Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 466 insertions, 0 deletions

diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
new file mode 100644
index 0000000..ef74f32
--- /dev/null
+++ b/src/include/storage/proc.h
@@ -0,0 +1,466 @@
+/*-------------------------------------------------------------------------
+ *
+ * proc.h
+ *	  per-process shared memory data structures
+ *
+ *
+ * Portions Copyright (c) 1996-2023, 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.
+ *
+ * See src/test/isolation/specs/subxid-overflow.spec if you change this.
+ */
+#define PGPROC_MAX_CACHED_SUBXIDS 64	/* XXX guessed-at value */
+
+typedef struct XidCacheStatus
+{
+	/* number of cached subxids, never more than PGPROC_MAX_CACHED_SUBXIDS */
+	uint8		count;
+	/* has PGPROC->subxids overflowed */
+	bool		overflowed;
+} XidCacheStatus;
+
+struct XidCache
+{
+	TransactionId xids[PGPROC_MAX_CACHED_SUBXIDS];
+};
+
+/*
+ * Flags for PGPROC->statusFlags and PROC_HDR->statusFlags[]
+ */
+#define		PROC_IS_AUTOVACUUM	0x01	/* is it an autovac worker? */
+#define		PROC_IN_VACUUM		0x02	/* currently running lazy vacuum */
+#define		PROC_IN_SAFE_IC		0x04	/* currently running CREATE INDEX
+										 * CONCURRENTLY or REINDEX
+										 * CONCURRENTLY on non-expressional,
+										 * non-partial index */
+#define		PROC_VACUUM_FOR_WRAPAROUND	0x08	/* set by autovac only */
+#define		PROC_IN_LOGICAL_DECODING	0x10	/* currently doing logical
+												 * decoding outside xact */
+#define		PROC_AFFECTS_ALL_HORIZONS	0x20	/* this proc's xmin must be
+												 * included in vacuum horizons
+												 * in all databases */
+
+/* flags reset at EOXact */
+#define		PROC_VACUUM_STATE_MASK \
+	(PROC_IN_VACUUM | PROC_IN_SAFE_IC | PROC_VACUUM_FOR_WRAPAROUND)
+
+/*
+ * Xmin-related flags. Make sure any flags that affect how the process' Xmin
+ * value is interpreted by VACUUM are included here.
+ */
+#define		PROC_XMIN_FLAGS (PROC_IN_VACUUM | PROC_IN_SAFE_IC)
+
+/*
+ * 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
+
+/*
+ * Flags for PGPROC.delayChkptFlags
+ *
+ * These flags can be used to delay the start or completion of a checkpoint
+ * for short periods. A flag is in effect if the corresponding bit is set in
+ * the PGPROC of any backend.
+ *
+ * For our purposes here, a checkpoint has three phases: (1) determine the
+ * location to which the redo pointer will be moved, (2) write all the
+ * data durably to disk, and (3) WAL-log the checkpoint.
+ *
+ * Setting DELAY_CHKPT_START prevents the system from moving from phase 1
+ * to phase 2. This is useful when we are performing a WAL-logged modification
+ * of data that will be flushed to disk in phase 2. By setting this flag
+ * before writing WAL and clearing it after we've both written WAL and
+ * performed the corresponding modification, we ensure that if the WAL record
+ * is inserted prior to the new redo point, the corresponding data changes will
+ * also be flushed to disk before the checkpoint can complete. (In the
+ * extremely common case where the data being modified is in shared buffers
+ * and we acquire an exclusive content lock on the relevant buffers before
+ * writing WAL, this mechanism is not needed, because phase 2 will block
+ * until we release the content lock and then flush the modified data to
+ * disk.)
+ *
+ * Setting DELAY_CHKPT_COMPLETE prevents the system from moving from phase 2
+ * to phase 3. This is useful if we are performing a WAL-logged operation that
+ * might invalidate buffers, such as relation truncation. In this case, we need
+ * to ensure that any buffers which were invalidated and thus not flushed by
+ * the checkpoint are actually destroyed on disk. Replay can cope with a file
+ * or block that doesn't exist, but not with a block that has the wrong
+ * contents.
+ */
+#define DELAY_CHKPT_START		(1<<0)
+#define DELAY_CHKPT_COMPLETE	(1<<1)
+
+typedef enum
+{
+	PROC_WAIT_STATUS_OK,
+	PROC_WAIT_STATUS_WAITING,
+	PROC_WAIT_STATUS_ERROR,
+} ProcWaitStatus;
+
+/*
+ * 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.
+ *
+ * We allow many fields of this struct to be accessed without locks, such as
+ * delayChkptFlags and isBackgroundWorker. However, keep in mind that writing
+ * mirrored ones (see below) requires holding ProcArrayLock or XidGenLock in
+ * at least shared mode, so that pgxactoff does not change concurrently.
+ *
+ * Mirrored fields:
+ *
+ * Some fields in PGPROC (see "mirrored in ..." comment) are mirrored into an
+ * element of more densely packed ProcGlobal arrays. These arrays are indexed
+ * by PGPROC->pgxactoff. Both copies need to be maintained coherently.
+ *
+ * NB: The pgxactoff indexed value can *never* be accessed without holding
+ * locks.
+ *
+ * See PROC_HDR for details.
+ */
+struct PGPROC
+{
+	/* proc->links MUST BE FIRST IN STRUCT (see ProcSleep,ProcWakeup,etc) */
+	dlist_node	links;			/* list link if process is in a list */
+	dlist_head *procgloballist; /* procglobal list that owns this PGPROC */
+
+	PGSemaphore sem;			/* ONE semaphore to sleep on */
+	ProcWaitStatus waitStatus;
+
+	Latch		procLatch;		/* generic latch for process */
+
+
+	TransactionId xid;			/* id of top-level transaction currently being
+								 * executed by this proc, if running and XID
+								 * is assigned; else InvalidTransactionId.
+								 * mirrored in ProcGlobal->xids[pgxactoff] */
+
+	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 ! */
+
+	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			pgxactoff;		/* offset into various ProcGlobal->arrays with
+								 * data mirrored from this PGPROC */
+
+	int			pgprocno;		/* Number of this PGPROC in
+								 * ProcGlobal->allProcs array. This is set
+								 * once by InitProcGlobal().
+								 * ProcGlobal->allProcs[n].pgprocno == n */
+
+	/* 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. */
+	uint8		lwWaiting;		/* see LWLockWaitState */
+	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 */
+	pg_atomic_uint64 waitStart; /* time at which wait for lock acquisition
+								 * started */
+
+	int			delayChkptFlags;	/* for DELAY_CHKPT_* flags */
+
+	uint8		statusFlags;	/* this backend's status flags, see PROC_*
+								 * above. mirrored in
+								 * ProcGlobal->statusFlags[pgxactoff] */
+
+	/*
+	 * 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 */
+	dlist_node	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.
+	 */
+	dlist_head	myProcLocks[NUM_LOCK_PARTITIONS];
+
+	XidCacheStatus subxidStatus;	/* mirrored with
+									 * ProcGlobal->subxidStates[i] */
+	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;
+
+/*
+ * There is one ProcGlobal struct for the whole database cluster.
+ *
+ * Adding/Removing an entry into the procarray requires holding *both*
+ * ProcArrayLock and XidGenLock in exclusive mode (in that order). Both are
+ * needed because the dense arrays (see below) are accessed from
+ * GetNewTransactionId() and GetSnapshotData(), and we don't want to add
+ * further contention by both using the same lock. Adding/Removing a procarray
+ * entry is much less frequent.
+ *
+ * Some fields in PGPROC are mirrored into more densely packed arrays (e.g.
+ * xids), with one entry for each backend. These arrays only contain entries
+ * for PGPROCs that have been added to the shared array with ProcArrayAdd()
+ * (in contrast to PGPROC array which has unused PGPROCs interspersed).
+ *
+ * The dense arrays are indexed by PGPROC->pgxactoff. Any concurrent
+ * ProcArrayAdd() / ProcArrayRemove() can lead to pgxactoff of a procarray
+ * member to change.  Therefore it is only safe to use PGPROC->pgxactoff to
+ * access the dense array while holding either ProcArrayLock or XidGenLock.
+ *
+ * As long as a PGPROC is in the procarray, the mirrored values need to be
+ * maintained in both places in a coherent manner.
+ *
+ * The denser separate arrays are beneficial for three main reasons: First, to
+ * allow for as tight loops accessing the data as possible. Second, to prevent
+ * updates of frequently changing data (e.g. xmin) from invalidating
+ * cachelines also containing less frequently changing data (e.g. xid,
+ * statusFlags). Third to condense frequently accessed data into as few
+ * cachelines as possible.
+ *
+ * There are two main reasons to have the data mirrored between these dense
+ * arrays and PGPROC. First, as explained above, a PGPROC's array entries can
+ * only be accessed with either ProcArrayLock or XidGenLock held, whereas the
+ * PGPROC entries do not require that (obviously there may still be locking
+ * requirements around the individual field, separate from the concerns
+ * here). That is particularly important for a backend to efficiently checks
+ * it own values, which it often can safely do without locking.  Second, the
+ * PGPROC fields allow to avoid unnecessary accesses and modification to the
+ * dense arrays. A backend's own PGPROC is more likely to be in a local cache,
+ * whereas the cachelines for the dense array will be modified by other
+ * backends (often removing it from the cache for other cores/sockets). At
+ * commit/abort time a check of the PGPROC value can avoid accessing/dirtying
+ * the corresponding array value.
+ *
+ * Basically it makes sense to access the PGPROC variable when checking a
+ * single backend's data, especially when already looking at the PGPROC for
+ * other reasons already.  It makes sense to look at the "dense" arrays if we
+ * need to look at many / most entries, because we then benefit from the
+ * reduced indirection and better cross-process cache-ability.
+ *
+ * When entering a PGPROC for 2PC transactions with ProcArrayAdd(), the data
+ * in the dense arrays is initialized from the PGPROC while it already holds
+ * ProcArrayLock.
+ */
+typedef struct PROC_HDR
+{
+	/* Array of PGPROC structures (not including dummies for prepared txns) */
+	PGPROC	   *allProcs;
+
+	/* Array mirroring PGPROC.xid for each PGPROC currently in the procarray */
+	TransactionId *xids;
+
+	/*
+	 * Array mirroring PGPROC.subxidStatus for each PGPROC currently in the
+	 * procarray.
+	 */
+	XidCacheStatus *subxidStates;
+
+	/*
+	 * Array mirroring PGPROC.statusFlags for each PGPROC currently in the
+	 * procarray.
+	 */
+	uint8	   *statusFlags;
+
+	/* Length of allProcs array */
+	uint32		allProcCount;
+	/* Head of list of free PGPROC structures */
+	dlist_head	freeProcs;
+	/* Head of list of autovacuum's free PGPROC structures */
+	dlist_head	autovacFreeProcs;
+	/* Head of list of bgworker free PGPROC structures */
+	dlist_head	bgworkerFreeProcs;
+	/* Head of list of walsender free PGPROC structures */
+	dlist_head	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;
+	/* Buffer id of the buffer that Startup process waits for pin on, or -1 */
+	int			startupBufferPinWaitBufId;
+} PROC_HDR;
+
+extern PGDLLIMPORT PROC_HDR *ProcGlobal;
+
+extern PGDLLIMPORT 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, WAL writer and archiver 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 5 slots.
+ */
+#define NUM_AUXILIARY_PROCS		5
+
+/* configurable options */
+extern PGDLLIMPORT int DeadlockTimeout;
+extern PGDLLIMPORT int StatementTimeout;
+extern PGDLLIMPORT int LockTimeout;
+extern PGDLLIMPORT int IdleInTransactionSessionTimeout;
+extern PGDLLIMPORT int IdleSessionTimeout;
+extern PGDLLIMPORT 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 SetStartupBufferPinWaitBufId(int bufid);
+extern int	GetStartupBufferPinWaitBufId(void);
+
+extern bool HaveNFreeProcs(int n, int *nfree);
+extern void ProcReleaseLocks(bool isCommit);
+
+extern ProcWaitStatus ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable);
+extern void ProcWakeup(PGPROC *proc, ProcWaitStatus 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 pgprocno);
+
+extern PGPROC *AuxiliaryPidGetProc(int pid);
+
+extern void BecomeLockGroupLeader(void);
+extern bool BecomeLockGroupMember(PGPROC *leader, int pid);
+
+#endif							/* _PROC_H_ */