID) + return false; + + xact_info = XLogRecGetInfo(record) & XLOG_XACT_OPMASK; + + if (xact_info == XLOG_XACT_COMMIT) + { + isCommit = true; + recordXid = XLogRecGetXid(record); + } + else if (xact_info == XLOG_XACT_COMMIT_PREPARED) + { + xl_xact_commit *xlrec = (xl_xact_commit *) XLogRecGetData(record); + xl_xact_parsed_commit parsed; + + isCommit = true; + ParseCommitRecord(XLogRecGetInfo(record), + xlrec, + &parsed); + recordXid = parsed.twophase_xid; + } + else if (xact_info == XLOG_XACT_ABORT) + { + isCommit = false; + recordXid = XLogRecGetXid(record); + } + else if (xact_info == XLOG_XACT_ABORT_PREPARED) + { + xl_xact_abort *xlrec = (xl_xact_abort *) XLogRecGetData(record); + xl_xact_parsed_abort parsed; + + isCommit = false; + ParseAbortRecord(XLogRecGetInfo(record), + xlrec, + &parsed); + recordXid = parsed.twophase_xid; + } + else + return false; + + if (recoveryTarget == RECOVERY_TARGET_XID && !recoveryTargetInclusive) + { + /* + * There can be only one transaction end record with this exact + * transactionid + * + * when testing for an xid, we MUST test for equality only, since + * transactions are numbered in the order they start, not the order + * they complete. A higher numbered xid will complete before you about + * 50% of the time... + */ + stopsHere = (recordXid == recoveryTargetXid); + } + + if (recoveryTarget == RECOVERY_TARGET_TIME && + getRecordTimestamp(record, &recordXtime)) + { + /* + * There can be many transactions that share the same commit time, so + * we stop after the last one, if we are inclusive, or stop at the + * first one if we are exclusive + */ + if (recoveryTargetInclusive) + stopsHere = (recordXtime > recoveryTargetTime); + else + stopsHere = (recordXtime >= recoveryTargetTime); + } + + if (stopsHere) + { + recoveryStopAfter = false; + recoveryStopXid = recordXid; + recoveryStopTime = recordXtime; + recoveryStopLSN = InvalidXLogRecPtr; + recoveryStopName[0] = '\0'; + + if (isCommit) + { + ereport(LOG, + (errmsg("recovery stopping before commit of transaction %u, time %s", + recoveryStopXid, + timestamptz_to_str(recoveryStopTime)))); + } + else + { + ereport(LOG, + (errmsg("recovery stopping before abort of transaction %u, time %s", + recoveryStopXid, + timestamptz_to_str(recoveryStopTime)))); + } + } + + return stopsHere; +} + +/* + * Same as recoveryStopsBefore, but called after applying the record. + * + * We also track the timestamp of the latest applied COMMIT/ABORT + * record in XLogCtl->recoveryLastXTime. + */ +static bool +recoveryStopsAfter(XLogReaderState *record) +{ + uint8 info; + uint8 xact_info; + uint8 rmid; + TimestampTz recordXtime; + + /* + * Ignore recovery target settings when not in archive recovery (meaning + * we are in crash recovery). + */ + if (!ArchiveRecoveryRequested) + return false; + + info = XLogRecGetInfo(record) & ~XLR_INFO_MASK; + rmid = XLogRecGetRmid(record); + + /* + * There can be many restore points that share the same name; we stop at + * the first one. + */ + if (recoveryTarget == RECOVERY_TARGET_NAME && + rmid == RM_XLOG_ID && info == XLOG_RESTORE_POINT) + { + xl_restore_point *recordRestorePointData; + + recordRestorePointData = (xl_restore_point *) XLogRecGetData(record); + + if (strcmp(recordRestorePointData->rp_name, recoveryTargetName) == 0) + { + recoveryStopAfter = true; + recoveryStopXid = InvalidTransactionId; + recoveryStopLSN = InvalidXLogRecPtr; + (void) getRecordTimestamp(record, &recoveryStopTime); + strlcpy(recoveryStopName, recordRestorePointData->rp_name, MAXFNAMELEN); + + ereport(LOG, + (errmsg("recovery stopping at restore point \"%s\", time %s", + recoveryStopName, + timestamptz_to_str(recoveryStopTime)))); + return true; + } + } + + /* Check if the target LSN has been reached */ + if (recoveryTarget == RECOVERY_TARGET_LSN && + recoveryTargetInclusive && + record->ReadRecPtr >= recoveryTargetLSN) + { + recoveryStopAfter = true; + recoveryStopXid = InvalidTransactionId; + recoveryStopLSN = record->ReadRecPtr; + recoveryStopTime = 0; + recoveryStopName[0] = '\0'; + ereport(LOG, + (errmsg("recovery stopping after WAL location (LSN) \"%X/%X\"", + LSN_FORMAT_ARGS(recoveryStopLSN)))); + return true; + } + + if (rmid != RM_XACT_ID) + return false; + + xact_info = info & XLOG_XACT_OPMASK; + + if (xact_info == XLOG_XACT_COMMIT || + xact_info == XLOG_XACT_COMMIT_PREPARED || + xact_info == XLOG_XACT_ABORT || + xact_info == XLOG_XACT_ABORT_PREPARED) + { + TransactionId recordXid; + + /* Update the last applied transaction timestamp */ + if (getRecordTimestamp(record, &recordXtime)) + SetLatestXTime(recordXtime); + + /* Extract the XID of the committed/aborted transaction */ + if (xact_info == XLOG_XACT_COMMIT_PREPARED) + { + xl_xact_commit *xlrec = (xl_xact_commit *) XLogRecGetData(record); + xl_xact_parsed_commit parsed; + + ParseCommitRecord(XLogRecGetInfo(record), + xlrec, + &parsed); + recordXid = parsed.twophase_xid; + } + else if (xact_info == XLOG_XACT_ABORT_PREPARED) + { + xl_xact_abort *xlrec = (xl_xact_abort *) XLogRecGetData(record); + xl_xact_parsed_abort parsed; + + ParseAbortRecord(XLogRecGetInfo(record), + xlrec, + &parsed); + recordXid = parsed.twophase_xid; + } + else + recordXid = XLogRecGetXid(record); + + /* + * There can be only one transaction end record with this exact + * transactionid + * + * when testing for an xid, we MUST test for equality only, since + * transactions are numbered in the order they start, not the order + * they complete. A higher numbered xid will complete before you about + * 50% of the time... + */ + if (recoveryTarget == RECOVERY_TARGET_XID && recoveryTargetInclusive && + recordXid == recoveryTargetXid) + { + recoveryStopAfter = true; + recoveryStopXid = recordXid; + recoveryStopTime = recordXtime; + recoveryStopLSN = InvalidXLogRecPtr; + recoveryStopName[0] = '\0'; + + if (xact_info == XLOG_XACT_COMMIT || + xact_info == XLOG_XACT_COMMIT_PREPARED) + { + ereport(LOG, + (errmsg("recovery stopping after commit of transaction %u, time %s", + recoveryStopXid, + timestamptz_to_str(recoveryStopTime)))); + } + else if (xact_info == XLOG_XACT_ABORT || + xact_info == XLOG_XACT_ABORT_PREPARED) + { + ereport(LOG, + (errmsg("recovery stopping after abort of transaction %u, time %s", + recoveryStopXid, + timestamptz_to_str(recoveryStopTime)))); + } + return true; + } + } + + /* Check if we should stop as soon as reaching consistency */ + if (recoveryTarget == RECOVERY_TARGET_IMMEDIATE && reachedConsistency) + { + ereport(LOG, + (errmsg("recovery stopping after reaching consistency"))); + + recoveryStopAfter = true; + recoveryStopXid = InvalidTransactionId; + recoveryStopTime = 0; + recoveryStopLSN = InvalidXLogRecPtr; + recoveryStopName[0] = '\0'; + return true; + } + + return false; +} + +/* + * Wait until shared recoveryPauseState is set to RECOVERY_NOT_PAUSED. + * + * endOfRecovery is true if the recovery target is reached and + * the paused state starts at the end of recovery because of + * recovery_target_action=pause, and false otherwise. + */ +static void +recoveryPausesHere(bool endOfRecovery) +{ + /* Don't pause unless users can connect! */ + if (!LocalHotStandbyActive) + return; + + /* Don't pause after standby promotion has been triggered */ + if (LocalPromoteIsTriggered) + return; + + if (endOfRecovery) + ereport(LOG, + (errmsg("pausing at the end of recovery"), + errhint("Execute pg_wal_replay_resume() to promote."))); + else + ereport(LOG, + (errmsg("recovery has paused"), + errhint("Execute pg_wal_replay_resume() to continue."))); + + /* loop until recoveryPauseState is set to RECOVERY_NOT_PAUSED */ + while (GetRecoveryPauseState() != RECOVERY_NOT_PAUSED) + { + HandleStartupProcInterrupts(); + if (CheckForStandbyTrigger()) + return; + + /* + * If recovery pause is requested then set it paused. While we are in + * the loop, user might resume and pause again so set this every time. + */ + ConfirmRecoveryPaused(); + + /* + * We wait on a condition variable that will wake us as soon as the + * pause ends, but we use a timeout so we can check the above exit + * condition periodically too. + */ + ConditionVariableTimedSleep(&XLogCtl->recoveryNotPausedCV, 1000, + WAIT_EVENT_RECOVERY_PAUSE); + } + ConditionVariableCancelSleep(); +} + +/* + * Get the current state of the recovery pause request. + */ +RecoveryPauseState +GetRecoveryPauseState(void) +{ + RecoveryPauseState state; + + SpinLockAcquire(&XLogCtl->info_lck); + state = XLogCtl->recoveryPauseState; + SpinLockRelease(&XLogCtl->info_lck); + + return state; +} + +/* + * Set the recovery pause state. + * + * If recovery pause is requested then sets the recovery pause state to + * 'pause requested' if it is not already 'paused'. Otherwise, sets it + * to 'not paused' to resume the recovery. The recovery pause will be + * confirmed by the ConfirmRecoveryPaused. + */ +void +SetRecoveryPause(bool recoveryPause) +{ + SpinLockAcquire(&XLogCtl->info_lck); + + if (!recoveryPause) + XLogCtl->recoveryPauseState = RECOVERY_NOT_PAUSED; + else if (XLogCtl->recoveryPauseState == RECOVERY_NOT_PAUSED) + XLogCtl->recoveryPauseState = RECOVERY_PAUSE_REQUESTED; + + SpinLockRelease(&XLogCtl->info_lck); + + if (!recoveryPause) + ConditionVariableBroadcast(&XLogCtl->recoveryNotPausedCV); +} + +/* + * Confirm the recovery pause by setting the recovery pause state to + * RECOVERY_PAUSED. + */ +static void +ConfirmRecoveryPaused(void) +{ + /* If recovery pause is requested then set it paused */ + SpinLockAcquire(&XLogCtl->info_lck); + if (XLogCtl->recoveryPauseState == RECOVERY_PAUSE_REQUESTED) + XLogCtl->recoveryPauseState = RECOVERY_PAUSED; + SpinLockRelease(&XLogCtl->info_lck); +} + +/* + * When recovery_min_apply_delay is set, we wait long enough to make sure + * certain record types are applied at least that interval behind the primary. + * + * Returns true if we waited. + * + * Note that the delay is calculated between the WAL record log time and + * the current time on standby. We would prefer to keep track of when this + * standby received each WAL record, which would allow a more consistent + * approach and one not affected by time synchronisation issues, but that + * is significantly more effort and complexity for little actual gain in + * usability. + */ +static bool +recoveryApplyDelay(XLogReaderState *record) +{ + uint8 xact_info; + TimestampTz xtime; + TimestampTz delayUntil; + long msecs; + + /* nothing to do if no delay configured */ + if (recovery_min_apply_delay <= 0) + return false; + + /* no delay is applied on a database not yet consistent */ + if (!reachedConsistency) + return false; + + /* nothing to do if crash recovery is requested */ + if (!ArchiveRecoveryRequested) + return false; + + /* + * Is it a COMMIT record? + * + * We deliberately choose not to delay aborts since they have no effect on + * MVCC. We already allow replay of records that don't have a timestamp, + * so there is already opportunity for issues caused by early conflicts on + * standbys. + */ + if (XLogRecGetRmid(record) != RM_XACT_ID) + return false; + + xact_info = XLogRecGetInfo(record) & XLOG_XACT_OPMASK; + + if (xact_info != XLOG_XACT_COMMIT && + xact_info != XLOG_XACT_COMMIT_PREPARED) + return false; + + if (!getRecordTimestamp(record, &xtime)) + return false; + + delayUntil = TimestampTzPlusMilliseconds(xtime, recovery_min_apply_delay); + + /* + * Exit without arming the latch if it's already past time to apply this + * record + */ + msecs = TimestampDifferenceMilliseconds(GetCurrentTimestamp(), delayUntil); + if (msecs <= 0) + return false; + + while (true) + { + ResetLatch(&XLogCtl->recoveryWakeupLatch); + + /* + * This might change recovery_min_apply_delay or the trigger file's + * location. + */ + HandleStartupProcInterrupts(); + + if (CheckForStandbyTrigger()) + break; + + /* + * Recalculate delayUntil as recovery_min_apply_delay could have + * changed while waiting in this loop. + */ + delayUntil = TimestampTzPlusMilliseconds(xtime, recovery_min_apply_delay); + + /* + * Wait for difference between GetCurrentTimestamp() and delayUntil. + */ + msecs = TimestampDifferenceMilliseconds(GetCurrentTimestamp(), + delayUntil); + + if (msecs <= 0) + break; + + elog(DEBUG2, "recovery apply delay %ld milliseconds", msecs); + + (void) WaitLatch(&XLogCtl->recoveryWakeupLatch, + WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH, + msecs, + WAIT_EVENT_RECOVERY_APPLY_DELAY); + } + return true; +} + +/* + * Save timestamp of latest processed commit/abort record. + * + * We keep this in XLogCtl, not a simple static variable, so that it can be + * seen by processes other than the startup process. Note in particular + * that CreateRestartPoint is executed in the checkpointer. + */ +static void +SetLatestXTime(TimestampTz xtime) +{ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->recoveryLastXTime = xtime; + SpinLockRelease(&XLogCtl->info_lck); +} + +/* + * Fetch timestamp of latest processed commit/abort record. + */ +TimestampTz +GetLatestXTime(void) +{ + TimestampTz xtime; + + SpinLockAcquire(&XLogCtl->info_lck); + xtime = XLogCtl->recoveryLastXTime; + SpinLockRelease(&XLogCtl->info_lck); + + return xtime; +} + +/* + * Save timestamp of the next chunk of WAL records to apply. + * + * We keep this in XLogCtl, not a simple static variable, so that it can be + * seen by all backends. + */ +static void +SetCurrentChunkStartTime(TimestampTz xtime) +{ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->currentChunkStartTime = xtime; + SpinLockRelease(&XLogCtl->info_lck); +} + +/* + * Fetch timestamp of latest processed commit/abort record. + * Startup process maintains an accurate local copy in XLogReceiptTime + */ +TimestampTz +GetCurrentChunkReplayStartTime(void) +{ + TimestampTz xtime; + + SpinLockAcquire(&XLogCtl->info_lck); + xtime = XLogCtl->currentChunkStartTime; + SpinLockRelease(&XLogCtl->info_lck); + + return xtime; +} + +/* + * Returns time of receipt of current chunk of XLOG data, as well as + * whether it was received from streaming replication or from archives. + */ +void +GetXLogReceiptTime(TimestampTz *rtime, bool *fromStream) +{ + /* + * This must be executed in the startup process, since we don't export the + * relevant state to shared memory. + */ + Assert(InRecovery); + + *rtime = XLogReceiptTime; + *fromStream = (XLogReceiptSource == XLOG_FROM_STREAM); +} + +/* + * Note that text field supplied is a parameter name and does not require + * translation + */ +static void +RecoveryRequiresIntParameter(const char *param_name, int currValue, int minValue) +{ + if (currValue < minValue) + { + if (LocalHotStandbyActive) + { + bool warned_for_promote = false; + + ereport(WARNING, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("hot standby is not possible because of insufficient parameter settings"), + errdetail("%s = %d is a lower setting than on the primary server, where its value was %d.", + param_name, + currValue, + minValue))); + + SetRecoveryPause(true); + + ereport(LOG, + (errmsg("recovery has paused"), + errdetail("If recovery is unpaused, the server will shut down."), + errhint("You can then restart the server after making the necessary configuration changes."))); + + while (GetRecoveryPauseState() != RECOVERY_NOT_PAUSED) + { + HandleStartupProcInterrupts(); + + if (CheckForStandbyTrigger()) + { + if (!warned_for_promote) + ereport(WARNING, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("promotion is not possible because of insufficient parameter settings"), + + /* + * Repeat the detail from above so it's easy to find + * in the log. + */ + errdetail("%s = %d is a lower setting than on the primary server, where its value was %d.", + param_name, + currValue, + minValue), + errhint("Restart the server after making the necessary configuration changes."))); + warned_for_promote = true; + } + + /* + * If recovery pause is requested then set it paused. While + * we are in the loop, user might resume and pause again so + * set this every time. + */ + ConfirmRecoveryPaused(); + + /* + * We wait on a condition variable that will wake us as soon + * as the pause ends, but we use a timeout so we can check the + * above conditions periodically too. + */ + ConditionVariableTimedSleep(&XLogCtl->recoveryNotPausedCV, 1000, + WAIT_EVENT_RECOVERY_PAUSE); + } + ConditionVariableCancelSleep(); + } + + ereport(FATAL, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("recovery aborted because of insufficient parameter settings"), + /* Repeat the detail from above so it's easy to find in the log. */ + errdetail("%s = %d is a lower setting than on the primary server, where its value was %d.", + param_name, + currValue, + minValue), + errhint("You can restart the server after making the necessary configuration changes."))); + } +} + +/* + * Check to see if required parameters are set high enough on this server + * for various aspects of recovery operation. + * + * Note that all the parameters which this function tests need to be + * listed in Administrator's Overview section in high-availability.sgml. + * If you change them, don't forget to update the list. + */ +static void +CheckRequiredParameterValues(void) +{ + /* + * For archive recovery, the WAL must be generated with at least 'replica' + * wal_level. + */ + if (ArchiveRecoveryRequested && ControlFile->wal_level == WAL_LEVEL_MINIMAL) + { + ereport(FATAL, + (errmsg("WAL was generated with wal_level=minimal, cannot continue recovering"), + errdetail("This happens if you temporarily set wal_level=minimal on the server."), + errhint("Use a backup taken after setting wal_level to higher than minimal."))); + } + + /* + * For Hot Standby, the WAL must be generated with 'replica' mode, and we + * must have at least as many backend slots as the primary. + */ + if (ArchiveRecoveryRequested && EnableHotStandby) + { + /* We ignore autovacuum_max_workers when we make this test. */ + RecoveryRequiresIntParameter("max_connections", + MaxConnections, + ControlFile->MaxConnections); + RecoveryRequiresIntParameter("max_worker_processes", + max_worker_processes, + ControlFile->max_worker_processes); + RecoveryRequiresIntParameter("max_wal_senders", + max_wal_senders, + ControlFile->max_wal_senders); + RecoveryRequiresIntParameter("max_prepared_transactions", + max_prepared_xacts, + ControlFile->max_prepared_xacts); + RecoveryRequiresIntParameter("max_locks_per_transaction", + max_locks_per_xact, + ControlFile->max_locks_per_xact); + } +} + +/* + * This must be called ONCE during postmaster or standalone-backend startup + */ +void +StartupXLOG(void) +{ + XLogCtlInsert *Insert; + CheckPoint checkPoint; + bool wasShutdown; + bool reachedRecoveryTarget = false; + bool haveBackupLabel = false; + bool haveTblspcMap = false; + XLogRecPtr RecPtr, + checkPointLoc, + EndOfLog; + TimeLineID EndOfLogTLI; + TimeLineID PrevTimeLineID; + XLogRecord *record; + TransactionId oldestActiveXID; + bool backupEndRequired = false; + bool backupFromStandby = false; + DBState dbstate_at_startup; + XLogReaderState *xlogreader; + XLogPageReadPrivate private; + bool promoted = false; + struct stat st; + + /* + * We should have an aux process resource owner to use, and we should not + * be in a transaction that's installed some other resowner. + */ + Assert(AuxProcessResourceOwner != NULL); + Assert(CurrentResourceOwner == NULL || + CurrentResourceOwner == AuxProcessResourceOwner); + CurrentResourceOwner = AuxProcessResourceOwner; + + /* + * Check that contents look valid. + */ + if (!XRecOffIsValid(ControlFile->checkPoint)) + ereport(FATAL, + (errmsg("control file contains invalid checkpoint location"))); + + switch (ControlFile->state) + { + case DB_SHUTDOWNED: + + /* + * This is the expected case, so don't be chatty in standalone + * mode + */ + ereport(IsPostmasterEnvironment ? LOG : NOTICE, + (errmsg("database system was shut down at %s", + str_time(ControlFile->time)))); + break; + + case DB_SHUTDOWNED_IN_RECOVERY: + ereport(LOG, + (errmsg("database system was shut down in recovery at %s", + str_time(ControlFile->time)))); + break; + + case DB_SHUTDOWNING: + ereport(LOG, + (errmsg("database system shutdown was interrupted; last known up at %s", + str_time(ControlFile->time)))); + break; + + case DB_IN_CRASH_RECOVERY: + ereport(LOG, + (errmsg("database system was interrupted while in recovery at %s", + str_time(ControlFile->time)), + errhint("This probably means that some data is corrupted and" + " you will have to use the last backup for recovery."))); + break; + + case DB_IN_ARCHIVE_RECOVERY: + ereport(LOG, + (errmsg("database system was interrupted while in recovery at log time %s", + str_time(ControlFile->checkPointCopy.time)), + errhint("If this has occurred more than once some data might be corrupted" + " and you might need to choose an earlier recovery target."))); + break; + + case DB_IN_PRODUCTION: + ereport(LOG, + (errmsg("database system was interrupted; last known up at %s", + str_time(ControlFile->time)))); + break; + + default: + ereport(FATAL, + (errmsg("control file contains invalid database cluster state"))); + } + + /* This is just to allow attaching to startup process with a debugger */ +#ifdef XLOG_REPLAY_DELAY + if (ControlFile->state != DB_SHUTDOWNED) + pg_usleep(60000000L); +#endif + + /* + * Verify that pg_wal and pg_wal/archive_status exist. In cases where + * someone has performed a copy for PITR, these directories may have been + * excluded and need to be re-created. + */ + ValidateXLOGDirectoryStructure(); + + /*---------- + * If we previously crashed, perform a couple of actions: + * + * - The pg_wal directory may still include some temporary WAL segments + * used when creating a new segment, so perform some clean up to not + * bloat this path. This is done first as there is no point to sync + * this temporary data. + * + * - There might be data which we had written, intending to fsync it, but + * which we had not actually fsync'd yet. Therefore, a power failure in + * the near future might cause earlier unflushed writes to be lost, even + * though more recent data written to disk from here on would be + * persisted. To avoid that, fsync the entire data directory. + */ + if (ControlFile->state != DB_SHUTDOWNED && + ControlFile->state != DB_SHUTDOWNED_IN_RECOVERY) + { + RemoveTempXlogFiles(); + SyncDataDirectory(); + } + + /* + * Initialize on the assumption we want to recover to the latest timeline + * that's active according to pg_control. + */ + if (ControlFile->minRecoveryPointTLI > + ControlFile->checkPointCopy.ThisTimeLineID) + recoveryTargetTLI = ControlFile->minRecoveryPointTLI; + else + recoveryTargetTLI = ControlFile->checkPointCopy.ThisTimeLineID; + + /* + * Check for signal files, and if so set up state for offline recovery + */ + readRecoverySignalFile(); + validateRecoveryParameters(); + + if (ArchiveRecoveryRequested) + { + if (StandbyModeRequested) + ereport(LOG, + (errmsg("entering standby mode"))); + else if (recoveryTarget == RECOVERY_TARGET_XID) + ereport(LOG, + (errmsg("starting point-in-time recovery to XID %u", + recoveryTargetXid))); + else if (recoveryTarget == RECOVERY_TARGET_TIME) + ereport(LOG, + (errmsg("starting point-in-time recovery to %s", + timestamptz_to_str(recoveryTargetTime)))); + else if (recoveryTarget == RECOVERY_TARGET_NAME) + ereport(LOG, + (errmsg("starting point-in-time recovery to \"%s\"", + recoveryTargetName))); + else if (recoveryTarget == RECOVERY_TARGET_LSN) + ereport(LOG, + (errmsg("starting point-in-time recovery to WAL location (LSN) \"%X/%X\"", + LSN_FORMAT_ARGS(recoveryTargetLSN)))); + else if (recoveryTarget == RECOVERY_TARGET_IMMEDIATE) + ereport(LOG, + (errmsg("starting point-in-time recovery to earliest consistent point"))); + else + ereport(LOG, + (errmsg("starting archive recovery"))); + } + + /* + * Take ownership of the wakeup latch if we're going to sleep during + * recovery. + */ + if (ArchiveRecoveryRequested) + OwnLatch(&XLogCtl->recoveryWakeupLatch); + + /* Set up XLOG reader facility */ + MemSet(&private, 0, sizeof(XLogPageReadPrivate)); + xlogreader = + XLogReaderAllocate(wal_segment_size, NULL, + XL_ROUTINE(.page_read = &XLogPageRead, + .segment_open = NULL, + .segment_close = wal_segment_close), + &private); + if (!xlogreader) + ereport(ERROR, + (errcode(ERRCODE_OUT_OF_MEMORY), + errmsg("out of memory"), + errdetail("Failed while allocating a WAL reading processor."))); + xlogreader->system_identifier = ControlFile->system_identifier; + + /* + * Allocate two page buffers dedicated to WAL consistency checks. We do + * it this way, rather than just making static arrays, for two reasons: + * (1) no need to waste the storage in most instantiations of the backend; + * (2) a static char array isn't guaranteed to have any particular + * alignment, whereas palloc() will provide MAXALIGN'd storage. + */ + replay_image_masked = (char *) palloc(BLCKSZ); + primary_image_masked = (char *) palloc(BLCKSZ); + + if (read_backup_label(&checkPointLoc, &backupEndRequired, + &backupFromStandby)) + { + List *tablespaces = NIL; + + /* + * Archive recovery was requested, and thanks to the backup label + * file, we know how far we need to replay to reach consistency. Enter + * archive recovery directly. + */ + InArchiveRecovery = true; + if (StandbyModeRequested) + StandbyMode = true; + + /* + * When a backup_label file is present, we want to roll forward from + * the checkpoint it identifies, rather than using pg_control. + */ + record = ReadCheckpointRecord(xlogreader, checkPointLoc, 0, true); + if (record != NULL) + { + memcpy(&checkPoint, XLogRecGetData(xlogreader), sizeof(CheckPoint)); + wasShutdown = ((record->xl_info & ~XLR_INFO_MASK) == XLOG_CHECKPOINT_SHUTDOWN); + ereport(DEBUG1, + (errmsg_internal("checkpoint record is at %X/%X", + LSN_FORMAT_ARGS(checkPointLoc)))); + InRecovery = true; /* force recovery even if SHUTDOWNED */ + + /* + * Make sure that REDO location exists. This may not be the case + * if there was a crash during an online backup, which left a + * backup_label around that references a WAL segment that's + * already been archived. + */ + if (checkPoint.redo < checkPointLoc) + { + XLogBeginRead(xlogreader, checkPoint.redo); + if (!ReadRecord(xlogreader, LOG, false)) + ereport(FATAL, + (errmsg("could not find redo location referenced by checkpoint record"), + errhint("If you are restoring from a backup, touch \"%s/recovery.signal\" and add required recovery options.\n" + "If you are not restoring from a backup, try removing the file \"%s/backup_label\".\n" + "Be careful: removing \"%s/backup_label\" will result in a corrupt cluster if restoring from a backup.", + DataDir, DataDir, DataDir))); + } + } + else + { + ereport(FATAL, + (errmsg("could not locate required checkpoint record"), + errhint("If you are restoring from a backup, touch \"%s/recovery.signal\" and add required recovery options.\n" + "If you are not restoring from a backup, try removing the file \"%s/backup_label\".\n" + "Be careful: removing \"%s/backup_label\" will result in a corrupt cluster if restoring from a backup.", + DataDir, DataDir, DataDir))); + wasShutdown = false; /* keep compiler quiet */ + } + + /* read the tablespace_map file if present and create symlinks. */ + if (read_tablespace_map(&tablespaces)) + { + ListCell *lc; + + foreach(lc, tablespaces) + { + tablespaceinfo *ti = lfirst(lc); + char *linkloc; + + linkloc = psprintf("pg_tblspc/%s", ti->oid); + + /* + * Remove the existing symlink if any and Create the symlink + * under PGDATA. + */ + remove_tablespace_symlink(linkloc); + + if (symlink(ti->path, linkloc) < 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not create symbolic link \"%s\": %m", + linkloc))); + + pfree(ti->oid); + pfree(ti->path); + pfree(ti); + } + + /* set flag to delete it later */ + haveTblspcMap = true; + } + + /* set flag to delete it later */ + haveBackupLabel = true; + } + else + { + /* + * If tablespace_map file is present without backup_label file, there + * is no use of such file. There is no harm in retaining it, but it + * is better to get rid of the map file so that we don't have any + * redundant file in data directory and it will avoid any sort of + * confusion. It seems prudent though to just rename the file out of + * the way rather than delete it completely, also we ignore any error + * that occurs in rename operation as even if map file is present + * without backup_label file, it is harmless. + */ + if (stat(TABLESPACE_MAP, &st) == 0) + { + unlink(TABLESPACE_MAP_OLD); + if (durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, DEBUG1) == 0) + ereport(LOG, + (errmsg("ignoring file \"%s\" because no file \"%s\" exists", + TABLESPACE_MAP, BACKUP_LABEL_FILE), + errdetail("File \"%s\" was renamed to \"%s\".", + TABLESPACE_MAP, TABLESPACE_MAP_OLD))); + else + ereport(LOG, + (errmsg("ignoring file \"%s\" because no file \"%s\" exists", + TABLESPACE_MAP, BACKUP_LABEL_FILE), + errdetail("Could not rename file \"%s\" to \"%s\": %m.", + TABLESPACE_MAP, TABLESPACE_MAP_OLD))); + } + + /* + * It's possible that archive recovery was requested, but we don't + * know how far we need to replay the WAL before we reach consistency. + * This can happen for example if a base backup is taken from a + * running server using an atomic filesystem snapshot, without calling + * pg_start/stop_backup. Or if you just kill a running primary server + * and put it into archive recovery by creating a recovery signal + * file. + * + * Our strategy in that case is to perform crash recovery first, + * replaying all the WAL present in pg_wal, and only enter archive + * recovery after that. + * + * But usually we already know how far we need to replay the WAL (up + * to minRecoveryPoint, up to backupEndPoint, or until we see an + * end-of-backup record), and we can enter archive recovery directly. + */ + if (ArchiveRecoveryRequested && + (ControlFile->minRecoveryPoint != InvalidXLogRecPtr || + ControlFile->backupEndRequired || + ControlFile->backupEndPoint != InvalidXLogRecPtr || + ControlFile->state == DB_SHUTDOWNED)) + { + InArchiveRecovery = true; + if (StandbyModeRequested) + StandbyMode = true; + } + + /* Get the last valid checkpoint record. */ + checkPointLoc = ControlFile->checkPoint; + RedoStartLSN = ControlFile->checkPointCopy.redo; + record = ReadCheckpointRecord(xlogreader, checkPointLoc, 1, true); + if (record != NULL) + { + ereport(DEBUG1, + (errmsg_internal("checkpoint record is at %X/%X", + LSN_FORMAT_ARGS(checkPointLoc)))); + } + else + { + /* + * We used to attempt to go back to a secondary checkpoint record + * here, but only when not in standby mode. We now just fail if we + * can't read the last checkpoint because this allows us to + * simplify processing around checkpoints. + */ + ereport(PANIC, + (errmsg("could not locate a valid checkpoint record"))); + } + memcpy(&checkPoint, XLogRecGetData(xlogreader), sizeof(CheckPoint)); + wasShutdown = ((record->xl_info & ~XLR_INFO_MASK) == XLOG_CHECKPOINT_SHUTDOWN); + } + + /* + * Clear out any old relcache cache files. This is *necessary* if we do + * any WAL replay, since that would probably result in the cache files + * being out of sync with database reality. In theory we could leave them + * in place if the database had been cleanly shut down, but it seems + * safest to just remove them always and let them be rebuilt during the + * first backend startup. These files needs to be removed from all + * directories including pg_tblspc, however the symlinks are created only + * after reading tablespace_map file in case of archive recovery from + * backup, so needs to clear old relcache files here after creating + * symlinks. + */ + RelationCacheInitFileRemove(); + + /* + * If the location of the checkpoint record is not on the expected + * timeline in the history of the requested timeline, we cannot proceed: + * the backup is not part of the history of the requested timeline. + */ + Assert(expectedTLEs); /* was initialized by reading checkpoint + * record */ + if (tliOfPointInHistory(checkPointLoc, expectedTLEs) != + checkPoint.ThisTimeLineID) + { + XLogRecPtr switchpoint; + + /* + * tliSwitchPoint will throw an error if the checkpoint's timeline is + * not in expectedTLEs at all. + */ + switchpoint = tliSwitchPoint(ControlFile->checkPointCopy.ThisTimeLineID, expectedTLEs, NULL); + ereport(FATAL, + (errmsg("requested timeline %u is not a child of this server's history", + recoveryTargetTLI), + errdetail("Latest checkpoint is at %X/%X on timeline %u, but in the history of the requested timeline, the server forked off from that timeline at %X/%X.", + LSN_FORMAT_ARGS(ControlFile->checkPoint), + ControlFile->checkPointCopy.ThisTimeLineID, + LSN_FORMAT_ARGS(switchpoint)))); + } + + /* + * The min recovery point should be part of the requested timeline's + * history, too. + */ + if (!XLogRecPtrIsInvalid(ControlFile->minRecoveryPoint) && + tliOfPointInHistory(ControlFile->minRecoveryPoint - 1, expectedTLEs) != + ControlFile->minRecoveryPointTLI) + ereport(FATAL, + (errmsg("requested timeline %u does not contain minimum recovery point %X/%X on timeline %u", + recoveryTargetTLI, + LSN_FORMAT_ARGS(ControlFile->minRecoveryPoint), + ControlFile->minRecoveryPointTLI))); + + LastRec = RecPtr = checkPointLoc; + + ereport(DEBUG1, + (errmsg_internal("redo record is at %X/%X; shutdown %s", + LSN_FORMAT_ARGS(checkPoint.redo), + wasShutdown ? "true" : "false"))); + ereport(DEBUG1, + (errmsg_internal("next transaction ID: " UINT64_FORMAT "; next OID: %u", + U64FromFullTransactionId(checkPoint.nextXid), + checkPoint.nextOid))); + ereport(DEBUG1, + (errmsg_internal("next MultiXactId: %u; next MultiXactOffset: %u", + checkPoint.nextMulti, checkPoint.nextMultiOffset))); + ereport(DEBUG1, + (errmsg_internal("oldest unfrozen transaction ID: %u, in database %u", + checkPoint.oldestXid, checkPoint.oldestXidDB))); + ereport(DEBUG1, + (errmsg_internal("oldest MultiXactId: %u, in database %u", + checkPoint.oldestMulti, checkPoint.oldestMultiDB))); + ereport(DEBUG1, + (errmsg_internal("commit timestamp Xid oldest/newest: %u/%u", + checkPoint.oldestCommitTsXid, + checkPoint.newestCommitTsXid))); + if (!TransactionIdIsNormal(XidFromFullTransactionId(checkPoint.nextXid))) + ereport(PANIC, + (errmsg("invalid next transaction ID"))); + + /* initialize shared memory variables from the checkpoint record */ + ShmemVariableCache->nextXid = checkPoint.nextXid; + ShmemVariableCache->nextOid = checkPoint.nextOid; + ShmemVariableCache->oidCount = 0; + MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); + AdvanceOldestClogXid(checkPoint.oldestXid); + SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); + SetMultiXactIdLimit(checkPoint.oldestMulti, checkPoint.oldestMultiDB, true); + SetCommitTsLimit(checkPoint.oldestCommitTsXid, + checkPoint.newestCommitTsXid); + XLogCtl->ckptFullXid = checkPoint.nextXid; + + /* + * Initialize replication slots, before there's a chance to remove + * required resources. + */ + StartupReplicationSlots(); + + /* + * Startup logical state, needs to be setup now so we have proper data + * during crash recovery. + */ + StartupReorderBuffer(); + + /* + * Startup CLOG. This must be done after ShmemVariableCache->nextXid has + * been initialized and before we accept connections or begin WAL replay. + */ + StartupCLOG(); + + /* + * Startup MultiXact. We need to do this early to be able to replay + * truncations. + */ + StartupMultiXact(); + + /* + * Ditto for commit timestamps. Activate the facility if the setting is + * enabled in the control file, as there should be no tracking of commit + * timestamps done when the setting was disabled. This facility can be + * started or stopped when replaying a XLOG_PARAMETER_CHANGE record. + */ + if (ControlFile->track_commit_timestamp) + StartupCommitTs(); + + /* + * Recover knowledge about replay progress of known replication partners. + */ + StartupReplicationOrigin(); + + /* + * Initialize unlogged LSN. On a clean shutdown, it's restored from the + * control file. On recovery, all unlogged relations are blown away, so + * the unlogged LSN counter can be reset too. + */ + if (ControlFile->state == DB_SHUTDOWNED) + XLogCtl->unloggedLSN = ControlFile->unloggedLSN; + else + XLogCtl->unloggedLSN = FirstNormalUnloggedLSN; + + /* + * We must replay WAL entries using the same TimeLineID they were created + * under, so temporarily adopt the TLI indicated by the checkpoint (see + * also xlog_redo()). + */ + ThisTimeLineID = checkPoint.ThisTimeLineID; + + /* + * Copy any missing timeline history files between 'now' and the recovery + * target timeline from archive to pg_wal. While we don't need those files + * ourselves - the history file of the recovery target timeline covers all + * the previous timelines in the history too - a cascading standby server + * might be interested in them. Or, if you archive the WAL from this + * server to a different archive than the primary, it'd be good for all + * the history files to get archived there after failover, so that you can + * use one of the old timelines as a PITR target. Timeline history files + * are small, so it's better to copy them unnecessarily than not copy them + * and regret later. + */ + restoreTimeLineHistoryFiles(ThisTimeLineID, recoveryTargetTLI); + + /* + * Before running in recovery, scan pg_twophase and fill in its status to + * be able to work on entries generated by redo. Doing a scan before + * taking any recovery action has the merit to discard any 2PC files that + * are newer than the first record to replay, saving from any conflicts at + * replay. This avoids as well any subsequent scans when doing recovery + * of the on-disk two-phase data. + */ + restoreTwoPhaseData(); + + lastFullPageWrites = checkPoint.fullPageWrites; + + RedoRecPtr = XLogCtl->RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo; + doPageWrites = lastFullPageWrites; + + if (RecPtr < checkPoint.redo) + ereport(PANIC, + (errmsg("invalid redo in checkpoint record"))); + + /* + * Check whether we need to force recovery from WAL. If it appears to + * have been a clean shutdown and we did not have a recovery signal file, + * then assume no recovery needed. + */ + if (checkPoint.redo < RecPtr) + { + if (wasShutdown) + ereport(PANIC, + (errmsg("invalid redo record in shutdown checkpoint"))); + InRecovery = true; + } + else if (ControlFile->state != DB_SHUTDOWNED) + InRecovery = true; + else if (ArchiveRecoveryRequested) + { + /* force recovery due to presence of recovery signal file */ + InRecovery = true; + } + + /* + * Start recovery assuming that the final record isn't lost. + */ + abortedRecPtr = InvalidXLogRecPtr; + missingContrecPtr = InvalidXLogRecPtr; + + /* REDO */ + if (InRecovery) + { + int rmid; + + /* + * Update pg_control to show that we are recovering and to show the + * selected checkpoint as the place we are starting from. We also mark + * pg_control with any minimum recovery stop point obtained from a + * backup history file. + */ + dbstate_at_startup = ControlFile->state; + if (InArchiveRecovery) + { + ControlFile->state = DB_IN_ARCHIVE_RECOVERY; + + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->SharedRecoveryState = RECOVERY_STATE_ARCHIVE; + SpinLockRelease(&XLogCtl->info_lck); + } + else + { + ereport(LOG, + (errmsg("database system was not properly shut down; " + "automatic recovery in progress"))); + if (recoveryTargetTLI > ControlFile->checkPointCopy.ThisTimeLineID) + ereport(LOG, + (errmsg("crash recovery starts in timeline %u " + "and has target timeline %u", + ControlFile->checkPointCopy.ThisTimeLineID, + recoveryTargetTLI))); + ControlFile->state = DB_IN_CRASH_RECOVERY; + + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->SharedRecoveryState = RECOVERY_STATE_CRASH; + SpinLockRelease(&XLogCtl->info_lck); + } + ControlFile->checkPoint = checkPointLoc; + ControlFile->checkPointCopy = checkPoint; + if (InArchiveRecovery) + { + /* initialize minRecoveryPoint if not set yet */ + if (ControlFile->minRecoveryPoint < checkPoint.redo) + { + ControlFile->minRecoveryPoint = checkPoint.redo; + ControlFile->minRecoveryPointTLI = checkPoint.ThisTimeLineID; + } + } + + /* + * Set backupStartPoint if we're starting recovery from a base backup. + * + * Also set backupEndPoint and use minRecoveryPoint as the backup end + * location if we're starting recovery from a base backup which was + * taken from a standby. In this case, the database system status in + * pg_control must indicate that the database was already in recovery. + * Usually that will be DB_IN_ARCHIVE_RECOVERY but also can be + * DB_SHUTDOWNED_IN_RECOVERY if recovery previously was interrupted + * before reaching this point; e.g. because restore_command or + * primary_conninfo were faulty. + * + * Any other state indicates that the backup somehow became corrupted + * and we can't sensibly continue with recovery. + */ + if (haveBackupLabel) + { + ControlFile->backupStartPoint = checkPoint.redo; + ControlFile->backupEndRequired = backupEndRequired; + + if (backupFromStandby) + { + if (dbstate_at_startup != DB_IN_ARCHIVE_RECOVERY && + dbstate_at_startup != DB_SHUTDOWNED_IN_RECOVERY) + ereport(FATAL, + (errmsg("backup_label contains data inconsistent with control file"), + errhint("This means that the backup is corrupted and you will " + "have to use another backup for recovery."))); + ControlFile->backupEndPoint = ControlFile->minRecoveryPoint; + } + } + ControlFile->time = (pg_time_t) time(NULL); + /* No need to hold ControlFileLock yet, we aren't up far enough */ + UpdateControlFile(); + + /* + * Initialize our local copy of minRecoveryPoint. When doing crash + * recovery we want to replay up to the end of WAL. Particularly, in + * the case of a promoted standby minRecoveryPoint value in the + * control file is only updated after the first checkpoint. However, + * if the instance crashes before the first post-recovery checkpoint + * is completed then recovery will use a stale location causing the + * startup process to think that there are still invalid page + * references when checking for data consistency. + */ + if (InArchiveRecovery) + { + minRecoveryPoint = ControlFile->minRecoveryPoint; + minRecoveryPointTLI = ControlFile->minRecoveryPointTLI; + } + else + { + minRecoveryPoint = InvalidXLogRecPtr; + minRecoveryPointTLI = 0; + } + + /* + * Reset pgstat data, because it may be invalid after recovery. + */ + pgstat_reset_all(); + + /* + * If there was a backup label file, it's done its job and the info + * has now been propagated into pg_control. We must get rid of the + * label file so that if we crash during recovery, we'll pick up at + * the latest recovery restartpoint instead of going all the way back + * to the backup start point. It seems prudent though to just rename + * the file out of the way rather than delete it completely. + */ + if (haveBackupLabel) + { + unlink(BACKUP_LABEL_OLD); + durable_rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD, FATAL); + } + + /* + * If there was a tablespace_map file, it's done its job and the + * symlinks have been created. We must get rid of the map file so + * that if we crash during recovery, we don't create symlinks again. + * It seems prudent though to just rename the file out of the way + * rather than delete it completely. + */ + if (haveTblspcMap) + { + unlink(TABLESPACE_MAP_OLD); + durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, FATAL); + } + + /* Check that the GUCs used to generate the WAL allow recovery */ + CheckRequiredParameterValues(); + + /* + * We're in recovery, so unlogged relations may be trashed and must be + * reset. This should be done BEFORE allowing Hot Standby + * connections, so that read-only backends don't try to read whatever + * garbage is left over from before. + */ + ResetUnloggedRelations(UNLOGGED_RELATION_CLEANUP); + + /* + * Likewise, delete any saved transaction snapshot files that got left + * behind by crashed backends. + */ + DeleteAllExportedSnapshotFiles(); + + /* + * Initialize for Hot Standby, if enabled. We won't let backends in + * yet, not until we've reached the min recovery point specified in + * control file and we've established a recovery snapshot from a + * running-xacts WAL record. + */ + if (ArchiveRecoveryRequested && EnableHotStandby) + { + TransactionId *xids; + int nxids; + + ereport(DEBUG1, + (errmsg_internal("initializing for hot standby"))); + + InitRecoveryTransactionEnvironment(); + + if (wasShutdown) + oldestActiveXID = PrescanPreparedTransactions(&xids, &nxids); + else + oldestActiveXID = checkPoint.oldestActiveXid; + Assert(TransactionIdIsValid(oldestActiveXID)); + + /* Tell procarray about the range of xids it has to deal with */ + ProcArrayInitRecovery(XidFromFullTransactionId(ShmemVariableCache->nextXid)); + + /* + * Startup subtrans only. CLOG, MultiXact and commit timestamp + * have already been started up and other SLRUs are not maintained + * during recovery and need not be started yet. + */ + StartupSUBTRANS(oldestActiveXID); + + /* + * If we're beginning at a shutdown checkpoint, we know that + * nothing was running on the primary at this point. So fake-up an + * empty running-xacts record and use that here and now. Recover + * additional standby state for prepared transactions. + */ + if (wasShutdown) + { + RunningTransactionsData running; + TransactionId latestCompletedXid; + + /* + * Construct a RunningTransactions snapshot representing a + * shut down server, with only prepared transactions still + * alive. We're never overflowed at this point because all + * subxids are listed with their parent prepared transactions. + */ + running.xcnt = nxids; + running.subxcnt = 0; + running.subxid_overflow = false; + running.nextXid = XidFromFullTransactionId(checkPoint.nextXid); + running.oldestRunningXid = oldestActiveXID; + latestCompletedXid = XidFromFullTransactionId(checkPoint.nextXid); + TransactionIdRetreat(latestCompletedXid); + Assert(TransactionIdIsNormal(latestCompletedXid)); + running.latestCompletedXid = latestCompletedXid; + running.xids = xids; + + ProcArrayApplyRecoveryInfo(&running); + + StandbyRecoverPreparedTransactions(); + } + } + + /* Initialize resource managers */ + for (rmid = 0; rmid <= RM_MAX_ID; rmid++) + { + if (RmgrTable[rmid].rm_startup != NULL) + RmgrTable[rmid].rm_startup(); + } + + /* + * Initialize shared variables for tracking progress of WAL replay, as + * if we had just replayed the record before the REDO location (or the + * checkpoint record itself, if it's a shutdown checkpoint). + */ + SpinLockAcquire(&XLogCtl->info_lck); + if (checkPoint.redo < RecPtr) + XLogCtl->replayEndRecPtr = checkPoint.redo; + else + XLogCtl->replayEndRecPtr = EndRecPtr; + XLogCtl->replayEndTLI = ThisTimeLineID; + XLogCtl->lastReplayedEndRecPtr = XLogCtl->replayEndRecPtr; + XLogCtl->lastReplayedTLI = XLogCtl->replayEndTLI; + XLogCtl->recoveryLastXTime = 0; + XLogCtl->currentChunkStartTime = 0; + XLogCtl->recoveryPauseState = RECOVERY_NOT_PAUSED; + SpinLockRelease(&XLogCtl->info_lck); + + /* Also ensure XLogReceiptTime has a sane value */ + XLogReceiptTime = GetCurrentTimestamp(); + + /* + * Let postmaster know we've started redo now, so that it can launch + * checkpointer to perform restartpoints. We don't bother during + * crash recovery as restartpoints can only be performed during + * archive recovery. And we'd like to keep crash recovery simple, to + * avoid introducing bugs that could affect you when recovering after + * crash. + * + * After this point, we can no longer assume that we're the only + * process in addition to postmaster! Also, fsync requests are + * subsequently to be handled by the checkpointer, not locally. + */ + if (ArchiveRecoveryRequested && IsUnderPostmaster) + { + PublishStartupProcessInformation(); + EnableSyncRequestForwarding(); + SendPostmasterSignal(PMSIGNAL_RECOVERY_STARTED); + bgwriterLaunched = true; + } + + /* + * Allow read-only connections immediately if we're consistent + * already. + */ + CheckRecoveryConsistency(); + + /* + * Find the first record that logically follows the checkpoint --- it + * might physically precede it, though. + */ + if (checkPoint.redo < RecPtr) + { + /* back up to find the record */ + XLogBeginRead(xlogreader, checkPoint.redo); + record = ReadRecord(xlogreader, PANIC, false); + } + else + { + /* just have to read next record after CheckPoint */ + record = ReadRecord(xlogreader, LOG, false); + } + + if (record != NULL) + { + ErrorContextCallback errcallback; + TimestampTz xtime; + PGRUsage ru0; + + pg_rusage_init(&ru0); + + InRedo = true; + + ereport(LOG, + (errmsg("redo starts at %X/%X", + LSN_FORMAT_ARGS(ReadRecPtr)))); + + /* + * main redo apply loop + */ + do + { + bool switchedTLI = false; + +#ifdef WAL_DEBUG + if (XLOG_DEBUG || + (rmid == RM_XACT_ID && trace_recovery_messages <= DEBUG2) || + (rmid != RM_XACT_ID && trace_recovery_messages <= DEBUG3)) + { + StringInfoData buf; + + initStringInfo(&buf); + appendStringInfo(&buf, "REDO @ %X/%X; LSN %X/%X: ", + LSN_FORMAT_ARGS(ReadRecPtr), + LSN_FORMAT_ARGS(EndRecPtr)); + xlog_outrec(&buf, xlogreader); + appendStringInfoString(&buf, " - "); + xlog_outdesc(&buf, xlogreader); + elog(LOG, "%s", buf.data); + pfree(buf.data); + } +#endif + + /* Handle interrupt signals of startup process */ + HandleStartupProcInterrupts(); + + /* + * Pause WAL replay, if requested by a hot-standby session via + * SetRecoveryPause(). + * + * Note that we intentionally don't take the info_lck spinlock + * here. We might therefore read a slightly stale value of + * the recoveryPause flag, but it can't be very stale (no + * worse than the last spinlock we did acquire). Since a + * pause request is a pretty asynchronous thing anyway, + * possibly responding to it one WAL record later than we + * otherwise would is a minor issue, so it doesn't seem worth + * adding another spinlock cycle to prevent that. + */ + if (((volatile XLogCtlData *) XLogCtl)->recoveryPauseState != + RECOVERY_NOT_PAUSED) + recoveryPausesHere(false); + + /* + * Have we reached our recovery target? + */ + if (recoveryStopsBefore(xlogreader)) + { + reachedRecoveryTarget = true; + break; + } + + /* + * If we've been asked to lag the primary, wait on latch until + * enough time has passed. + */ + if (recoveryApplyDelay(xlogreader)) + { + /* + * We test for paused recovery again here. If user sets + * delayed apply, it may be because they expect to pause + * recovery in case of problems, so we must test again + * here otherwise pausing during the delay-wait wouldn't + * work. + */ + if (((volatile XLogCtlData *) XLogCtl)->recoveryPauseState != + RECOVERY_NOT_PAUSED) + recoveryPausesHere(false); + } + + /* Setup error traceback support for ereport() */ + errcallback.callback = rm_redo_error_callback; + errcallback.arg = (void *) xlogreader; + errcallback.previous = error_context_stack; + error_context_stack = &errcallback; + + /* + * ShmemVariableCache->nextXid must be beyond record's xid. + */ + AdvanceNextFullTransactionIdPastXid(record->xl_xid); + + /* + * Before replaying this record, check if this record causes + * the current timeline to change. The record is already + * considered to be part of the new timeline, so we update + * ThisTimeLineID before replaying it. That's important so + * that replayEndTLI, which is recorded as the minimum + * recovery point's TLI if recovery stops after this record, + * is set correctly. + */ + if (record->xl_rmid == RM_XLOG_ID) + { + TimeLineID newTLI = ThisTimeLineID; + TimeLineID prevTLI = ThisTimeLineID; + uint8 info = record->xl_info & ~XLR_INFO_MASK; + + if (info == XLOG_CHECKPOINT_SHUTDOWN) + { + CheckPoint checkPoint; + + memcpy(&checkPoint, XLogRecGetData(xlogreader), sizeof(CheckPoint)); + newTLI = checkPoint.ThisTimeLineID; + prevTLI = checkPoint.PrevTimeLineID; + } + else if (info == XLOG_END_OF_RECOVERY) + { + xl_end_of_recovery xlrec; + + memcpy(&xlrec, XLogRecGetData(xlogreader), sizeof(xl_end_of_recovery)); + newTLI = xlrec.ThisTimeLineID; + prevTLI = xlrec.PrevTimeLineID; + } + + if (newTLI != ThisTimeLineID) + { + /* Check that it's OK to switch to this TLI */ + checkTimeLineSwitch(EndRecPtr, newTLI, prevTLI); + + /* Following WAL records should be run with new TLI */ + ThisTimeLineID = newTLI; + switchedTLI = true; + } + } + + /* + * Update shared replayEndRecPtr before replaying this record, + * so that XLogFlush will update minRecoveryPoint correctly. + */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->replayEndRecPtr = EndRecPtr; + XLogCtl->replayEndTLI = ThisTimeLineID; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * If we are attempting to enter Hot Standby mode, process + * XIDs we see + */ + if (standbyState >= STANDBY_INITIALIZED && + TransactionIdIsValid(record->xl_xid)) + RecordKnownAssignedTransactionIds(record->xl_xid); + + /* Now apply the WAL record itself */ + RmgrTable[record->xl_rmid].rm_redo(xlogreader); + + /* + * After redo, check whether the backup pages associated with + * the WAL record are consistent with the existing pages. This + * check is done only if consistency check is enabled for this + * record. + */ + if ((record->xl_info & XLR_CHECK_CONSISTENCY) != 0) + checkXLogConsistency(xlogreader); + + /* Pop the error context stack */ + error_context_stack = errcallback.previous; + + /* + * Update lastReplayedEndRecPtr after this record has been + * successfully replayed. + */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->lastReplayedEndRecPtr = EndRecPtr; + XLogCtl->lastReplayedTLI = ThisTimeLineID; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * If rm_redo called XLogRequestWalReceiverReply, then we wake + * up the receiver so that it notices the updated + * lastReplayedEndRecPtr and sends a reply to the primary. + */ + if (doRequestWalReceiverReply) + { + doRequestWalReceiverReply = false; + WalRcvForceReply(); + } + + /* Remember this record as the last-applied one */ + LastRec = ReadRecPtr; + + /* Allow read-only connections if we're consistent now */ + CheckRecoveryConsistency(); + + /* Is this a timeline switch? */ + if (switchedTLI) + { + /* + * Before we continue on the new timeline, clean up any + * (possibly bogus) future WAL segments on the old + * timeline. + */ + RemoveNonParentXlogFiles(EndRecPtr, ThisTimeLineID); + + /* + * Wake up any walsenders to notice that we are on a new + * timeline. + */ + if (AllowCascadeReplication()) + WalSndWakeup(); + } + + /* Exit loop if we reached inclusive recovery target */ + if (recoveryStopsAfter(xlogreader)) + { + reachedRecoveryTarget = true; + break; + } + + /* Else, try to fetch the next WAL record */ + record = ReadRecord(xlogreader, LOG, false); + } while (record != NULL); + + /* + * end of main redo apply loop + */ + + if (reachedRecoveryTarget) + { + if (!reachedConsistency) + ereport(FATAL, + (errmsg("requested recovery stop point is before consistent recovery point"))); + + /* + * This is the last point where we can restart recovery with a + * new recovery target, if we shutdown and begin again. After + * this, Resource Managers may choose to do permanent + * corrective actions at end of recovery. + */ + switch (recoveryTargetAction) + { + case RECOVERY_TARGET_ACTION_SHUTDOWN: + + /* + * exit with special return code to request shutdown + * of postmaster. Log messages issued from + * postmaster. + */ + proc_exit(3); + + case RECOVERY_TARGET_ACTION_PAUSE: + SetRecoveryPause(true); + recoveryPausesHere(true); + + /* drop into promote */ + + case RECOVERY_TARGET_ACTION_PROMOTE: + break; + } + } + + /* Allow resource managers to do any required cleanup. */ + for (rmid = 0; rmid <= RM_MAX_ID; rmid++) + { + if (RmgrTable[rmid].rm_cleanup != NULL) + RmgrTable[rmid].rm_cleanup(); + } + + ereport(LOG, + (errmsg("redo done at %X/%X system usage: %s", + LSN_FORMAT_ARGS(ReadRecPtr), + pg_rusage_show(&ru0)))); + xtime = GetLatestXTime(); + if (xtime) + ereport(LOG, + (errmsg("last completed transaction was at log time %s", + timestamptz_to_str(xtime)))); + + InRedo = false; + } + else + { + /* there are no WAL records following the checkpoint */ + ereport(LOG, + (errmsg("redo is not required"))); + + } + + /* + * This check is intentionally after the above log messages that + * indicate how far recovery went. + */ + if (ArchiveRecoveryRequested && + recoveryTarget != RECOVERY_TARGET_UNSET && + !reachedRecoveryTarget) + ereport(FATAL, + (errmsg("recovery ended before configured recovery target was reached"))); + } + + /* + * Kill WAL receiver, if it's still running, before we continue to write + * the startup checkpoint and aborted-contrecord records. It will trump + * over these records and subsequent ones if it's still alive when we + * start writing WAL. + */ + ShutdownWalRcv(); + + /* + * Reset unlogged relations to the contents of their INIT fork. This is + * done AFTER recovery is complete so as to include any unlogged relations + * created during recovery, but BEFORE recovery is marked as having + * completed successfully. Otherwise we'd not retry if any of the post + * end-of-recovery steps fail. + */ + if (InRecovery) + ResetUnloggedRelations(UNLOGGED_RELATION_INIT); + + /* + * We don't need the latch anymore. It's not strictly necessary to disown + * it, but let's do it for the sake of tidiness. + */ + if (ArchiveRecoveryRequested) + DisownLatch(&XLogCtl->recoveryWakeupLatch); + + /* + * We are now done reading the xlog from stream. Turn off streaming + * recovery to force fetching the files (which would be required at end of + * recovery, e.g., timeline history file) from archive or pg_wal. + * + * Note that standby mode must be turned off after killing WAL receiver, + * i.e., calling ShutdownWalRcv(). + */ + Assert(!WalRcvStreaming()); + StandbyMode = false; + + /* + * Determine where to start writing WAL next. + * + * When recovery ended in an incomplete record, write a WAL record about + * that and continue after it. In all other cases, re-fetch the last + * valid or last applied record, so we can identify the exact endpoint of + * what we consider the valid portion of WAL. + */ + XLogBeginRead(xlogreader, LastRec); + record = ReadRecord(xlogreader, PANIC, false); + EndOfLog = EndRecPtr; + + /* + * EndOfLogTLI is the TLI in the filename of the XLOG segment containing + * the end-of-log. It could be different from the timeline that EndOfLog + * nominally belongs to, if there was a timeline switch in that segment, + * and we were reading the old WAL from a segment belonging to a higher + * timeline. + */ + EndOfLogTLI = xlogreader->seg.ws_tli; + + /* + * Complain if we did not roll forward far enough to render the backup + * dump consistent. Note: it is indeed okay to look at the local variable + * minRecoveryPoint here, even though ControlFile->minRecoveryPoint might + * be further ahead --- ControlFile->minRecoveryPoint cannot have been + * advanced beyond the WAL we processed. + */ + if (InRecovery && + (EndOfLog < minRecoveryPoint || + !XLogRecPtrIsInvalid(ControlFile->backupStartPoint))) + { + /* + * Ran off end of WAL before reaching end-of-backup WAL record, or + * minRecoveryPoint. That's usually a bad sign, indicating that you + * tried to recover from an online backup but never called + * pg_stop_backup(), or you didn't archive all the WAL up to that + * point. However, this also happens in crash recovery, if the system + * crashes while an online backup is in progress. We must not treat + * that as an error, or the database will refuse to start up. + */ + if (ArchiveRecoveryRequested || ControlFile->backupEndRequired) + { + if (ControlFile->backupEndRequired) + ereport(FATAL, + (errmsg("WAL ends before end of online backup"), + errhint("All WAL generated while online backup was taken must be available at recovery."))); + else if (!XLogRecPtrIsInvalid(ControlFile->backupStartPoint)) + ereport(FATAL, + (errmsg("WAL ends before end of online backup"), + errhint("Online backup started with pg_start_backup() must be ended with pg_stop_backup(), and all WAL up to that point must be available at recovery."))); + else + ereport(FATAL, + (errmsg("WAL ends before consistent recovery point"))); + } + } + + /* + * Pre-scan prepared transactions to find out the range of XIDs present. + * This information is not quite needed yet, but it is positioned here so + * as potential problems are detected before any on-disk change is done. + */ + oldestActiveXID = PrescanPreparedTransactions(NULL, NULL); + + /* + * Consider whether we need to assign a new timeline ID. + * + * If we are doing an archive recovery, we always assign a new ID. This + * handles a couple of issues. If we stopped short of the end of WAL + * during recovery, then we are clearly generating a new timeline and must + * assign it a unique new ID. Even if we ran to the end, modifying the + * current last segment is problematic because it may result in trying to + * overwrite an already-archived copy of that segment, and we encourage + * DBAs to make their archive_commands reject that. We can dodge the + * problem by making the new active segment have a new timeline ID. + * + * In a normal crash recovery, we can just extend the timeline we were in. + */ + PrevTimeLineID = ThisTimeLineID; + if (ArchiveRecoveryRequested) + { + char reason[200]; + char recoveryPath[MAXPGPATH]; + + Assert(InArchiveRecovery); + + ThisTimeLineID = findNewestTimeLine(recoveryTargetTLI) + 1; + ereport(LOG, + (errmsg("selected new timeline ID: %u", ThisTimeLineID))); + + /* + * Create a comment for the history file to explain why and where + * timeline changed. + */ + if (recoveryTarget == RECOVERY_TARGET_XID) + snprintf(reason, sizeof(reason), + "%s transaction %u", + recoveryStopAfter ? "after" : "before", + recoveryStopXid); + else if (recoveryTarget == RECOVERY_TARGET_TIME) + snprintf(reason, sizeof(reason), + "%s %s\n", + recoveryStopAfter ? "after" : "before", + timestamptz_to_str(recoveryStopTime)); + else if (recoveryTarget == RECOVERY_TARGET_LSN) + snprintf(reason, sizeof(reason), + "%s LSN %X/%X\n", + recoveryStopAfter ? "after" : "before", + LSN_FORMAT_ARGS(recoveryStopLSN)); + else if (recoveryTarget == RECOVERY_TARGET_NAME) + snprintf(reason, sizeof(reason), + "at restore point \"%s\"", + recoveryStopName); + else if (recoveryTarget == RECOVERY_TARGET_IMMEDIATE) + snprintf(reason, sizeof(reason), "reached consistency"); + else + snprintf(reason, sizeof(reason), "no recovery target specified"); + + /* + * We are now done reading the old WAL. Turn off archive fetching if + * it was active, and make a writable copy of the last WAL segment. + * (Note that we also have a copy of the last block of the old WAL in + * readBuf; we will use that below.) + */ + exitArchiveRecovery(EndOfLogTLI, EndOfLog); + + /* + * Write the timeline history file, and have it archived. After this + * point (or rather, as soon as the file is archived), the timeline + * will appear as "taken" in the WAL archive and to any standby + * servers. If we crash before actually switching to the new + * timeline, standby servers will nevertheless think that we switched + * to the new timeline, and will try to connect to the new timeline. + * To minimize the window for that, try to do as little as possible + * between here and writing the end-of-recovery record. + */ + writeTimeLineHistory(ThisTimeLineID, recoveryTargetTLI, + EndRecPtr, reason); + + /* + * Since there might be a partial WAL segment named RECOVERYXLOG, get + * rid of it. + */ + snprintf(recoveryPath, MAXPGPATH, XLOGDIR "/RECOVERYXLOG"); + unlink(recoveryPath); /* ignore any error */ + + /* Get rid of any remaining recovered timeline-history file, too */ + snprintf(recoveryPath, MAXPGPATH, XLOGDIR "/RECOVERYHISTORY"); + unlink(recoveryPath); /* ignore any error */ + } + + /* Save the selected TimeLineID in shared memory, too */ + XLogCtl->ThisTimeLineID = ThisTimeLineID; + XLogCtl->PrevTimeLineID = PrevTimeLineID; + + /* + * Actually, if WAL ended in an incomplete record, skip the parts that + * made it through and start writing after the portion that persisted. + * (It's critical to first write an OVERWRITE_CONTRECORD message, which + * we'll do as soon as we're open for writing new WAL.) + */ + if (!XLogRecPtrIsInvalid(missingContrecPtr)) + { + Assert(!XLogRecPtrIsInvalid(abortedRecPtr)); + EndOfLog = missingContrecPtr; + } + + /* + * Prepare to write WAL starting at EndOfLog location, and init xlog + * buffer cache using the block containing the last record from the + * previous incarnation. + */ + Insert = &XLogCtl->Insert; + Insert->PrevBytePos = XLogRecPtrToBytePos(LastRec); + Insert->CurrBytePos = XLogRecPtrToBytePos(EndOfLog); + + /* + * Tricky point here: readBuf contains the *last* block that the LastRec + * record spans, not the one it starts in. The last block is indeed the + * one we want to use. + */ + if (EndOfLog % XLOG_BLCKSZ != 0) + { + char *page; + int len; + int firstIdx; + XLogRecPtr pageBeginPtr; + + pageBeginPtr = EndOfLog - (EndOfLog % XLOG_BLCKSZ); + Assert(readOff == XLogSegmentOffset(pageBeginPtr, wal_segment_size)); + + firstIdx = XLogRecPtrToBufIdx(EndOfLog); + + /* Copy the valid part of the last block, and zero the rest */ + page = &XLogCtl->pages[firstIdx * XLOG_BLCKSZ]; + len = EndOfLog % XLOG_BLCKSZ; + memcpy(page, xlogreader->readBuf, len); + memset(page + len, 0, XLOG_BLCKSZ - len); + + XLogCtl->xlblocks[firstIdx] = pageBeginPtr + XLOG_BLCKSZ; + XLogCtl->InitializedUpTo = pageBeginPtr + XLOG_BLCKSZ; + } + else + { + /* + * There is no partial block to copy. Just set InitializedUpTo, and + * let the first attempt to insert a log record to initialize the next + * buffer. + */ + XLogCtl->InitializedUpTo = EndOfLog; + } + + LogwrtResult.Write = LogwrtResult.Flush = EndOfLog; + + XLogCtl->LogwrtResult = LogwrtResult; + + XLogCtl->LogwrtRqst.Write = EndOfLog; + XLogCtl->LogwrtRqst.Flush = EndOfLog; + + LocalSetXLogInsertAllowed(); + + /* If necessary, write overwrite-contrecord before doing anything else */ + if (!XLogRecPtrIsInvalid(abortedRecPtr)) + { + Assert(!XLogRecPtrIsInvalid(missingContrecPtr)); + CreateOverwriteContrecordRecord(abortedRecPtr); + abortedRecPtr = InvalidXLogRecPtr; + missingContrecPtr = InvalidXLogRecPtr; + } + + /* + * Update full_page_writes in shared memory and write an XLOG_FPW_CHANGE + * record before resource manager writes cleanup WAL records or checkpoint + * record is written. + */ + Insert->fullPageWrites = lastFullPageWrites; + UpdateFullPageWrites(); + LocalXLogInsertAllowed = -1; + + if (InRecovery) + { + /* + * Perform a checkpoint to update all our recovery activity to disk. + * + * Note that we write a shutdown checkpoint rather than an on-line + * one. This is not particularly critical, but since we may be + * assigning a new TLI, using a shutdown checkpoint allows us to have + * the rule that TLI only changes in shutdown checkpoints, which + * allows some extra error checking in xlog_redo. + * + * In promotion, only create a lightweight end-of-recovery record + * instead of a full checkpoint. A checkpoint is requested later, + * after we're fully out of recovery mode and already accepting + * queries. + */ + if (bgwriterLaunched) + { + if (LocalPromoteIsTriggered) + { + checkPointLoc = ControlFile->checkPoint; + + /* + * Confirm the last checkpoint is available for us to recover + * from if we fail. + */ + record = ReadCheckpointRecord(xlogreader, checkPointLoc, 1, false); + if (record != NULL) + { + promoted = true; + + /* + * Insert a special WAL record to mark the end of + * recovery, since we aren't doing a checkpoint. That + * means that the checkpointer process may likely be in + * the middle of a time-smoothed restartpoint and could + * continue to be for minutes after this. That sounds + * strange, but the effect is roughly the same and it + * would be stranger to try to come out of the + * restartpoint and then checkpoint. We request a + * checkpoint later anyway, just for safety. + */ + CreateEndOfRecoveryRecord(); + } + } + + if (!promoted) + RequestCheckpoint(CHECKPOINT_END_OF_RECOVERY | + CHECKPOINT_IMMEDIATE | + CHECKPOINT_WAIT); + } + else + CreateCheckPoint(CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_IMMEDIATE); + } + + if (ArchiveRecoveryRequested) + { + /* + * And finally, execute the recovery_end_command, if any. + */ + if (recoveryEndCommand && strcmp(recoveryEndCommand, "") != 0) + ExecuteRecoveryCommand(recoveryEndCommand, + "recovery_end_command", + true); + + /* + * We switched to a new timeline. Clean up segments on the old + * timeline. + * + * If there are any higher-numbered segments on the old timeline, + * remove them. They might contain valid WAL, but they might also be + * pre-allocated files containing garbage. In any case, they are not + * part of the new timeline's history so we don't need them. + */ + RemoveNonParentXlogFiles(EndOfLog, ThisTimeLineID); + + /* + * If the switch happened in the middle of a segment, what to do with + * the last, partial segment on the old timeline? If we don't archive + * it, and the server that created the WAL never archives it either + * (e.g. because it was hit by a meteor), it will never make it to the + * archive. That's OK from our point of view, because the new segment + * that we created with the new TLI contains all the WAL from the old + * timeline up to the switch point. But if you later try to do PITR to + * the "missing" WAL on the old timeline, recovery won't find it in + * the archive. It's physically present in the new file with new TLI, + * but recovery won't look there when it's recovering to the older + * timeline. On the other hand, if we archive the partial segment, and + * the original server on that timeline is still running and archives + * the completed version of the same segment later, it will fail. (We + * used to do that in 9.4 and below, and it caused such problems). + * + * As a compromise, we rename the last segment with the .partial + * suffix, and archive it. Archive recovery will never try to read + * .partial segments, so they will normally go unused. But in the odd + * PITR case, the administrator can copy them manually to the pg_wal + * directory (removing the suffix). They can be useful in debugging, + * too. + * + * If a .done or .ready file already exists for the old timeline, + * however, we had already determined that the segment is complete, so + * we can let it be archived normally. (In particular, if it was + * restored from the archive to begin with, it's expected to have a + * .done file). + */ + if (XLogSegmentOffset(EndOfLog, wal_segment_size) != 0 && + XLogArchivingActive()) + { + char origfname[MAXFNAMELEN]; + XLogSegNo endLogSegNo; + + XLByteToPrevSeg(EndOfLog, endLogSegNo, wal_segment_size); + XLogFileName(origfname, EndOfLogTLI, endLogSegNo, wal_segment_size); + + if (!XLogArchiveIsReadyOrDone(origfname)) + { + char origpath[MAXPGPATH]; + char partialfname[MAXFNAMELEN]; + char partialpath[MAXPGPATH]; + + XLogFilePath(origpath, EndOfLogTLI, endLogSegNo, wal_segment_size); + snprintf(partialfname, MAXFNAMELEN, "%s.partial", origfname); + snprintf(partialpath, MAXPGPATH, "%s.partial", origpath); + + /* + * Make sure there's no .done or .ready file for the .partial + * file. + */ + XLogArchiveCleanup(partialfname); + + durable_rename(origpath, partialpath, ERROR); + XLogArchiveNotify(partialfname); + } + } + } + + /* + * Preallocate additional log files, if wanted. + */ + PreallocXlogFiles(EndOfLog); + + /* + * Okay, we're officially UP. + */ + InRecovery = false; + + /* start the archive_timeout timer and LSN running */ + XLogCtl->lastSegSwitchTime = (pg_time_t) time(NULL); + XLogCtl->lastSegSwitchLSN = EndOfLog; + + /* also initialize latestCompletedXid, to nextXid - 1 */ + LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); + ShmemVariableCache->latestCompletedXid = ShmemVariableCache->nextXid; + FullTransactionIdRetreat(&ShmemVariableCache->latestCompletedXid); + LWLockRelease(ProcArrayLock); + + /* + * Start up subtrans, if not already done for hot standby. (commit + * timestamps are started below, if necessary.) + */ + if (standbyState == STANDBY_DISABLED) + StartupSUBTRANS(oldestActiveXID); + + /* + * Perform end of recovery actions for any SLRUs that need it. + */ + TrimCLOG(); + TrimMultiXact(); + + /* Reload shared-memory state for prepared transactions */ + RecoverPreparedTransactions(); + + /* Shut down xlogreader */ + if (readFile >= 0) + { + close(readFile); + readFile = -1; + } + XLogReaderFree(xlogreader); + + /* + * If any of the critical GUCs have changed, log them before we allow + * backends to write WAL. + */ + LocalSetXLogInsertAllowed(); + XLogReportParameters(); + + /* + * Local WAL inserts enabled, so it's time to finish initialization of + * commit timestamp. + */ + CompleteCommitTsInitialization(); + + /* + * All done with end-of-recovery actions. + * + * Now allow backends to write WAL and update the control file status in + * consequence. SharedRecoveryState, that controls if backends can write + * WAL, is updated while holding ControlFileLock to prevent other backends + * to look at an inconsistent state of the control file in shared memory. + * There is still a small window during which backends can write WAL and + * the control file is still referring to a system not in DB_IN_PRODUCTION + * state while looking at the on-disk control file. + * + * Also, we use info_lck to update SharedRecoveryState to ensure that + * there are no race conditions concerning visibility of other recent + * updates to shared memory. + */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->state = DB_IN_PRODUCTION; + ControlFile->time = (pg_time_t) time(NULL); + + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->SharedRecoveryState = RECOVERY_STATE_DONE; + SpinLockRelease(&XLogCtl->info_lck); + + UpdateControlFile(); + LWLockRelease(ControlFileLock); + + /* + * Shutdown the recovery environment. This must occur after + * RecoverPreparedTransactions() (see notes in lock_twophase_recover()) + * and after switching SharedRecoveryState to RECOVERY_STATE_DONE so as + * any session building a snapshot will not rely on KnownAssignedXids as + * RecoveryInProgress() would return false at this stage. This is + * particularly critical for prepared 2PC transactions, that would still + * need to be included in snapshots once recovery has ended. + */ + if (standbyState != STANDBY_DISABLED) + ShutdownRecoveryTransactionEnvironment(); + + /* + * If there were cascading standby servers connected to us, nudge any wal + * sender processes to notice that we've been promoted. + */ + WalSndWakeup(); + + /* + * If this was a promotion, request an (online) checkpoint now. This isn't + * required for consistency, but the last restartpoint might be far back, + * and in case of a crash, recovering from it might take a longer than is + * appropriate now that we're not in standby mode anymore. + */ + if (promoted) + RequestCheckpoint(CHECKPOINT_FORCE); +} + +/* + * Verify that, in non-test mode, ./pg_tblspc doesn't contain any real + * directories. + * + * Replay of database creation XLOG records for databases that were later + * dropped can create fake directories in pg_tblspc. By the time consistency + * is reached these directories should have been removed; here we verify + * that this did indeed happen. This is to be called at the point where + * consistent state is reached. + * + * allow_in_place_tablespaces turns the PANIC into a WARNING, which is + * useful for testing purposes, and also allows for an escape hatch in case + * things go south. + */ +static void +CheckTablespaceDirectory(void) +{ + DIR *dir; + struct dirent *de; + + dir = AllocateDir("pg_tblspc"); + while ((de = ReadDir(dir, "pg_tblspc")) != NULL) + { + char path[MAXPGPATH + 10]; + + /* Skip entries of non-oid names */ + if (strspn(de->d_name, "0123456789") != strlen(de->d_name)) + continue; + + snprintf(path, sizeof(path), "pg_tblspc/%s", de->d_name); + + if (get_dirent_type(path, de, false, ERROR) != PGFILETYPE_LNK) + ereport(allow_in_place_tablespaces ? WARNING : PANIC, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg("unexpected directory entry \"%s\" found in %s", + de->d_name, "pg_tblspc/"), + errdetail("All directory entries in pg_tblspc/ should be symbolic links."), + errhint("Remove those directories, or set allow_in_place_tablespaces to ON transiently to let recovery complete."))); + } +} + +/* + * Checks if recovery has reached a consistent state. When consistency is + * reached and we have a valid starting standby snapshot, tell postmaster + * that it can start accepting read-only connections. + */ +static void +CheckRecoveryConsistency(void) +{ + XLogRecPtr lastReplayedEndRecPtr; + + /* + * During crash recovery, we don't reach a consistent state until we've + * replayed all the WAL. + */ + if (XLogRecPtrIsInvalid(minRecoveryPoint)) + return; + + Assert(InArchiveRecovery); + + /* + * assume that we are called in the startup process, and hence don't need + * a lock to read lastReplayedEndRecPtr + */ + lastReplayedEndRecPtr = XLogCtl->lastReplayedEndRecPtr; + + /* + * Have we reached the point where our base backup was completed? + */ + if (!XLogRecPtrIsInvalid(ControlFile->backupEndPoint) && + ControlFile->backupEndPoint <= lastReplayedEndRecPtr) + { + /* + * We have reached the end of base backup, as indicated by pg_control. + * The data on disk is now consistent. Reset backupStartPoint and + * backupEndPoint, and update minRecoveryPoint to make sure we don't + * allow starting up at an earlier point even if recovery is stopped + * and restarted soon after this. + */ + elog(DEBUG1, "end of backup reached"); + + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + + if (ControlFile->minRecoveryPoint < lastReplayedEndRecPtr) + ControlFile->minRecoveryPoint = lastReplayedEndRecPtr; + + ControlFile->backupStartPoint = InvalidXLogRecPtr; + ControlFile->backupEndPoint = InvalidXLogRecPtr; + ControlFile->backupEndRequired = false; + UpdateControlFile(); + + LWLockRelease(ControlFileLock); + } + + /* + * Have we passed our safe starting point? Note that minRecoveryPoint is + * known to be incorrectly set if ControlFile->backupEndRequired, until + * the XLOG_BACKUP_END arrives to advise us of the correct + * minRecoveryPoint. All we know prior to that is that we're not + * consistent yet. + */ + if (!reachedConsistency && !ControlFile->backupEndRequired && + minRecoveryPoint <= lastReplayedEndRecPtr && + XLogRecPtrIsInvalid(ControlFile->backupStartPoint)) + { + /* + * Check to see if the XLOG sequence contained any unresolved + * references to uninitialized pages. + */ + XLogCheckInvalidPages(); + + /* + * Check that pg_tblspc doesn't contain any real directories. Replay + * of Database/CREATE_* records may have created ficticious tablespace + * directories that should have been removed by the time consistency + * was reached. + */ + CheckTablespaceDirectory(); + + reachedConsistency = true; + ereport(LOG, + (errmsg("consistent recovery state reached at %X/%X", + LSN_FORMAT_ARGS(lastReplayedEndRecPtr)))); + } + + /* + * Have we got a valid starting snapshot that will allow queries to be + * run? If so, we can tell postmaster that the database is consistent now, + * enabling connections. + */ + if (standbyState == STANDBY_SNAPSHOT_READY && + !LocalHotStandbyActive && + reachedConsistency && + IsUnderPostmaster) + { + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->SharedHotStandbyActive = true; + SpinLockRelease(&XLogCtl->info_lck); + + LocalHotStandbyActive = true; + + SendPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY); + } +} + +/* + * Is the system still in recovery? + * + * Unlike testing InRecovery, this works in any process that's connected to + * shared memory. + * + * As a side-effect, we initialize the local TimeLineID and RedoRecPtr + * variables the first time we see that recovery is finished. + */ +bool +RecoveryInProgress(void) +{ + /* + * We check shared state each time only until we leave recovery mode. We + * can't re-enter recovery, so there's no need to keep checking after the + * shared variable has once been seen false. + */ + if (!LocalRecoveryInProgress) + return false; + else + { + /* + * use volatile pointer to make sure we make a fresh read of the + * shared variable. + */ + volatile XLogCtlData *xlogctl = XLogCtl; + + LocalRecoveryInProgress = (xlogctl->SharedRecoveryState != RECOVERY_STATE_DONE); + + /* + * Initialize TimeLineID and RedoRecPtr when we discover that recovery + * is finished. InitPostgres() relies upon this behaviour to ensure + * that InitXLOGAccess() is called at backend startup. (If you change + * this, see also LocalSetXLogInsertAllowed.) + */ + if (!LocalRecoveryInProgress) + { + /* + * If we just exited recovery, make sure we read TimeLineID and + * RedoRecPtr after SharedRecoveryState (for machines with weak + * memory ordering). + */ + pg_memory_barrier(); + InitXLOGAccess(); + } + + /* + * Note: We don't need a memory barrier when we're still in recovery. + * We might exit recovery immediately after return, so the caller + * can't rely on 'true' meaning that we're still in recovery anyway. + */ + + return LocalRecoveryInProgress; + } +} + +/* + * Returns current recovery state from shared memory. + * + * This returned state is kept consistent with the contents of the control + * file. See details about the possible values of RecoveryState in xlog.h. + */ +RecoveryState +GetRecoveryState(void) +{ + RecoveryState retval; + + SpinLockAcquire(&XLogCtl->info_lck); + retval = XLogCtl->SharedRecoveryState; + SpinLockRelease(&XLogCtl->info_lck); + + return retval; +} + +/* + * Is HotStandby active yet? This is only important in special backends + * since normal backends won't ever be able to connect until this returns + * true. Postmaster knows this by way of signal, not via shared memory. + * + * Unlike testing standbyState, this works in any process that's connected to + * shared memory. (And note that standbyState alone doesn't tell the truth + * anyway.) + */ +bool +HotStandbyActive(void) +{ + /* + * We check shared state each time only until Hot Standby is active. We + * can't de-activate Hot Standby, so there's no need to keep checking + * after the shared variable has once been seen true. + */ + if (LocalHotStandbyActive) + return true; + else + { + /* spinlock is essential on machines with weak memory ordering! */ + SpinLockAcquire(&XLogCtl->info_lck); + LocalHotStandbyActive = XLogCtl->SharedHotStandbyActive; + SpinLockRelease(&XLogCtl->info_lck); + + return LocalHotStandbyActive; + } +} + +/* + * Like HotStandbyActive(), but to be used only in WAL replay code, + * where we don't need to ask any other process what the state is. + */ +bool +HotStandbyActiveInReplay(void) +{ + Assert(AmStartupProcess() || !IsPostmasterEnvironment); + return LocalHotStandbyActive; +} + +/* + * Is this process allowed to insert new WAL records? + * + * Ordinarily this is essentially equivalent to !RecoveryInProgress(). + * But we also have provisions for forcing the result "true" or "false" + * within specific processes regardless of the global state. + */ +bool +XLogInsertAllowed(void) +{ + /* + * If value is "unconditionally true" or "unconditionally false", just + * return it. This provides the normal fast path once recovery is known + * done. + */ + if (LocalXLogInsertAllowed >= 0) + return (bool) LocalXLogInsertAllowed; + + /* + * Else, must check to see if we're still in recovery. + */ + if (RecoveryInProgress()) + return false; + + /* + * On exit from recovery, reset to "unconditionally true", since there is + * no need to keep checking. + */ + LocalXLogInsertAllowed = 1; + return true; +} + +/* + * Make XLogInsertAllowed() return true in the current process only. + * + * Note: it is allowed to switch LocalXLogInsertAllowed back to -1 later, + * and even call LocalSetXLogInsertAllowed() again after that. + */ +static void +LocalSetXLogInsertAllowed(void) +{ + Assert(LocalXLogInsertAllowed == -1); + LocalXLogInsertAllowed = 1; + + /* Initialize as RecoveryInProgress() would do when switching state */ + InitXLOGAccess(); +} + +/* + * Subroutine to try to fetch and validate a prior checkpoint record. + * + * whichChkpt identifies the checkpoint (merely for reporting purposes). + * 1 for "primary", 0 for "other" (backup_label) + */ +static XLogRecord * +ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr, + int whichChkpt, bool report) +{ + XLogRecord *record; + uint8 info; + + if (!XRecOffIsValid(RecPtr)) + { + if (!report) + return NULL; + + switch (whichChkpt) + { + case 1: + ereport(LOG, + (errmsg("invalid primary checkpoint link in control file"))); + break; + default: + ereport(LOG, + (errmsg("invalid checkpoint link in backup_label file"))); + break; + } + return NULL; + } + + XLogBeginRead(xlogreader, RecPtr); + record = ReadRecord(xlogreader, LOG, true); + + if (record == NULL) + { + if (!report) + return NULL; + + switch (whichChkpt) + { + case 1: + ereport(LOG, + (errmsg("invalid primary checkpoint record"))); + break; + default: + ereport(LOG, + (errmsg("invalid checkpoint record"))); + break; + } + return NULL; + } + if (record->xl_rmid != RM_XLOG_ID) + { + switch (whichChkpt) + { + case 1: + ereport(LOG, + (errmsg("invalid resource manager ID in primary checkpoint record"))); + break; + default: + ereport(LOG, + (errmsg("invalid resource manager ID in checkpoint record"))); + break; + } + return NULL; + } + info = record->xl_info & ~XLR_INFO_MASK; + if (info != XLOG_CHECKPOINT_SHUTDOWN && + info != XLOG_CHECKPOINT_ONLINE) + { + switch (whichChkpt) + { + case 1: + ereport(LOG, + (errmsg("invalid xl_info in primary checkpoint record"))); + break; + default: + ereport(LOG, + (errmsg("invalid xl_info in checkpoint record"))); + break; + } + return NULL; + } + if (record->xl_tot_len != SizeOfXLogRecord + SizeOfXLogRecordDataHeaderShort + sizeof(CheckPoint)) + { + switch (whichChkpt) + { + case 1: + ereport(LOG, + (errmsg("invalid length of primary checkpoint record"))); + break; + default: + ereport(LOG, + (errmsg("invalid length of checkpoint record"))); + break; + } + return NULL; + } + return record; +} + +/* + * This must be called in a backend process before creating WAL records + * (except in a standalone backend, which does StartupXLOG instead). We need + * to initialize the local copies of ThisTimeLineID and RedoRecPtr. + * + * Note: before Postgres 8.0, we went to some effort to keep the postmaster + * process's copies of ThisTimeLineID and RedoRecPtr valid too. This was + * unnecessary however, since the postmaster itself never touches XLOG anyway. + */ +void +InitXLOGAccess(void) +{ + XLogCtlInsert *Insert = &XLogCtl->Insert; + + /* ThisTimeLineID doesn't change so we need no lock to copy it */ + ThisTimeLineID = XLogCtl->ThisTimeLineID; + Assert(ThisTimeLineID != 0 || IsBootstrapProcessingMode()); + + /* set wal_segment_size */ + wal_segment_size = ControlFile->xlog_seg_size; + + /* Use GetRedoRecPtr to copy the RedoRecPtr safely */ + (void) GetRedoRecPtr(); + /* Also update our copy of doPageWrites. */ + doPageWrites = (Insert->fullPageWrites || Insert->forcePageWrites); + + /* Also initialize the working areas for constructing WAL records */ + InitXLogInsert(); +} + +/* + * Return the current Redo pointer from shared memory. + * + * As a side-effect, the local RedoRecPtr copy is updated. + */ +XLogRecPtr +GetRedoRecPtr(void) +{ + XLogRecPtr ptr; + + /* + * The possibly not up-to-date copy in XlogCtl is enough. Even if we + * grabbed a WAL insertion lock to read the authoritative value in + * Insert->RedoRecPtr, someone might update it just after we've released + * the lock. + */ + SpinLockAcquire(&XLogCtl->info_lck); + ptr = XLogCtl->RedoRecPtr; + SpinLockRelease(&XLogCtl->info_lck); + + if (RedoRecPtr < ptr) + RedoRecPtr = ptr; + + return RedoRecPtr; +} + +/* + * Return information needed to decide whether a modified block needs a + * full-page image to be included in the WAL record. + * + * The returned values are cached copies from backend-private memory, and + * possibly out-of-date. XLogInsertRecord will re-check them against + * up-to-date values, while holding the WAL insert lock. + */ +void +GetFullPageWriteInfo(XLogRecPtr *RedoRecPtr_p, bool *doPageWrites_p) +{ + *RedoRecPtr_p = RedoRecPtr; + *doPageWrites_p = doPageWrites; +} + +/* + * GetInsertRecPtr -- Returns the current insert position. + * + * NOTE: The value *actually* returned is the position of the last full + * xlog page. It lags behind the real insert position by at most 1 page. + * For that, we don't need to scan through WAL insertion locks, and an + * approximation is enough for the current usage of this function. + */ +XLogRecPtr +GetInsertRecPtr(void) +{ + XLogRecPtr recptr; + + SpinLockAcquire(&XLogCtl->info_lck); + recptr = XLogCtl->LogwrtRqst.Write; + SpinLockRelease(&XLogCtl->info_lck); + + return recptr; +} + +/* + * GetFlushRecPtr -- Returns the current flush position, ie, the last WAL + * position known to be fsync'd to disk. + */ +XLogRecPtr +GetFlushRecPtr(void) +{ + SpinLockAcquire(&XLogCtl->info_lck); + LogwrtResult = XLogCtl->LogwrtResult; + SpinLockRelease(&XLogCtl->info_lck); + + return LogwrtResult.Flush; +} + +/* + * GetLastImportantRecPtr -- Returns the LSN of the last important record + * inserted. All records not explicitly marked as unimportant are considered + * important. + * + * The LSN is determined by computing the maximum of + * WALInsertLocks[i].lastImportantAt. + */ +XLogRecPtr +GetLastImportantRecPtr(void) +{ + XLogRecPtr res = InvalidXLogRecPtr; + int i; + + for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++) + { + XLogRecPtr last_important; + + /* + * Need to take a lock to prevent torn reads of the LSN, which are + * possible on some of the supported platforms. WAL insert locks only + * support exclusive mode, so we have to use that. + */ + LWLockAcquire(&WALInsertLocks[i].l.lock, LW_EXCLUSIVE); + last_important = WALInsertLocks[i].l.lastImportantAt; + LWLockRelease(&WALInsertLocks[i].l.lock); + + if (res < last_important) + res = last_important; + } + + return res; +} + +/* + * Get the time and LSN of the last xlog segment switch + */ +pg_time_t +GetLastSegSwitchData(XLogRecPtr *lastSwitchLSN) +{ + pg_time_t result; + + /* Need WALWriteLock, but shared lock is sufficient */ + LWLockAcquire(WALWriteLock, LW_SHARED); + result = XLogCtl->lastSegSwitchTime; + *lastSwitchLSN = XLogCtl->lastSegSwitchLSN; + LWLockRelease(WALWriteLock); + + return result; +} + +/* + * This must be called ONCE during postmaster or standalone-backend shutdown + */ +void +ShutdownXLOG(int code, Datum arg) +{ + /* + * We should have an aux process resource owner to use, and we should not + * be in a transaction that's installed some other resowner. + */ + Assert(AuxProcessResourceOwner != NULL); + Assert(CurrentResourceOwner == NULL || + CurrentResourceOwner == AuxProcessResourceOwner); + CurrentResourceOwner = AuxProcessResourceOwner; + + /* Don't be chatty in standalone mode */ + ereport(IsPostmasterEnvironment ? LOG : NOTICE, + (errmsg("shutting down"))); + + /* + * Signal walsenders to move to stopping state. + */ + WalSndInitStopping(); + + /* + * Wait for WAL senders to be in stopping state. This prevents commands + * from writing new WAL. + */ + WalSndWaitStopping(); + + if (RecoveryInProgress()) + CreateRestartPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE); + else + { + /* + * If archiving is enabled, rotate the last XLOG file so that all the + * remaining records are archived (postmaster wakes up the archiver + * process one more time at the end of shutdown). The checkpoint + * record will go to the next XLOG file and won't be archived (yet). + */ + if (XLogArchivingActive() && XLogArchiveCommandSet()) + RequestXLogSwitch(false); + + CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE); + } +} + +/* + * Log start of a checkpoint. + */ +static void +LogCheckpointStart(int flags, bool restartpoint) +{ + if (restartpoint) + ereport(LOG, + /* translator: the placeholders show checkpoint options */ + (errmsg("restartpoint starting:%s%s%s%s%s%s%s%s", + (flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "", + (flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "", + (flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "", + (flags & CHECKPOINT_FORCE) ? " force" : "", + (flags & CHECKPOINT_WAIT) ? " wait" : "", + (flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "", + (flags & CHECKPOINT_CAUSE_TIME) ? " time" : "", + (flags & CHECKPOINT_FLUSH_ALL) ? " flush-all" : ""))); + else + ereport(LOG, + /* translator: the placeholders show checkpoint options */ + (errmsg("checkpoint starting:%s%s%s%s%s%s%s%s", + (flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "", + (flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "", + (flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "", + (flags & CHECKPOINT_FORCE) ? " force" : "", + (flags & CHECKPOINT_WAIT) ? " wait" : "", + (flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "", + (flags & CHECKPOINT_CAUSE_TIME) ? " time" : "", + (flags & CHECKPOINT_FLUSH_ALL) ? " flush-all" : ""))); +} + +/* + * Log end of a checkpoint. + */ +static void +LogCheckpointEnd(bool restartpoint) +{ + long write_msecs, + sync_msecs, + total_msecs, + longest_msecs, + average_msecs; + uint64 average_sync_time; + + CheckpointStats.ckpt_end_t = GetCurrentTimestamp(); + + write_msecs = TimestampDifferenceMilliseconds(CheckpointStats.ckpt_write_t, + CheckpointStats.ckpt_sync_t); + + sync_msecs = TimestampDifferenceMilliseconds(CheckpointStats.ckpt_sync_t, + CheckpointStats.ckpt_sync_end_t); + + /* Accumulate checkpoint timing summary data, in milliseconds. */ + BgWriterStats.m_checkpoint_write_time += write_msecs; + BgWriterStats.m_checkpoint_sync_time += sync_msecs; + + /* + * All of the published timing statistics are accounted for. Only + * continue if a log message is to be written. + */ + if (!log_checkpoints) + return; + + total_msecs = TimestampDifferenceMilliseconds(CheckpointStats.ckpt_start_t, + CheckpointStats.ckpt_end_t); + + /* + * Timing values returned from CheckpointStats are in microseconds. + * Convert to milliseconds for consistent printing. + */ + longest_msecs = (long) ((CheckpointStats.ckpt_longest_sync + 999) / 1000); + + average_sync_time = 0; + if (CheckpointStats.ckpt_sync_rels > 0) + average_sync_time = CheckpointStats.ckpt_agg_sync_time / + CheckpointStats.ckpt_sync_rels; + average_msecs = (long) ((average_sync_time + 999) / 1000); + + if (restartpoint) + ereport(LOG, + (errmsg("restartpoint complete: wrote %d buffers (%.1f%%); " + "%d WAL file(s) added, %d removed, %d recycled; " + "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; " + "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s; " + "distance=%d kB, estimate=%d kB", + CheckpointStats.ckpt_bufs_written, + (double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers, + CheckpointStats.ckpt_segs_added, + CheckpointStats.ckpt_segs_removed, + CheckpointStats.ckpt_segs_recycled, + write_msecs / 1000, (int) (write_msecs % 1000), + sync_msecs / 1000, (int) (sync_msecs % 1000), + total_msecs / 1000, (int) (total_msecs % 1000), + CheckpointStats.ckpt_sync_rels, + longest_msecs / 1000, (int) (longest_msecs % 1000), + average_msecs / 1000, (int) (average_msecs % 1000), + (int) (PrevCheckPointDistance / 1024.0), + (int) (CheckPointDistanceEstimate / 1024.0)))); + else + ereport(LOG, + (errmsg("checkpoint complete: wrote %d buffers (%.1f%%); " + "%d WAL file(s) added, %d removed, %d recycled; " + "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; " + "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s; " + "distance=%d kB, estimate=%d kB", + CheckpointStats.ckpt_bufs_written, + (double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers, + CheckpointStats.ckpt_segs_added, + CheckpointStats.ckpt_segs_removed, + CheckpointStats.ckpt_segs_recycled, + write_msecs / 1000, (int) (write_msecs % 1000), + sync_msecs / 1000, (int) (sync_msecs % 1000), + total_msecs / 1000, (int) (total_msecs % 1000), + CheckpointStats.ckpt_sync_rels, + longest_msecs / 1000, (int) (longest_msecs % 1000), + average_msecs / 1000, (int) (average_msecs % 1000), + (int) (PrevCheckPointDistance / 1024.0), + (int) (CheckPointDistanceEstimate / 1024.0)))); +} + +/* + * Update the estimate of distance between checkpoints. + * + * The estimate is used to calculate the number of WAL segments to keep + * preallocated, see XLOGfileslop(). + */ +static void +UpdateCheckPointDistanceEstimate(uint64 nbytes) +{ + /* + * To estimate the number of segments consumed between checkpoints, keep a + * moving average of the amount of WAL generated in previous checkpoint + * cycles. However, if the load is bursty, with quiet periods and busy + * periods, we want to cater for the peak load. So instead of a plain + * moving average, let the average decline slowly if the previous cycle + * used less WAL than estimated, but bump it up immediately if it used + * more. + * + * When checkpoints are triggered by max_wal_size, this should converge to + * CheckpointSegments * wal_segment_size, + * + * Note: This doesn't pay any attention to what caused the checkpoint. + * Checkpoints triggered manually with CHECKPOINT command, or by e.g. + * starting a base backup, are counted the same as those created + * automatically. The slow-decline will largely mask them out, if they are + * not frequent. If they are frequent, it seems reasonable to count them + * in as any others; if you issue a manual checkpoint every 5 minutes and + * never let a timed checkpoint happen, it makes sense to base the + * preallocation on that 5 minute interval rather than whatever + * checkpoint_timeout is set to. + */ + PrevCheckPointDistance = nbytes; + if (CheckPointDistanceEstimate < nbytes) + CheckPointDistanceEstimate = nbytes; + else + CheckPointDistanceEstimate = + (0.90 * CheckPointDistanceEstimate + 0.10 * (double) nbytes); +} + +/* + * Update the ps display for a process running a checkpoint. Note that + * this routine should not do any allocations so as it can be called + * from a critical section. + */ +static void +update_checkpoint_display(int flags, bool restartpoint, bool reset) +{ + /* + * The status is reported only for end-of-recovery and shutdown + * checkpoints or shutdown restartpoints. Updating the ps display is + * useful in those situations as it may not be possible to rely on + * pg_stat_activity to see the status of the checkpointer or the startup + * process. + */ + if ((flags & (CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_IS_SHUTDOWN)) == 0) + return; + + if (reset) + set_ps_display(""); + else + { + char activitymsg[128]; + + snprintf(activitymsg, sizeof(activitymsg), "performing %s%s%s", + (flags & CHECKPOINT_END_OF_RECOVERY) ? "end-of-recovery " : "", + (flags & CHECKPOINT_IS_SHUTDOWN) ? "shutdown " : "", + restartpoint ? "restartpoint" : "checkpoint"); + set_ps_display(activitymsg); + } +} + + +/* + * Perform a checkpoint --- either during shutdown, or on-the-fly + * + * flags is a bitwise OR of the following: + * CHECKPOINT_IS_SHUTDOWN: checkpoint is for database shutdown. + * CHECKPOINT_END_OF_RECOVERY: checkpoint is for end of WAL recovery. + * CHECKPOINT_IMMEDIATE: finish the checkpoint ASAP, + * ignoring checkpoint_completion_target parameter. + * CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occurred + * since the last one (implied by CHECKPOINT_IS_SHUTDOWN or + * CHECKPOINT_END_OF_RECOVERY). + * CHECKPOINT_FLUSH_ALL: also flush buffers of unlogged tables. + * + * Note: flags contains other bits, of interest here only for logging purposes. + * In particular note that this routine is synchronous and does not pay + * attention to CHECKPOINT_WAIT. + * + * If !shutdown then we are writing an online checkpoint. This is a very special + * kind of operation and WAL record because the checkpoint action occurs over + * a period of time yet logically occurs at just a single LSN. The logical + * position of the WAL record (redo ptr) is the same or earlier than the + * physical position. When we replay WAL we locate the checkpoint via its + * physical position then read the redo ptr and actually start replay at the + * earlier logical position. Note that we don't write *anything* to WAL at + * the logical position, so that location could be any other kind of WAL record. + * All of this mechanism allows us to continue working while we checkpoint. + * As a result, timing of actions is critical here and be careful to note that + * this function will likely take minutes to execute on a busy system. + */ +void +CreateCheckPoint(int flags) +{ + bool shutdown; + CheckPoint checkPoint; + XLogRecPtr recptr; + XLogSegNo _logSegNo; + XLogCtlInsert *Insert = &XLogCtl->Insert; + uint32 freespace; + XLogRecPtr PriorRedoPtr; + XLogRecPtr curInsert; + XLogRecPtr last_important_lsn; + VirtualTransactionId *vxids; + int nvxids; + + /* + * An end-of-recovery checkpoint is really a shutdown checkpoint, just + * issued at a different time. + */ + if (flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY)) + shutdown = true; + else + shutdown = false; + + /* sanity check */ + if (RecoveryInProgress() && (flags & CHECKPOINT_END_OF_RECOVERY) == 0) + elog(ERROR, "can't create a checkpoint during recovery"); + + /* + * Initialize InitXLogInsert working areas before entering the critical + * section. Normally, this is done by the first call to + * RecoveryInProgress() or LocalSetXLogInsertAllowed(), but when creating + * an end-of-recovery checkpoint, the LocalSetXLogInsertAllowed call is + * done below in a critical section, and InitXLogInsert cannot be called + * in a critical section. + */ + InitXLogInsert(); + + /* + * Prepare to accumulate statistics. + * + * Note: because it is possible for log_checkpoints to change while a + * checkpoint proceeds, we always accumulate stats, even if + * log_checkpoints is currently off. + */ + MemSet(&CheckpointStats, 0, sizeof(CheckpointStats)); + CheckpointStats.ckpt_start_t = GetCurrentTimestamp(); + + /* + * Let smgr prepare for checkpoint; this has to happen outside the + * critical section and before we determine the REDO pointer. Note that + * smgr must not do anything that'd have to be undone if we decide no + * checkpoint is needed. + */ + SyncPreCheckpoint(); + + /* + * Use a critical section to force system panic if we have trouble. + */ + START_CRIT_SECTION(); + + if (shutdown) + { + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->state = DB_SHUTDOWNING; + ControlFile->time = (pg_time_t) time(NULL); + UpdateControlFile(); + LWLockRelease(ControlFileLock); + } + + /* Begin filling in the checkpoint WAL record */ + MemSet(&checkPoint, 0, sizeof(checkPoint)); + checkPoint.time = (pg_time_t) time(NULL); + + /* + * For Hot Standby, derive the oldestActiveXid before we fix the redo + * pointer. This allows us to begin accumulating changes to assemble our + * starting snapshot of locks and transactions. + */ + if (!shutdown && XLogStandbyInfoActive()) + checkPoint.oldestActiveXid = GetOldestActiveTransactionId(); + else + checkPoint.oldestActiveXid = InvalidTransactionId; + + /* + * Get location of last important record before acquiring insert locks (as + * GetLastImportantRecPtr() also locks WAL locks). + */ + last_important_lsn = GetLastImportantRecPtr(); + + /* + * We must block concurrent insertions while examining insert state to + * determine the checkpoint REDO pointer. + */ + WALInsertLockAcquireExclusive(); + curInsert = XLogBytePosToRecPtr(Insert->CurrBytePos); + + /* + * If this isn't a shutdown or forced checkpoint, and if there has been no + * WAL activity requiring a checkpoint, skip it. The idea here is to + * avoid inserting duplicate checkpoints when the system is idle. + */ + if ((flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY | + CHECKPOINT_FORCE)) == 0) + { + if (last_important_lsn == ControlFile->checkPoint) + { + WALInsertLockRelease(); + END_CRIT_SECTION(); + ereport(DEBUG1, + (errmsg_internal("checkpoint skipped because system is idle"))); + return; + } + } + + /* + * An end-of-recovery checkpoint is created before anyone is allowed to + * write WAL. To allow us to write the checkpoint record, temporarily + * enable XLogInsertAllowed. (This also ensures ThisTimeLineID is + * initialized, which we need here and in AdvanceXLInsertBuffer.) + */ + if (flags & CHECKPOINT_END_OF_RECOVERY) + LocalSetXLogInsertAllowed(); + + checkPoint.ThisTimeLineID = ThisTimeLineID; + if (flags & CHECKPOINT_END_OF_RECOVERY) + checkPoint.PrevTimeLineID = XLogCtl->PrevTimeLineID; + else + checkPoint.PrevTimeLineID = ThisTimeLineID; + + checkPoint.fullPageWrites = Insert->fullPageWrites; + + /* + * Compute new REDO record ptr = location of next XLOG record. + * + * NB: this is NOT necessarily where the checkpoint record itself will be, + * since other backends may insert more XLOG records while we're off doing + * the buffer flush work. Those XLOG records are logically after the + * checkpoint, even though physically before it. Got that? + */ + freespace = INSERT_FREESPACE(curInsert); + if (freespace == 0) + { + if (XLogSegmentOffset(curInsert, wal_segment_size) == 0) + curInsert += SizeOfXLogLongPHD; + else + curInsert += SizeOfXLogShortPHD; + } + checkPoint.redo = curInsert; + + /* + * Here we update the shared RedoRecPtr for future XLogInsert calls; this + * must be done while holding all the insertion locks. + * + * Note: if we fail to complete the checkpoint, RedoRecPtr will be left + * pointing past where it really needs to point. This is okay; the only + * consequence is that XLogInsert might back up whole buffers that it + * didn't really need to. We can't postpone advancing RedoRecPtr because + * XLogInserts that happen while we are dumping buffers must assume that + * their buffer changes are not included in the checkpoint. + */ + RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo; + + /* + * Now we can release the WAL insertion locks, allowing other xacts to + * proceed while we are flushing disk buffers. + */ + WALInsertLockRelease(); + + /* Update the info_lck-protected copy of RedoRecPtr as well */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->RedoRecPtr = checkPoint.redo; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * If enabled, log checkpoint start. We postpone this until now so as not + * to log anything if we decided to skip the checkpoint. + */ + if (log_checkpoints) + LogCheckpointStart(flags, false); + + /* Update the process title */ + update_checkpoint_display(flags, false, false); + + TRACE_POSTGRESQL_CHECKPOINT_START(flags); + + /* + * Get the other info we need for the checkpoint record. + * + * We don't need to save oldestClogXid in the checkpoint, it only matters + * for the short period in which clog is being truncated, and if we crash + * during that we'll redo the clog truncation and fix up oldestClogXid + * there. + */ + LWLockAcquire(XidGenLock, LW_SHARED); + checkPoint.nextXid = ShmemVariableCache->nextXid; + checkPoint.oldestXid = ShmemVariableCache->oldestXid; + checkPoint.oldestXidDB = ShmemVariableCache->oldestXidDB; + LWLockRelease(XidGenLock); + + LWLockAcquire(CommitTsLock, LW_SHARED); + checkPoint.oldestCommitTsXid = ShmemVariableCache->oldestCommitTsXid; + checkPoint.newestCommitTsXid = ShmemVariableCache->newestCommitTsXid; + LWLockRelease(CommitTsLock); + + LWLockAcquire(OidGenLock, LW_SHARED); + checkPoint.nextOid = ShmemVariableCache->nextOid; + if (!shutdown) + checkPoint.nextOid += ShmemVariableCache->oidCount; + LWLockRelease(OidGenLock); + + MultiXactGetCheckptMulti(shutdown, + &checkPoint.nextMulti, + &checkPoint.nextMultiOffset, + &checkPoint.oldestMulti, + &checkPoint.oldestMultiDB); + + /* + * Having constructed the checkpoint record, ensure all shmem disk buffers + * and commit-log buffers are flushed to disk. + * + * This I/O could fail for various reasons. If so, we will fail to + * complete the checkpoint, but there is no reason to force a system + * panic. Accordingly, exit critical section while doing it. + */ + END_CRIT_SECTION(); + + /* + * In some cases there are groups of actions that must all occur on one + * side or the other of a checkpoint record. Before flushing the + * checkpoint record we must explicitly wait for any backend currently + * performing those groups of actions. + * + * One example is end of transaction, so we must wait for any transactions + * that are currently in commit critical sections. If an xact inserted + * its commit record into XLOG just before the REDO point, then a crash + * restart from the REDO point would not replay that record, which means + * that our flushing had better include the xact's update of pg_xact. So + * we wait till he's out of his commit critical section before proceeding. + * See notes in RecordTransactionCommit(). + * + * Because we've already released the insertion locks, this test is a bit + * fuzzy: it is possible that we will wait for xacts we didn't really need + * to wait for. But the delay should be short and it seems better to make + * checkpoint take a bit longer than to hold off insertions longer than + * necessary. (In fact, the whole reason we have this issue is that xact.c + * does commit record XLOG insertion and clog update as two separate steps + * protected by different locks, but again that seems best on grounds of + * minimizing lock contention.) + * + * A transaction that has not yet set delayChkpt when we look cannot be at + * risk, since he's not inserted his commit record yet; and one that's + * already cleared it is not at risk either, since he's done fixing clog + * and we will correctly flush the update below. So we cannot miss any + * xacts we need to wait for. + */ + vxids = GetVirtualXIDsDelayingChkpt(&nvxids); + if (nvxids > 0) + { + do + { + pg_usleep(10000L); /* wait for 10 msec */ + } while (HaveVirtualXIDsDelayingChkpt(vxids, nvxids)); + } + pfree(vxids); + + CheckPointGuts(checkPoint.redo, flags); + + vxids = GetVirtualXIDsDelayingChkptEnd(&nvxids); + if (nvxids > 0) + { + do + { + pg_usleep(10000L); /* wait for 10 msec */ + } while (HaveVirtualXIDsDelayingChkptEnd(vxids, nvxids)); + } + pfree(vxids); + + /* + * Take a snapshot of running transactions and write this to WAL. This + * allows us to reconstruct the state of running transactions during + * archive recovery, if required. Skip, if this info disabled. + * + * If we are shutting down, or Startup process is completing crash + * recovery we don't need to write running xact data. + */ + if (!shutdown && XLogStandbyInfoActive()) + LogStandbySnapshot(); + + START_CRIT_SECTION(); + + /* + * Now insert the checkpoint record into XLOG. + */ + XLogBeginInsert(); + XLogRegisterData((char *) (&checkPoint), sizeof(checkPoint)); + recptr = XLogInsert(RM_XLOG_ID, + shutdown ? XLOG_CHECKPOINT_SHUTDOWN : + XLOG_CHECKPOINT_ONLINE); + + XLogFlush(recptr); + + /* + * We mustn't write any new WAL after a shutdown checkpoint, or it will be + * overwritten at next startup. No-one should even try, this just allows + * sanity-checking. In the case of an end-of-recovery checkpoint, we want + * to just temporarily disable writing until the system has exited + * recovery. + */ + if (shutdown) + { + if (flags & CHECKPOINT_END_OF_RECOVERY) + LocalXLogInsertAllowed = -1; /* return to "check" state */ + else + LocalXLogInsertAllowed = 0; /* never again write WAL */ + } + + /* + * We now have ProcLastRecPtr = start of actual checkpoint record, recptr + * = end of actual checkpoint record. + */ + if (shutdown && checkPoint.redo != ProcLastRecPtr) + ereport(PANIC, + (errmsg("concurrent write-ahead log activity while database system is shutting down"))); + + /* + * Remember the prior checkpoint's redo ptr for + * UpdateCheckPointDistanceEstimate() + */ + PriorRedoPtr = ControlFile->checkPointCopy.redo; + + /* + * Update the control file. + */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + if (shutdown) + ControlFile->state = DB_SHUTDOWNED; + ControlFile->checkPoint = ProcLastRecPtr; + ControlFile->checkPointCopy = checkPoint; + ControlFile->time = (pg_time_t) time(NULL); + /* crash recovery should always recover to the end of WAL */ + ControlFile->minRecoveryPoint = InvalidXLogRecPtr; + ControlFile->minRecoveryPointTLI = 0; + + /* + * Persist unloggedLSN value. It's reset on crash recovery, so this goes + * unused on non-shutdown checkpoints, but seems useful to store it always + * for debugging purposes. + */ + SpinLockAcquire(&XLogCtl->ulsn_lck); + ControlFile->unloggedLSN = XLogCtl->unloggedLSN; + SpinLockRelease(&XLogCtl->ulsn_lck); + + UpdateControlFile(); + LWLockRelease(ControlFileLock); + + /* Update shared-memory copy of checkpoint XID/epoch */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->ckptFullXid = checkPoint.nextXid; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * We are now done with critical updates; no need for system panic if we + * have trouble while fooling with old log segments. + */ + END_CRIT_SECTION(); + + /* + * Let smgr do post-checkpoint cleanup (eg, deleting old files). + */ + SyncPostCheckpoint(); + + /* + * Update the average distance between checkpoints if the prior checkpoint + * exists. + */ + if (PriorRedoPtr != InvalidXLogRecPtr) + UpdateCheckPointDistanceEstimate(RedoRecPtr - PriorRedoPtr); + + /* + * Delete old log files, those no longer needed for last checkpoint to + * prevent the disk holding the xlog from growing full. + */ + XLByteToSeg(RedoRecPtr, _logSegNo, wal_segment_size); + KeepLogSeg(recptr, &_logSegNo); + if (InvalidateObsoleteReplicationSlots(_logSegNo)) + { + /* + * Some slots have been invalidated; recalculate the old-segment + * horizon, starting again from RedoRecPtr. + */ + XLByteToSeg(RedoRecPtr, _logSegNo, wal_segment_size); + KeepLogSeg(recptr, &_logSegNo); + } + _logSegNo--; + RemoveOldXlogFiles(_logSegNo, RedoRecPtr, recptr); + + /* + * Make more log segments if needed. (Do this after recycling old log + * segments, since that may supply some of the needed files.) + */ + if (!shutdown) + PreallocXlogFiles(recptr); + + /* + * Truncate pg_subtrans if possible. We can throw away all data before + * the oldest XMIN of any running transaction. No future transaction will + * attempt to reference any pg_subtrans entry older than that (see Asserts + * in subtrans.c). During recovery, though, we mustn't do this because + * StartupSUBTRANS hasn't been called yet. + */ + if (!RecoveryInProgress()) + TruncateSUBTRANS(GetOldestTransactionIdConsideredRunning()); + + /* Real work is done; log and update stats. */ + LogCheckpointEnd(false); + + /* Reset the process title */ + update_checkpoint_display(flags, false, true); + + TRACE_POSTGRESQL_CHECKPOINT_DONE(CheckpointStats.ckpt_bufs_written, + NBuffers, + CheckpointStats.ckpt_segs_added, + CheckpointStats.ckpt_segs_removed, + CheckpointStats.ckpt_segs_recycled); +} + +/* + * Mark the end of recovery in WAL though without running a full checkpoint. + * We can expect that a restartpoint is likely to be in progress as we + * do this, though we are unwilling to wait for it to complete. + * + * CreateRestartPoint() allows for the case where recovery may end before + * the restartpoint completes so there is no concern of concurrent behaviour. + */ +static void +CreateEndOfRecoveryRecord(void) +{ + xl_end_of_recovery xlrec; + XLogRecPtr recptr; + + /* sanity check */ + if (!RecoveryInProgress()) + elog(ERROR, "can only be used to end recovery"); + + xlrec.end_time = GetCurrentTimestamp(); + + WALInsertLockAcquireExclusive(); + xlrec.ThisTimeLineID = ThisTimeLineID; + xlrec.PrevTimeLineID = XLogCtl->PrevTimeLineID; + WALInsertLockRelease(); + + LocalSetXLogInsertAllowed(); + + START_CRIT_SECTION(); + + XLogBeginInsert(); + XLogRegisterData((char *) &xlrec, sizeof(xl_end_of_recovery)); + recptr = XLogInsert(RM_XLOG_ID, XLOG_END_OF_RECOVERY); + + XLogFlush(recptr); + + /* + * Update the control file so that crash recovery can follow the timeline + * changes to this point. + */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->time = (pg_time_t) time(NULL); + ControlFile->minRecoveryPoint = recptr; + ControlFile->minRecoveryPointTLI = ThisTimeLineID; + UpdateControlFile(); + LWLockRelease(ControlFileLock); + + END_CRIT_SECTION(); + + LocalXLogInsertAllowed = -1; /* return to "check" state */ +} + +/* + * Write an OVERWRITE_CONTRECORD message. + * + * When on WAL replay we expect a continuation record at the start of a page + * that is not there, recovery ends and WAL writing resumes at that point. + * But it's wrong to resume writing new WAL back at the start of the record + * that was broken, because downstream consumers of that WAL (physical + * replicas) are not prepared to "rewind". So the first action after + * finishing replay of all valid WAL must be to write a record of this type + * at the point where the contrecord was missing; to support xlogreader + * detecting the special case, XLP_FIRST_IS_OVERWRITE_CONTRECORD is also added + * to the page header where the record occurs. xlogreader has an ad-hoc + * mechanism to report metadata about the broken record, which is what we + * use here. + * + * At replay time, XLP_FIRST_IS_OVERWRITE_CONTRECORD instructs xlogreader to + * skip the record it was reading, and pass back the LSN of the skipped + * record, so that its caller can verify (on "replay" of that record) that the + * XLOG_OVERWRITE_CONTRECORD matches what was effectively overwritten. + */ +static XLogRecPtr +CreateOverwriteContrecordRecord(XLogRecPtr aborted_lsn) +{ + xl_overwrite_contrecord xlrec; + XLogRecPtr recptr; + + /* sanity check */ + if (!RecoveryInProgress()) + elog(ERROR, "can only be used at end of recovery"); + + xlrec.overwritten_lsn = aborted_lsn; + xlrec.overwrite_time = GetCurrentTimestamp(); + + START_CRIT_SECTION(); + + XLogBeginInsert(); + XLogRegisterData((char *) &xlrec, sizeof(xl_overwrite_contrecord)); + + recptr = XLogInsert(RM_XLOG_ID, XLOG_OVERWRITE_CONTRECORD); + + XLogFlush(recptr); + + END_CRIT_SECTION(); + + return recptr; +} + +/* + * Flush all data in shared memory to disk, and fsync + * + * This is the common code shared between regular checkpoints and + * recovery restartpoints. + */ +static void +CheckPointGuts(XLogRecPtr checkPointRedo, int flags) +{ + CheckPointRelationMap(); + CheckPointReplicationSlots(); + CheckPointSnapBuild(); + CheckPointLogicalRewriteHeap(); + CheckPointReplicationOrigin(); + + /* Write out all dirty data in SLRUs and the main buffer pool */ + TRACE_POSTGRESQL_BUFFER_CHECKPOINT_START(flags); + CheckpointStats.ckpt_write_t = GetCurrentTimestamp(); + CheckPointCLOG(); + CheckPointCommitTs(); + CheckPointSUBTRANS(); + CheckPointMultiXact(); + CheckPointPredicate(); + CheckPointBuffers(flags); + + /* Perform all queued up fsyncs */ + TRACE_POSTGRESQL_BUFFER_CHECKPOINT_SYNC_START(); + CheckpointStats.ckpt_sync_t = GetCurrentTimestamp(); + ProcessSyncRequests(); + CheckpointStats.ckpt_sync_end_t = GetCurrentTimestamp(); + TRACE_POSTGRESQL_BUFFER_CHECKPOINT_DONE(); + + /* We deliberately delay 2PC checkpointing as long as possible */ + CheckPointTwoPhase(checkPointRedo); +} + +/* + * Save a checkpoint for recovery restart if appropriate + * + * This function is called each time a checkpoint record is read from XLOG. + * It must determine whether the checkpoint represents a safe restartpoint or + * not. If so, the checkpoint record is stashed in shared memory so that + * CreateRestartPoint can consult it. (Note that the latter function is + * executed by the checkpointer, while this one will be executed by the + * startup process.) + */ +static void +RecoveryRestartPoint(const CheckPoint *checkPoint) +{ + /* + * Also refrain from creating a restartpoint if we have seen any + * references to non-existent pages. Restarting recovery from the + * restartpoint would not see the references, so we would lose the + * cross-check that the pages belonged to a relation that was dropped + * later. + */ + if (XLogHaveInvalidPages()) + { + elog(trace_recovery(DEBUG2), + "could not record restart point at %X/%X because there " + "are unresolved references to invalid pages", + LSN_FORMAT_ARGS(checkPoint->redo)); + return; + } + + /* + * Copy the checkpoint record to shared memory, so that checkpointer can + * work out the next time it wants to perform a restartpoint. + */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->lastCheckPointRecPtr = ReadRecPtr; + XLogCtl->lastCheckPointEndPtr = EndRecPtr; + XLogCtl->lastCheckPoint = *checkPoint; + SpinLockRelease(&XLogCtl->info_lck); +} + +/* + * Establish a restartpoint if possible. + * + * This is similar to CreateCheckPoint, but is used during WAL recovery + * to establish a point from which recovery can roll forward without + * replaying the entire recovery log. + * + * Returns true if a new restartpoint was established. We can only establish + * a restartpoint if we have replayed a safe checkpoint record since last + * restartpoint. + */ +bool +CreateRestartPoint(int flags) +{ + XLogRecPtr lastCheckPointRecPtr; + XLogRecPtr lastCheckPointEndPtr; + CheckPoint lastCheckPoint; + XLogRecPtr PriorRedoPtr; + XLogRecPtr receivePtr; + XLogRecPtr replayPtr; + TimeLineID replayTLI; + XLogRecPtr endptr; + XLogSegNo _logSegNo; + TimestampTz xtime; + + /* Get a local copy of the last safe checkpoint record. */ + SpinLockAcquire(&XLogCtl->info_lck); + lastCheckPointRecPtr = XLogCtl->lastCheckPointRecPtr; + lastCheckPointEndPtr = XLogCtl->lastCheckPointEndPtr; + lastCheckPoint = XLogCtl->lastCheckPoint; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * Check that we're still in recovery mode. It's ok if we exit recovery + * mode after this check, the restart point is valid anyway. + */ + if (!RecoveryInProgress()) + { + ereport(DEBUG2, + (errmsg_internal("skipping restartpoint, recovery has already ended"))); + return false; + } + + /* + * If the last checkpoint record we've replayed is already our last + * restartpoint, we can't perform a new restart point. We still update + * minRecoveryPoint in that case, so that if this is a shutdown restart + * point, we won't start up earlier than before. That's not strictly + * necessary, but when hot standby is enabled, it would be rather weird if + * the database opened up for read-only connections at a point-in-time + * before the last shutdown. Such time travel is still possible in case of + * immediate shutdown, though. + * + * We don't explicitly advance minRecoveryPoint when we do create a + * restartpoint. It's assumed that flushing the buffers will do that as a + * side-effect. + */ + if (XLogRecPtrIsInvalid(lastCheckPointRecPtr) || + lastCheckPoint.redo <= ControlFile->checkPointCopy.redo) + { + ereport(DEBUG2, + (errmsg_internal("skipping restartpoint, already performed at %X/%X", + LSN_FORMAT_ARGS(lastCheckPoint.redo)))); + + UpdateMinRecoveryPoint(InvalidXLogRecPtr, true); + if (flags & CHECKPOINT_IS_SHUTDOWN) + { + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->state = DB_SHUTDOWNED_IN_RECOVERY; + ControlFile->time = (pg_time_t) time(NULL); + UpdateControlFile(); + LWLockRelease(ControlFileLock); + } + return false; + } + + /* + * Update the shared RedoRecPtr so that the startup process can calculate + * the number of segments replayed since last restartpoint, and request a + * restartpoint if it exceeds CheckPointSegments. + * + * Like in CreateCheckPoint(), hold off insertions to update it, although + * during recovery this is just pro forma, because no WAL insertions are + * happening. + */ + WALInsertLockAcquireExclusive(); + RedoRecPtr = XLogCtl->Insert.RedoRecPtr = lastCheckPoint.redo; + WALInsertLockRelease(); + + /* Also update the info_lck-protected copy */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->RedoRecPtr = lastCheckPoint.redo; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * Prepare to accumulate statistics. + * + * Note: because it is possible for log_checkpoints to change while a + * checkpoint proceeds, we always accumulate stats, even if + * log_checkpoints is currently off. + */ + MemSet(&CheckpointStats, 0, sizeof(CheckpointStats)); + CheckpointStats.ckpt_start_t = GetCurrentTimestamp(); + + if (log_checkpoints) + LogCheckpointStart(flags, true); + + /* Update the process title */ + update_checkpoint_display(flags, true, false); + + CheckPointGuts(lastCheckPoint.redo, flags); + + /* + * Remember the prior checkpoint's redo ptr for + * UpdateCheckPointDistanceEstimate() + */ + PriorRedoPtr = ControlFile->checkPointCopy.redo; + + /* + * Update pg_control, using current time. Check that it still shows an + * older checkpoint, else do nothing; this is a quick hack to make sure + * nothing really bad happens if somehow we get here after the + * end-of-recovery checkpoint. + */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + if (ControlFile->checkPointCopy.redo < lastCheckPoint.redo) + { + /* + * Update the checkpoint information. We do this even if the cluster + * does not show DB_IN_ARCHIVE_RECOVERY to match with the set of WAL + * segments recycled below. + */ + ControlFile->checkPoint = lastCheckPointRecPtr; + ControlFile->checkPointCopy = lastCheckPoint; + ControlFile->time = (pg_time_t) time(NULL); + + /* + * Ensure minRecoveryPoint is past the checkpoint record and update it + * if the control file still shows DB_IN_ARCHIVE_RECOVERY. Normally, + * this will have happened already while writing out dirty buffers, + * but not necessarily - e.g. because no buffers were dirtied. We do + * this because a non-exclusive base backup uses minRecoveryPoint to + * determine which WAL files must be included in the backup, and the + * file (or files) containing the checkpoint record must be included, + * at a minimum. Note that for an ordinary restart of recovery there's + * no value in having the minimum recovery point any earlier than this + * anyway, because redo will begin just after the checkpoint record. + * this because a non-exclusive base backup uses minRecoveryPoint to + * determine which WAL files must be included in the backup, and the + * file (or files) containing the checkpoint record must be included, + * at a minimum. Note that for an ordinary restart of recovery there's + * no value in having the minimum recovery point any earlier than this + * anyway, because redo will begin just after the checkpoint record. + */ + if (ControlFile->state == DB_IN_ARCHIVE_RECOVERY) + { + if (ControlFile->minRecoveryPoint < lastCheckPointEndPtr) + { + ControlFile->minRecoveryPoint = lastCheckPointEndPtr; + ControlFile->minRecoveryPointTLI = lastCheckPoint.ThisTimeLineID; + + /* update local copy */ + minRecoveryPoint = ControlFile->minRecoveryPoint; + minRecoveryPointTLI = ControlFile->minRecoveryPointTLI; + } + if (flags & CHECKPOINT_IS_SHUTDOWN) + ControlFile->state = DB_SHUTDOWNED_IN_RECOVERY; + } + UpdateControlFile(); + } + LWLockRelease(ControlFileLock); + + /* + * Update the average distance between checkpoints/restartpoints if the + * prior checkpoint exists. + */ + if (PriorRedoPtr != InvalidXLogRecPtr) + UpdateCheckPointDistanceEstimate(RedoRecPtr - PriorRedoPtr); + + /* + * Delete old log files, those no longer needed for last restartpoint to + * prevent the disk holding the xlog from growing full. + */ + XLByteToSeg(RedoRecPtr, _logSegNo, wal_segment_size); + + /* + * Retreat _logSegNo using the current end of xlog replayed or received, + * whichever is later. + */ + receivePtr = GetWalRcvFlushRecPtr(NULL, NULL); + replayPtr = GetXLogReplayRecPtr(&replayTLI); + endptr = (receivePtr < replayPtr) ? replayPtr : receivePtr; + KeepLogSeg(endptr, &_logSegNo); + if (InvalidateObsoleteReplicationSlots(_logSegNo)) + { + /* + * Some slots have been invalidated; recalculate the old-segment + * horizon, starting again from RedoRecPtr. + */ + XLByteToSeg(RedoRecPtr, _logSegNo, wal_segment_size); + KeepLogSeg(endptr, &_logSegNo); + } + _logSegNo--; + + /* + * Try to recycle segments on a useful timeline. If we've been promoted + * since the beginning of this restartpoint, use the new timeline chosen + * at end of recovery (RecoveryInProgress() sets ThisTimeLineID in that + * case). If we're still in recovery, use the timeline we're currently + * replaying. + * + * There is no guarantee that the WAL segments will be useful on the + * current timeline; if recovery proceeds to a new timeline right after + * this, the pre-allocated WAL segments on this timeline will not be used, + * and will go wasted until recycled on the next restartpoint. We'll live + * with that. + */ + if (RecoveryInProgress()) + ThisTimeLineID = replayTLI; + + RemoveOldXlogFiles(_logSegNo, RedoRecPtr, endptr); + + /* + * Make more log segments if needed. (Do this after recycling old log + * segments, since that may supply some of the needed files.) + */ + PreallocXlogFiles(endptr); + + /* + * ThisTimeLineID is normally not set when we're still in recovery. + * However, recycling/preallocating segments above needed ThisTimeLineID + * to determine which timeline to install the segments on. Reset it now, + * to restore the normal state of affairs for debugging purposes. + */ + if (RecoveryInProgress()) + ThisTimeLineID = 0; + + /* + * Truncate pg_subtrans if possible. We can throw away all data before + * the oldest XMIN of any running transaction. No future transaction will + * attempt to reference any pg_subtrans entry older than that (see Asserts + * in subtrans.c). When hot standby is disabled, though, we mustn't do + * this because StartupSUBTRANS hasn't been called yet. + */ + if (EnableHotStandby) + TruncateSUBTRANS(GetOldestTransactionIdConsideredRunning()); + + /* Real work is done; log and update stats. */ + LogCheckpointEnd(true); + + /* Reset the process title */ + update_checkpoint_display(flags, true, true); + + xtime = GetLatestXTime(); + ereport((log_checkpoints ? LOG : DEBUG2), + (errmsg("recovery restart point at %X/%X", + LSN_FORMAT_ARGS(lastCheckPoint.redo)), + xtime ? errdetail("Last completed transaction was at log time %s.", + timestamptz_to_str(xtime)) : 0)); + + /* + * Finally, execute archive_cleanup_command, if any. + */ + if (archiveCleanupCommand && strcmp(archiveCleanupCommand, "") != 0) + ExecuteRecoveryCommand(archiveCleanupCommand, + "archive_cleanup_command", + false); + + return true; +} + +/* + * Report availability of WAL for the given target LSN + * (typically a slot's restart_lsn) + * + * Returns one of the following enum values: + * + * * WALAVAIL_RESERVED means targetLSN is available and it is in the range of + * max_wal_size. + * + * * WALAVAIL_EXTENDED means it is still available by preserving extra + * segments beyond max_wal_size. If max_slot_wal_keep_size is smaller + * than max_wal_size, this state is not returned. + * + * * WALAVAIL_UNRESERVED means it is being lost and the next checkpoint will + * remove reserved segments. The walsender using this slot may return to the + * above. + * + * * WALAVAIL_REMOVED means it has been removed. A replication stream on + * a slot with this LSN cannot continue after a restart. + * + * * WALAVAIL_INVALID_LSN means the slot hasn't been set to reserve WAL. + */ +WALAvailability +GetWALAvailability(XLogRecPtr targetLSN) +{ + XLogRecPtr currpos; /* current write LSN */ + XLogSegNo currSeg; /* segid of currpos */ + XLogSegNo targetSeg; /* segid of targetLSN */ + XLogSegNo oldestSeg; /* actual oldest segid */ + XLogSegNo oldestSegMaxWalSize; /* oldest segid kept by max_wal_size */ + XLogSegNo oldestSlotSeg; /* oldest segid kept by slot */ + uint64 keepSegs; + + /* + * slot does not reserve WAL. Either deactivated, or has never been active + */ + if (XLogRecPtrIsInvalid(targetLSN)) + return WALAVAIL_INVALID_LSN; + + /* + * Calculate the oldest segment currently reserved by all slots, + * considering wal_keep_size and max_slot_wal_keep_size. Initialize + * oldestSlotSeg to the current segment. + */ + currpos = GetXLogWriteRecPtr(); + XLByteToSeg(currpos, oldestSlotSeg, wal_segment_size); + KeepLogSeg(currpos, &oldestSlotSeg); + + /* + * Find the oldest extant segment file. We get 1 until checkpoint removes + * the first WAL segment file since startup, which causes the status being + * wrong under certain abnormal conditions but that doesn't actually harm. + */ + oldestSeg = XLogGetLastRemovedSegno() + 1; + + /* calculate oldest segment by max_wal_size */ + XLByteToSeg(currpos, currSeg, wal_segment_size); + keepSegs = ConvertToXSegs(max_wal_size_mb, wal_segment_size) + 1; + + if (currSeg > keepSegs) + oldestSegMaxWalSize = currSeg - keepSegs; + else + oldestSegMaxWalSize = 1; + + /* the segment we care about */ + XLByteToSeg(targetLSN, targetSeg, wal_segment_size); + + /* + * No point in returning reserved or extended status values if the + * targetSeg is known to be lost. + */ + if (targetSeg >= oldestSlotSeg) + { + /* show "reserved" when targetSeg is within max_wal_size */ + if (targetSeg >= oldestSegMaxWalSize) + return WALAVAIL_RESERVED; + + /* being retained by slots exceeding max_wal_size */ + return WALAVAIL_EXTENDED; + } + + /* WAL segments are no longer retained but haven't been removed yet */ + if (targetSeg >= oldestSeg) + return WALAVAIL_UNRESERVED; + + /* Definitely lost */ + return WALAVAIL_REMOVED; +} + + +/* + * Retreat *logSegNo to the last segment that we need to retain because of + * either wal_keep_size or replication slots. + * + * This is calculated by subtracting wal_keep_size from the given xlog + * location, recptr and by making sure that that result is below the + * requirement of replication slots. For the latter criterion we do consider + * the effects of max_slot_wal_keep_size: reserve at most that much space back + * from recptr. + * + * Note about replication slots: if this function calculates a value + * that's further ahead than what slots need reserved, then affected + * slots need to be invalidated and this function invoked again. + * XXX it might be a good idea to rewrite this function so that + * invalidation is optionally done here, instead. + */ +static void +KeepLogSeg(XLogRecPtr recptr, XLogSegNo *logSegNo) +{ + XLogSegNo currSegNo; + XLogSegNo segno; + XLogRecPtr keep; + + XLByteToSeg(recptr, currSegNo, wal_segment_size); + segno = currSegNo; + + /* + * Calculate how many segments are kept by slots first, adjusting for + * max_slot_wal_keep_size. + */ + keep = XLogGetReplicationSlotMinimumLSN(); + if (keep != InvalidXLogRecPtr) + { + XLByteToSeg(keep, segno, wal_segment_size); + + /* Cap by max_slot_wal_keep_size ... */ + if (max_slot_wal_keep_size_mb >= 0) + { + uint64 slot_keep_segs; + + slot_keep_segs = + ConvertToXSegs(max_slot_wal_keep_size_mb, wal_segment_size); + + if (currSegNo - segno > slot_keep_segs) + segno = currSegNo - slot_keep_segs; + } + } + + /* but, keep at least wal_keep_size if that's set */ + if (wal_keep_size_mb > 0) + { + uint64 keep_segs; + + keep_segs = ConvertToXSegs(wal_keep_size_mb, wal_segment_size); + if (currSegNo - segno < keep_segs) + { + /* avoid underflow, don't go below 1 */ + if (currSegNo <= keep_segs) + segno = 1; + else + segno = currSegNo - keep_segs; + } + } + + /* don't delete WAL segments newer than the calculated segment */ + if (segno < *logSegNo) + *logSegNo = segno; +} + +/* + * Write a NEXTOID log record + */ +void +XLogPutNextOid(Oid nextOid) +{ + XLogBeginInsert(); + XLogRegisterData((char *) (&nextOid), sizeof(Oid)); + (void) XLogInsert(RM_XLOG_ID, XLOG_NEXTOID); + + /* + * We need not flush the NEXTOID record immediately, because any of the + * just-allocated OIDs could only reach disk as part of a tuple insert or + * update that would have its own XLOG record that must follow the NEXTOID + * record. Therefore, the standard buffer LSN interlock applied to those + * records will ensure no such OID reaches disk before the NEXTOID record + * does. + * + * Note, however, that the above statement only covers state "within" the + * database. When we use a generated OID as a file or directory name, we + * are in a sense violating the basic WAL rule, because that filesystem + * change may reach disk before the NEXTOID WAL record does. The impact + * of this is that if a database crash occurs immediately afterward, we + * might after restart re-generate the same OID and find that it conflicts + * with the leftover file or directory. But since for safety's sake we + * always loop until finding a nonconflicting filename, this poses no real + * problem in practice. See pgsql-hackers discussion 27-Sep-2006. + */ +} + +/* + * Write an XLOG SWITCH record. + * + * Here we just blindly issue an XLogInsert request for the record. + * All the magic happens inside XLogInsert. + * + * The return value is either the end+1 address of the switch record, + * or the end+1 address of the prior segment if we did not need to + * write a switch record because we are already at segment start. + */ +XLogRecPtr +RequestXLogSwitch(bool mark_unimportant) +{ + XLogRecPtr RecPtr; + + /* XLOG SWITCH has no data */ + XLogBeginInsert(); + + if (mark_unimportant) + XLogSetRecordFlags(XLOG_MARK_UNIMPORTANT); + RecPtr = XLogInsert(RM_XLOG_ID, XLOG_SWITCH); + + return RecPtr; +} + +/* + * Write a RESTORE POINT record + */ +XLogRecPtr +XLogRestorePoint(const char *rpName) +{ + XLogRecPtr RecPtr; + xl_restore_point xlrec; + + xlrec.rp_time = GetCurrentTimestamp(); + strlcpy(xlrec.rp_name, rpName, MAXFNAMELEN); + + XLogBeginInsert(); + XLogRegisterData((char *) &xlrec, sizeof(xl_restore_point)); + + RecPtr = XLogInsert(RM_XLOG_ID, XLOG_RESTORE_POINT); + + ereport(LOG, + (errmsg("restore point \"%s\" created at %X/%X", + rpName, LSN_FORMAT_ARGS(RecPtr)))); + + return RecPtr; +} + +/* + * Check if any of the GUC parameters that are critical for hot standby + * have changed, and update the value in pg_control file if necessary. + */ +static void +XLogReportParameters(void) +{ + if (wal_level != ControlFile->wal_level || + wal_log_hints != ControlFile->wal_log_hints || + MaxConnections != ControlFile->MaxConnections || + max_worker_processes != ControlFile->max_worker_processes || + max_wal_senders != ControlFile->max_wal_senders || + max_prepared_xacts != ControlFile->max_prepared_xacts || + max_locks_per_xact != ControlFile->max_locks_per_xact || + track_commit_timestamp != ControlFile->track_commit_timestamp) + { + /* + * The change in number of backend slots doesn't need to be WAL-logged + * if archiving is not enabled, as you can't start archive recovery + * with wal_level=minimal anyway. We don't really care about the + * values in pg_control either if wal_level=minimal, but seems better + * to keep them up-to-date to avoid confusion. + */ + if (wal_level != ControlFile->wal_level || XLogIsNeeded()) + { + xl_parameter_change xlrec; + XLogRecPtr recptr; + + xlrec.MaxConnections = MaxConnections; + xlrec.max_worker_processes = max_worker_processes; + xlrec.max_wal_senders = max_wal_senders; + xlrec.max_prepared_xacts = max_prepared_xacts; + xlrec.max_locks_per_xact = max_locks_per_xact; + xlrec.wal_level = wal_level; + xlrec.wal_log_hints = wal_log_hints; + xlrec.track_commit_timestamp = track_commit_timestamp; + + XLogBeginInsert(); + XLogRegisterData((char *) &xlrec, sizeof(xlrec)); + + recptr = XLogInsert(RM_XLOG_ID, XLOG_PARAMETER_CHANGE); + XLogFlush(recptr); + } + + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + + ControlFile->MaxConnections = MaxConnections; + ControlFile->max_worker_processes = max_worker_processes; + ControlFile->max_wal_senders = max_wal_senders; + ControlFile->max_prepared_xacts = max_prepared_xacts; + ControlFile->max_locks_per_xact = max_locks_per_xact; + ControlFile->wal_level = wal_level; + ControlFile->wal_log_hints = wal_log_hints; + ControlFile->track_commit_timestamp = track_commit_timestamp; + UpdateControlFile(); + + LWLockRelease(ControlFileLock); + } +} + +/* + * Update full_page_writes in shared memory, and write an + * XLOG_FPW_CHANGE record if necessary. + * + * Note: this function assumes there is no other process running + * concurrently that could update it. + */ +void +UpdateFullPageWrites(void) +{ + XLogCtlInsert *Insert = &XLogCtl->Insert; + bool recoveryInProgress; + + /* + * Do nothing if full_page_writes has not been changed. + * + * It's safe to check the shared full_page_writes without the lock, + * because we assume that there is no concurrently running process which + * can update it. + */ + if (fullPageWrites == Insert->fullPageWrites) + return; + + /* + * Perform this outside critical section so that the WAL insert + * initialization done by RecoveryInProgress() doesn't trigger an + * assertion failure. + */ + recoveryInProgress = RecoveryInProgress(); + + START_CRIT_SECTION(); + + /* + * It's always safe to take full page images, even when not strictly + * required, but not the other round. So if we're setting full_page_writes + * to true, first set it true and then write the WAL record. If we're + * setting it to false, first write the WAL record and then set the global + * flag. + */ + if (fullPageWrites) + { + WALInsertLockAcquireExclusive(); + Insert->fullPageWrites = true; + WALInsertLockRelease(); + } + + /* + * Write an XLOG_FPW_CHANGE record. This allows us to keep track of + * full_page_writes during archive recovery, if required. + */ + if (XLogStandbyInfoActive() && !recoveryInProgress) + { + XLogBeginInsert(); + XLogRegisterData((char *) (&fullPageWrites), sizeof(bool)); + + XLogInsert(RM_XLOG_ID, XLOG_FPW_CHANGE); + } + + if (!fullPageWrites) + { + WALInsertLockAcquireExclusive(); + Insert->fullPageWrites = false; + WALInsertLockRelease(); + } + END_CRIT_SECTION(); +} + +/* + * Check that it's OK to switch to new timeline during recovery. + * + * 'lsn' is the address of the shutdown checkpoint record we're about to + * replay. (Currently, timeline can only change at a shutdown checkpoint). + */ +static void +checkTimeLineSwitch(XLogRecPtr lsn, TimeLineID newTLI, TimeLineID prevTLI) +{ + /* Check that the record agrees on what the current (old) timeline is */ + if (prevTLI != ThisTimeLineID) + ereport(PANIC, + (errmsg("unexpected previous timeline ID %u (current timeline ID %u) in checkpoint record", + prevTLI, ThisTimeLineID))); + + /* + * The new timeline better be in the list of timelines we expect to see, + * according to the timeline history. It should also not decrease. + */ + if (newTLI < ThisTimeLineID || !tliInHistory(newTLI, expectedTLEs)) + ereport(PANIC, + (errmsg("unexpected timeline ID %u (after %u) in checkpoint record", + newTLI, ThisTimeLineID))); + + /* + * If we have not yet reached min recovery point, and we're about to + * switch to a timeline greater than the timeline of the min recovery + * point: trouble. After switching to the new timeline, we could not + * possibly visit the min recovery point on the correct timeline anymore. + * This can happen if there is a newer timeline in the archive that + * branched before the timeline the min recovery point is on, and you + * attempt to do PITR to the new timeline. + */ + if (!XLogRecPtrIsInvalid(minRecoveryPoint) && + lsn < minRecoveryPoint && + newTLI > minRecoveryPointTLI) + ereport(PANIC, + (errmsg("unexpected timeline ID %u in checkpoint record, before reaching minimum recovery point %X/%X on timeline %u", + newTLI, + LSN_FORMAT_ARGS(minRecoveryPoint), + minRecoveryPointTLI))); + + /* Looks good */ +} + +/* + * XLOG resource manager's routines + * + * Definitions of info values are in include/catalog/pg_control.h, though + * not all record types are related to control file updates. + */ +void +xlog_redo(XLogReaderState *record) +{ + uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK; + XLogRecPtr lsn = record->EndRecPtr; + + /* in XLOG rmgr, backup blocks are only used by XLOG_FPI records */ + Assert(info == XLOG_FPI || info == XLOG_FPI_FOR_HINT || + !XLogRecHasAnyBlockRefs(record)); + + if (info == XLOG_NEXTOID) + { + Oid nextOid; + + /* + * We used to try to take the maximum of ShmemVariableCache->nextOid + * and the recorded nextOid, but that fails if the OID counter wraps + * around. Since no OID allocation should be happening during replay + * anyway, better to just believe the record exactly. We still take + * OidGenLock while setting the variable, just in case. + */ + memcpy(&nextOid, XLogRecGetData(record), sizeof(Oid)); + LWLockAcquire(OidGenLock, LW_EXCLUSIVE); + ShmemVariableCache->nextOid = nextOid; + ShmemVariableCache->oidCount = 0; + LWLockRelease(OidGenLock); + } + else if (info == XLOG_CHECKPOINT_SHUTDOWN) + { + CheckPoint checkPoint; + + memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); + /* In a SHUTDOWN checkpoint, believe the counters exactly */ + LWLockAcquire(XidGenLock, LW_EXCLUSIVE); + ShmemVariableCache->nextXid = checkPoint.nextXid; + LWLockRelease(XidGenLock); + LWLockAcquire(OidGenLock, LW_EXCLUSIVE); + ShmemVariableCache->nextOid = checkPoint.nextOid; + ShmemVariableCache->oidCount = 0; + LWLockRelease(OidGenLock); + MultiXactSetNextMXact(checkPoint.nextMulti, + checkPoint.nextMultiOffset); + + MultiXactAdvanceOldest(checkPoint.oldestMulti, + checkPoint.oldestMultiDB); + + /* + * No need to set oldestClogXid here as well; it'll be set when we + * redo an xl_clog_truncate if it changed since initialization. + */ + SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); + + /* + * If we see a shutdown checkpoint while waiting for an end-of-backup + * record, the backup was canceled and the end-of-backup record will + * never arrive. + */ + if (ArchiveRecoveryRequested && + !XLogRecPtrIsInvalid(ControlFile->backupStartPoint) && + XLogRecPtrIsInvalid(ControlFile->backupEndPoint)) + ereport(PANIC, + (errmsg("online backup was canceled, recovery cannot continue"))); + + /* + * If we see a shutdown checkpoint, we know that nothing was running + * on the primary at this point. So fake-up an empty running-xacts + * record and use that here and now. Recover additional standby state + * for prepared transactions. + */ + if (standbyState >= STANDBY_INITIALIZED) + { + TransactionId *xids; + int nxids; + TransactionId oldestActiveXID; + TransactionId latestCompletedXid; + RunningTransactionsData running; + + oldestActiveXID = PrescanPreparedTransactions(&xids, &nxids); + + /* + * Construct a RunningTransactions snapshot representing a shut + * down server, with only prepared transactions still alive. We're + * never overflowed at this point because all subxids are listed + * with their parent prepared transactions. + */ + running.xcnt = nxids; + running.subxcnt = 0; + running.subxid_overflow = false; + running.nextXid = XidFromFullTransactionId(checkPoint.nextXid); + running.oldestRunningXid = oldestActiveXID; + latestCompletedXid = XidFromFullTransactionId(checkPoint.nextXid); + TransactionIdRetreat(latestCompletedXid); + Assert(TransactionIdIsNormal(latestCompletedXid)); + running.latestCompletedXid = latestCompletedXid; + running.xids = xids; + + ProcArrayApplyRecoveryInfo(&running); + + StandbyRecoverPreparedTransactions(); + } + + /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->checkPointCopy.nextXid = checkPoint.nextXid; + LWLockRelease(ControlFileLock); + + /* Update shared-memory copy of checkpoint XID/epoch */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->ckptFullXid = checkPoint.nextXid; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * We should've already switched to the new TLI before replaying this + * record. + */ + if (checkPoint.ThisTimeLineID != ThisTimeLineID) + ereport(PANIC, + (errmsg("unexpected timeline ID %u (should be %u) in checkpoint record", + checkPoint.ThisTimeLineID, ThisTimeLineID))); + + RecoveryRestartPoint(&checkPoint); + } + else if (info == XLOG_CHECKPOINT_ONLINE) + { + CheckPoint checkPoint; + + memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); + /* In an ONLINE checkpoint, treat the XID counter as a minimum */ + LWLockAcquire(XidGenLock, LW_EXCLUSIVE); + if (FullTransactionIdPrecedes(ShmemVariableCache->nextXid, + checkPoint.nextXid)) + ShmemVariableCache->nextXid = checkPoint.nextXid; + LWLockRelease(XidGenLock); + + /* + * We ignore the nextOid counter in an ONLINE checkpoint, preferring + * to track OID assignment through XLOG_NEXTOID records. The nextOid + * counter is from the start of the checkpoint and might well be stale + * compared to later XLOG_NEXTOID records. We could try to take the + * maximum of the nextOid counter and our latest value, but since + * there's no particular guarantee about the speed with which the OID + * counter wraps around, that's a risky thing to do. In any case, + * users of the nextOid counter are required to avoid assignment of + * duplicates, so that a somewhat out-of-date value should be safe. + */ + + /* Handle multixact */ + MultiXactAdvanceNextMXact(checkPoint.nextMulti, + checkPoint.nextMultiOffset); + + /* + * NB: This may perform multixact truncation when replaying WAL + * generated by an older primary. + */ + MultiXactAdvanceOldest(checkPoint.oldestMulti, + checkPoint.oldestMultiDB); + if (TransactionIdPrecedes(ShmemVariableCache->oldestXid, + checkPoint.oldestXid)) + SetTransactionIdLimit(checkPoint.oldestXid, + checkPoint.oldestXidDB); + /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->checkPointCopy.nextXid = checkPoint.nextXid; + LWLockRelease(ControlFileLock); + + /* Update shared-memory copy of checkpoint XID/epoch */ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->ckptFullXid = checkPoint.nextXid; + SpinLockRelease(&XLogCtl->info_lck); + + /* TLI should not change in an on-line checkpoint */ + if (checkPoint.ThisTimeLineID != ThisTimeLineID) + ereport(PANIC, + (errmsg("unexpected timeline ID %u (should be %u) in checkpoint record", + checkPoint.ThisTimeLineID, ThisTimeLineID))); + + RecoveryRestartPoint(&checkPoint); + } + else if (info == XLOG_OVERWRITE_CONTRECORD) + { + xl_overwrite_contrecord xlrec; + + memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_overwrite_contrecord)); + VerifyOverwriteContrecord(&xlrec, record); + } + else if (info == XLOG_END_OF_RECOVERY) + { + xl_end_of_recovery xlrec; + + memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_end_of_recovery)); + + /* + * For Hot Standby, we could treat this like a Shutdown Checkpoint, + * but this case is rarer and harder to test, so the benefit doesn't + * outweigh the potential extra cost of maintenance. + */ + + /* + * We should've already switched to the new TLI before replaying this + * record. + */ + if (xlrec.ThisTimeLineID != ThisTimeLineID) + ereport(PANIC, + (errmsg("unexpected timeline ID %u (should be %u) in checkpoint record", + xlrec.ThisTimeLineID, ThisTimeLineID))); + } + else if (info == XLOG_NOOP) + { + /* nothing to do here */ + } + else if (info == XLOG_SWITCH) + { + /* nothing to do here */ + } + else if (info == XLOG_RESTORE_POINT) + { + /* nothing to do here */ + } + else if (info == XLOG_FPI || info == XLOG_FPI_FOR_HINT) + { + /* + * Full-page image (FPI) records contain nothing else but a backup + * block (or multiple backup blocks). Every block reference must + * include a full-page image - otherwise there would be no point in + * this record. + * + * No recovery conflicts are generated by these generic records - if a + * resource manager needs to generate conflicts, it has to define a + * separate WAL record type and redo routine. + * + * XLOG_FPI_FOR_HINT records are generated when a page needs to be + * WAL- logged because of a hint bit update. They are only generated + * when checksums are enabled. There is no difference in handling + * XLOG_FPI and XLOG_FPI_FOR_HINT records, they use a different info + * code just to distinguish them for statistics purposes. + */ + for (uint8 block_id = 0; block_id <= record->max_block_id; block_id++) + { + Buffer buffer; + + if (XLogReadBufferForRedo(record, block_id, &buffer) != BLK_RESTORED) + elog(ERROR, "unexpected XLogReadBufferForRedo result when restoring backup block"); + UnlockReleaseBuffer(buffer); + } + } + else if (info == XLOG_BACKUP_END) + { + XLogRecPtr startpoint; + + memcpy(&startpoint, XLogRecGetData(record), sizeof(startpoint)); + + if (ControlFile->backupStartPoint == startpoint) + { + /* + * We have reached the end of base backup, the point where + * pg_stop_backup() was done. The data on disk is now consistent. + * Reset backupStartPoint, and update minRecoveryPoint to make + * sure we don't allow starting up at an earlier point even if + * recovery is stopped and restarted soon after this. + */ + elog(DEBUG1, "end of backup reached"); + + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + + if (ControlFile->minRecoveryPoint < lsn) + { + ControlFile->minRecoveryPoint = lsn; + ControlFile->minRecoveryPointTLI = ThisTimeLineID; + } + ControlFile->backupStartPoint = InvalidXLogRecPtr; + ControlFile->backupEndRequired = false; + UpdateControlFile(); + + LWLockRelease(ControlFileLock); + } + } + else if (info == XLOG_PARAMETER_CHANGE) + { + xl_parameter_change xlrec; + + /* Update our copy of the parameters in pg_control */ + memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_parameter_change)); + + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->MaxConnections = xlrec.MaxConnections; + ControlFile->max_worker_processes = xlrec.max_worker_processes; + ControlFile->max_wal_senders = xlrec.max_wal_senders; + ControlFile->max_prepared_xacts = xlrec.max_prepared_xacts; + ControlFile->max_locks_per_xact = xlrec.max_locks_per_xact; + ControlFile->wal_level = xlrec.wal_level; + ControlFile->wal_log_hints = xlrec.wal_log_hints; + + /* + * Update minRecoveryPoint to ensure that if recovery is aborted, we + * recover back up to this point before allowing hot standby again. + * This is important if the max_* settings are decreased, to ensure + * you don't run queries against the WAL preceding the change. The + * local copies cannot be updated as long as crash recovery is + * happening and we expect all the WAL to be replayed. + */ + if (InArchiveRecovery) + { + minRecoveryPoint = ControlFile->minRecoveryPoint; + minRecoveryPointTLI = ControlFile->minRecoveryPointTLI; + } + if (minRecoveryPoint != InvalidXLogRecPtr && minRecoveryPoint < lsn) + { + ControlFile->minRecoveryPoint = lsn; + ControlFile->minRecoveryPointTLI = ThisTimeLineID; + } + + CommitTsParameterChange(xlrec.track_commit_timestamp, + ControlFile->track_commit_timestamp); + ControlFile->track_commit_timestamp = xlrec.track_commit_timestamp; + + UpdateControlFile(); + LWLockRelease(ControlFileLock); + + /* Check to see if any parameter change gives a problem on recovery */ + CheckRequiredParameterValues(); + } + else if (info == XLOG_FPW_CHANGE) + { + bool fpw; + + memcpy(&fpw, XLogRecGetData(record), sizeof(bool)); + + /* + * Update the LSN of the last replayed XLOG_FPW_CHANGE record so that + * do_pg_start_backup() and do_pg_stop_backup() can check whether + * full_page_writes has been disabled during online backup. + */ + if (!fpw) + { + SpinLockAcquire(&XLogCtl->info_lck); + if (XLogCtl->lastFpwDisableRecPtr < ReadRecPtr) + XLogCtl->lastFpwDisableRecPtr = ReadRecPtr; + SpinLockRelease(&XLogCtl->info_lck); + } + + /* Keep track of full_page_writes */ + lastFullPageWrites = fpw; + } +} + +/* + * Verify the payload of a XLOG_OVERWRITE_CONTRECORD record. + */ +static void +VerifyOverwriteContrecord(xl_overwrite_contrecord *xlrec, XLogReaderState *state) +{ + if (xlrec->overwritten_lsn != state->overwrittenRecPtr) + elog(FATAL, "mismatching overwritten LSN %X/%X -> %X/%X", + LSN_FORMAT_ARGS(xlrec->overwritten_lsn), + LSN_FORMAT_ARGS(state->overwrittenRecPtr)); + + /* We have safely skipped the aborted record */ + abortedRecPtr = InvalidXLogRecPtr; + missingContrecPtr = InvalidXLogRecPtr; + + ereport(LOG, + (errmsg("successfully skipped missing contrecord at %X/%X, overwritten at %s", + LSN_FORMAT_ARGS(xlrec->overwritten_lsn), + timestamptz_to_str(xlrec->overwrite_time)))); + + /* Verifying the record should only happen once */ + state->overwrittenRecPtr = InvalidXLogRecPtr; +} + +#ifdef WAL_DEBUG + +static void +xlog_outrec(StringInfo buf, XLogReaderState *record) +{ + appendStringInfo(buf, "prev %X/%X; xid %u", + LSN_FORMAT_ARGS(XLogRecGetPrev(record)), + XLogRecGetXid(record)); + + appendStringInfo(buf, "; len %u", + XLogRecGetDataLen(record)); + + xlog_block_info(buf, record); +} +#endif /* WAL_DEBUG */ + +/* + * Returns a string giving information about all the blocks in an + * XLogRecord. + */ +static void +xlog_block_info(StringInfo buf, XLogReaderState *record) +{ + int block_id; + + /* decode block references */ + for (block_id = 0; block_id <= record->max_block_id; block_id++) + { + RelFileNode rnode; + ForkNumber forknum; + BlockNumber blk; + + if (!XLogRecHasBlockRef(record, block_id)) + continue; + + XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blk); + if (forknum != MAIN_FORKNUM) + appendStringInfo(buf, "; blkref #%u: rel %u/%u/%u, fork %u, blk %u", + block_id, + rnode.spcNode, rnode.dbNode, rnode.relNode, + forknum, + blk); + else + appendStringInfo(buf, "; blkref #%u: rel %u/%u/%u, blk %u", + block_id, + rnode.spcNode, rnode.dbNode, rnode.relNode, + blk); + if (XLogRecHasBlockImage(record, block_id)) + appendStringInfoString(buf, " FPW"); + } +} + +/* + * Returns a string describing an XLogRecord, consisting of its identity + * optionally followed by a colon, a space, and a further description. + */ +static void +xlog_outdesc(StringInfo buf, XLogReaderState *record) +{ + RmgrId rmid = XLogRecGetRmid(record); + uint8 info = XLogRecGetInfo(record); + const char *id; + + appendStringInfoString(buf, RmgrTable[rmid].rm_name); + appendStringInfoChar(buf, '/'); + + id = RmgrTable[rmid].rm_identify(info); + if (id == NULL) + appendStringInfo(buf, "UNKNOWN (%X): ", info & ~XLR_INFO_MASK); + else + appendStringInfo(buf, "%s: ", id); + + RmgrTable[rmid].rm_desc(buf, record); +} + + +/* + * Return the (possible) sync flag used for opening a file, depending on the + * value of the GUC wal_sync_method. + */ +static int +get_sync_bit(int method) +{ + int o_direct_flag = 0; + + /* If fsync is disabled, never open in sync mode */ + if (!enableFsync) + return 0; + + /* + * Optimize writes by bypassing kernel cache with O_DIRECT when using + * O_SYNC/O_FSYNC and O_DSYNC. But only if archiving and streaming are + * disabled, otherwise the archive command or walsender process will read + * the WAL soon after writing it, which is guaranteed to cause a physical + * read if we bypassed the kernel cache. We also skip the + * posix_fadvise(POSIX_FADV_DONTNEED) call in XLogFileClose() for the same + * reason. + * + * Never use O_DIRECT in walreceiver process for similar reasons; the WAL + * written by walreceiver is normally read by the startup process soon + * after it's written. Also, walreceiver performs unaligned writes, which + * don't work with O_DIRECT, so it is required for correctness too. + */ + if (!XLogIsNeeded() && !AmWalReceiverProcess()) + o_direct_flag = PG_O_DIRECT; + + switch (method) + { + /* + * enum values for all sync options are defined even if they are + * not supported on the current platform. But if not, they are + * not included in the enum option array, and therefore will never + * be seen here. + */ + case SYNC_METHOD_FSYNC: + case SYNC_METHOD_FSYNC_WRITETHROUGH: + case SYNC_METHOD_FDATASYNC: + return 0; +#ifdef OPEN_SYNC_FLAG + case SYNC_METHOD_OPEN: + return OPEN_SYNC_FLAG | o_direct_flag; +#endif +#ifdef OPEN_DATASYNC_FLAG + case SYNC_METHOD_OPEN_DSYNC: + return OPEN_DATASYNC_FLAG | o_direct_flag; +#endif + default: + /* can't happen (unless we are out of sync with option array) */ + elog(ERROR, "unrecognized wal_sync_method: %d", method); + return 0; /* silence warning */ + } +} + +/* + * GUC support + */ +void +assign_xlog_sync_method(int new_sync_method, void *extra) +{ + if (sync_method != new_sync_method) + { + /* + * To ensure that no blocks escape unsynced, force an fsync on the + * currently open log segment (if any). Also, if the open flag is + * changing, close the log file so it will be reopened (with new flag + * bit) at next use. + */ + if (openLogFile >= 0) + { + pgstat_report_wait_start(WAIT_EVENT_WAL_SYNC_METHOD_ASSIGN); + if (pg_fsync(openLogFile) != 0) + { + char xlogfname[MAXFNAMELEN]; + int save_errno; + + save_errno = errno; + XLogFileName(xlogfname, ThisTimeLineID, openLogSegNo, + wal_segment_size); + errno = save_errno; + ereport(PANIC, + (errcode_for_file_access(), + errmsg("could not fsync file \"%s\": %m", xlogfname))); + } + + pgstat_report_wait_end(); + if (get_sync_bit(sync_method) != get_sync_bit(new_sync_method)) + XLogFileClose(); + } + } +} + + +/* + * Issue appropriate kind of fsync (if any) for an XLOG output file. + * + * 'fd' is a file descriptor for the XLOG file to be fsync'd. + * 'segno' is for error reporting purposes. + */ +void +issue_xlog_fsync(int fd, XLogSegNo segno) +{ + char *msg = NULL; + instr_time start; + + /* + * Quick exit if fsync is disabled or write() has already synced the WAL + * file. + */ + if (!enableFsync || + sync_method == SYNC_METHOD_OPEN || + sync_method == SYNC_METHOD_OPEN_DSYNC) + return; + + /* Measure I/O timing to sync the WAL file */ + if (track_wal_io_timing) + INSTR_TIME_SET_CURRENT(start); + + pgstat_report_wait_start(WAIT_EVENT_WAL_SYNC); + switch (sync_method) + { + case SYNC_METHOD_FSYNC: + if (pg_fsync_no_writethrough(fd) != 0) + msg = _("could not fsync file \"%s\": %m"); + break; +#ifdef HAVE_FSYNC_WRITETHROUGH + case SYNC_METHOD_FSYNC_WRITETHROUGH: + if (pg_fsync_writethrough(fd) != 0) + msg = _("could not fsync write-through file \"%s\": %m"); + break; +#endif +#ifdef HAVE_FDATASYNC + case SYNC_METHOD_FDATASYNC: + if (pg_fdatasync(fd) != 0) + msg = _("could not fdatasync file \"%s\": %m"); + break; +#endif + case SYNC_METHOD_OPEN: + case SYNC_METHOD_OPEN_DSYNC: + /* not reachable */ + Assert(false); + break; + default: + elog(PANIC, "unrecognized wal_sync_method: %d", sync_method); + break; + } + + /* PANIC if failed to fsync */ + if (msg) + { + char xlogfname[MAXFNAMELEN]; + int save_errno = errno; + + XLogFileName(xlogfname, ThisTimeLineID, segno, + wal_segment_size); + errno = save_errno; + ereport(PANIC, + (errcode_for_file_access(), + errmsg(msg, xlogfname))); + } + + pgstat_report_wait_end(); + + /* + * Increment the I/O timing and the number of times WAL files were synced. + */ + if (track_wal_io_timing) + { + instr_time duration; + + INSTR_TIME_SET_CURRENT(duration); + INSTR_TIME_SUBTRACT(duration, start); + WalStats.m_wal_sync_time += INSTR_TIME_GET_MICROSEC(duration); + } + + WalStats.m_wal_sync++; +} + +/* + * do_pg_start_backup + * + * Utility function called at the start of an online backup. It creates the + * necessary starting checkpoint and constructs the backup label file. + * + * There are two kind of backups: exclusive and non-exclusive. An exclusive + * backup is started with pg_start_backup(), and there can be only one active + * at a time. The backup and tablespace map files of an exclusive backup are + * written to $PGDATA/backup_label and $PGDATA/tablespace_map, and they are + * removed by pg_stop_backup(). + * + * A non-exclusive backup is used for the streaming base backups (see + * src/backend/replication/basebackup.c). The difference to exclusive backups + * is that the backup label and tablespace map files are not written to disk. + * Instead, their would-be contents are returned in *labelfile and *tblspcmapfile, + * and the caller is responsible for including them in the backup archive as + * 'backup_label' and 'tablespace_map'. There can be many non-exclusive backups + * active at the same time, and they don't conflict with an exclusive backup + * either. + * + * labelfile and tblspcmapfile must be passed as NULL when starting an + * exclusive backup, and as initially-empty StringInfos for a non-exclusive + * backup. + * + * If "tablespaces" isn't NULL, it receives a list of tablespaceinfo structs + * describing the cluster's tablespaces. + * + * tblspcmapfile is required mainly for tar format in windows as native windows + * utilities are not able to create symlinks while extracting files from tar. + * However for consistency, the same is used for all platforms. + * + * Returns the minimum WAL location that must be present to restore from this + * backup, and the corresponding timeline ID in *starttli_p. + * + * Every successfully started non-exclusive backup must be stopped by calling + * do_pg_stop_backup() or do_pg_abort_backup(). + * + * It is the responsibility of the caller of this function to verify the + * permissions of the calling user! + */ +XLogRecPtr +do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p, + StringInfo labelfile, List **tablespaces, + StringInfo tblspcmapfile) +{ + bool exclusive = (labelfile == NULL); + bool backup_started_in_recovery = false; + XLogRecPtr checkpointloc; + XLogRecPtr startpoint; + TimeLineID starttli; + pg_time_t stamp_time; + char strfbuf[128]; + char xlogfilename[MAXFNAMELEN]; + XLogSegNo _logSegNo; + struct stat stat_buf; + FILE *fp; + + backup_started_in_recovery = RecoveryInProgress(); + + /* + * Currently only non-exclusive backup can be taken during recovery. + */ + if (backup_started_in_recovery && exclusive) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("recovery is in progress"), + errhint("WAL control functions cannot be executed during recovery."))); + + /* + * During recovery, we don't need to check WAL level. Because, if WAL + * level is not sufficient, it's impossible to get here during recovery. + */ + if (!backup_started_in_recovery && !XLogIsNeeded()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("WAL level not sufficient for making an online backup"), + errhint("wal_level must be set to \"replica\" or \"logical\" at server start."))); + + if (strlen(backupidstr) > MAXPGPATH) + ereport(ERROR, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("backup label too long (max %d bytes)", + MAXPGPATH))); + + /* + * Mark backup active in shared memory. We must do full-page WAL writes + * during an on-line backup even if not doing so at other times, because + * it's quite possible for the backup dump to obtain a "torn" (partially + * written) copy of a database page if it reads the page concurrently with + * our write to the same page. This can be fixed as long as the first + * write to the page in the WAL sequence is a full-page write. Hence, we + * turn on forcePageWrites and then force a CHECKPOINT, to ensure there + * are no dirty pages in shared memory that might get dumped while the + * backup is in progress without having a corresponding WAL record. (Once + * the backup is complete, we need not force full-page writes anymore, + * since we expect that any pages not modified during the backup interval + * must have been correctly captured by the backup.) + * + * Note that forcePageWrites has no effect during an online backup from + * the standby. + * + * We must hold all the insertion locks to change the value of + * forcePageWrites, to ensure adequate interlocking against + * XLogInsertRecord(). + */ + WALInsertLockAcquireExclusive(); + if (exclusive) + { + /* + * At first, mark that we're now starting an exclusive backup, to + * ensure that there are no other sessions currently running + * pg_start_backup() or pg_stop_backup(). + */ + if (XLogCtl->Insert.exclusiveBackupState != EXCLUSIVE_BACKUP_NONE) + { + WALInsertLockRelease(); + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("a backup is already in progress"), + errhint("Run pg_stop_backup() and try again."))); + } + XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_STARTING; + } + else + XLogCtl->Insert.nonExclusiveBackups++; + XLogCtl->Insert.forcePageWrites = true; + WALInsertLockRelease(); + + /* Ensure we release forcePageWrites if fail below */ + PG_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) BoolGetDatum(exclusive)); + { + bool gotUniqueStartpoint = false; + DIR *tblspcdir; + struct dirent *de; + tablespaceinfo *ti; + int datadirpathlen; + + /* + * Force an XLOG file switch before the checkpoint, to ensure that the + * WAL segment the checkpoint is written to doesn't contain pages with + * old timeline IDs. That would otherwise happen if you called + * pg_start_backup() right after restoring from a PITR archive: the + * first WAL segment containing the startup checkpoint has pages in + * the beginning with the old timeline ID. That can cause trouble at + * recovery: we won't have a history file covering the old timeline if + * pg_wal directory was not included in the base backup and the WAL + * archive was cleared too before starting the backup. + * + * This also ensures that we have emitted a WAL page header that has + * XLP_BKP_REMOVABLE off before we emit the checkpoint record. + * Therefore, if a WAL archiver (such as pglesslog) is trying to + * compress out removable backup blocks, it won't remove any that + * occur after this point. + * + * During recovery, we skip forcing XLOG file switch, which means that + * the backup taken during recovery is not available for the special + * recovery case described above. + */ + if (!backup_started_in_recovery) + RequestXLogSwitch(false); + + do + { + bool checkpointfpw; + + /* + * Force a CHECKPOINT. Aside from being necessary to prevent torn + * page problems, this guarantees that two successive backup runs + * will have different checkpoint positions and hence different + * history file names, even if nothing happened in between. + * + * During recovery, establish a restartpoint if possible. We use + * the last restartpoint as the backup starting checkpoint. This + * means that two successive backup runs can have same checkpoint + * positions. + * + * Since the fact that we are executing do_pg_start_backup() + * during recovery means that checkpointer is running, we can use + * RequestCheckpoint() to establish a restartpoint. + * + * We use CHECKPOINT_IMMEDIATE only if requested by user (via + * passing fast = true). Otherwise this can take awhile. + */ + RequestCheckpoint(CHECKPOINT_FORCE | CHECKPOINT_WAIT | + (fast ? CHECKPOINT_IMMEDIATE : 0)); + + /* + * Now we need to fetch the checkpoint record location, and also + * its REDO pointer. The oldest point in WAL that would be needed + * to restore starting from the checkpoint is precisely the REDO + * pointer. + */ + LWLockAcquire(ControlFileLock, LW_SHARED); + checkpointloc = ControlFile->checkPoint; + startpoint = ControlFile->checkPointCopy.redo; + starttli = ControlFile->checkPointCopy.ThisTimeLineID; + checkpointfpw = ControlFile->checkPointCopy.fullPageWrites; + LWLockRelease(ControlFileLock); + + if (backup_started_in_recovery) + { + XLogRecPtr recptr; + + /* + * Check to see if all WAL replayed during online backup + * (i.e., since last restartpoint used as backup starting + * checkpoint) contain full-page writes. + */ + SpinLockAcquire(&XLogCtl->info_lck); + recptr = XLogCtl->lastFpwDisableRecPtr; + SpinLockRelease(&XLogCtl->info_lck); + + if (!checkpointfpw || startpoint <= recptr) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("WAL generated with full_page_writes=off was replayed " + "since last restartpoint"), + errhint("This means that the backup being taken on the standby " + "is corrupt and should not be used. " + "Enable full_page_writes and run CHECKPOINT on the primary, " + "and then try an online backup again."))); + + /* + * During recovery, since we don't use the end-of-backup WAL + * record and don't write the backup history file, the + * starting WAL location doesn't need to be unique. This means + * that two base backups started at the same time might use + * the same checkpoint as starting locations. + */ + gotUniqueStartpoint = true; + } + + /* + * If two base backups are started at the same time (in WAL sender + * processes), we need to make sure that they use different + * checkpoints as starting locations, because we use the starting + * WAL location as a unique identifier for the base backup in the + * end-of-backup WAL record and when we write the backup history + * file. Perhaps it would be better generate a separate unique ID + * for each backup instead of forcing another checkpoint, but + * taking a checkpoint right after another is not that expensive + * either because only few buffers have been dirtied yet. + */ + WALInsertLockAcquireExclusive(); + if (XLogCtl->Insert.lastBackupStart < startpoint) + { + XLogCtl->Insert.lastBackupStart = startpoint; + gotUniqueStartpoint = true; + } + WALInsertLockRelease(); + } while (!gotUniqueStartpoint); + + XLByteToSeg(startpoint, _logSegNo, wal_segment_size); + XLogFileName(xlogfilename, starttli, _logSegNo, wal_segment_size); + + /* + * Construct tablespace_map file. If caller isn't interested in this, + * we make a local StringInfo. + */ + if (tblspcmapfile == NULL) + tblspcmapfile = makeStringInfo(); + + datadirpathlen = strlen(DataDir); + + /* Collect information about all tablespaces */ + tblspcdir = AllocateDir("pg_tblspc"); + while ((de = ReadDir(tblspcdir, "pg_tblspc")) != NULL) + { + char fullpath[MAXPGPATH + 10]; + char linkpath[MAXPGPATH]; + char *relpath = NULL; + int rllen; + StringInfoData escapedpath; + char *s; + + /* Skip anything that doesn't look like a tablespace */ + if (strspn(de->d_name, "0123456789") != strlen(de->d_name)) + continue; + + snprintf(fullpath, sizeof(fullpath), "pg_tblspc/%s", de->d_name); + + /* + * Skip anything that isn't a symlink/junction. For testing only, + * we sometimes use allow_in_place_tablespaces to create + * directories directly under pg_tblspc, which would fail below. + */ + if (get_dirent_type(fullpath, de, false, ERROR) != PGFILETYPE_LNK) + continue; + +#if defined(HAVE_READLINK) || defined(WIN32) + rllen = readlink(fullpath, linkpath, sizeof(linkpath)); + if (rllen < 0) + { + ereport(WARNING, + (errmsg("could not read symbolic link \"%s\": %m", + fullpath))); + continue; + } + else if (rllen >= sizeof(linkpath)) + { + ereport(WARNING, + (errmsg("symbolic link \"%s\" target is too long", + fullpath))); + continue; + } + linkpath[rllen] = '\0'; + + /* + * Build a backslash-escaped version of the link path to include + * in the tablespace map file. + */ + initStringInfo(&escapedpath); + for (s = linkpath; *s; s++) + { + if (*s == '\n' || *s == '\r' || *s == '\\') + appendStringInfoChar(&escapedpath, '\\'); + appendStringInfoChar(&escapedpath, *s); + } + + /* + * Relpath holds the relative path of the tablespace directory + * when it's located within PGDATA, or NULL if it's located + * elsewhere. + */ + if (rllen > datadirpathlen && + strncmp(linkpath, DataDir, datadirpathlen) == 0 && + IS_DIR_SEP(linkpath[datadirpathlen])) + relpath = linkpath + datadirpathlen + 1; + + ti = palloc(sizeof(tablespaceinfo)); + ti->oid = pstrdup(de->d_name); + ti->path = pstrdup(linkpath); + ti->rpath = relpath ? pstrdup(relpath) : NULL; + ti->size = -1; + + if (tablespaces) + *tablespaces = lappend(*tablespaces, ti); + + appendStringInfo(tblspcmapfile, "%s %s\n", + ti->oid, escapedpath.data); + + pfree(escapedpath.data); +#else + + /* + * If the platform does not have symbolic links, it should not be + * possible to have tablespaces - clearly somebody else created + * them. Warn about it and ignore. + */ + ereport(WARNING, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("tablespaces are not supported on this platform"))); +#endif + } + FreeDir(tblspcdir); + + /* + * Construct backup label file. If caller isn't interested in this, + * we make a local StringInfo. + */ + if (labelfile == NULL) + labelfile = makeStringInfo(); + + /* Use the log timezone here, not the session timezone */ + stamp_time = (pg_time_t) time(NULL); + pg_strftime(strfbuf, sizeof(strfbuf), + "%Y-%m-%d %H:%M:%S %Z", + pg_localtime(&stamp_time, log_timezone)); + appendStringInfo(labelfile, "START WAL LOCATION: %X/%X (file %s)\n", + LSN_FORMAT_ARGS(startpoint), xlogfilename); + appendStringInfo(labelfile, "CHECKPOINT LOCATION: %X/%X\n", + LSN_FORMAT_ARGS(checkpointloc)); + appendStringInfo(labelfile, "BACKUP METHOD: %s\n", + exclusive ? "pg_start_backup" : "streamed"); + appendStringInfo(labelfile, "BACKUP FROM: %s\n", + backup_started_in_recovery ? "standby" : "primary"); + appendStringInfo(labelfile, "START TIME: %s\n", strfbuf); + appendStringInfo(labelfile, "LABEL: %s\n", backupidstr); + appendStringInfo(labelfile, "START TIMELINE: %u\n", starttli); + + /* + * Okay, write the file, or return its contents to caller. + */ + if (exclusive) + { + /* + * Check for existing backup label --- implies a backup is already + * running. (XXX given that we checked exclusiveBackupState + * above, maybe it would be OK to just unlink any such label + * file?) + */ + if (stat(BACKUP_LABEL_FILE, &stat_buf) != 0) + { + if (errno != ENOENT) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not stat file \"%s\": %m", + BACKUP_LABEL_FILE))); + } + else + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("a backup is already in progress"), + errhint("If you're sure there is no backup in progress, remove file \"%s\" and try again.", + BACKUP_LABEL_FILE))); + + fp = AllocateFile(BACKUP_LABEL_FILE, "w"); + + if (!fp) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", + BACKUP_LABEL_FILE))); + if (fwrite(labelfile->data, labelfile->len, 1, fp) != 1 || + fflush(fp) != 0 || + pg_fsync(fileno(fp)) != 0 || + ferror(fp) || + FreeFile(fp)) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not write file \"%s\": %m", + BACKUP_LABEL_FILE))); + /* Allocated locally for exclusive backups, so free separately */ + pfree(labelfile->data); + pfree(labelfile); + + /* Write backup tablespace_map file. */ + if (tblspcmapfile->len > 0) + { + if (stat(TABLESPACE_MAP, &stat_buf) != 0) + { + if (errno != ENOENT) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not stat file \"%s\": %m", + TABLESPACE_MAP))); + } + else + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("a backup is already in progress"), + errhint("If you're sure there is no backup in progress, remove file \"%s\" and try again.", + TABLESPACE_MAP))); + + fp = AllocateFile(TABLESPACE_MAP, "w"); + + if (!fp) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", + TABLESPACE_MAP))); + if (fwrite(tblspcmapfile->data, tblspcmapfile->len, 1, fp) != 1 || + fflush(fp) != 0 || + pg_fsync(fileno(fp)) != 0 || + ferror(fp) || + FreeFile(fp)) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not write file \"%s\": %m", + TABLESPACE_MAP))); + } + + /* Allocated locally for exclusive backups, so free separately */ + pfree(tblspcmapfile->data); + pfree(tblspcmapfile); + } + } + PG_END_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) BoolGetDatum(exclusive)); + + /* + * Mark that start phase has correctly finished for an exclusive backup. + * Session-level locks are updated as well to reflect that state. + * + * Note that CHECK_FOR_INTERRUPTS() must not occur while updating backup + * counters and session-level lock. Otherwise they can be updated + * inconsistently, and which might cause do_pg_abort_backup() to fail. + */ + if (exclusive) + { + WALInsertLockAcquireExclusive(); + XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_IN_PROGRESS; + + /* Set session-level lock */ + sessionBackupState = SESSION_BACKUP_EXCLUSIVE; + WALInsertLockRelease(); + } + else + sessionBackupState = SESSION_BACKUP_NON_EXCLUSIVE; + + /* + * We're done. As a convenience, return the starting WAL location. + */ + if (starttli_p) + *starttli_p = starttli; + return startpoint; +} + +/* Error cleanup callback for pg_start_backup */ +static void +pg_start_backup_callback(int code, Datum arg) +{ + bool exclusive = DatumGetBool(arg); + + /* Update backup counters and forcePageWrites on failure */ + WALInsertLockAcquireExclusive(); + if (exclusive) + { + Assert(XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_STARTING); + XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_NONE; + } + else + { + Assert(XLogCtl->Insert.nonExclusiveBackups > 0); + XLogCtl->Insert.nonExclusiveBackups--; + } + + if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE && + XLogCtl->Insert.nonExclusiveBackups == 0) + { + XLogCtl->Insert.forcePageWrites = false; + } + WALInsertLockRelease(); +} + +/* + * Error cleanup callback for pg_stop_backup + */ +static void +pg_stop_backup_callback(int code, Datum arg) +{ + bool exclusive = DatumGetBool(arg); + + /* Update backup status on failure */ + WALInsertLockAcquireExclusive(); + if (exclusive) + { + Assert(XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_STOPPING); + XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_IN_PROGRESS; + } + WALInsertLockRelease(); +} + +/* + * Utility routine to fetch the session-level status of a backup running. + */ +SessionBackupState +get_backup_status(void) +{ + return sessionBackupState; +} + +/* + * do_pg_stop_backup + * + * Utility function called at the end of an online backup. It cleans up the + * backup state and can optionally wait for WAL segments to be archived. + * + * If labelfile is NULL, this stops an exclusive backup. Otherwise this stops + * the non-exclusive backup specified by 'labelfile'. + * + * Returns the last WAL location that must be present to restore from this + * backup, and the corresponding timeline ID in *stoptli_p. + * + * It is the responsibility of the caller of this function to verify the + * permissions of the calling user! + */ +XLogRecPtr +do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p) +{ + bool exclusive = (labelfile == NULL); + bool backup_started_in_recovery = false; + XLogRecPtr startpoint; + XLogRecPtr stoppoint; + TimeLineID stoptli; + pg_time_t stamp_time; + char strfbuf[128]; + char histfilepath[MAXPGPATH]; + char startxlogfilename[MAXFNAMELEN]; + char stopxlogfilename[MAXFNAMELEN]; + char lastxlogfilename[MAXFNAMELEN]; + char histfilename[MAXFNAMELEN]; + char backupfrom[20]; + XLogSegNo _logSegNo; + FILE *lfp; + FILE *fp; + char ch; + int seconds_before_warning; + int waits = 0; + bool reported_waiting = false; + char *remaining; + char *ptr; + uint32 hi, + lo; + + backup_started_in_recovery = RecoveryInProgress(); + + /* + * Currently only non-exclusive backup can be taken during recovery. + */ + if (backup_started_in_recovery && exclusive) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("recovery is in progress"), + errhint("WAL control functions cannot be executed during recovery."))); + + /* + * During recovery, we don't need to check WAL level. Because, if WAL + * level is not sufficient, it's impossible to get here during recovery. + */ + if (!backup_started_in_recovery && !XLogIsNeeded()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("WAL level not sufficient for making an online backup"), + errhint("wal_level must be set to \"replica\" or \"logical\" at server start."))); + + if (exclusive) + { + /* + * At first, mark that we're now stopping an exclusive backup, to + * ensure that there are no other sessions currently running + * pg_start_backup() or pg_stop_backup(). + */ + WALInsertLockAcquireExclusive(); + if (XLogCtl->Insert.exclusiveBackupState != EXCLUSIVE_BACKUP_IN_PROGRESS) + { + WALInsertLockRelease(); + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("exclusive backup not in progress"))); + } + XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_STOPPING; + WALInsertLockRelease(); + + /* + * Remove backup_label. In case of failure, the state for an exclusive + * backup is switched back to in-progress. + */ + PG_ENSURE_ERROR_CLEANUP(pg_stop_backup_callback, (Datum) BoolGetDatum(exclusive)); + { + /* + * Read the existing label file into memory. + */ + struct stat statbuf; + int r; + + if (stat(BACKUP_LABEL_FILE, &statbuf)) + { + /* should not happen per the upper checks */ + if (errno != ENOENT) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not stat file \"%s\": %m", + BACKUP_LABEL_FILE))); + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("a backup is not in progress"))); + } + + lfp = AllocateFile(BACKUP_LABEL_FILE, "r"); + if (!lfp) + { + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + BACKUP_LABEL_FILE))); + } + labelfile = palloc(statbuf.st_size + 1); + r = fread(labelfile, statbuf.st_size, 1, lfp); + labelfile[statbuf.st_size] = '\0'; + + /* + * Close and remove the backup label file + */ + if (r != 1 || ferror(lfp) || FreeFile(lfp)) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + BACKUP_LABEL_FILE))); + durable_unlink(BACKUP_LABEL_FILE, ERROR); + + /* + * Remove tablespace_map file if present, it is created only if + * there are tablespaces. + */ + durable_unlink(TABLESPACE_MAP, DEBUG1); + } + PG_END_ENSURE_ERROR_CLEANUP(pg_stop_backup_callback, (Datum) BoolGetDatum(exclusive)); + } + + /* + * OK to update backup counters, forcePageWrites and session-level lock. + * + * Note that CHECK_FOR_INTERRUPTS() must not occur while updating them. + * Otherwise they can be updated inconsistently, and which might cause + * do_pg_abort_backup() to fail. + */ + WALInsertLockAcquireExclusive(); + if (exclusive) + { + XLogCtl->Insert.exclusiveBackupState = EXCLUSIVE_BACKUP_NONE; + } + else + { + /* + * The user-visible pg_start/stop_backup() functions that operate on + * exclusive backups can be called at any time, but for non-exclusive + * backups, it is expected that each do_pg_start_backup() call is + * matched by exactly one do_pg_stop_backup() call. + */ + Assert(XLogCtl->Insert.nonExclusiveBackups > 0); + XLogCtl->Insert.nonExclusiveBackups--; + } + + if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE && + XLogCtl->Insert.nonExclusiveBackups == 0) + { + XLogCtl->Insert.forcePageWrites = false; + } + + /* + * Clean up session-level lock. + * + * You might think that WALInsertLockRelease() can be called before + * cleaning up session-level lock because session-level lock doesn't need + * to be protected with WAL insertion lock. But since + * CHECK_FOR_INTERRUPTS() can occur in it, session-level lock must be + * cleaned up before it. + */ + sessionBackupState = SESSION_BACKUP_NONE; + + WALInsertLockRelease(); + + /* + * Read and parse the START WAL LOCATION line (this code is pretty crude, + * but we are not expecting any variability in the file format). + */ + if (sscanf(labelfile, "START WAL LOCATION: %X/%X (file %24s)%c", + &hi, &lo, startxlogfilename, + &ch) != 4 || ch != '\n') + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); + startpoint = ((uint64) hi) << 32 | lo; + remaining = strchr(labelfile, '\n') + 1; /* %n is not portable enough */ + + /* + * Parse the BACKUP FROM line. If we are taking an online backup from the + * standby, we confirm that the standby has not been promoted during the + * backup. + */ + ptr = strstr(remaining, "BACKUP FROM:"); + if (!ptr || sscanf(ptr, "BACKUP FROM: %19s\n", backupfrom) != 1) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); + if (strcmp(backupfrom, "standby") == 0 && !backup_started_in_recovery) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("the standby was promoted during online backup"), + errhint("This means that the backup being taken is corrupt " + "and should not be used. " + "Try taking another online backup."))); + + /* + * During recovery, we don't write an end-of-backup record. We assume that + * pg_control was backed up last and its minimum recovery point can be + * available as the backup end location. Since we don't have an + * end-of-backup record, we use the pg_control value to check whether + * we've reached the end of backup when starting recovery from this + * backup. We have no way of checking if pg_control wasn't backed up last + * however. + * + * We don't force a switch to new WAL file but it is still possible to + * wait for all the required files to be archived if waitforarchive is + * true. This is okay if we use the backup to start a standby and fetch + * the missing WAL using streaming replication. But in the case of an + * archive recovery, a user should set waitforarchive to true and wait for + * them to be archived to ensure that all the required files are + * available. + * + * We return the current minimum recovery point as the backup end + * location. Note that it can be greater than the exact backup end + * location if the minimum recovery point is updated after the backup of + * pg_control. This is harmless for current uses. + * + * XXX currently a backup history file is for informational and debug + * purposes only. It's not essential for an online backup. Furthermore, + * even if it's created, it will not be archived during recovery because + * an archiver is not invoked. So it doesn't seem worthwhile to write a + * backup history file during recovery. + */ + if (backup_started_in_recovery) + { + XLogRecPtr recptr; + + /* + * Check to see if all WAL replayed during online backup contain + * full-page writes. + */ + SpinLockAcquire(&XLogCtl->info_lck); + recptr = XLogCtl->lastFpwDisableRecPtr; + SpinLockRelease(&XLogCtl->info_lck); + + if (startpoint <= recptr) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("WAL generated with full_page_writes=off was replayed " + "during online backup"), + errhint("This means that the backup being taken on the standby " + "is corrupt and should not be used. " + "Enable full_page_writes and run CHECKPOINT on the primary, " + "and then try an online backup again."))); + + + LWLockAcquire(ControlFileLock, LW_SHARED); + stoppoint = ControlFile->minRecoveryPoint; + stoptli = ControlFile->minRecoveryPointTLI; + LWLockRelease(ControlFileLock); + } + else + { + /* + * Write the backup-end xlog record + */ + XLogBeginInsert(); + XLogRegisterData((char *) (&startpoint), sizeof(startpoint)); + stoppoint = XLogInsert(RM_XLOG_ID, XLOG_BACKUP_END); + stoptli = ThisTimeLineID; + + /* + * Force a switch to a new xlog segment file, so that the backup is + * valid as soon as archiver moves out the current segment file. + */ + RequestXLogSwitch(false); + + XLByteToPrevSeg(stoppoint, _logSegNo, wal_segment_size); + XLogFileName(stopxlogfilename, stoptli, _logSegNo, wal_segment_size); + + /* Use the log timezone here, not the session timezone */ + stamp_time = (pg_time_t) time(NULL); + pg_strftime(strfbuf, sizeof(strfbuf), + "%Y-%m-%d %H:%M:%S %Z", + pg_localtime(&stamp_time, log_timezone)); + + /* + * Write the backup history file + */ + XLByteToSeg(startpoint, _logSegNo, wal_segment_size); + BackupHistoryFilePath(histfilepath, stoptli, _logSegNo, + startpoint, wal_segment_size); + fp = AllocateFile(histfilepath, "w"); + if (!fp) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", + histfilepath))); + fprintf(fp, "START WAL LOCATION: %X/%X (file %s)\n", + LSN_FORMAT_ARGS(startpoint), startxlogfilename); + fprintf(fp, "STOP WAL LOCATION: %X/%X (file %s)\n", + LSN_FORMAT_ARGS(stoppoint), stopxlogfilename); + + /* + * Transfer remaining lines including label and start timeline to + * history file. + */ + fprintf(fp, "%s", remaining); + fprintf(fp, "STOP TIME: %s\n", strfbuf); + fprintf(fp, "STOP TIMELINE: %u\n", stoptli); + if (fflush(fp) || ferror(fp) || FreeFile(fp)) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not write file \"%s\": %m", + histfilepath))); + + /* + * Clean out any no-longer-needed history files. As a side effect, + * this will post a .ready file for the newly created history file, + * notifying the archiver that history file may be archived + * immediately. + */ + CleanupBackupHistory(); + } + + /* + * If archiving is enabled, wait for all the required WAL files to be + * archived before returning. If archiving isn't enabled, the required WAL + * needs to be transported via streaming replication (hopefully with + * wal_keep_size set high enough), or some more exotic mechanism like + * polling and copying files from pg_wal with script. We have no knowledge + * of those mechanisms, so it's up to the user to ensure that he gets all + * the required WAL. + * + * We wait until both the last WAL file filled during backup and the + * history file have been archived, and assume that the alphabetic sorting + * property of the WAL files ensures any earlier WAL files are safely + * archived as well. + * + * We wait forever, since archive_command is supposed to work and we + * assume the admin wanted his backup to work completely. If you don't + * wish to wait, then either waitforarchive should be passed in as false, + * or you can set statement_timeout. Also, some notices are issued to + * clue in anyone who might be doing this interactively. + */ + + if (waitforarchive && + ((!backup_started_in_recovery && XLogArchivingActive()) || + (backup_started_in_recovery && XLogArchivingAlways()))) + { + XLByteToPrevSeg(stoppoint, _logSegNo, wal_segment_size); + XLogFileName(lastxlogfilename, stoptli, _logSegNo, wal_segment_size); + + XLByteToSeg(startpoint, _logSegNo, wal_segment_size); + BackupHistoryFileName(histfilename, stoptli, _logSegNo, + startpoint, wal_segment_size); + + seconds_before_warning = 60; + waits = 0; + + while (XLogArchiveIsBusy(lastxlogfilename) || + XLogArchiveIsBusy(histfilename)) + { + CHECK_FOR_INTERRUPTS(); + + if (!reported_waiting && waits > 5) + { + ereport(NOTICE, + (errmsg("base backup done, waiting for required WAL segments to be archived"))); + reported_waiting = true; + } + + pgstat_report_wait_start(WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE); + pg_usleep(1000000L); + pgstat_report_wait_end(); + + if (++waits >= seconds_before_warning) + { + seconds_before_warning *= 2; /* This wraps in >10 years... */ + ereport(WARNING, + (errmsg("still waiting for all required WAL segments to be archived (%d seconds elapsed)", + waits), + errhint("Check that your archive_command is executing properly. " + "You can safely cancel this backup, " + "but the database backup will not be usable without all the WAL segments."))); + } + } + + ereport(NOTICE, + (errmsg("all required WAL segments have been archived"))); + } + else if (waitforarchive) + ereport(NOTICE, + (errmsg("WAL archiving is not enabled; you must ensure that all required WAL segments are copied through other means to complete the backup"))); + + /* + * We're done. As a convenience, return the ending WAL location. + */ + if (stoptli_p) + *stoptli_p = stoptli; + return stoppoint; +} + + +/* + * do_pg_abort_backup: abort a running backup + * + * This does just the most basic steps of do_pg_stop_backup(), by taking the + * system out of backup mode, thus making it a lot more safe to call from + * an error handler. + * + * The caller can pass 'arg' as 'true' or 'false' to control whether a warning + * is emitted. + * + * NB: This is only for aborting a non-exclusive backup that doesn't write + * backup_label. A backup started with pg_start_backup() needs to be finished + * with pg_stop_backup(). + * + * NB: This gets used as a before_shmem_exit handler, hence the odd-looking + * signature. + */ +void +do_pg_abort_backup(int code, Datum arg) +{ + bool emit_warning = DatumGetBool(arg); + + /* + * Quick exit if session is not keeping around a non-exclusive backup + * already started. + */ + if (sessionBackupState != SESSION_BACKUP_NON_EXCLUSIVE) + return; + + WALInsertLockAcquireExclusive(); + Assert(XLogCtl->Insert.nonExclusiveBackups > 0); + XLogCtl->Insert.nonExclusiveBackups--; + + if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE && + XLogCtl->Insert.nonExclusiveBackups == 0) + { + XLogCtl->Insert.forcePageWrites = false; + } + + sessionBackupState = SESSION_BACKUP_NONE; + WALInsertLockRelease(); + + if (emit_warning) + ereport(WARNING, + (errmsg("aborting backup due to backend exiting before pg_stop_backup was called"))); +} + +/* + * Register a handler that will warn about unterminated backups at end of + * session, unless this has already been done. + */ +void +register_persistent_abort_backup_handler(void) +{ + static bool already_done = false; + + if (already_done) + return; + before_shmem_exit(do_pg_abort_backup, DatumGetBool(true)); + already_done = true; +} + +/* + * Get latest redo apply position. + * + * Exported to allow WALReceiver to read the pointer directly. + */ +XLogRecPtr +GetXLogReplayRecPtr(TimeLineID *replayTLI) +{ + XLogRecPtr recptr; + TimeLineID tli; + + SpinLockAcquire(&XLogCtl->info_lck); + recptr = XLogCtl->lastReplayedEndRecPtr; + tli = XLogCtl->lastReplayedTLI; + SpinLockRelease(&XLogCtl->info_lck); + + if (replayTLI) + *replayTLI = tli; + return recptr; +} + +/* + * Get latest WAL insert pointer + */ +XLogRecPtr +GetXLogInsertRecPtr(void) +{ + XLogCtlInsert *Insert = &XLogCtl->Insert; + uint64 current_bytepos; + + SpinLockAcquire(&Insert->insertpos_lck); + current_bytepos = Insert->CurrBytePos; + SpinLockRelease(&Insert->insertpos_lck); + + return XLogBytePosToRecPtr(current_bytepos); +} + +/* + * Get latest WAL write pointer + */ +XLogRecPtr +GetXLogWriteRecPtr(void) +{ + SpinLockAcquire(&XLogCtl->info_lck); + LogwrtResult = XLogCtl->LogwrtResult; + SpinLockRelease(&XLogCtl->info_lck); + + return LogwrtResult.Write; +} + +/* + * Returns the redo pointer of the last checkpoint or restartpoint. This is + * the oldest point in WAL that we still need, if we have to restart recovery. + */ +void +GetOldestRestartPoint(XLogRecPtr *oldrecptr, TimeLineID *oldtli) +{ + LWLockAcquire(ControlFileLock, LW_SHARED); + *oldrecptr = ControlFile->checkPointCopy.redo; + *oldtli = ControlFile->checkPointCopy.ThisTimeLineID; + LWLockRelease(ControlFileLock); +} + +/* + * read_backup_label: check to see if a backup_label file is present + * + * If we see a backup_label during recovery, we assume that we are recovering + * from a backup dump file, and we therefore roll forward from the checkpoint + * identified by the label file, NOT what pg_control says. This avoids the + * problem that pg_control might have been archived one or more checkpoints + * later than the start of the dump, and so if we rely on it as the start + * point, we will fail to restore a consistent database state. + * + * Returns true if a backup_label was found (and fills the checkpoint + * location and its REDO location into *checkPointLoc and RedoStartLSN, + * respectively); returns false if not. If this backup_label came from a + * streamed backup, *backupEndRequired is set to true. If this backup_label + * was created during recovery, *backupFromStandby is set to true. + */ +static bool +read_backup_label(XLogRecPtr *checkPointLoc, bool *backupEndRequired, + bool *backupFromStandby) +{ + char startxlogfilename[MAXFNAMELEN]; + TimeLineID tli_from_walseg, + tli_from_file; + FILE *lfp; + char ch; + char backuptype[20]; + char backupfrom[20]; + char backuplabel[MAXPGPATH]; + char backuptime[128]; + uint32 hi, + lo; + + *backupEndRequired = false; + *backupFromStandby = false; + + /* + * See if label file is present + */ + lfp = AllocateFile(BACKUP_LABEL_FILE, "r"); + if (!lfp) + { + if (errno != ENOENT) + ereport(FATAL, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + BACKUP_LABEL_FILE))); + return false; /* it's not there, all is fine */ + } + + /* + * Read and parse the START WAL LOCATION and CHECKPOINT lines (this code + * is pretty crude, but we are not expecting any variability in the file + * format). + */ + if (fscanf(lfp, "START WAL LOCATION: %X/%X (file %08X%16s)%c", + &hi, &lo, &tli_from_walseg, startxlogfilename, &ch) != 5 || ch != '\n') + ereport(FATAL, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); + RedoStartLSN = ((uint64) hi) << 32 | lo; + if (fscanf(lfp, "CHECKPOINT LOCATION: %X/%X%c", + &hi, &lo, &ch) != 3 || ch != '\n') + ereport(FATAL, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); + *checkPointLoc = ((uint64) hi) << 32 | lo; + + /* + * BACKUP METHOD and BACKUP FROM lines are new in 9.2. We can't restore + * from an older backup anyway, but since the information on it is not + * strictly required, don't error out if it's missing for some reason. + */ + if (fscanf(lfp, "BACKUP METHOD: %19s\n", backuptype) == 1) + { + if (strcmp(backuptype, "streamed") == 0) + *backupEndRequired = true; + } + + if (fscanf(lfp, "BACKUP FROM: %19s\n", backupfrom) == 1) + { + if (strcmp(backupfrom, "standby") == 0) + *backupFromStandby = true; + } + + /* + * Parse START TIME and LABEL. Those are not mandatory fields for recovery + * but checking for their presence is useful for debugging and the next + * sanity checks. Cope also with the fact that the result buffers have a + * pre-allocated size, hence if the backup_label file has been generated + * with strings longer than the maximum assumed here an incorrect parsing + * happens. That's fine as only minor consistency checks are done + * afterwards. + */ + if (fscanf(lfp, "START TIME: %127[^\n]\n", backuptime) == 1) + ereport(DEBUG1, + (errmsg_internal("backup time %s in file \"%s\"", + backuptime, BACKUP_LABEL_FILE))); + + if (fscanf(lfp, "LABEL: %1023[^\n]\n", backuplabel) == 1) + ereport(DEBUG1, + (errmsg_internal("backup label %s in file \"%s\"", + backuplabel, BACKUP_LABEL_FILE))); + + /* + * START TIMELINE is new as of 11. Its parsing is not mandatory, still use + * it as a sanity check if present. + */ + if (fscanf(lfp, "START TIMELINE: %u\n", &tli_from_file) == 1) + { + if (tli_from_walseg != tli_from_file) + ereport(FATAL, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE), + errdetail("Timeline ID parsed is %u, but expected %u.", + tli_from_file, tli_from_walseg))); + + ereport(DEBUG1, + (errmsg_internal("backup timeline %u in file \"%s\"", + tli_from_file, BACKUP_LABEL_FILE))); + } + + if (ferror(lfp) || FreeFile(lfp)) + ereport(FATAL, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + BACKUP_LABEL_FILE))); + + return true; +} + +/* + * read_tablespace_map: check to see if a tablespace_map file is present + * + * If we see a tablespace_map file during recovery, we assume that we are + * recovering from a backup dump file, and we therefore need to create symlinks + * as per the information present in tablespace_map file. + * + * Returns true if a tablespace_map file was found (and fills *tablespaces + * with a tablespaceinfo struct for each tablespace listed in the file); + * returns false if not. + */ +static bool +read_tablespace_map(List **tablespaces) +{ + tablespaceinfo *ti; + FILE *lfp; + char str[MAXPGPATH]; + int ch, + i, + n; + bool was_backslash; + + /* + * See if tablespace_map file is present + */ + lfp = AllocateFile(TABLESPACE_MAP, "r"); + if (!lfp) + { + if (errno != ENOENT) + ereport(FATAL, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + TABLESPACE_MAP))); + return false; /* it's not there, all is fine */ + } + + /* + * Read and parse the link name and path lines from tablespace_map file + * (this code is pretty crude, but we are not expecting any variability in + * the file format). De-escape any backslashes that were inserted. + */ + i = 0; + was_backslash = false; + while ((ch = fgetc(lfp)) != EOF) + { + if (!was_backslash && (ch == '\n' || ch == '\r')) + { + if (i == 0) + continue; /* \r immediately followed by \n */ + + /* + * The de-escaped line should contain an OID followed by exactly + * one space followed by a path. The path might start with + * spaces, so don't be too liberal about parsing. + */ + str[i] = '\0'; + n = 0; + while (str[n] && str[n] != ' ') + n++; + if (n < 1 || n >= i - 1) + ereport(FATAL, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("invalid data in file \"%s\"", TABLESPACE_MAP))); + str[n++] = '\0'; + + ti = palloc0(sizeof(tablespaceinfo)); + ti->oid = pstrdup(str); + ti->path = pstrdup(str + n); + *tablespaces = lappend(*tablespaces, ti); + + i = 0; + continue; + } + else if (!was_backslash && ch == '\\') + was_backslash = true; + else + { + if (i < sizeof(str) - 1) + str[i++] = ch; + was_backslash = false; + } + } + + if (i != 0 || was_backslash) /* last line not terminated? */ + ereport(FATAL, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("invalid data in file \"%s\"", TABLESPACE_MAP))); + + if (ferror(lfp) || FreeFile(lfp)) + ereport(FATAL, + (errcode_for_file_access(), + errmsg("could not read file \"%s\": %m", + TABLESPACE_MAP))); + + return true; +} + +/* + * Error context callback for errors occurring during rm_redo(). + */ +static void +rm_redo_error_callback(void *arg) +{ + XLogReaderState *record = (XLogReaderState *) arg; + StringInfoData buf; + + initStringInfo(&buf); + xlog_outdesc(&buf, record); + xlog_block_info(&buf, record); + + /* translator: %s is a WAL record description */ + errcontext("WAL redo at %X/%X for %s", + LSN_FORMAT_ARGS(record->ReadRecPtr), + buf.data); + + pfree(buf.data); +} + +/* + * BackupInProgress: check if online backup mode is active + * + * This is done by checking for existence of the "backup_label" file. + */ +bool +BackupInProgress(void) +{ + struct stat stat_buf; + + return (stat(BACKUP_LABEL_FILE, &stat_buf) == 0); +} + +/* + * CancelBackup: rename the "backup_label" and "tablespace_map" + * files to cancel backup mode + * + * If the "backup_label" file exists, it will be renamed to "backup_label.old". + * Similarly, if the "tablespace_map" file exists, it will be renamed to + * "tablespace_map.old". + * + * Note that this will render an online backup in progress + * useless. To correctly finish an online backup, pg_stop_backup must be + * called. + */ +void +CancelBackup(void) +{ + struct stat stat_buf; + + /* if the backup_label file is not there, return */ + if (stat(BACKUP_LABEL_FILE, &stat_buf) < 0) + return; + + /* remove leftover file from previously canceled backup if it exists */ + unlink(BACKUP_LABEL_OLD); + + if (durable_rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD, DEBUG1) != 0) + { + ereport(WARNING, + (errcode_for_file_access(), + errmsg("online backup mode was not canceled"), + errdetail("File \"%s\" could not be renamed to \"%s\": %m.", + BACKUP_LABEL_FILE, BACKUP_LABEL_OLD))); + return; + } + + /* if the tablespace_map file is not there, return */ + if (stat(TABLESPACE_MAP, &stat_buf) < 0) + { + ereport(LOG, + (errmsg("online backup mode canceled"), + errdetail("File \"%s\" was renamed to \"%s\".", + BACKUP_LABEL_FILE, BACKUP_LABEL_OLD))); + return; + } + + /* remove leftover file from previously canceled backup if it exists */ + unlink(TABLESPACE_MAP_OLD); + + if (durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, DEBUG1) == 0) + { + ereport(LOG, + (errmsg("online backup mode canceled"), + errdetail("Files \"%s\" and \"%s\" were renamed to " + "\"%s\" and \"%s\", respectively.", + BACKUP_LABEL_FILE, TABLESPACE_MAP, + BACKUP_LABEL_OLD, TABLESPACE_MAP_OLD))); + } + else + { + ereport(WARNING, + (errcode_for_file_access(), + errmsg("online backup mode canceled"), + errdetail("File \"%s\" was renamed to \"%s\", but " + "file \"%s\" could not be renamed to \"%s\": %m.", + BACKUP_LABEL_FILE, BACKUP_LABEL_OLD, + TABLESPACE_MAP, TABLESPACE_MAP_OLD))); + } +} + +/* + * Read the XLOG page containing RecPtr into readBuf (if not read already). + * Returns number of bytes read, if the page is read successfully, or -1 + * in case of errors. When errors occur, they are ereport'ed, but only + * if they have not been previously reported. + * + * This is responsible for restoring files from archive as needed, as well + * as for waiting for the requested WAL record to arrive in standby mode. + * + * 'emode' specifies the log level used for reporting "file not found" or + * "end of WAL" situations in archive recovery, or in standby mode when a + * trigger file is found. If set to WARNING or below, XLogPageRead() returns + * false in those situations, on higher log levels the ereport() won't + * return. + * + * In standby mode, if after a successful return of XLogPageRead() the + * caller finds the record it's interested in to be broken, it should + * ereport the error with the level determined by + * emode_for_corrupt_record(), and then set lastSourceFailed + * and call XLogPageRead() again with the same arguments. This lets + * XLogPageRead() to try fetching the record from another source, or to + * sleep and retry. + */ +static int +XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr, int reqLen, + XLogRecPtr targetRecPtr, char *readBuf) +{ + XLogPageReadPrivate *private = + (XLogPageReadPrivate *) xlogreader->private_data; + int emode = private->emode; + uint32 targetPageOff; + XLogSegNo targetSegNo PG_USED_FOR_ASSERTS_ONLY; + int r; + + XLByteToSeg(targetPagePtr, targetSegNo, wal_segment_size); + targetPageOff = XLogSegmentOffset(targetPagePtr, wal_segment_size); + + /* + * See if we need to switch to a new segment because the requested record + * is not in the currently open one. + */ + if (readFile >= 0 && + !XLByteInSeg(targetPagePtr, readSegNo, wal_segment_size)) + { + /* + * Request a restartpoint if we've replayed too much xlog since the + * last one. + */ + if (bgwriterLaunched) + { + if (XLogCheckpointNeeded(readSegNo)) + { + (void) GetRedoRecPtr(); + if (XLogCheckpointNeeded(readSegNo)) + RequestCheckpoint(CHECKPOINT_CAUSE_XLOG); + } + } + + close(readFile); + readFile = -1; + readSource = XLOG_FROM_ANY; + } + + XLByteToSeg(targetPagePtr, readSegNo, wal_segment_size); + +retry: + /* See if we need to retrieve more data */ + if (readFile < 0 || + (readSource == XLOG_FROM_STREAM && + flushedUpto < targetPagePtr + reqLen)) + { + if (!WaitForWALToBecomeAvailable(targetPagePtr + reqLen, + private->randAccess, + private->fetching_ckpt, + targetRecPtr)) + { + if (readFile >= 0) + close(readFile); + readFile = -1; + readLen = 0; + readSource = XLOG_FROM_ANY; + + return -1; + } + } + + /* + * At this point, we have the right segment open and if we're streaming we + * know the requested record is in it. + */ + Assert(readFile != -1); + + /* + * If the current segment is being streamed from the primary, calculate + * how much of the current page we have received already. We know the + * requested record has been received, but this is for the benefit of + * future calls, to allow quick exit at the top of this function. + */ + if (readSource == XLOG_FROM_STREAM) + { + if (((targetPagePtr) / XLOG_BLCKSZ) != (flushedUpto / XLOG_BLCKSZ)) + readLen = XLOG_BLCKSZ; + else + readLen = XLogSegmentOffset(flushedUpto, wal_segment_size) - + targetPageOff; + } + else + readLen = XLOG_BLCKSZ; + + /* Read the requested page */ + readOff = targetPageOff; + + pgstat_report_wait_start(WAIT_EVENT_WAL_READ); + r = pg_pread(readFile, readBuf, XLOG_BLCKSZ, (off_t) readOff); + if (r != XLOG_BLCKSZ) + { + char fname[MAXFNAMELEN]; + int save_errno = errno; + + pgstat_report_wait_end(); + XLogFileName(fname, curFileTLI, readSegNo, wal_segment_size); + if (r < 0) + { + errno = save_errno; + ereport(emode_for_corrupt_record(emode, targetPagePtr + reqLen), + (errcode_for_file_access(), + errmsg("could not read from log segment %s, offset %u: %m", + fname, readOff))); + } + else + ereport(emode_for_corrupt_record(emode, targetPagePtr + reqLen), + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg("could not read from log segment %s, offset %u: read %d of %zu", + fname, readOff, r, (Size) XLOG_BLCKSZ))); + goto next_record_is_invalid; + } + pgstat_report_wait_end(); + + Assert(targetSegNo == readSegNo); + Assert(targetPageOff == readOff); + Assert(reqLen <= readLen); + + xlogreader->seg.ws_tli = curFileTLI; + + /* + * Check the page header immediately, so that we can retry immediately if + * it's not valid. This may seem unnecessary, because XLogReadRecord() + * validates the page header anyway, and would propagate the failure up to + * ReadRecord(), which would retry. However, there's a corner case with + * continuation records, if a record is split across two pages such that + * we would need to read the two pages from different sources. For + * example, imagine a scenario where a streaming replica is started up, + * and replay reaches a record that's split across two WAL segments. The + * first page is only available locally, in pg_wal, because it's already + * been recycled on the primary. The second page, however, is not present + * in pg_wal, and we should stream it from the primary. There is a + * recycled WAL segment present in pg_wal, with garbage contents, however. + * We would read the first page from the local WAL segment, but when + * reading the second page, we would read the bogus, recycled, WAL + * segment. If we didn't catch that case here, we would never recover, + * because ReadRecord() would retry reading the whole record from the + * beginning. + * + * Of course, this only catches errors in the page header, which is what + * happens in the case of a recycled WAL segment. Other kinds of errors or + * corruption still has the same problem. But this at least fixes the + * common case, which can happen as part of normal operation. + * + * Validating the page header is cheap enough that doing it twice + * shouldn't be a big deal from a performance point of view. + */ + if (!XLogReaderValidatePageHeader(xlogreader, targetPagePtr, readBuf)) + { + /* reset any error XLogReaderValidatePageHeader() might have set */ + xlogreader->errormsg_buf[0] = '\0'; + goto next_record_is_invalid; + } + + return readLen; + +next_record_is_invalid: + lastSourceFailed = true; + + if (readFile >= 0) + close(readFile); + readFile = -1; + readLen = 0; + readSource = XLOG_FROM_ANY; + + /* In standby-mode, keep trying */ + if (StandbyMode) + goto retry; + else + return -1; +} + +/* + * Open the WAL segment containing WAL location 'RecPtr'. + * + * The segment can be fetched via restore_command, or via walreceiver having + * streamed the record, or it can already be present in pg_wal. Checking + * pg_wal is mainly for crash recovery, but it will be polled in standby mode + * too, in case someone copies a new segment directly to pg_wal. That is not + * documented or recommended, though. + * + * If 'fetching_ckpt' is true, we're fetching a checkpoint record, and should + * prepare to read WAL starting from RedoStartLSN after this. + * + * 'RecPtr' might not point to the beginning of the record we're interested + * in, it might also point to the page or segment header. In that case, + * 'tliRecPtr' is the position of the WAL record we're interested in. It is + * used to decide which timeline to stream the requested WAL from. + * + * If the record is not immediately available, the function returns false + * if we're not in standby mode. In standby mode, waits for it to become + * available. + * + * When the requested record becomes available, the function opens the file + * containing it (if not open already), and returns true. When end of standby + * mode is triggered by the user, and there is no more WAL available, returns + * false. + */ +static bool +WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess, + bool fetching_ckpt, XLogRecPtr tliRecPtr) +{ + static TimestampTz last_fail_time = 0; + TimestampTz now; + bool streaming_reply_sent = false; + + /*------- + * Standby mode is implemented by a state machine: + * + * 1. Read from either archive or pg_wal (XLOG_FROM_ARCHIVE), or just + * pg_wal (XLOG_FROM_PG_WAL) + * 2. Check trigger file + * 3. Read from primary server via walreceiver (XLOG_FROM_STREAM) + * 4. Rescan timelines + * 5. Sleep wal_retrieve_retry_interval milliseconds, and loop back to 1. + * + * Failure to read from the current source advances the state machine to + * the next state. + * + * 'currentSource' indicates the current state. There are no currentSource + * values for "check trigger", "rescan timelines", and "sleep" states, + * those actions are taken when reading from the previous source fails, as + * part of advancing to the next state. + * + * If standby mode is turned off while reading WAL from stream, we move + * to XLOG_FROM_ARCHIVE and reset lastSourceFailed, to force fetching + * the files (which would be required at end of recovery, e.g., timeline + * history file) from archive or pg_wal. We don't need to kill WAL receiver + * here because it's already stopped when standby mode is turned off at + * the end of recovery. + *------- + */ + if (!InArchiveRecovery) + currentSource = XLOG_FROM_PG_WAL; + else if (currentSource == XLOG_FROM_ANY || + (!StandbyMode && currentSource == XLOG_FROM_STREAM)) + { + lastSourceFailed = false; + currentSource = XLOG_FROM_ARCHIVE; + } + + for (;;) + { + XLogSource oldSource = currentSource; + bool startWalReceiver = false; + + /* + * First check if we failed to read from the current source, and + * advance the state machine if so. The failure to read might've + * happened outside this function, e.g when a CRC check fails on a + * record, or within this loop. + */ + if (lastSourceFailed) + { + switch (currentSource) + { + case XLOG_FROM_ARCHIVE: + case XLOG_FROM_PG_WAL: + + /* + * Check to see if the trigger file exists. Note that we + * do this only after failure, so when you create the + * trigger file, we still finish replaying as much as we + * can from archive and pg_wal before failover. + */ + if (StandbyMode && CheckForStandbyTrigger()) + { + ShutdownWalRcv(); + return false; + } + + /* + * Not in standby mode, and we've now tried the archive + * and pg_wal. + */ + if (!StandbyMode) + return false; + + /* + * Move to XLOG_FROM_STREAM state, and set to start a + * walreceiver if necessary. + */ + currentSource = XLOG_FROM_STREAM; + startWalReceiver = true; + break; + + case XLOG_FROM_STREAM: + + /* + * Failure while streaming. Most likely, we got here + * because streaming replication was terminated, or + * promotion was triggered. But we also get here if we + * find an invalid record in the WAL streamed from the + * primary, in which case something is seriously wrong. + * There's little chance that the problem will just go + * away, but PANIC is not good for availability either, + * especially in hot standby mode. So, we treat that the + * same as disconnection, and retry from archive/pg_wal + * again. The WAL in the archive should be identical to + * what was streamed, so it's unlikely that it helps, but + * one can hope... + */ + + /* + * We should be able to move to XLOG_FROM_STREAM only in + * standby mode. + */ + Assert(StandbyMode); + + /* + * Before we leave XLOG_FROM_STREAM state, make sure that + * walreceiver is not active, so that it won't overwrite + * WAL that we restore from archive. + */ + if (WalRcvStreaming()) + ShutdownWalRcv(); + + /* + * Before we sleep, re-scan for possible new timelines if + * we were requested to recover to the latest timeline. + */ + if (recoveryTargetTimeLineGoal == RECOVERY_TARGET_TIMELINE_LATEST) + { + if (rescanLatestTimeLine()) + { + currentSource = XLOG_FROM_ARCHIVE; + break; + } + } + + /* + * XLOG_FROM_STREAM is the last state in our state + * machine, so we've exhausted all the options for + * obtaining the requested WAL. We're going to loop back + * and retry from the archive, but if it hasn't been long + * since last attempt, sleep wal_retrieve_retry_interval + * milliseconds to avoid busy-waiting. + */ + now = GetCurrentTimestamp(); + if (!TimestampDifferenceExceeds(last_fail_time, now, + wal_retrieve_retry_interval)) + { + long wait_time; + + wait_time = wal_retrieve_retry_interval - + TimestampDifferenceMilliseconds(last_fail_time, now); + + (void) WaitLatch(&XLogCtl->recoveryWakeupLatch, + WL_LATCH_SET | WL_TIMEOUT | + WL_EXIT_ON_PM_DEATH, + wait_time, + WAIT_EVENT_RECOVERY_RETRIEVE_RETRY_INTERVAL); + ResetLatch(&XLogCtl->recoveryWakeupLatch); + now = GetCurrentTimestamp(); + + /* Handle interrupt signals of startup process */ + HandleStartupProcInterrupts(); + } + last_fail_time = now; + currentSource = XLOG_FROM_ARCHIVE; + break; + + default: + elog(ERROR, "unexpected WAL source %d", currentSource); + } + } + else if (currentSource == XLOG_FROM_PG_WAL) + { + /* + * We just successfully read a file in pg_wal. We prefer files in + * the archive over ones in pg_wal, so try the next file again + * from the archive first. + */ + if (InArchiveRecovery) + currentSource = XLOG_FROM_ARCHIVE; + } + + if (currentSource != oldSource) + elog(DEBUG2, "switched WAL source from %s to %s after %s", + xlogSourceNames[oldSource], xlogSourceNames[currentSource], + lastSourceFailed ? "failure" : "success"); + + /* + * We've now handled possible failure. Try to read from the chosen + * source. + */ + lastSourceFailed = false; + + switch (currentSource) + { + case XLOG_FROM_ARCHIVE: + case XLOG_FROM_PG_WAL: + + /* + * WAL receiver must not be running when reading WAL from + * archive or pg_wal. + */ + Assert(!WalRcvStreaming()); + + /* Close any old file we might have open. */ + if (readFile >= 0) + { + close(readFile); + readFile = -1; + } + /* Reset curFileTLI if random fetch. */ + if (randAccess) + curFileTLI = 0; + + /* + * Try to restore the file from archive, or read an existing + * file from pg_wal. + */ + readFile = XLogFileReadAnyTLI(readSegNo, DEBUG2, + currentSource == XLOG_FROM_ARCHIVE ? XLOG_FROM_ANY : + currentSource); + if (readFile >= 0) + return true; /* success! */ + + /* + * Nope, not found in archive or pg_wal. + */ + lastSourceFailed = true; + break; + + case XLOG_FROM_STREAM: + { + bool havedata; + + /* + * We should be able to move to XLOG_FROM_STREAM only in + * standby mode. + */ + Assert(StandbyMode); + + /* + * First, shutdown walreceiver if its restart has been + * requested -- but no point if we're already slated for + * starting it. + */ + if (pendingWalRcvRestart && !startWalReceiver) + { + ShutdownWalRcv(); + + /* + * Re-scan for possible new timelines if we were + * requested to recover to the latest timeline. + */ + if (recoveryTargetTimeLineGoal == + RECOVERY_TARGET_TIMELINE_LATEST) + rescanLatestTimeLine(); + + startWalReceiver = true; + } + pendingWalRcvRestart = false; + + /* + * Launch walreceiver if needed. + * + * If fetching_ckpt is true, RecPtr points to the initial + * checkpoint location. In that case, we use RedoStartLSN + * as the streaming start position instead of RecPtr, so + * that when we later jump backwards to start redo at + * RedoStartLSN, we will have the logs streamed already. + */ + if (startWalReceiver && + PrimaryConnInfo && strcmp(PrimaryConnInfo, "") != 0) + { + XLogRecPtr ptr; + TimeLineID tli; + + if (fetching_ckpt) + { + ptr = RedoStartLSN; + tli = ControlFile->checkPointCopy.ThisTimeLineID; + } + else + { + ptr = RecPtr; + + /* + * Use the record begin position to determine the + * TLI, rather than the position we're reading. + */ + tli = tliOfPointInHistory(tliRecPtr, expectedTLEs); + + if (curFileTLI > 0 && tli < curFileTLI) + elog(ERROR, "according to history file, WAL location %X/%X belongs to timeline %u, but previous recovered WAL file came from timeline %u", + LSN_FORMAT_ARGS(tliRecPtr), + tli, curFileTLI); + } + curFileTLI = tli; + RequestXLogStreaming(tli, ptr, PrimaryConnInfo, + PrimarySlotName, + wal_receiver_create_temp_slot); + flushedUpto = 0; + } + + /* + * Check if WAL receiver is active or wait to start up. + */ + if (!WalRcvStreaming()) + { + lastSourceFailed = true; + break; + } + + /* + * Walreceiver is active, so see if new data has arrived. + * + * We only advance XLogReceiptTime when we obtain fresh + * WAL from walreceiver and observe that we had already + * processed everything before the most recent "chunk" + * that it flushed to disk. In steady state where we are + * keeping up with the incoming data, XLogReceiptTime will + * be updated on each cycle. When we are behind, + * XLogReceiptTime will not advance, so the grace time + * allotted to conflicting queries will decrease. + */ + if (RecPtr < flushedUpto) + havedata = true; + else + { + XLogRecPtr latestChunkStart; + + flushedUpto = GetWalRcvFlushRecPtr(&latestChunkStart, &receiveTLI); + if (RecPtr < flushedUpto && receiveTLI == curFileTLI) + { + havedata = true; + if (latestChunkStart <= RecPtr) + { + XLogReceiptTime = GetCurrentTimestamp(); + SetCurrentChunkStartTime(XLogReceiptTime); + } + } + else + havedata = false; + } + if (havedata) + { + /* + * Great, streamed far enough. Open the file if it's + * not open already. Also read the timeline history + * file if we haven't initialized timeline history + * yet; it should be streamed over and present in + * pg_wal by now. Use XLOG_FROM_STREAM so that source + * info is set correctly and XLogReceiptTime isn't + * changed. + * + * NB: We must set readTimeLineHistory based on + * recoveryTargetTLI, not receiveTLI. Normally they'll + * be the same, but if recovery_target_timeline is + * 'latest' and archiving is configured, then it's + * possible that we managed to retrieve one or more + * new timeline history files from the archive, + * updating recoveryTargetTLI. + */ + if (readFile < 0) + { + if (!expectedTLEs) + expectedTLEs = readTimeLineHistory(recoveryTargetTLI); + readFile = XLogFileRead(readSegNo, PANIC, + receiveTLI, + XLOG_FROM_STREAM, false); + Assert(readFile >= 0); + } + else + { + /* just make sure source info is correct... */ + readSource = XLOG_FROM_STREAM; + XLogReceiptSource = XLOG_FROM_STREAM; + return true; + } + break; + } + + /* + * Data not here yet. Check for trigger, then wait for + * walreceiver to wake us up when new WAL arrives. + */ + if (CheckForStandbyTrigger()) + { + /* + * Note that we don't "return false" immediately here. + * After being triggered, we still want to replay all + * the WAL that was already streamed. It's in pg_wal + * now, so we just treat this as a failure, and the + * state machine will move on to replay the streamed + * WAL from pg_wal, and then recheck the trigger and + * exit replay. + */ + lastSourceFailed = true; + break; + } + + /* + * Since we have replayed everything we have received so + * far and are about to start waiting for more WAL, let's + * tell the upstream server our replay location now so + * that pg_stat_replication doesn't show stale + * information. + */ + if (!streaming_reply_sent) + { + WalRcvForceReply(); + streaming_reply_sent = true; + } + + /* + * Wait for more WAL to arrive. Time out after 5 seconds + * to react to a trigger file promptly and to check if the + * WAL receiver is still active. + */ + (void) WaitLatch(&XLogCtl->recoveryWakeupLatch, + WL_LATCH_SET | WL_TIMEOUT | + WL_EXIT_ON_PM_DEATH, + 5000L, WAIT_EVENT_RECOVERY_WAL_STREAM); + ResetLatch(&XLogCtl->recoveryWakeupLatch); + break; + } + + default: + elog(ERROR, "unexpected WAL source %d", currentSource); + } + + /* + * Check for recovery pause here so that we can confirm more quickly + * that a requested pause has actually taken effect. + */ + if (((volatile XLogCtlData *) XLogCtl)->recoveryPauseState != + RECOVERY_NOT_PAUSED) + recoveryPausesHere(false); + + /* + * This possibly-long loop needs to handle interrupts of startup + * process. + */ + HandleStartupProcInterrupts(); + } + + return false; /* not reached */ +} + +/* + * Set flag to signal the walreceiver to restart. (The startup process calls + * this on noticing a relevant configuration change.) + */ +void +StartupRequestWalReceiverRestart(void) +{ + if (currentSource == XLOG_FROM_STREAM && WalRcvRunning()) + { + ereport(LOG, + (errmsg("WAL receiver process shutdown requested"))); + + pendingWalRcvRestart = true; + } +} + +/* + * Determine what log level should be used to report a corrupt WAL record + * in the current WAL page, previously read by XLogPageRead(). + * + * 'emode' is the error mode that would be used to report a file-not-found + * or legitimate end-of-WAL situation. Generally, we use it as-is, but if + * we're retrying the exact same record that we've tried previously, only + * complain the first time to keep the noise down. However, we only do when + * reading from pg_wal, because we don't expect any invalid records in archive + * or in records streamed from the primary. Files in the archive should be complete, + * and we should never hit the end of WAL because we stop and wait for more WAL + * to arrive before replaying it. + * + * NOTE: This function remembers the RecPtr value it was last called with, + * to suppress repeated messages about the same record. Only call this when + * you are about to ereport(), or you might cause a later message to be + * erroneously suppressed. + */ +static int +emode_for_corrupt_record(int emode, XLogRecPtr RecPtr) +{ + static XLogRecPtr lastComplaint = 0; + + if (readSource == XLOG_FROM_PG_WAL && emode == LOG) + { + if (RecPtr == lastComplaint) + emode = DEBUG1; + else + lastComplaint = RecPtr; + } + return emode; +} + +/* + * Has a standby promotion already been triggered? + * + * Unlike CheckForStandbyTrigger(), this works in any process + * that's connected to shared memory. + */ +bool +PromoteIsTriggered(void) +{ + /* + * We check shared state each time only until a standby promotion is + * triggered. We can't trigger a promotion again, so there's no need to + * keep checking after the shared variable has once been seen true. + */ + if (LocalPromoteIsTriggered) + return true; + + SpinLockAcquire(&XLogCtl->info_lck); + LocalPromoteIsTriggered = XLogCtl->SharedPromoteIsTriggered; + SpinLockRelease(&XLogCtl->info_lck); + + return LocalPromoteIsTriggered; +} + +static void +SetPromoteIsTriggered(void) +{ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->SharedPromoteIsTriggered = true; + SpinLockRelease(&XLogCtl->info_lck); + + /* + * Mark the recovery pause state as 'not paused' because the paused state + * ends and promotion continues if a promotion is triggered while recovery + * is paused. Otherwise pg_get_wal_replay_pause_state() can mistakenly + * return 'paused' while a promotion is ongoing. + */ + SetRecoveryPause(false); + + LocalPromoteIsTriggered = true; +} + +/* + * Check to see whether the user-specified trigger file exists and whether a + * promote request has arrived. If either condition holds, return true. + */ +static bool +CheckForStandbyTrigger(void) +{ + struct stat stat_buf; + + if (LocalPromoteIsTriggered) + return true; + + if (IsPromoteSignaled() && CheckPromoteSignal()) + { + ereport(LOG, (errmsg("received promote request"))); + RemovePromoteSignalFiles(); + ResetPromoteSignaled(); + SetPromoteIsTriggered(); + return true; + } + + if (PromoteTriggerFile == NULL || strcmp(PromoteTriggerFile, "") == 0) + return false; + + if (stat(PromoteTriggerFile, &stat_buf) == 0) + { + ereport(LOG, + (errmsg("promote trigger file found: %s", PromoteTriggerFile))); + unlink(PromoteTriggerFile); + SetPromoteIsTriggered(); + return true; + } + else if (errno != ENOENT) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not stat promote trigger file \"%s\": %m", + PromoteTriggerFile))); + + return false; +} + +/* + * Remove the files signaling a standby promotion request. + */ +void +RemovePromoteSignalFiles(void) +{ + unlink(PROMOTE_SIGNAL_FILE); +} + +/* + * Check to see if a promote request has arrived. + */ +bool +CheckPromoteSignal(void) +{ + struct stat stat_buf; + + if (stat(PROMOTE_SIGNAL_FILE, &stat_buf) == 0) + return true; + + return false; +} + +/* + * Wake up startup process to replay newly arrived WAL, or to notice that + * failover has been requested. + */ +void +WakeupRecovery(void) +{ + SetLatch(&XLogCtl->recoveryWakeupLatch); +} + +/* + * Update the WalWriterSleeping flag. + */ +void +SetWalWriterSleeping(bool sleeping) +{ + SpinLockAcquire(&XLogCtl->info_lck); + XLogCtl->WalWriterSleeping = sleeping; + SpinLockRelease(&XLogCtl->info_lck); +} + +/* + * Schedule a walreceiver wakeup in the main recovery loop. + */ +void +XLogRequestWalReceiverReply(void) +{ + doRequestWalReceiverReply = true; +} |