lwlock.h File Reference

#include "port/atomics.h"
#include "storage/lwlocknames.h"
#include "storage/proclist_types.h"
#include "storage/lwlocklist.h"

Include dependency graph for lwlock.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	LWLock
union	LWLockPadded

Macros
#define	LWLOCK_PADDED_SIZE   PG_CACHE_LINE_SIZE
#define	NUM_BUFFER_PARTITIONS   128
#define	LOG2_NUM_LOCK_PARTITIONS   4
#define	NUM_LOCK_PARTITIONS   (1 << LOG2_NUM_LOCK_PARTITIONS)
#define	LOG2_NUM_PREDICATELOCK_PARTITIONS   4
#define	NUM_PREDICATELOCK_PARTITIONS   (1 << LOG2_NUM_PREDICATELOCK_PARTITIONS)
#define	BUFFER_MAPPING_LWLOCK_OFFSET   NUM_INDIVIDUAL_LWLOCKS
#define	LOCK_MANAGER_LWLOCK_OFFSET    (BUFFER_MAPPING_LWLOCK_OFFSET + NUM_BUFFER_PARTITIONS)
#define	PREDICATELOCK_MANAGER_LWLOCK_OFFSET    (LOCK_MANAGER_LWLOCK_OFFSET + NUM_LOCK_PARTITIONS)
#define	NUM_FIXED_LWLOCKS    (PREDICATELOCK_MANAGER_LWLOCK_OFFSET + NUM_PREDICATELOCK_PARTITIONS)
#define	PG_LWLOCK(id, name)
#define	PG_LWLOCKTRANCHE(id, name)   LWTRANCHE_##id,

Typedefs
typedef enum LWLockWaitState	LWLockWaitState
typedef struct LWLock	LWLock
typedef union LWLockPadded	LWLockPadded
typedef struct NamedLWLockTrancheRequest	NamedLWLockTrancheRequest
typedef enum LWLockMode	LWLockMode
typedef enum BuiltinTrancheIds	BuiltinTrancheIds
typedef LWLock *	LWLockId

Enumerations
enum	LWLockWaitState { LW_WS_NOT_WAITING , LW_WS_WAITING , LW_WS_PENDING_WAKEUP }
enum	LWLockMode { LW_EXCLUSIVE , LW_SHARED , LW_WAIT_UNTIL_FREE }
enum	BuiltinTrancheIds { LWTRANCHE_INVALID = NUM_INDIVIDUAL_LWLOCKS - 1 , LWTRANCHE_FIRST_USER_DEFINED }

Functions
	StaticAssertDecl (sizeof(LWLock)<=LWLOCK_PADDED_SIZE, "Miscalculated LWLock padding")
bool	LWLockAcquire (LWLock *lock, LWLockMode mode)
bool	LWLockConditionalAcquire (LWLock *lock, LWLockMode mode)
bool	LWLockAcquireOrWait (LWLock *lock, LWLockMode mode)
void	LWLockRelease (LWLock *lock)
void	LWLockReleaseClearVar (LWLock *lock, pg_atomic_uint64 *valptr, uint64 val)
void	LWLockReleaseAll (void)
bool	LWLockHeldByMe (LWLock *lock)
bool	LWLockAnyHeldByMe (LWLock *lock, int nlocks, size_t stride)
bool	LWLockHeldByMeInMode (LWLock *lock, LWLockMode mode)
bool	LWLockWaitForVar (LWLock *lock, pg_atomic_uint64 *valptr, uint64 oldval, uint64 *newval)
void	LWLockUpdateVar (LWLock *lock, pg_atomic_uint64 *valptr, uint64 val)
Size	LWLockShmemSize (void)
void	CreateLWLocks (void)
void	InitLWLockAccess (void)
const char *	GetLWLockIdentifier (uint32 classId, uint16 eventId)
void	RequestNamedLWLockTranche (const char *tranche_name, int num_lwlocks)
LWLockPadded *	GetNamedLWLockTranche (const char *tranche_name)
int	LWLockNewTrancheId (const char *name)
void	LWLockInitialize (LWLock *lock, int tranche_id)

Variables
PGDLLIMPORT LWLockPadded *	MainLWLockArray
PGDLLIMPORT char **	LWLockTrancheNames
PGDLLIMPORT int	NamedLWLockTrancheRequests
PGDLLIMPORT NamedLWLockTrancheRequest *	NamedLWLockTrancheRequestArray
PGDLLIMPORT int *	LWLockCounter

Macro Definition Documentation

BUFFER_MAPPING_LWLOCK_OFFSET

#define BUFFER_MAPPING_LWLOCK_OFFSET   NUM_INDIVIDUAL_LWLOCKS

Definition at line 102 of file lwlock.h.

LOCK_MANAGER_LWLOCK_OFFSET

#define LOCK_MANAGER_LWLOCK_OFFSET    (BUFFER_MAPPING_LWLOCK_OFFSET + NUM_BUFFER_PARTITIONS)

Definition at line 103 of file lwlock.h.

{
    LW_EXCLUSIVE,
    LW_SHARED,
    LW_WAIT_UNTIL_FREE,         /* A special mode used in PGPROC->lwWaitMode,
                                 * when waiting for lock to become free. Not
                                 * to be used as LWLockAcquire argument */
} LWLockMode;
 
 
#ifdef LOCK_DEBUG
extern PGDLLIMPORT bool Trace_lwlocks;
#endif
 
extern bool LWLockAcquire(LWLock *lock, LWLockMode mode);
extern bool LWLockConditionalAcquire(LWLock *lock, LWLockMode mode);
extern bool LWLockAcquireOrWait(LWLock *lock, LWLockMode mode);
extern void LWLockRelease(LWLock *lock);
extern void LWLockReleaseClearVar(LWLock *lock, pg_atomic_uint64 *valptr, uint64 val);
extern void LWLockReleaseAll(void);
extern bool LWLockHeldByMe(LWLock *lock);
extern bool LWLockAnyHeldByMe(LWLock *lock, int nlocks, size_t stride);
extern bool LWLockHeldByMeInMode(LWLock *lock, LWLockMode mode);
 
extern bool LWLockWaitForVar(LWLock *lock, pg_atomic_uint64 *valptr, uint64 oldval, uint64 *newval);
extern void LWLockUpdateVar(LWLock *lock, pg_atomic_uint64 *valptr, uint64 val);
 
extern Size LWLockShmemSize(void);
extern void CreateLWLocks(void);
extern void InitLWLockAccess(void);
 
extern const char *GetLWLockIdentifier(uint32 classId, uint16 eventId);
 
/*
 * Extensions (or core code) can obtain an LWLocks by calling
 * RequestNamedLWLockTranche() during postmaster startup.  Subsequently,
 * call GetNamedLWLockTranche() to obtain a pointer to an array containing
 * the number of LWLocks requested.
 */
extern void RequestNamedLWLockTranche(const char *tranche_name, int num_lwlocks);
extern LWLockPadded *GetNamedLWLockTranche(const char *tranche_name);
 
/*
 * There is another, more flexible method of obtaining lwlocks. First, call
 * LWLockNewTrancheId to obtain a tranche ID; this allocates from a shared
 * counter.  Second, LWLockInitialize should be called just once per lwlock,
 * passing the tranche ID as an argument.
 */
extern int  LWLockNewTrancheId(const char *name);
extern void LWLockInitialize(LWLock *lock, int tranche_id);
 
/*
 * Every tranche ID less than NUM_INDIVIDUAL_LWLOCKS is reserved; also,
 * we reserve additional tranche IDs for builtin tranches not included in
 * the set of individual LWLocks.  A call to LWLockNewTrancheId will never
 * return a value less than LWTRANCHE_FIRST_USER_DEFINED.  The actual list of
 * built-in tranches is kept in lwlocklist.h.
 */
typedef enum BuiltinTrancheIds
{
    /*
     * LWTRANCHE_INVALID is an unused value that only exists to initialize the
     * rest of the tranches to appropriate values.
     */
    LWTRANCHE_INVALID = NUM_INDIVIDUAL_LWLOCKS - 1,
 
#define PG_LWLOCK(id, name)
#define PG_LWLOCKTRANCHE(id, name) LWTRANCHE_##id,
#include "storage/lwlocklist.h"
#undef PG_LWLOCK
#undef PG_LWLOCKTRANCHE
 
    LWTRANCHE_FIRST_USER_DEFINED,
}           BuiltinTrancheIds;
 
/*
 * Prior to PostgreSQL 9.4, we used an enum type called LWLockId to refer
 * to LWLocks.  New code should instead use LWLock *.  However, for the
 * convenience of third-party code, we include the following typedef.
 */
typedef LWLock *LWLockId;
 
#endif                          /* LWLOCK_H */

LOG2_NUM_LOCK_PARTITIONS

#define LOG2_NUM_LOCK_PARTITIONS   4

Definition at line 94 of file lwlock.h.

LOG2_NUM_PREDICATELOCK_PARTITIONS

#define LOG2_NUM_PREDICATELOCK_PARTITIONS   4

Definition at line 98 of file lwlock.h.

LWLOCK_PADDED_SIZE

#define LWLOCK_PADDED_SIZE   PG_CACHE_LINE_SIZE

Definition at line 62 of file lwlock.h.

NUM_BUFFER_PARTITIONS

#define NUM_BUFFER_PARTITIONS   128

Definition at line 91 of file lwlock.h.

NUM_FIXED_LWLOCKS

#define NUM_FIXED_LWLOCKS    (PREDICATELOCK_MANAGER_LWLOCK_OFFSET + NUM_PREDICATELOCK_PARTITIONS)

Definition at line 107 of file lwlock.h.

NUM_LOCK_PARTITIONS

#define NUM_LOCK_PARTITIONS   (1 << LOG2_NUM_LOCK_PARTITIONS)

Definition at line 95 of file lwlock.h.

NUM_PREDICATELOCK_PARTITIONS

#define NUM_PREDICATELOCK_PARTITIONS   (1 << LOG2_NUM_PREDICATELOCK_PARTITIONS)

Definition at line 99 of file lwlock.h.

PG_LWLOCK

#define PG_LWLOCK	(		id,
			name
	)

Definition at line 176 of file lwlock.h.

PG_LWLOCKTRANCHE

#define PG_LWLOCKTRANCHE	(		id,
			name
	)		LWTRANCHE_##id,

Definition at line 177 of file lwlock.h.

PREDICATELOCK_MANAGER_LWLOCK_OFFSET

#define PREDICATELOCK_MANAGER_LWLOCK_OFFSET    (LOCK_MANAGER_LWLOCK_OFFSET + NUM_LOCK_PARTITIONS)

Definition at line 105 of file lwlock.h.

Typedef Documentation

BuiltinTrancheIds

typedef enum BuiltinTrancheIds BuiltinTrancheIds

LWLock

typedef struct LWLock LWLock

LWLockId

typedef LWLock* LWLockId

Definition at line 190 of file lwlock.h.

LWLockMode

typedef enum LWLockMode LWLockMode

LWLockPadded

typedef union LWLockPadded LWLockPadded

LWLockWaitState

typedef enum LWLockWaitState LWLockWaitState

NamedLWLockTrancheRequest

typedef struct NamedLWLockTrancheRequest NamedLWLockTrancheRequest

Definition at line 77 of file lwlock.h.

Enumeration Type Documentation

BuiltinTrancheIds

enum BuiltinTrancheIds

Enumerator
LWTRANCHE_INVALID
LWTRANCHE_FIRST_USER_DEFINED

Definition at line 168 of file lwlock.h.

{
    /*
     * LWTRANCHE_INVALID is an unused value that only exists to initialize the
     * rest of the tranches to appropriate values.
     */
    LWTRANCHE_INVALID = NUM_INDIVIDUAL_LWLOCKS - 1,
 
#define PG_LWLOCK(id, name)
#define PG_LWLOCKTRANCHE(id, name) LWTRANCHE_##id,
#include "storage/lwlocklist.h"
#undef PG_LWLOCK
#undef PG_LWLOCKTRANCHE
 
    LWTRANCHE_FIRST_USER_DEFINED,
}           BuiltinTrancheIds;

LWLockMode

enum LWLockMode

Enumerator
LW_EXCLUSIVE
LW_SHARED
LW_WAIT_UNTIL_FREE

Definition at line 110 of file lwlock.h.

{
    LW_EXCLUSIVE,
    LW_SHARED,
    LW_WAIT_UNTIL_FREE,         /* A special mode used in PGPROC->lwWaitMode,
                                 * when waiting for lock to become free. Not
                                 * to be used as LWLockAcquire argument */
} LWLockMode;

LWLockWaitState

enum LWLockWaitState

Enumerator
LW_WS_NOT_WAITING
LW_WS_WAITING
LW_WS_PENDING_WAKEUP

Definition at line 28 of file lwlock.h.

{
    LW_WS_NOT_WAITING,          /* not currently waiting / woken up */
    LW_WS_WAITING,              /* currently waiting */
    LW_WS_PENDING_WAKEUP,       /* removed from waitlist, but not yet
                                 * signalled */
}           LWLockWaitState;

Function Documentation

CreateLWLocks()

void CreateLWLocks ( void  )

extern

Definition at line 442 of file lwlock.c.

{
    if (!IsUnderPostmaster)
    {
        Size        spaceLocks = LWLockShmemSize();
        char       *ptr;
 
        /* Allocate space */
        ptr = (char *) ShmemAlloc(spaceLocks);
 
        /* Initialize the dynamic-allocation counter for tranches */
        LWLockCounter = (int *) ptr;
        *LWLockCounter = LWTRANCHE_FIRST_USER_DEFINED;
        ptr += MAXALIGN(sizeof(int));
 
        /* Initialize tranche names */
        LWLockTrancheNames = (char **) ptr;
        ptr += MAX_NAMED_TRANCHES * sizeof(char *);
        for (int i = 0; i < MAX_NAMED_TRANCHES; i++)
        {
            LWLockTrancheNames[i] = ptr;
            ptr += NAMEDATALEN;
        }
 
        /*
         * Move named tranche requests to shared memory.  This is done for the
         * benefit of EXEC_BACKEND builds, which otherwise wouldn't be able to
         * call GetNamedLWLockTranche() outside postmaster.
         */
        if (NamedLWLockTrancheRequests > 0)
        {
            /*
             * Save the pointer to the request array in postmaster's local
             * memory.  We'll need it if we ever need to re-initialize shared
             * memory after a crash.
             */
            LocalNamedLWLockTrancheRequestArray = NamedLWLockTrancheRequestArray;
 
            memcpy(ptr, NamedLWLockTrancheRequestArray,
                   NamedLWLockTrancheRequests * sizeof(NamedLWLockTrancheRequest));
            NamedLWLockTrancheRequestArray = (NamedLWLockTrancheRequest *) ptr;
            ptr += NamedLWLockTrancheRequests * sizeof(NamedLWLockTrancheRequest);
        }
 
        /* Ensure desired alignment of LWLock array */
        ptr += LWLOCK_PADDED_SIZE - ((uintptr_t) ptr) % LWLOCK_PADDED_SIZE;
        MainLWLockArray = (LWLockPadded *) ptr;
 
        /* Initialize all LWLocks */
        InitializeLWLocks();
    }
}

References fb(), i, InitializeLWLocks(), IsUnderPostmaster, LocalNamedLWLockTrancheRequestArray, LWLOCK_PADDED_SIZE, LWLockCounter, LWLockShmemSize(), LWLockTrancheNames, LWTRANCHE_FIRST_USER_DEFINED, MainLWLockArray, MAX_NAMED_TRANCHES, MAXALIGN, NAMEDATALEN, NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, and ShmemAlloc().

Referenced by CreateOrAttachShmemStructs().

GetLWLockIdentifier()

const char * GetLWLockIdentifier ( uint32  classId, uint16  eventId  )

extern

Definition at line 774 of file lwlock.c.

{
    Assert(classId == PG_WAIT_LWLOCK);
    /* The event IDs are just tranche numbers. */
    return GetLWTrancheName(eventId);
}

References Assert, fb(), GetLWTrancheName(), and PG_WAIT_LWLOCK.

Referenced by pgstat_get_wait_event().

GetNamedLWLockTranche()

LWLockPadded * GetNamedLWLockTranche ( const char *  tranche_name )

extern

Definition at line 567 of file lwlock.c.

{
    int         lock_pos;
    int         i;
 
    /*
     * Obtain the position of base address of LWLock belonging to requested
     * tranche_name in MainLWLockArray.  LWLocks for named tranches are placed
     * in MainLWLockArray after fixed locks.
     */
    lock_pos = NUM_FIXED_LWLOCKS;
    for (i = 0; i < NamedLWLockTrancheRequests; i++)
    {
        if (strcmp(NamedLWLockTrancheRequestArray[i].tranche_name,
                   tranche_name) == 0)
            return &MainLWLockArray[lock_pos];
 
        lock_pos += NamedLWLockTrancheRequestArray[i].num_lwlocks;
    }
 
    elog(ERROR, "requested tranche is not registered");
 
    /* just to keep compiler quiet */
    return NULL;
}

References elog, ERROR, fb(), i, MainLWLockArray, NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, NUM_FIXED_LWLOCKS, and NamedLWLockTrancheRequest::num_lwlocks.

Referenced by pgss_shmem_startup(), and test_lwlock_tranche_lookup().

InitLWLockAccess()

void InitLWLockAccess ( void  )

extern

Definition at line 551 of file lwlock.c.

{
#ifdef LWLOCK_STATS
    init_lwlock_stats();
#endif
}

References fb().

Referenced by InitAuxiliaryProcess(), and InitProcess().

LWLockAcquire()

bool LWLockAcquire ( LWLock *  lock, LWLockMode  mode  )

extern

Definition at line 1177 of file lwlock.c.

{
    PGPROC     *proc = MyProc;
    bool        result = true;
    int         extraWaits = 0;
#ifdef LWLOCK_STATS
    lwlock_stats *lwstats;
 
    lwstats = get_lwlock_stats_entry(lock);
#endif
 
    Assert(mode == LW_SHARED || mode == LW_EXCLUSIVE);
 
    PRINT_LWDEBUG("LWLockAcquire", lock, mode);
 
#ifdef LWLOCK_STATS
    /* Count lock acquisition attempts */
    if (mode == LW_EXCLUSIVE)
        lwstats->ex_acquire_count++;
    else
        lwstats->sh_acquire_count++;
#endif                          /* LWLOCK_STATS */
 
    /*
     * We can't wait if we haven't got a PGPROC.  This should only occur
     * during bootstrap or shared memory initialization.  Put an Assert here
     * to catch unsafe coding practices.
     */
    Assert(!(proc == NULL && IsUnderPostmaster));
 
    /* Ensure we will have room to remember the lock */
    if (num_held_lwlocks >= MAX_SIMUL_LWLOCKS)
        elog(ERROR, "too many LWLocks taken");
 
    /*
     * Lock out cancel/die interrupts until we exit the code section protected
     * by the LWLock.  This ensures that interrupts will not interfere with
     * manipulations of data structures in shared memory.
     */
    HOLD_INTERRUPTS();
 
    /*
     * Loop here to try to acquire lock after each time we are signaled by
     * LWLockRelease.
     *
     * NOTE: it might seem better to have LWLockRelease actually grant us the
     * lock, rather than retrying and possibly having to go back to sleep. But
     * in practice that is no good because it means a process swap for every
     * lock acquisition when two or more processes are contending for the same
     * lock.  Since LWLocks are normally used to protect not-very-long
     * sections of computation, a process needs to be able to acquire and
     * release the same lock many times during a single CPU time slice, even
     * in the presence of contention.  The efficiency of being able to do that
     * outweighs the inefficiency of sometimes wasting a process dispatch
     * cycle because the lock is not free when a released waiter finally gets
     * to run.  See pgsql-hackers archives for 29-Dec-01.
     */
    for (;;)
    {
        bool        mustwait;
 
        /*
         * Try to grab the lock the first time, we're not in the waitqueue
         * yet/anymore.
         */
        mustwait = LWLockAttemptLock(lock, mode);
 
        if (!mustwait)
        {
            LOG_LWDEBUG("LWLockAcquire", lock, "immediately acquired lock");
            break;              /* got the lock */
        }
 
        /*
         * Ok, at this point we couldn't grab the lock on the first try. We
         * cannot simply queue ourselves to the end of the list and wait to be
         * woken up because by now the lock could long have been released.
         * Instead add us to the queue and try to grab the lock again. If we
         * succeed we need to revert the queuing and be happy, otherwise we
         * recheck the lock. If we still couldn't grab it, we know that the
         * other locker will see our queue entries when releasing since they
         * existed before we checked for the lock.
         */
 
        /* add to the queue */
        LWLockQueueSelf(lock, mode);
 
        /* we're now guaranteed to be woken up if necessary */
        mustwait = LWLockAttemptLock(lock, mode);
 
        /* ok, grabbed the lock the second time round, need to undo queueing */
        if (!mustwait)
        {
            LOG_LWDEBUG("LWLockAcquire", lock, "acquired, undoing queue");
 
            LWLockDequeueSelf(lock);
            break;
        }
 
        /*
         * Wait until awakened.
         *
         * It is possible that we get awakened for a reason other than being
         * signaled by LWLockRelease.  If so, loop back and wait again.  Once
         * we've gotten the LWLock, re-increment the sema by the number of
         * additional signals received.
         */
        LOG_LWDEBUG("LWLockAcquire", lock, "waiting");
 
#ifdef LWLOCK_STATS
        lwstats->block_count++;
#endif
 
        LWLockReportWaitStart(lock);
        if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
 
        for (;;)
        {
            PGSemaphoreLock(proc->sem);
            if (proc->lwWaiting == LW_WS_NOT_WAITING)
                break;
            extraWaits++;
        }
 
        /* Retrying, allow LWLockRelease to release waiters again. */
        pg_atomic_fetch_and_u32(&lock->state, ~LW_FLAG_WAKE_IN_PROGRESS);
 
#ifdef LOCK_DEBUG
        {
            /* not waiting anymore */
            uint32      nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
 
            Assert(nwaiters < MAX_BACKENDS);
        }
#endif
 
        if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
        LWLockReportWaitEnd();
 
        LOG_LWDEBUG("LWLockAcquire", lock, "awakened");
 
        /* Now loop back and try to acquire lock again. */
        result = false;
    }
 
    if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_ENABLED())
        TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode);
 
    /* Add lock to list of locks held by this backend */
    held_lwlocks[num_held_lwlocks].lock = lock;
    held_lwlocks[num_held_lwlocks++].mode = mode;
 
    /*
     * Fix the process wait semaphore's count for any absorbed wakeups.
     */
    while (extraWaits-- > 0)
        PGSemaphoreUnlock(proc->sem);
 
    return result;
}

References Assert, elog, ERROR, fb(), held_lwlocks, HOLD_INTERRUPTS, IsUnderPostmaster, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_WAKE_IN_PROGRESS, LW_SHARED, LW_WS_NOT_WAITING, LWLockAttemptLock(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MAX_SIMUL_LWLOCKS, LWLockHandle::mode, mode, MyProc, num_held_lwlocks, pg_atomic_fetch_and_u32(), pg_atomic_fetch_sub_u32(), PG_USED_FOR_ASSERTS_ONLY, PGSemaphoreLock(), PGSemaphoreUnlock(), PRINT_LWDEBUG, PGPROC::sem, LWLock::state, and T_NAME.

Referenced by _bt_end_vacuum(), _bt_parallel_done(), _bt_parallel_primscan_schedule(), _bt_parallel_release(), _bt_parallel_seize(), _bt_start_vacuum(), _bt_vacuum_cycleid(), abort_logical_decoding_activation(), AbsorbSyncRequests(), ActivateCommitTs(), addLSNWaiter(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_load_buffers(), AsyncNotifyFreezeXids(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AtAbort_Twophase(), AtEOXact_LogicalRepWorkers(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), AutoVacLauncherMain(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BecomeRegisteredListener(), btparallelrescan(), BufferAlloc(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckLogicalSlotExists(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), ComputeXidHorizons(), consume_xids_shortcut(), copy_replication_slot(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), deleteLSNWaiter(), destroy_superblock(), DisableLogicalDecoding(), DisableLogicalDecodingIfNecessary(), do_autovacuum(), do_pg_backup_start(), do_pg_backup_stop(), do_start_worker(), DropAllPredicateLocksFromTable(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), dsa_get_total_size(), dsa_get_total_size_from_handle(), dsa_pin(), dsa_release_in_place(), dsa_set_size_limit(), dsa_trim(), dsa_unpin(), dshash_delete_key(), dshash_dump(), dshash_find(), dshash_find_or_insert_extended(), dshash_seq_next(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), EnableLogicalDecoding(), ensure_active_superblock(), entry_reset(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendBufferedRelShared(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), FindAndDropRelationBuffers(), FindDeletedTupleInLocalRel(), FinishPreparedTransaction(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_local_synced_slots(), get_val_in_shmem(), get_xid_status(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLeaderApplyWorkerPid(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetMultiXactInfo(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldestUnsummarizedLSN(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionData(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetStrictOldestNonRemovableTransactionId(), GetVirtualXIDsDelayingChkpt(), GetWaitEventCustomIdentifier(), GetWaitEventCustomNames(), GetWalSummarizerState(), HaveVirtualXIDsDelayingChkpt(), init_conflict_slot_xmin(), init_dsm_registry(), initGlobalChannelTable(), InitWalSender(), injection_shmem_startup(), InjectionPointAttach(), InjectionPointDetach(), InjectionPointList(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), InvalidatePossiblyObsoleteSlot(), InvalidateVictimBuffer(), IoWorkerMain(), IsInstallXLogFileSegmentActive(), IsLogicalDecodingEnabled(), IsXLogLogicalInfoEnabled(), KnownAssignedXidsCompress(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_launcher_attach_dshmem(), logicalrep_pa_worker_stop(), logicalrep_reset_seqsync_start_time(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_stop_internal(), logicalrep_worker_wakeup(), logicalrep_workers_find(), LookupGXact(), LookupGXactBySubid(), MarkAsPrepared(), MarkAsPreparing(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), PageIsPredicateLocked(), perform_relmap_update(), pg_control_checkpoint(), pg_control_init(), pg_control_recovery(), pg_control_system(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_get_shmem_allocations_numa(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgaio_worker_die(), pgaio_worker_register(), pgss_shmem_startup(), pgss_store(), pgstat_archiver_reset_all_cb(), pgstat_archiver_snapshot_cb(), pgstat_bgwriter_reset_all_cb(), pgstat_bgwriter_snapshot_cb(), pgstat_build_snapshot(), pgstat_checkpointer_reset_all_cb(), pgstat_checkpointer_snapshot_cb(), pgstat_fetch_replslot(), pgstat_io_flush_cb(), pgstat_io_reset_all_cb(), pgstat_io_snapshot_cb(), pgstat_lock_entry(), pgstat_lock_entry_shared(), pgstat_reset_matching_entries(), pgstat_reset_replslot(), pgstat_reset_slru_counter_internal(), pgstat_slru_flush_cb(), pgstat_slru_snapshot_cb(), pgstat_wal_flush_cb(), pgstat_wal_reset_all_cb(), pgstat_wal_snapshot_cb(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchSharedBuffer(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayClearTransaction(), ProcArrayEndTransaction(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), ProcessSequencesForSync(), ProcessSyncingTablesForApply(), ProcKill(), ProcNumberGetTransactionIds(), ProcSleep(), ReachedEndOfBackup(), read_relmap_file(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadReplicationSlot(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePreInvalidate(), RelationMapCopy(), RelationMapFinishBootstrap(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), relmap_redo(), RemoveScratchTarget(), ReplicationSlotAcquire(), ReplicationSlotCleanup(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotName(), ReplicationSlotRelease(), ReplicationSlotReserveWal(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset_internal(), replorigin_session_setup(), replorigin_state_clear(), RequestDisableLogicalDecoding(), reserve_wal_for_local_slot(), ResetInstallXLogFileSegmentActive(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), SaveSlotToPath(), SearchNamedReplicationSlot(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialInit(), SerialSetActiveSerXmin(), set_indexsafe_procflags(), set_val_in_shmem(), SetCommitTsLimit(), SetInstallXLogFileSegmentActive(), SetMultiXactIdLimit(), SetNextObjectId(), SetOldestOffset(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SignalRecoveryConflict(), SignalRecoveryConflictWithDatabase(), SignalRecoveryConflictWithVirtualXID(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SimpleLruZeroAndWritePage(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), StandbyRecoverPreparedTransactions(), StandbySlotsHaveCaughtup(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SummarizeWAL(), SwitchIntoArchiveRecovery(), synchronize_one_slot(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateBackgroundWorkersForDatabase(), TerminateOtherDBBackends(), test_aio_shmem_startup(), test_custom_stats_fixed_reset_all_cb(), test_custom_stats_fixed_snapshot_cb(), test_custom_stats_fixed_update(), test_slru_page_exists(), test_slru_page_read(), test_slru_page_write(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), TwoPhaseGetOldestXidInCommit(), TwoPhaseGetXidByVirtualXID(), update_cached_xid_range(), update_synced_slots_inactive_since(), UpdateLogicalDecodingStatusEndOfRecovery(), UpdateMinRecoveryPoint(), vac_truncate_clog(), vacuum_rel(), VacuumUpdateCosts(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_table_state_change(), wait_for_worker_state_change(), WaitEventCustomNew(), WaitForReplicationWorkerAttach(), WaitForWalSummarization(), wakeupWaiters(), WakeupWalSummarizer(), WALInsertLockAcquire(), WALInsertLockAcquireExclusive(), WalSummarizerMain(), WalSummarizerShutdown(), write_relcache_init_file(), xact_redo(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), and XLogReportParameters().

LWLockAcquireOrWait()

bool LWLockAcquireOrWait ( LWLock *  lock, LWLockMode  mode  )

extern

Definition at line 1405 of file lwlock.c.

{
    PGPROC     *proc = MyProc;
    bool        mustwait;
    int         extraWaits = 0;
#ifdef LWLOCK_STATS
    lwlock_stats *lwstats;
 
    lwstats = get_lwlock_stats_entry(lock);
#endif
 
    Assert(mode == LW_SHARED || mode == LW_EXCLUSIVE);
 
    PRINT_LWDEBUG("LWLockAcquireOrWait", lock, mode);
 
    /* Ensure we will have room to remember the lock */
    if (num_held_lwlocks >= MAX_SIMUL_LWLOCKS)
        elog(ERROR, "too many LWLocks taken");
 
    /*
     * Lock out cancel/die interrupts until we exit the code section protected
     * by the LWLock.  This ensures that interrupts will not interfere with
     * manipulations of data structures in shared memory.
     */
    HOLD_INTERRUPTS();
 
    /*
     * NB: We're using nearly the same twice-in-a-row lock acquisition
     * protocol as LWLockAcquire(). Check its comments for details.
     */
    mustwait = LWLockAttemptLock(lock, mode);
 
    if (mustwait)
    {
        LWLockQueueSelf(lock, LW_WAIT_UNTIL_FREE);
 
        mustwait = LWLockAttemptLock(lock, mode);
 
        if (mustwait)
        {
            /*
             * Wait until awakened.  Like in LWLockAcquire, be prepared for
             * bogus wakeups.
             */
            LOG_LWDEBUG("LWLockAcquireOrWait", lock, "waiting");
 
#ifdef LWLOCK_STATS
            lwstats->block_count++;
#endif
 
            LWLockReportWaitStart(lock);
            if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED())
                TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
 
            for (;;)
            {
                PGSemaphoreLock(proc->sem);
                if (proc->lwWaiting == LW_WS_NOT_WAITING)
                    break;
                extraWaits++;
            }
 
#ifdef LOCK_DEBUG
            {
                /* not waiting anymore */
                uint32      nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
 
                Assert(nwaiters < MAX_BACKENDS);
            }
#endif
            if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED())
                TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
            LWLockReportWaitEnd();
 
            LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened");
        }
        else
        {
            LOG_LWDEBUG("LWLockAcquireOrWait", lock, "acquired, undoing queue");
 
            /*
             * Got lock in the second attempt, undo queueing. We need to treat
             * this as having successfully acquired the lock, otherwise we'd
             * not necessarily wake up people we've prevented from acquiring
             * the lock.
             */
            LWLockDequeueSelf(lock);
        }
    }
 
    /*
     * Fix the process wait semaphore's count for any absorbed wakeups.
     */
    while (extraWaits-- > 0)
        PGSemaphoreUnlock(proc->sem);
 
    if (mustwait)
    {
        /* Failed to get lock, so release interrupt holdoff */
        RESUME_INTERRUPTS();
        LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed");
        if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode);
    }
    else
    {
        LOG_LWDEBUG("LWLockAcquireOrWait", lock, "succeeded");
        /* Add lock to list of locks held by this backend */
        held_lwlocks[num_held_lwlocks].lock = lock;
        held_lwlocks[num_held_lwlocks++].mode = mode;
        if (TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode);
    }
 
    return !mustwait;
}

References Assert, elog, ERROR, fb(), held_lwlocks, HOLD_INTERRUPTS, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_SHARED, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LWLockAttemptLock(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MAX_SIMUL_LWLOCKS, LWLockHandle::mode, mode, MyProc, num_held_lwlocks, pg_atomic_fetch_sub_u32(), PG_USED_FOR_ASSERTS_ONLY, PGSemaphoreLock(), PGSemaphoreUnlock(), PRINT_LWDEBUG, RESUME_INTERRUPTS, PGPROC::sem, and T_NAME.

Referenced by XLogFlush().

LWLockAnyHeldByMe()

bool LWLockAnyHeldByMe ( LWLock *  lock, int  nlocks, size_t  stride  )

extern

Definition at line 1930 of file lwlock.c.

{
    char       *held_lock_addr;
    char       *begin;
    char       *end;
    int         i;
 
    begin = (char *) lock;
    end = begin + nlocks * stride;
    for (i = 0; i < num_held_lwlocks; i++)
    {
        held_lock_addr = (char *) held_lwlocks[i].lock;
        if (held_lock_addr >= begin &&
            held_lock_addr < end &&
            (held_lock_addr - begin) % stride == 0)
            return true;
    }
    return false;
}

References fb(), held_lwlocks, i, and num_held_lwlocks.

LWLockConditionalAcquire()

bool LWLockConditionalAcquire ( LWLock *  lock, LWLockMode  mode  )

extern

Definition at line 1348 of file lwlock.c.

{
    bool        mustwait;
 
    Assert(mode == LW_SHARED || mode == LW_EXCLUSIVE);
 
    PRINT_LWDEBUG("LWLockConditionalAcquire", lock, mode);
 
    /* Ensure we will have room to remember the lock */
    if (num_held_lwlocks >= MAX_SIMUL_LWLOCKS)
        elog(ERROR, "too many LWLocks taken");
 
    /*
     * Lock out cancel/die interrupts until we exit the code section protected
     * by the LWLock.  This ensures that interrupts will not interfere with
     * manipulations of data structures in shared memory.
     */
    HOLD_INTERRUPTS();
 
    /* Check for the lock */
    mustwait = LWLockAttemptLock(lock, mode);
 
    if (mustwait)
    {
        /* Failed to get lock, so release interrupt holdoff */
        RESUME_INTERRUPTS();
 
        LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed");
        if (TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode);
    }
    else
    {
        /* Add lock to list of locks held by this backend */
        held_lwlocks[num_held_lwlocks].lock = lock;
        held_lwlocks[num_held_lwlocks++].mode = mode;
        if (TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode);
    }
    return !mustwait;
}

References Assert, elog, ERROR, fb(), held_lwlocks, HOLD_INTERRUPTS, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_SHARED, LWLockAttemptLock(), MAX_SIMUL_LWLOCKS, LWLockHandle::mode, mode, num_held_lwlocks, PRINT_LWDEBUG, RESUME_INTERRUPTS, and T_NAME.

Referenced by pgaio_worker_submit_internal(), pgstat_io_flush_cb(), pgstat_lock_entry(), pgstat_lock_entry_shared(), pgstat_slru_flush_cb(), pgstat_wal_flush_cb(), ProcArrayEndTransaction(), SimpleLruWaitIO(), ss_report_location(), TransactionIdSetPageStatus(), and XLogNeedsFlush().

LWLockHeldByMe()

bool LWLockHeldByMe ( LWLock *  lock )

extern

Definition at line 1912 of file lwlock.c.

{
    int         i;
 
    for (i = 0; i < num_held_lwlocks; i++)
    {
        if (held_lwlocks[i].lock == lock)
            return true;
    }
    return false;
}

References held_lwlocks, i, and num_held_lwlocks.

Referenced by alloc_object(), autovac_recalculate_workers_for_balance(), check_for_freed_segments_locked(), CompactCheckpointerRequestQueue(), delete_item(), DeleteLockTarget(), dshash_dump(), ensure_active_superblock(), get_best_segment(), GetLockHoldersAndWaiters(), GetOldestSafeDecodingTransactionId(), GetSnapshotDataReuse(), init_span(), InvalidatePossiblyObsoleteSlot(), logicalrep_pa_worker_count(), logicalrep_sync_worker_count(), logicalrep_worker_find(), logicalrep_worker_wakeup_ptr(), logicalrep_workers_find(), MaintainLatestCompletedXid(), MaintainLatestCompletedXidRecovery(), make_new_segment(), OnConflict_CheckForSerializationFailure(), ProcArrayEndTransaction(), ProcArraySetReplicationSlotXmin(), ProcSleep(), ReleaseOneSerializableXact(), RemoveScratchTarget(), RemoveTargetIfNoLongerUsed(), resize(), RestoreScratchTarget(), SetNewSxactGlobalXmin(), SlruSelectLRUPage(), test_slru_page_readonly(), TransactionIdInRecentPast(), TwoPhaseGetGXact(), and VacuumUpdateCosts().

LWLockHeldByMeInMode()

bool LWLockHeldByMeInMode ( LWLock *  lock, LWLockMode  mode  )

extern

Definition at line 1956 of file lwlock.c.

{
    int         i;
 
    for (i = 0; i < num_held_lwlocks; i++)
    {
        if (held_lwlocks[i].lock == lock && held_lwlocks[i].mode == mode)
            return true;
    }
    return false;
}

References held_lwlocks, i, mode, and num_held_lwlocks.

Referenced by DeleteLockTarget(), dshash_delete_current(), dshash_delete_entry(), dshash_seq_next(), InvalidatePossiblyObsoleteSlot(), JoinWaitQueue(), logicalrep_worker_cleanup(), logicalrep_worker_stop_internal(), MarkAsPreparingGuts(), pgstat_create_replslot(), pgstat_drop_replslot(), PrepareRedoAdd(), PrepareRedoRemoveFull(), ProcArrayEndTransactionInternal(), ProcessTwoPhaseBuffer(), RemoveGXact(), ReplicationSlotsComputeRequiredXmin(), SimpleLruReadPage(), SimpleLruZeroPage(), SlruInternalWritePage(), SyncRepWakeQueue(), TransactionIdSetPageStatusInternal(), TransactionIdSetStatusBit(), TransferPredicateLocksToNewTarget(), and write_relmap_file().

LWLockInitialize()

void LWLockInitialize ( LWLock *  lock, int  tranche_id  )

extern

Definition at line 699 of file lwlock.c.

{
    /* verify the tranche_id is valid */
    (void) GetLWTrancheName(tranche_id);
 
    pg_atomic_init_u32(&lock->state, 0);
#ifdef LOCK_DEBUG
    pg_atomic_init_u32(&lock->nwaiters, 0);
#endif
    lock->tranche = tranche_id;
    proclist_init(&lock->waiters);
}

References fb(), GetLWTrancheName(), pg_atomic_init_u32(), proclist_init(), LWLock::state, LWLock::tranche, and LWLock::waiters.

Referenced by apw_init_state(), btinitparallelscan(), create_internal(), dshash_create(), ExecAppendInitializeDSM(), ExecHashJoinInitializeDSM(), init_tdr_dsm(), InitializeLWLocks(), InitProcGlobal(), pgstat_archiver_init_shmem_cb(), pgstat_bgwriter_init_shmem_cb(), pgstat_checkpointer_init_shmem_cb(), pgstat_init_entry(), pgstat_io_init_shmem_cb(), pgstat_slru_init_shmem_cb(), pgstat_wal_init_shmem_cb(), PredicateLockShmemInit(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), SimpleLruInit(), sts_initialize(), tbm_prepare_shared_iterate(), test_custom_stats_fixed_init_shmem_cb(), test_lwlock_initialize(), and XLOGShmemInit().

LWLockNewTrancheId()

int LWLockNewTrancheId ( const char *  name )

extern

Definition at line 597 of file lwlock.c.

{
    int         result;
 
    if (!name)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_NAME),
                 errmsg("tranche name cannot be NULL")));
 
    if (strlen(name) >= NAMEDATALEN)
        ereport(ERROR,
                (errcode(ERRCODE_NAME_TOO_LONG),
                 errmsg("tranche name too long"),
                 errdetail("LWLock tranche names must be no longer than %d bytes.",
                           NAMEDATALEN - 1)));
 
    /*
     * We use the ShmemLock spinlock to protect LWLockCounter and
     * LWLockTrancheNames.
     */
    SpinLockAcquire(ShmemLock);
 
    if (*LWLockCounter - LWTRANCHE_FIRST_USER_DEFINED >= MAX_NAMED_TRANCHES)
    {
        SpinLockRelease(ShmemLock);
        ereport(ERROR,
                (errmsg("maximum number of tranches already registered"),
                 errdetail("No more than %d tranches may be registered.",
                           MAX_NAMED_TRANCHES)));
    }
 
    result = (*LWLockCounter)++;
    LocalLWLockCounter = *LWLockCounter;
    strlcpy(LWLockTrancheNames[result - LWTRANCHE_FIRST_USER_DEFINED], name, NAMEDATALEN);
 
    SpinLockRelease(ShmemLock);
 
    return result;
}

References ereport, errcode(), errdetail(), errmsg, ERROR, fb(), LocalLWLockCounter, LWLockCounter, LWLockTrancheNames, LWTRANCHE_FIRST_USER_DEFINED, MAX_NAMED_TRANCHES, name, NAMEDATALEN, ShmemLock, SpinLockAcquire(), SpinLockRelease(), and strlcpy().

Referenced by apw_init_state(), GetNamedDSA(), GetNamedDSHash(), init_tdr_dsm(), init_tranche(), InitializeLWLocks(), test_basic(), test_create(), test_empty(), test_lwlock_tranche_creation(), test_lwlock_tranches(), test_random(), and test_slru_shmem_startup().

LWLockRelease()

void LWLockRelease ( LWLock *  lock )

extern

Definition at line 1794 of file lwlock.c.

{
    LWLockMode  mode;
    uint32      oldstate;
    bool        check_waiters;
    int         i;
 
    /*
     * Remove lock from list of locks held.  Usually, but not always, it will
     * be the latest-acquired lock; so search array backwards.
     */
    for (i = num_held_lwlocks; --i >= 0;)
        if (lock == held_lwlocks[i].lock)
            break;
 
    if (i < 0)
        elog(ERROR, "lock %s is not held", T_NAME(lock));
 
    mode = held_lwlocks[i].mode;
 
    num_held_lwlocks--;
    for (; i < num_held_lwlocks; i++)
        held_lwlocks[i] = held_lwlocks[i + 1];
 
    PRINT_LWDEBUG("LWLockRelease", lock, mode);
 
    /*
     * Release my hold on lock, after that it can immediately be acquired by
     * others, even if we still have to wakeup other waiters.
     */
    if (mode == LW_EXCLUSIVE)
        oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_EXCLUSIVE);
    else
        oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_SHARED);
 
    /* nobody else can have that kind of lock */
    Assert(!(oldstate & LW_VAL_EXCLUSIVE));
 
    if (TRACE_POSTGRESQL_LWLOCK_RELEASE_ENABLED())
        TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
 
    /*
     * Check if we're still waiting for backends to get scheduled, if so,
     * don't wake them up again.
     */
    if ((oldstate & LW_FLAG_HAS_WAITERS) &&
        !(oldstate & LW_FLAG_WAKE_IN_PROGRESS) &&
        (oldstate & LW_LOCK_MASK) == 0)
        check_waiters = true;
    else
        check_waiters = false;
 
    /*
     * As waking up waiters requires the spinlock to be acquired, only do so
     * if necessary.
     */
    if (check_waiters)
    {
        /* XXX: remove before commit? */
        LOG_LWDEBUG("LWLockRelease", lock, "releasing waiters");
        LWLockWakeup(lock);
    }
 
    /*
     * Now okay to allow cancel/die interrupts.
     */
    RESUME_INTERRUPTS();
}

References Assert, elog, ERROR, fb(), held_lwlocks, i, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_HAS_WAITERS, LW_FLAG_WAKE_IN_PROGRESS, LW_LOCK_MASK, LW_VAL_EXCLUSIVE, LW_VAL_SHARED, LWLockWakeup(), LWLockHandle::mode, mode, num_held_lwlocks, pg_atomic_sub_fetch_u32(), PRINT_LWDEBUG, RESUME_INTERRUPTS, LWLock::state, and T_NAME.

Referenced by _bt_end_vacuum(), _bt_parallel_done(), _bt_parallel_primscan_schedule(), _bt_parallel_release(), _bt_parallel_seize(), _bt_start_vacuum(), _bt_vacuum_cycleid(), abort_logical_decoding_activation(), AbsorbSyncRequests(), ActivateCommitTs(), addLSNWaiter(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_load_buffers(), AsyncNotifyFreezeXids(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueProcessPageEntries(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AtAbort_Twophase(), AtEOXact_LogicalRepWorkers(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), AutoVacLauncherMain(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BecomeRegisteredListener(), btparallelrescan(), BufferAlloc(), check_for_freed_segments(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckLogicalSlotExists(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), ComputeXidHorizons(), consume_xids_shortcut(), copy_replication_slot(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), deleteLSNWaiter(), destroy_superblock(), DisableLogicalDecoding(), DisableLogicalDecodingIfNecessary(), do_autovacuum(), do_pg_backup_start(), do_pg_backup_stop(), do_start_worker(), DropAllPredicateLocksFromTable(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), dsa_get_total_size(), dsa_get_total_size_from_handle(), dsa_pin(), dsa_release_in_place(), dsa_set_size_limit(), dsa_trim(), dsa_unpin(), dshash_delete_entry(), dshash_delete_key(), dshash_dump(), dshash_find(), dshash_find_or_insert_extended(), dshash_release_lock(), dshash_seq_next(), dshash_seq_term(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), EnableLogicalDecoding(), ensure_active_superblock(), entry_reset(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendBufferedRelShared(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), find_multixact_start(), FindAndDropRelationBuffers(), FindDeletedTupleInLocalRel(), FinishPreparedTransaction(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_local_synced_slots(), get_val_in_shmem(), get_xid_status(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLeaderApplyWorkerPid(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetMultiXactInfo(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldestUnsummarizedLSN(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetStrictOldestNonRemovableTransactionId(), GetVirtualXIDsDelayingChkpt(), GetWaitEventCustomIdentifier(), GetWaitEventCustomNames(), GetWalSummarizerState(), HaveVirtualXIDsDelayingChkpt(), init_conflict_slot_xmin(), init_dsm_registry(), initGlobalChannelTable(), InitWalSender(), injection_shmem_startup(), InjectionPointAttach(), InjectionPointDetach(), InjectionPointList(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), InvalidatePossiblyObsoleteSlot(), InvalidateVictimBuffer(), IoWorkerMain(), IsInstallXLogFileSegmentActive(), IsLogicalDecodingEnabled(), IsXLogLogicalInfoEnabled(), KnownAssignedXidsCompress(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_launcher_attach_dshmem(), logicalrep_pa_worker_stop(), logicalrep_reset_seqsync_start_time(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_stop_internal(), logicalrep_worker_wakeup(), logicalrep_workers_find(), LogStandbySnapshot(), LookupGXact(), LookupGXactBySubid(), LWLockReleaseAll(), LWLockReleaseClearVar(), MarkAsPrepared(), MarkAsPreparing(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), OnConflict_CheckForSerializationFailure(), PageIsPredicateLocked(), perform_relmap_update(), pg_control_checkpoint(), pg_control_init(), pg_control_recovery(), pg_control_system(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_get_shmem_allocations_numa(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgaio_worker_die(), pgaio_worker_register(), pgaio_worker_submit_internal(), pgss_shmem_startup(), pgss_store(), pgstat_archiver_reset_all_cb(), pgstat_archiver_snapshot_cb(), pgstat_bgwriter_reset_all_cb(), pgstat_bgwriter_snapshot_cb(), pgstat_build_snapshot(), pgstat_checkpointer_reset_all_cb(), pgstat_checkpointer_snapshot_cb(), pgstat_fetch_replslot(), pgstat_io_flush_cb(), pgstat_io_reset_all_cb(), pgstat_io_snapshot_cb(), pgstat_reset_matching_entries(), pgstat_reset_replslot(), pgstat_reset_slru_counter_internal(), pgstat_slru_flush_cb(), pgstat_slru_snapshot_cb(), pgstat_unlock_entry(), pgstat_wal_flush_cb(), pgstat_wal_reset_all_cb(), pgstat_wal_snapshot_cb(), PostPrepare_Locks(), PostPrepare_MultiXact(), PostPrepare_Twophase(), PreCommit_CheckForSerializationFailure(), PreCommit_Notify(), predicatelock_twophase_recover(), PredicateLockPageSplit(), PredicateLockTwoPhaseFinish(), PrefetchSharedBuffer(), PrescanPreparedTransactions(), ProcArrayAdd(), ProcArrayApplyRecoveryInfo(), ProcArrayApplyXidAssignment(), ProcArrayClearTransaction(), ProcArrayEndTransaction(), ProcArrayGetReplicationSlotXmin(), ProcArrayGroupClearXid(), ProcArrayInstallImportedXmin(), ProcArrayInstallRestoredXmin(), ProcArrayRemove(), ProcArraySetReplicationSlotXmin(), ProcessSequencesForSync(), ProcessSyncingTablesForApply(), ProcKill(), ProcNumberGetTransactionIds(), ProcSleep(), ReachedEndOfBackup(), read_relmap_file(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadReplicationSlot(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePostInvalidate(), RelationMapCopy(), RelationMapFinishBootstrap(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), relmap_redo(), RemoveScratchTarget(), ReplicationSlotAcquire(), ReplicationSlotCleanup(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotName(), ReplicationSlotRelease(), ReplicationSlotReserveWal(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset_internal(), replorigin_session_setup(), replorigin_state_clear(), RequestDisableLogicalDecoding(), reserve_wal_for_local_slot(), ResetInstallXLogFileSegmentActive(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), SaveSlotToPath(), SearchNamedReplicationSlot(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialInit(), SerialSetActiveSerXmin(), set_indexsafe_procflags(), set_val_in_shmem(), SetCommitTsLimit(), SetInstallXLogFileSegmentActive(), SetMultiXactIdLimit(), SetNextObjectId(), SetOldestOffset(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SignalRecoveryConflict(), SignalRecoveryConflictWithDatabase(), SignalRecoveryConflictWithVirtualXID(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SimpleLruZeroAndWritePage(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), ss_report_location(), StandbyRecoverPreparedTransactions(), StandbySlotsHaveCaughtup(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransGetParent(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SummarizeWAL(), SwitchIntoArchiveRecovery(), synchronize_one_slot(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateBackgroundWorkersForDatabase(), TerminateOtherDBBackends(), test_aio_shmem_startup(), test_custom_stats_fixed_reset_all_cb(), test_custom_stats_fixed_snapshot_cb(), test_custom_stats_fixed_update(), test_slru_page_exists(), test_slru_page_read(), test_slru_page_readonly(), test_slru_page_write(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdGetStatus(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), TwoPhaseGetOldestXidInCommit(), TwoPhaseGetXidByVirtualXID(), update_cached_xid_range(), update_synced_slots_inactive_since(), UpdateLogicalDecodingStatusEndOfRecovery(), UpdateMinRecoveryPoint(), vac_truncate_clog(), vacuum_rel(), VacuumUpdateCosts(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_table_state_change(), wait_for_worker_state_change(), WaitEventCustomNew(), WaitForReplicationWorkerAttach(), WaitForWalSummarization(), wakeupWaiters(), WakeupWalSummarizer(), WalSummarizerMain(), WalSummarizerShutdown(), write_relcache_init_file(), xact_redo(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), XLogFlush(), XLogNeedsFlush(), and XLogReportParameters().

LWLockReleaseAll()

void LWLockReleaseAll ( void  )

extern

Definition at line 1893 of file lwlock.c.

{
    while (num_held_lwlocks > 0)
    {
        HOLD_INTERRUPTS();      /* match the upcoming RESUME_INTERRUPTS */
 
        LWLockRelease(held_lwlocks[num_held_lwlocks - 1].lock);
    }
 
    Assert(num_held_lwlocks == 0);
}

References Assert, held_lwlocks, HOLD_INTERRUPTS, LWLockRelease(), and num_held_lwlocks.

Referenced by AbortSubTransaction(), AbortTransaction(), AutoVacLauncherMain(), AuxiliaryProcKill(), BackgroundWriterMain(), CheckpointerMain(), IoWorkerMain(), pgarch_archiveXlog(), ProcKill(), shmem_exit(), ShutdownAuxiliaryProcess(), WalSndErrorCleanup(), WalSummarizerMain(), and WalWriterMain().

LWLockReleaseClearVar()

void LWLockReleaseClearVar ( LWLock *  lock, pg_atomic_uint64 *  valptr, uint64  val  )

extern

Definition at line 1867 of file lwlock.c.

{
    /*
     * Note that pg_atomic_exchange_u64 is a full barrier, so we're guaranteed
     * that the variable is updated before releasing the lock.
     */
    pg_atomic_exchange_u64(valptr, val);
 
    LWLockRelease(lock);
}

References fb(), LWLockRelease(), pg_atomic_exchange_u64(), and val.

Referenced by WALInsertLockRelease().

LWLockShmemSize()

Size LWLockShmemSize ( void  )

extern

Definition at line 398 of file lwlock.c.

{
    Size        size;
    int         numLocks = NUM_FIXED_LWLOCKS;
 
    /*
     * If re-initializing shared memory, the request array will no longer be
     * accessible, so switch to the copy in postmaster's local memory.  We'll
     * copy it back into shared memory later when CreateLWLocks() is called
     * again.
     */
    if (LocalNamedLWLockTrancheRequestArray)
        NamedLWLockTrancheRequestArray = LocalNamedLWLockTrancheRequestArray;
 
    /* Calculate total number of locks needed in the main array. */
    numLocks += NumLWLocksForNamedTranches();
 
    /* Space for dynamic allocation counter. */
    size = MAXALIGN(sizeof(int));
 
    /* Space for named tranches. */
    size = add_size(size, mul_size(MAX_NAMED_TRANCHES, sizeof(char *)));
    size = add_size(size, mul_size(MAX_NAMED_TRANCHES, NAMEDATALEN));
 
    /*
     * Make space for named tranche requests.  This is done for the benefit of
     * EXEC_BACKEND builds, which otherwise wouldn't be able to call
     * GetNamedLWLockTranche() outside postmaster.
     */
    size = add_size(size, mul_size(NamedLWLockTrancheRequests,
                                   sizeof(NamedLWLockTrancheRequest)));
 
    /* Space for the LWLock array, plus room for cache line alignment. */
    size = add_size(size, LWLOCK_PADDED_SIZE);
    size = add_size(size, mul_size(numLocks, sizeof(LWLockPadded)));
 
    return size;
}

References add_size(), LocalNamedLWLockTrancheRequestArray, LWLOCK_PADDED_SIZE, MAX_NAMED_TRANCHES, MAXALIGN, mul_size(), NAMEDATALEN, NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, NUM_FIXED_LWLOCKS, and NumLWLocksForNamedTranches().

Referenced by CalculateShmemSize(), and CreateLWLocks().

LWLockUpdateVar()

void LWLockUpdateVar ( LWLock *  lock, pg_atomic_uint64 *  valptr, uint64  val  )

extern

Definition at line 1729 of file lwlock.c.

{
    proclist_head wakeup;
    proclist_mutable_iter iter;
 
    PRINT_LWDEBUG("LWLockUpdateVar", lock, LW_EXCLUSIVE);
 
    /*
     * Note that pg_atomic_exchange_u64 is a full barrier, so we're guaranteed
     * that the variable is updated before waking up waiters.
     */
    pg_atomic_exchange_u64(valptr, val);
 
    proclist_init(&wakeup);
 
    LWLockWaitListLock(lock);
 
    Assert(pg_atomic_read_u32(&lock->state) & LW_VAL_EXCLUSIVE);
 
    /*
     * See if there are any LW_WAIT_UNTIL_FREE waiters that need to be woken
     * up. They are always in the front of the queue.
     */
    proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
    {
        PGPROC     *waiter = GetPGProcByNumber(iter.cur);
 
        if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
            break;
 
        proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
        proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
 
        /* see LWLockWakeup() */
        Assert(waiter->lwWaiting == LW_WS_WAITING);
        waiter->lwWaiting = LW_WS_PENDING_WAKEUP;
    }
 
    /* We are done updating shared state of the lock itself. */
    LWLockWaitListUnlock(lock);
 
    /*
     * Awaken any waiters I removed from the queue.
     */
    proclist_foreach_modify(iter, &wakeup, lwWaitLink)
    {
        PGPROC     *waiter = GetPGProcByNumber(iter.cur);
 
        proclist_delete(&wakeup, iter.cur, lwWaitLink);
        /* check comment in LWLockWakeup() about this barrier */
        pg_write_barrier();
        waiter->lwWaiting = LW_WS_NOT_WAITING;
        PGSemaphoreUnlock(waiter->sem);
    }
}

References Assert, proclist_mutable_iter::cur, fb(), GetPGProcByNumber, LW_EXCLUSIVE, LW_VAL_EXCLUSIVE, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LW_WS_PENDING_WAKEUP, LW_WS_WAITING, LWLockWaitListLock(), LWLockWaitListUnlock(), PGPROC::lwWaiting, PGPROC::lwWaitMode, pg_atomic_exchange_u64(), pg_atomic_read_u32(), pg_write_barrier, PGSemaphoreUnlock(), PRINT_LWDEBUG, proclist_delete, proclist_foreach_modify, proclist_init(), proclist_push_tail, PGPROC::sem, LWLock::state, val, LWLock::waiters, and wakeup.

Referenced by WALInsertLockAcquireExclusive(), and WALInsertLockUpdateInsertingAt().

LWLockWaitForVar()

bool LWLockWaitForVar ( LWLock *  lock, pg_atomic_uint64 *  valptr, uint64  oldval, uint64 *  newval  )

extern

Definition at line 1593 of file lwlock.c.

{
    PGPROC     *proc = MyProc;
    int         extraWaits = 0;
    bool        result = false;
#ifdef LWLOCK_STATS
    lwlock_stats *lwstats;
 
    lwstats = get_lwlock_stats_entry(lock);
#endif
 
    PRINT_LWDEBUG("LWLockWaitForVar", lock, LW_WAIT_UNTIL_FREE);
 
    /*
     * Lock out cancel/die interrupts while we sleep on the lock.  There is no
     * cleanup mechanism to remove us from the wait queue if we got
     * interrupted.
     */
    HOLD_INTERRUPTS();
 
    /*
     * Loop here to check the lock's status after each time we are signaled.
     */
    for (;;)
    {
        bool        mustwait;
 
        mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
                                          &result);
 
        if (!mustwait)
            break;              /* the lock was free or value didn't match */
 
        /*
         * Add myself to wait queue. Note that this is racy, somebody else
         * could wakeup before we're finished queuing. NB: We're using nearly
         * the same twice-in-a-row lock acquisition protocol as
         * LWLockAcquire(). Check its comments for details. The only
         * difference is that we also have to check the variable's values when
         * checking the state of the lock.
         */
        LWLockQueueSelf(lock, LW_WAIT_UNTIL_FREE);
 
        /*
         * Clear LW_FLAG_WAKE_IN_PROGRESS flag, to make sure we get woken up
         * as soon as the lock is released.
         */
        pg_atomic_fetch_and_u32(&lock->state, ~LW_FLAG_WAKE_IN_PROGRESS);
 
        /*
         * We're now guaranteed to be woken up if necessary. Recheck the lock
         * and variables state.
         */
        mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
                                          &result);
 
        /* Ok, no conflict after we queued ourselves. Undo queueing. */
        if (!mustwait)
        {
            LOG_LWDEBUG("LWLockWaitForVar", lock, "free, undoing queue");
 
            LWLockDequeueSelf(lock);
            break;
        }
 
        /*
         * Wait until awakened.
         *
         * It is possible that we get awakened for a reason other than being
         * signaled by LWLockRelease.  If so, loop back and wait again.  Once
         * we've gotten the LWLock, re-increment the sema by the number of
         * additional signals received.
         */
        LOG_LWDEBUG("LWLockWaitForVar", lock, "waiting");
 
#ifdef LWLOCK_STATS
        lwstats->block_count++;
#endif
 
        LWLockReportWaitStart(lock);
        if (TRACE_POSTGRESQL_LWLOCK_WAIT_START_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE);
 
        for (;;)
        {
            PGSemaphoreLock(proc->sem);
            if (proc->lwWaiting == LW_WS_NOT_WAITING)
                break;
            extraWaits++;
        }
 
#ifdef LOCK_DEBUG
        {
            /* not waiting anymore */
            uint32      nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
 
            Assert(nwaiters < MAX_BACKENDS);
        }
#endif
 
        if (TRACE_POSTGRESQL_LWLOCK_WAIT_DONE_ENABLED())
            TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE);
        LWLockReportWaitEnd();
 
        LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened");
 
        /* Now loop back and check the status of the lock again. */
    }
 
    /*
     * Fix the process wait semaphore's count for any absorbed wakeups.
     */
    while (extraWaits-- > 0)
        PGSemaphoreUnlock(proc->sem);
 
    /*
     * Now okay to allow cancel/die interrupts.
     */
    RESUME_INTERRUPTS();
 
    return result;
}

References Assert, fb(), HOLD_INTERRUPTS, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_WAKE_IN_PROGRESS, LW_WAIT_UNTIL_FREE, LW_WS_NOT_WAITING, LWLockConflictsWithVar(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MyProc, newval, pg_atomic_fetch_and_u32(), pg_atomic_fetch_sub_u32(), PG_USED_FOR_ASSERTS_ONLY, PGSemaphoreLock(), PGSemaphoreUnlock(), PRINT_LWDEBUG, RESUME_INTERRUPTS, PGPROC::sem, LWLock::state, and T_NAME.

Referenced by WaitXLogInsertionsToFinish().

RequestNamedLWLockTranche()

void RequestNamedLWLockTranche ( const char *  tranche_name, int  num_lwlocks  )

extern

Definition at line 650 of file lwlock.c.

{
    NamedLWLockTrancheRequest *request;
    static int  NamedLWLockTrancheRequestsAllocated;
 
    if (!process_shmem_requests_in_progress)
        elog(FATAL, "cannot request additional LWLocks outside shmem_request_hook");
 
    if (!tranche_name)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_NAME),
                 errmsg("tranche name cannot be NULL")));
 
    if (strlen(tranche_name) >= NAMEDATALEN)
        ereport(ERROR,
                (errcode(ERRCODE_NAME_TOO_LONG),
                 errmsg("tranche name too long"),
                 errdetail("LWLock tranche names must be no longer than %d bytes.",
                           NAMEDATALEN - 1)));
 
    if (NamedLWLockTrancheRequestArray == NULL)
    {
        NamedLWLockTrancheRequestsAllocated = 16;
        NamedLWLockTrancheRequestArray = (NamedLWLockTrancheRequest *)
            MemoryContextAlloc(TopMemoryContext,
                               NamedLWLockTrancheRequestsAllocated
                               * sizeof(NamedLWLockTrancheRequest));
    }
 
    if (NamedLWLockTrancheRequests >= NamedLWLockTrancheRequestsAllocated)
    {
        int         i = pg_nextpower2_32(NamedLWLockTrancheRequests + 1);
 
        NamedLWLockTrancheRequestArray = (NamedLWLockTrancheRequest *)
            repalloc(NamedLWLockTrancheRequestArray,
                     i * sizeof(NamedLWLockTrancheRequest));
        NamedLWLockTrancheRequestsAllocated = i;
    }
 
    request = &NamedLWLockTrancheRequestArray[NamedLWLockTrancheRequests];
    strlcpy(request->tranche_name, tranche_name, NAMEDATALEN);
    request->num_lwlocks = num_lwlocks;
    NamedLWLockTrancheRequests++;
}

References elog, ereport, errcode(), errdetail(), errmsg, ERROR, FATAL, fb(), i, MemoryContextAlloc(), NAMEDATALEN, NamedLWLockTrancheRequestArray, NamedLWLockTrancheRequests, pg_nextpower2_32(), process_shmem_requests_in_progress, repalloc(), strlcpy(), and TopMemoryContext.

Referenced by pgss_shmem_request(), and test_lwlock_tranches_shmem_request().

StaticAssertDecl()

StaticAssertDecl	(	sizeof(LWLock)<=	LWLOCK_PADDED_SIZE,
		"Miscalculated LWLock padding"
	)

Variable Documentation

LWLockCounter

PGDLLIMPORT int* LWLockCounter

extern

Definition at line 200 of file lwlock.c.

Referenced by CreateLWLocks(), GetLWTrancheName(), and LWLockNewTrancheId().

LWLockTrancheNames

PGDLLIMPORT char** LWLockTrancheNames

extern

Definition at line 155 of file lwlock.c.

Referenced by CreateLWLocks(), GetLWTrancheName(), and LWLockNewTrancheId().

MainLWLockArray

PGDLLIMPORT LWLockPadded* MainLWLockArray

extern

Definition at line 162 of file lwlock.c.

Referenced by BufMappingPartitionLock(), BufMappingPartitionLockByIndex(), CreateLWLocks(), GetNamedLWLockTranche(), and InitializeLWLocks().

NamedLWLockTrancheRequestArray

PGDLLIMPORT NamedLWLockTrancheRequest* NamedLWLockTrancheRequestArray

extern

Definition at line 194 of file lwlock.c.

Referenced by CreateLWLocks(), GetNamedLWLockTranche(), InitializeLWLocks(), LWLockShmemSize(), NumLWLocksForNamedTranches(), and RequestNamedLWLockTranche().

NamedLWLockTrancheRequests

PGDLLIMPORT int NamedLWLockTrancheRequests

extern

Definition at line 193 of file lwlock.c.

Referenced by CreateLWLocks(), GetNamedLWLockTranche(), InitializeLWLocks(), LWLockShmemSize(), NumLWLocksForNamedTranches(), and RequestNamedLWLockTranche().