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Diffstat (limited to 'src/include/storage/proc.h')
| -rw-r--r-- | src/include/storage/proc.h | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h new file mode 100644 index 0000000..1ee9000 --- /dev/null +++ b/src/include/storage/proc.h @@ -0,0 +1,333 @@ +/*------------------------------------------------------------------------- + * + * proc.h + * per-process shared memory data structures + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/storage/proc.h + * + *------------------------------------------------------------------------- + */ +#ifndef _PROC_H_ +#define _PROC_H_ + +#include "access/clog.h" +#include "access/xlogdefs.h" +#include "lib/ilist.h" +#include "storage/latch.h" +#include "storage/lock.h" +#include "storage/pg_sema.h" +#include "storage/proclist_types.h" + +/* + * Each backend advertises up to PGPROC_MAX_CACHED_SUBXIDS TransactionIds + * for non-aborted subtransactions of its current top transaction. These + * have to be treated as running XIDs by other backends. + * + * We also keep track of whether the cache overflowed (ie, the transaction has + * generated at least one subtransaction that didn't fit in the cache). + * If none of the caches have overflowed, we can assume that an XID that's not + * listed anywhere in the PGPROC array is not a running transaction. Else we + * have to look at pg_subtrans. + */ +#define PGPROC_MAX_CACHED_SUBXIDS 64 /* XXX guessed-at value */ + +struct XidCache +{ + TransactionId xids[PGPROC_MAX_CACHED_SUBXIDS]; +}; + +/* + * Flags for PGXACT->vacuumFlags + * + * Note: If you modify these flags, you need to modify PROCARRAY_XXX flags + * in src/include/storage/procarray.h. + * + * PROC_RESERVED may later be assigned for use in vacuumFlags, but its value is + * used for PROCARRAY_SLOTS_XMIN in procarray.h, so GetOldestXmin won't be able + * to match and ignore processes with this flag set. + */ +#define PROC_IS_AUTOVACUUM 0x01 /* is it an autovac worker? */ +#define PROC_IN_VACUUM 0x02 /* currently running lazy vacuum */ +#define PROC_IN_ANALYZE 0x04 /* currently running analyze */ +#define PROC_VACUUM_FOR_WRAPAROUND 0x08 /* set by autovac only */ +#define PROC_IN_LOGICAL_DECODING 0x10 /* currently doing logical + * decoding outside xact */ +#define PROC_RESERVED 0x20 /* reserved for procarray */ + +/* flags reset at EOXact */ +#define PROC_VACUUM_STATE_MASK \ + (PROC_IN_VACUUM | PROC_IN_ANALYZE | PROC_VACUUM_FOR_WRAPAROUND) + +/* + * We allow a small number of "weak" relation locks (AccessShareLock, + * RowShareLock, RowExclusiveLock) to be recorded in the PGPROC structure + * rather than the main lock table. This eases contention on the lock + * manager LWLocks. See storage/lmgr/README for additional details. + */ +#define FP_LOCK_SLOTS_PER_BACKEND 16 + +/* + * An invalid pgprocno. Must be larger than the maximum number of PGPROC + * structures we could possibly have. See comments for MAX_BACKENDS. + */ +#define INVALID_PGPROCNO PG_INT32_MAX + +/* + * Each backend has a PGPROC struct in shared memory. There is also a list of + * currently-unused PGPROC structs that will be reallocated to new backends. + * + * links: list link for any list the PGPROC is in. When waiting for a lock, + * the PGPROC is linked into that lock's waitProcs queue. A recycled PGPROC + * is linked into ProcGlobal's freeProcs list. + * + * Note: twophase.c also sets up a dummy PGPROC struct for each currently + * prepared transaction. These PGPROCs appear in the ProcArray data structure + * so that the prepared transactions appear to be still running and are + * correctly shown as holding locks. A prepared transaction PGPROC can be + * distinguished from a real one at need by the fact that it has pid == 0. + * The semaphore and lock-activity fields in a prepared-xact PGPROC are unused, + * but its myProcLocks[] lists are valid. + */ +struct PGPROC +{ + /* proc->links MUST BE FIRST IN STRUCT (see ProcSleep,ProcWakeup,etc) */ + SHM_QUEUE links; /* list link if process is in a list */ + PGPROC **procgloballist; /* procglobal list that owns this PGPROC */ + + PGSemaphore sem; /* ONE semaphore to sleep on */ + int waitStatus; /* STATUS_WAITING, STATUS_OK or STATUS_ERROR */ + + Latch procLatch; /* generic latch for process */ + + LocalTransactionId lxid; /* local id of top-level transaction currently + * being executed by this proc, if running; + * else InvalidLocalTransactionId */ + int pid; /* Backend's process ID; 0 if prepared xact */ + int pgprocno; + + /* These fields are zero while a backend is still starting up: */ + BackendId backendId; /* This backend's backend ID (if assigned) */ + Oid databaseId; /* OID of database this backend is using */ + Oid roleId; /* OID of role using this backend */ + + Oid tempNamespaceId; /* OID of temp schema this backend is + * using */ + + bool isBackgroundWorker; /* true if background worker. */ + + /* + * While in hot standby mode, shows that a conflict signal has been sent + * for the current transaction. Set/cleared while holding ProcArrayLock, + * though not required. Accessed without lock, if needed. + */ + bool recoveryConflictPending; + + /* Info about LWLock the process is currently waiting for, if any. */ + bool lwWaiting; /* true if waiting for an LW lock */ + uint8 lwWaitMode; /* lwlock mode being waited for */ + proclist_node lwWaitLink; /* position in LW lock wait list */ + + /* Support for condition variables. */ + proclist_node cvWaitLink; /* position in CV wait list */ + + /* Info about lock the process is currently waiting for, if any. */ + /* waitLock and waitProcLock are NULL if not currently waiting. */ + LOCK *waitLock; /* Lock object we're sleeping on ... */ + PROCLOCK *waitProcLock; /* Per-holder info for awaited lock */ + LOCKMODE waitLockMode; /* type of lock we're waiting for */ + LOCKMASK heldLocks; /* bitmask for lock types already held on this + * lock object by this backend */ + + bool delayChkpt; /* true if this proc delays checkpoint start */ + + /* + * Info to allow us to wait for synchronous replication, if needed. + * waitLSN is InvalidXLogRecPtr if not waiting; set only by user backend. + * syncRepState must not be touched except by owning process or WALSender. + * syncRepLinks used only while holding SyncRepLock. + */ + XLogRecPtr waitLSN; /* waiting for this LSN or higher */ + int syncRepState; /* wait state for sync rep */ + SHM_QUEUE syncRepLinks; /* list link if process is in syncrep queue */ + + /* + * All PROCLOCK objects for locks held or awaited by this backend are + * linked into one of these lists, according to the partition number of + * their lock. + */ + SHM_QUEUE myProcLocks[NUM_LOCK_PARTITIONS]; + + struct XidCache subxids; /* cache for subtransaction XIDs */ + + /* Support for group XID clearing. */ + /* true, if member of ProcArray group waiting for XID clear */ + bool procArrayGroupMember; + /* next ProcArray group member waiting for XID clear */ + pg_atomic_uint32 procArrayGroupNext; + + /* + * latest transaction id among the transaction's main XID and + * subtransactions + */ + TransactionId procArrayGroupMemberXid; + + uint32 wait_event_info; /* proc's wait information */ + + /* Support for group transaction status update. */ + bool clogGroupMember; /* true, if member of clog group */ + pg_atomic_uint32 clogGroupNext; /* next clog group member */ + TransactionId clogGroupMemberXid; /* transaction id of clog group member */ + XidStatus clogGroupMemberXidStatus; /* transaction status of clog + * group member */ + int clogGroupMemberPage; /* clog page corresponding to + * transaction id of clog group member */ + XLogRecPtr clogGroupMemberLsn; /* WAL location of commit record for clog + * group member */ + + /* Lock manager data, recording fast-path locks taken by this backend. */ + LWLock fpInfoLock; /* protects per-backend fast-path state */ + uint64 fpLockBits; /* lock modes held for each fast-path slot */ + Oid fpRelId[FP_LOCK_SLOTS_PER_BACKEND]; /* slots for rel oids */ + bool fpVXIDLock; /* are we holding a fast-path VXID lock? */ + LocalTransactionId fpLocalTransactionId; /* lxid for fast-path VXID + * lock */ + + /* + * Support for lock groups. Use LockHashPartitionLockByProc on the group + * leader to get the LWLock protecting these fields. + */ + PGPROC *lockGroupLeader; /* lock group leader, if I'm a member */ + dlist_head lockGroupMembers; /* list of members, if I'm a leader */ + dlist_node lockGroupLink; /* my member link, if I'm a member */ +}; + +/* NOTE: "typedef struct PGPROC PGPROC" appears in storage/lock.h. */ + + +extern PGDLLIMPORT PGPROC *MyProc; +extern PGDLLIMPORT struct PGXACT *MyPgXact; + +/* + * Prior to PostgreSQL 9.2, the fields below were stored as part of the + * PGPROC. However, benchmarking revealed that packing these particular + * members into a separate array as tightly as possible sped up GetSnapshotData + * considerably on systems with many CPU cores, by reducing the number of + * cache lines needing to be fetched. Thus, think very carefully before adding + * anything else here. + */ +typedef struct PGXACT +{ + TransactionId xid; /* id of top-level transaction currently being + * executed by this proc, if running and XID + * is assigned; else InvalidTransactionId */ + + TransactionId xmin; /* minimal running XID as it was when we were + * starting our xact, excluding LAZY VACUUM: + * vacuum must not remove tuples deleted by + * xid >= xmin ! */ + + uint8 vacuumFlags; /* vacuum-related flags, see above */ + bool overflowed; + + uint8 nxids; +} PGXACT; + +/* + * There is one ProcGlobal struct for the whole database cluster. + */ +typedef struct PROC_HDR +{ + /* Array of PGPROC structures (not including dummies for prepared txns) */ + PGPROC *allProcs; + /* Array of PGXACT structures (not including dummies for prepared txns) */ + PGXACT *allPgXact; + /* Length of allProcs array */ + uint32 allProcCount; + /* Head of list of free PGPROC structures */ + PGPROC *freeProcs; + /* Head of list of autovacuum's free PGPROC structures */ + PGPROC *autovacFreeProcs; + /* Head of list of bgworker free PGPROC structures */ + PGPROC *bgworkerFreeProcs; + /* Head of list of walsender free PGPROC structures */ + PGPROC *walsenderFreeProcs; + /* First pgproc waiting for group XID clear */ + pg_atomic_uint32 procArrayGroupFirst; + /* First pgproc waiting for group transaction status update */ + pg_atomic_uint32 clogGroupFirst; + /* WALWriter process's latch */ + Latch *walwriterLatch; + /* Checkpointer process's latch */ + Latch *checkpointerLatch; + /* Current shared estimate of appropriate spins_per_delay value */ + int spins_per_delay; + /* The proc of the Startup process, since not in ProcArray */ + PGPROC *startupProc; + int startupProcPid; + /* Buffer id of the buffer that Startup process waits for pin on, or -1 */ + int startupBufferPinWaitBufId; +} PROC_HDR; + +extern PGDLLIMPORT PROC_HDR *ProcGlobal; + +extern PGPROC *PreparedXactProcs; + +/* Accessor for PGPROC given a pgprocno. */ +#define GetPGProcByNumber(n) (&ProcGlobal->allProcs[(n)]) + +/* + * We set aside some extra PGPROC structures for auxiliary processes, + * ie things that aren't full-fledged backends but need shmem access. + * + * Background writer, checkpointer and WAL writer run during normal operation. + * Startup process and WAL receiver also consume 2 slots, but WAL writer is + * launched only after startup has exited, so we only need 4 slots. + */ +#define NUM_AUXILIARY_PROCS 4 + +/* configurable options */ +extern PGDLLIMPORT int DeadlockTimeout; +extern PGDLLIMPORT int StatementTimeout; +extern PGDLLIMPORT int LockTimeout; +extern PGDLLIMPORT int IdleInTransactionSessionTimeout; +extern bool log_lock_waits; + + +/* + * Function Prototypes + */ +extern int ProcGlobalSemas(void); +extern Size ProcGlobalShmemSize(void); +extern void InitProcGlobal(void); +extern void InitProcess(void); +extern void InitProcessPhase2(void); +extern void InitAuxiliaryProcess(void); + +extern void PublishStartupProcessInformation(void); +extern void SetStartupBufferPinWaitBufId(int bufid); +extern int GetStartupBufferPinWaitBufId(void); + +extern bool HaveNFreeProcs(int n); +extern void ProcReleaseLocks(bool isCommit); + +extern void ProcQueueInit(PROC_QUEUE *queue); +extern int ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable); +extern PGPROC *ProcWakeup(PGPROC *proc, int waitStatus); +extern void ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock); +extern void CheckDeadLockAlert(void); +extern bool IsWaitingForLock(void); +extern void LockErrorCleanup(void); + +extern void ProcWaitForSignal(uint32 wait_event_info); +extern void ProcSendSignal(int pid); + +extern PGPROC *AuxiliaryPidGetProc(int pid); + +extern void BecomeLockGroupLeader(void); +extern bool BecomeLockGroupMember(PGPROC *leader, int pid); + +#endif /* _PROC_H_ */ |