PostgreSQL Source Code  git master
lwlock.h File Reference
#include "port/atomics.h"
#include "storage/proclist_types.h"
#include "storage/lwlocknames.h"
Include dependency graph for lwlock.h:
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Data Structures

struct  LWLock
 
union  LWLockPadded
 
union  LWLockMinimallyPadded
 
struct  NamedLWLockTranche
 

Macros

#define LWLOCK_PADDED_SIZE   PG_CACHE_LINE_SIZE
 
#define LWLOCK_MINIMAL_SIZE   (sizeof(LWLock) <= 32 ? 32 : 64)
 
#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)
 

Typedefs

typedef struct LWLock LWLock
 
typedef union LWLockPadded LWLockPadded
 
typedef union LWLockMinimallyPadded LWLockMinimallyPadded
 
typedef struct NamedLWLockTranche NamedLWLockTranche
 
typedef enum LWLockMode LWLockMode
 
typedef enum BuiltinTrancheIds BuiltinTrancheIds
 
typedef LWLockLWLockId
 

Enumerations

enum  LWLockMode { LW_EXCLUSIVE, LW_SHARED, LW_WAIT_UNTIL_FREE }
 
enum  BuiltinTrancheIds {
  LWTRANCHE_XACT_BUFFER = NUM_INDIVIDUAL_LWLOCKS, LWTRANCHE_COMMITTS_BUFFER, LWTRANCHE_SUBTRANS_BUFFER, LWTRANCHE_MULTIXACTOFFSET_BUFFER,
  LWTRANCHE_MULTIXACTMEMBER_BUFFER, LWTRANCHE_NOTIFY_BUFFER, LWTRANCHE_SERIAL_BUFFER, LWTRANCHE_WAL_INSERT,
  LWTRANCHE_BUFFER_CONTENT, LWTRANCHE_BUFFER_IO, LWTRANCHE_REPLICATION_ORIGIN_STATE, LWTRANCHE_REPLICATION_SLOT_IO,
  LWTRANCHE_LOCK_FASTPATH, LWTRANCHE_BUFFER_MAPPING, LWTRANCHE_LOCK_MANAGER, LWTRANCHE_PREDICATE_LOCK_MANAGER,
  LWTRANCHE_PARALLEL_HASH_JOIN, LWTRANCHE_PARALLEL_QUERY_DSA, LWTRANCHE_PER_SESSION_DSA, LWTRANCHE_PER_SESSION_RECORD_TYPE,
  LWTRANCHE_PER_SESSION_RECORD_TYPMOD, LWTRANCHE_SHARED_TUPLESTORE, LWTRANCHE_SHARED_TIDBITMAP, LWTRANCHE_PARALLEL_APPEND,
  LWTRANCHE_PER_XACT_PREDICATE_LIST, LWTRANCHE_FIRST_USER_DEFINED
}
 

Functions

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, uint64 *valptr, uint64 val)
 
void LWLockReleaseAll (void)
 
bool LWLockHeldByMe (LWLock *lock)
 
bool LWLockHeldByMeInMode (LWLock *lock, LWLockMode mode)
 
bool LWLockWaitForVar (LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
 
void LWLockUpdateVar (LWLock *lock, uint64 *valptr, uint64 value)
 
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)
 
LWLockPaddedGetNamedLWLockTranche (const char *tranche_name)
 
int LWLockNewTrancheId (void)
 
void LWLockRegisterTranche (int tranche_id, const char *tranche_name)
 
void LWLockInitialize (LWLock *lock, int tranche_id)
 

Variables

PGDLLIMPORT LWLockPaddedMainLWLockArray
 
PGDLLIMPORT NamedLWLockTrancheNamedLWLockTrancheArray
 
PGDLLIMPORT int NamedLWLockTrancheRequests
 

Macro Definition Documentation

◆ BUFFER_MAPPING_LWLOCK_OFFSET

#define BUFFER_MAPPING_LWLOCK_OFFSET   NUM_INDIVIDUAL_LWLOCKS

Definition at line 122 of file lwlock.h.

◆ LOCK_MANAGER_LWLOCK_OFFSET

#define LOCK_MANAGER_LWLOCK_OFFSET   (BUFFER_MAPPING_LWLOCK_OFFSET + NUM_BUFFER_PARTITIONS)

Definition at line 123 of file lwlock.h.

◆ LOG2_NUM_LOCK_PARTITIONS

#define LOG2_NUM_LOCK_PARTITIONS   4

Definition at line 114 of file lwlock.h.

Referenced by proclock_hash(), and ProcLockHashCode().

◆ LOG2_NUM_PREDICATELOCK_PARTITIONS

#define LOG2_NUM_PREDICATELOCK_PARTITIONS   4

Definition at line 118 of file lwlock.h.

◆ LWLOCK_MINIMAL_SIZE

#define LWLOCK_MINIMAL_SIZE   (sizeof(LWLock) <= 32 ? 32 : 64)

Definition at line 73 of file lwlock.h.

Referenced by CreateLWLocks().

◆ LWLOCK_PADDED_SIZE

#define LWLOCK_PADDED_SIZE   PG_CACHE_LINE_SIZE

Definition at line 72 of file lwlock.h.

Referenced by CreateLWLocks(), and LWLockShmemSize().

◆ NUM_BUFFER_PARTITIONS

#define NUM_BUFFER_PARTITIONS   128

Definition at line 111 of file lwlock.h.

Referenced by InitBufTable(), InitializeLWLocks(), StrategyInitialize(), and StrategyShmemSize().

◆ NUM_FIXED_LWLOCKS

Definition at line 127 of file lwlock.h.

Referenced by GetNamedLWLockTranche(), InitializeLWLocks(), and LWLockShmemSize().

◆ NUM_LOCK_PARTITIONS

◆ NUM_PREDICATELOCK_PARTITIONS

◆ PREDICATELOCK_MANAGER_LWLOCK_OFFSET

#define PREDICATELOCK_MANAGER_LWLOCK_OFFSET   (LOCK_MANAGER_LWLOCK_OFFSET + NUM_LOCK_PARTITIONS)

Definition at line 125 of file lwlock.h.

Typedef Documentation

◆ BuiltinTrancheIds

◆ LWLock

typedef struct LWLock LWLock

◆ LWLockId

typedef LWLock* LWLockId

Definition at line 229 of file lwlock.h.

◆ LWLockMinimallyPadded

◆ LWLockMode

typedef enum LWLockMode LWLockMode

◆ LWLockPadded

typedef union LWLockPadded LWLockPadded

◆ NamedLWLockTranche

Enumeration Type Documentation

◆ BuiltinTrancheIds

Enumerator
LWTRANCHE_XACT_BUFFER 
LWTRANCHE_COMMITTS_BUFFER 
LWTRANCHE_SUBTRANS_BUFFER 
LWTRANCHE_MULTIXACTOFFSET_BUFFER 
LWTRANCHE_MULTIXACTMEMBER_BUFFER 
LWTRANCHE_NOTIFY_BUFFER 
LWTRANCHE_SERIAL_BUFFER 
LWTRANCHE_WAL_INSERT 
LWTRANCHE_BUFFER_CONTENT 
LWTRANCHE_BUFFER_IO 
LWTRANCHE_REPLICATION_ORIGIN_STATE 
LWTRANCHE_REPLICATION_SLOT_IO 
LWTRANCHE_LOCK_FASTPATH 
LWTRANCHE_BUFFER_MAPPING 
LWTRANCHE_LOCK_MANAGER 
LWTRANCHE_PREDICATE_LOCK_MANAGER 
LWTRANCHE_PARALLEL_HASH_JOIN 
LWTRANCHE_PARALLEL_QUERY_DSA 
LWTRANCHE_PER_SESSION_DSA 
LWTRANCHE_PER_SESSION_RECORD_TYPE 
LWTRANCHE_PER_SESSION_RECORD_TYPMOD 
LWTRANCHE_SHARED_TUPLESTORE 
LWTRANCHE_SHARED_TIDBITMAP 
LWTRANCHE_PARALLEL_APPEND 
LWTRANCHE_PER_XACT_PREDICATE_LIST 
LWTRANCHE_FIRST_USER_DEFINED 

Definition at line 194 of file lwlock.h.

195 {
196  LWTRANCHE_XACT_BUFFER = NUM_INDIVIDUAL_LWLOCKS,
BuiltinTrancheIds
Definition: lwlock.h:194

◆ LWLockMode

enum LWLockMode
Enumerator
LW_EXCLUSIVE 
LW_SHARED 
LW_WAIT_UNTIL_FREE 

Definition at line 130 of file lwlock.h.

131 {
132  LW_EXCLUSIVE,
133  LW_SHARED,
134  LW_WAIT_UNTIL_FREE /* A special mode used in PGPROC->lwWaitMode,
135  * when waiting for lock to become free. Not
136  * to be used as LWLockAcquire argument */
137 } LWLockMode;
LWLockMode
Definition: lwlock.h:130

Function Documentation

◆ CreateLWLocks()

void CreateLWLocks ( void  )

Definition at line 468 of file lwlock.c.

References i, InitializeLWLocks(), IsUnderPostmaster, LW_VAL_EXCLUSIVE, LWLOCK_MINIMAL_SIZE, LWLOCK_PADDED_SIZE, LWLockRegisterTranche(), LWLockShmemSize(), LWTRANCHE_FIRST_USER_DEFINED, MAX_BACKENDS, NamedLWLockTrancheRequests, ShmemAlloc(), and StaticAssertStmt.

Referenced by CreateSharedMemoryAndSemaphores().

469 {
471  "MAX_BACKENDS too big for lwlock.c");
472 
474  sizeof(LWLock) <= LWLOCK_PADDED_SIZE,
475  "Miscalculated LWLock padding");
476 
477  if (!IsUnderPostmaster)
478  {
479  Size spaceLocks = LWLockShmemSize();
480  int *LWLockCounter;
481  char *ptr;
482 
483  /* Allocate space */
484  ptr = (char *) ShmemAlloc(spaceLocks);
485 
486  /* Leave room for dynamic allocation of tranches */
487  ptr += sizeof(int);
488 
489  /* Ensure desired alignment of LWLock array */
490  ptr += LWLOCK_PADDED_SIZE - ((uintptr_t) ptr) % LWLOCK_PADDED_SIZE;
491 
492  MainLWLockArray = (LWLockPadded *) ptr;
493 
494  /*
495  * Initialize the dynamic-allocation counter for tranches, which is
496  * stored just before the first LWLock.
497  */
498  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
499  *LWLockCounter = LWTRANCHE_FIRST_USER_DEFINED;
500 
501  /* Initialize all LWLocks */
503  }
504 
505  /* Register named extension LWLock tranches in the current process. */
506  for (int i = 0; i < NamedLWLockTrancheRequests; i++)
508  NamedLWLockTrancheArray[i].trancheName);
509 }
Definition: lwlock.h:31
void * ShmemAlloc(Size size)
Definition: shmem.c:161
NamedLWLockTranche * NamedLWLockTrancheArray
Definition: lwlock.c:239
Size LWLockShmemSize(void)
Definition: lwlock.c:435
void LWLockRegisterTranche(int tranche_id, const char *tranche_name)
Definition: lwlock.c:653
#define StaticAssertStmt(condition, errmessage)
Definition: c.h:860
#define LWLOCK_MINIMAL_SIZE
Definition: lwlock.h:73
#define MAX_BACKENDS
Definition: postmaster.h:75
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
bool IsUnderPostmaster
Definition: globals.c:109
unsigned int uint32
Definition: c.h:375
static void InitializeLWLocks(void)
Definition: lwlock.c:515
size_t Size
Definition: c.h:474
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
int i
#define LWLOCK_PADDED_SIZE
Definition: lwlock.h:72
LWLockPadded * MainLWLockArray
Definition: lwlock.c:200

◆ GetLWLockIdentifier()

const char* GetLWLockIdentifier ( uint32  classId,
uint16  eventId 
)

Definition at line 809 of file lwlock.c.

References Assert, GetLWTrancheName(), and PG_WAIT_LWLOCK.

Referenced by pgstat_get_wait_event().

810 {
811  Assert(classId == PG_WAIT_LWLOCK);
812  /* The event IDs are just tranche numbers. */
813  return GetLWTrancheName(eventId);
814 }
static const char * GetLWTrancheName(uint16 trancheId)
Definition: lwlock.c:781
#define Assert(condition)
Definition: c.h:746
#define PG_WAIT_LWLOCK
Definition: pgstat.h:855

◆ GetNamedLWLockTranche()

LWLockPadded* GetNamedLWLockTranche ( const char *  tranche_name)

Definition at line 599 of file lwlock.c.

References elog, ERROR, i, NamedLWLockTrancheRequests, NUM_FIXED_LWLOCKS, and NamedLWLockTrancheRequest::num_lwlocks.

Referenced by pgss_shmem_startup().

600 {
601  int lock_pos;
602  int i;
603 
604  /*
605  * Obtain the position of base address of LWLock belonging to requested
606  * tranche_name in MainLWLockArray. LWLocks for named tranches are placed
607  * in MainLWLockArray after fixed locks.
608  */
609  lock_pos = NUM_FIXED_LWLOCKS;
610  for (i = 0; i < NamedLWLockTrancheRequests; i++)
611  {
612  if (strcmp(NamedLWLockTrancheRequestArray[i].tranche_name,
613  tranche_name) == 0)
614  return &MainLWLockArray[lock_pos];
615 
617  }
618 
619  elog(ERROR, "requested tranche is not registered");
620 
621  /* just to keep compiler quiet */
622  return NULL;
623 }
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:127
#define ERROR
Definition: elog.h:43
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
static NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:227
#define elog(elevel,...)
Definition: elog.h:214
int i
LWLockPadded * MainLWLockArray
Definition: lwlock.c:200

◆ InitLWLockAccess()

void InitLWLockAccess ( void  )

Definition at line 583 of file lwlock.c.

Referenced by InitProcess().

584 {
585 #ifdef LWLOCK_STATS
586  init_lwlock_stats();
587 #endif
588 }

◆ LWLockAcquire()

bool LWLockAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1208 of file lwlock.c.

References Assert, AssertArg, elog, ERROR, HOLD_INTERRUPTS, IsUnderPostmaster, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_RELEASE_OK, LW_SHARED, LWLockAttemptLock(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MAX_SIMUL_LWLOCKS, LWLockHandle::mode, MyProc, num_held_lwlocks, pg_atomic_fetch_or_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_start_vacuum(), _bt_vacuum_cycleid(), AbortBufferIO(), AbsorbSyncRequests(), ActivateCommitTs(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_init_shmem(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AtAbort_Twophase(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), AutoVacLauncherMain(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendIdGetProc(), BackendIdGetTransactionIds(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BootStrapCLOG(), BootStrapMultiXact(), BootStrapSUBTRANS(), BufferAlloc(), CancelDBBackends(), CancelVirtualTransaction(), check_for_freed_segments(), CheckBuffer(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckRecoveryConsistency(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), ComputeXidHorizons(), copy_replication_slot(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), destroy_superblock(), do_autovacuum(), do_pg_start_backup(), do_pg_stop_backup(), do_start_worker(), DropAllPredicateLocksFromTable(), DropSubscription(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), 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(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), ensure_active_superblock(), entry_reset(), Exec_ListenPreCommit(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), FlushRelationsAllBuffers(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_xid_status(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldSnapshotFromTimeMapping(), GetOldSnapshotTimeMapping(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionData(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetVirtualXIDsDelayingChkpt(), HandleAutoVacLauncherInterrupts(), HaveVirtualXIDsDelayingChkpt(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), KnownAssignedXidsAdd(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockBuffer(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_wakeup(), MaintainOldSnapshotTimeMapping(), MarkAsPrepared(), MarkAsPreparing(), MaybeExtendOffsetSlru(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), PageIsPredicateLocked(), perform_relmap_update(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgss_shmem_startup(), pgss_store(), pgstat_reset_replslot_counter(), 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(), process_syncing_tables_for_apply(), ProcKill(), ProcSleep(), ReadBuffer_common(), ReadMultiXactCounts(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadRecord(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePreInvalidate(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquireInternal(), ReplicationSlotCleanup(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotRelease(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_drop(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset(), replorigin_session_setup(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), SaveSlotToPath(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialSetActiveSerXmin(), SetCommitTsLimit(), SetMultiXactIdLimit(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), StandbyRecoverPreparedTransactions(), StartBufferIO(), StartupCLOG(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateOtherDBBackends(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), update_cached_xid_range(), UpdateMinRecoveryPoint(), vac_truncate_clog(), vacuum_rel(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_relation_state_change(), wait_for_worker_state_change(), WaitForReplicationWorkerAttach(), WaitIO(), WALInsertLockAcquire(), WALInsertLockAcquireExclusive(), write_relcache_init_file(), xact_redo(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), and XLogReportParameters().

1209 {
1210  PGPROC *proc = MyProc;
1211  bool result = true;
1212  int extraWaits = 0;
1213 #ifdef LWLOCK_STATS
1214  lwlock_stats *lwstats;
1215 
1216  lwstats = get_lwlock_stats_entry(lock);
1217 #endif
1218 
1220 
1221  PRINT_LWDEBUG("LWLockAcquire", lock, mode);
1222 
1223 #ifdef LWLOCK_STATS
1224  /* Count lock acquisition attempts */
1225  if (mode == LW_EXCLUSIVE)
1226  lwstats->ex_acquire_count++;
1227  else
1228  lwstats->sh_acquire_count++;
1229 #endif /* LWLOCK_STATS */
1230 
1231  /*
1232  * We can't wait if we haven't got a PGPROC. This should only occur
1233  * during bootstrap or shared memory initialization. Put an Assert here
1234  * to catch unsafe coding practices.
1235  */
1236  Assert(!(proc == NULL && IsUnderPostmaster));
1237 
1238  /* Ensure we will have room to remember the lock */
1240  elog(ERROR, "too many LWLocks taken");
1241 
1242  /*
1243  * Lock out cancel/die interrupts until we exit the code section protected
1244  * by the LWLock. This ensures that interrupts will not interfere with
1245  * manipulations of data structures in shared memory.
1246  */
1247  HOLD_INTERRUPTS();
1248 
1249  /*
1250  * Loop here to try to acquire lock after each time we are signaled by
1251  * LWLockRelease.
1252  *
1253  * NOTE: it might seem better to have LWLockRelease actually grant us the
1254  * lock, rather than retrying and possibly having to go back to sleep. But
1255  * in practice that is no good because it means a process swap for every
1256  * lock acquisition when two or more processes are contending for the same
1257  * lock. Since LWLocks are normally used to protect not-very-long
1258  * sections of computation, a process needs to be able to acquire and
1259  * release the same lock many times during a single CPU time slice, even
1260  * in the presence of contention. The efficiency of being able to do that
1261  * outweighs the inefficiency of sometimes wasting a process dispatch
1262  * cycle because the lock is not free when a released waiter finally gets
1263  * to run. See pgsql-hackers archives for 29-Dec-01.
1264  */
1265  for (;;)
1266  {
1267  bool mustwait;
1268 
1269  /*
1270  * Try to grab the lock the first time, we're not in the waitqueue
1271  * yet/anymore.
1272  */
1273  mustwait = LWLockAttemptLock(lock, mode);
1274 
1275  if (!mustwait)
1276  {
1277  LOG_LWDEBUG("LWLockAcquire", lock, "immediately acquired lock");
1278  break; /* got the lock */
1279  }
1280 
1281  /*
1282  * Ok, at this point we couldn't grab the lock on the first try. We
1283  * cannot simply queue ourselves to the end of the list and wait to be
1284  * woken up because by now the lock could long have been released.
1285  * Instead add us to the queue and try to grab the lock again. If we
1286  * succeed we need to revert the queuing and be happy, otherwise we
1287  * recheck the lock. If we still couldn't grab it, we know that the
1288  * other locker will see our queue entries when releasing since they
1289  * existed before we checked for the lock.
1290  */
1291 
1292  /* add to the queue */
1293  LWLockQueueSelf(lock, mode);
1294 
1295  /* we're now guaranteed to be woken up if necessary */
1296  mustwait = LWLockAttemptLock(lock, mode);
1297 
1298  /* ok, grabbed the lock the second time round, need to undo queueing */
1299  if (!mustwait)
1300  {
1301  LOG_LWDEBUG("LWLockAcquire", lock, "acquired, undoing queue");
1302 
1303  LWLockDequeueSelf(lock);
1304  break;
1305  }
1306 
1307  /*
1308  * Wait until awakened.
1309  *
1310  * Since we share the process wait semaphore with the regular lock
1311  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1312  * while one of those is pending, it is possible that we get awakened
1313  * for a reason other than being signaled by LWLockRelease. If so,
1314  * loop back and wait again. Once we've gotten the LWLock,
1315  * re-increment the sema by the number of additional signals received,
1316  * so that the lock manager or signal manager will see the received
1317  * signal when it next waits.
1318  */
1319  LOG_LWDEBUG("LWLockAcquire", lock, "waiting");
1320 
1321 #ifdef LWLOCK_STATS
1322  lwstats->block_count++;
1323 #endif
1324 
1325  LWLockReportWaitStart(lock);
1326  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1327 
1328  for (;;)
1329  {
1330  PGSemaphoreLock(proc->sem);
1331  if (!proc->lwWaiting)
1332  break;
1333  extraWaits++;
1334  }
1335 
1336  /* Retrying, allow LWLockRelease to release waiters again. */
1338 
1339 #ifdef LOCK_DEBUG
1340  {
1341  /* not waiting anymore */
1342  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1343 
1344  Assert(nwaiters < MAX_BACKENDS);
1345  }
1346 #endif
1347 
1348  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1350 
1351  LOG_LWDEBUG("LWLockAcquire", lock, "awakened");
1352 
1353  /* Now loop back and try to acquire lock again. */
1354  result = false;
1355  }
1356 
1357  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode);
1358 
1359  /* Add lock to list of locks held by this backend */
1362 
1363  /*
1364  * Fix the process wait semaphore's count for any absorbed wakeups.
1365  */
1366  while (extraWaits-- > 0)
1367  PGSemaphoreUnlock(proc->sem);
1368 
1369  return result;
1370 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:343
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:826
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:161
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:208
pg_atomic_uint32 state
Definition: lwlock.h:34
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:43
#define MAX_BACKENDS
Definition: postmaster.h:75
LWLockMode mode
Definition: lwlock.c:214
bool IsUnderPostmaster
Definition: globals.c:109
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:772
unsigned int uint32
Definition: c.h:375
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1113
#define AssertArg(condition)
Definition: c.h:748
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:763
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1069
static int num_held_lwlocks
Definition: lwlock.c:217
#define Assert(condition)
Definition: c.h:746
LWLock * lock
Definition: lwlock.c:213
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:320
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:116
#define elog(elevel,...)
Definition: elog.h:214
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:372
PGSemaphore sem
Definition: proc.h:118
Definition: proc.h:112
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:122
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockAcquireOrWait()

bool LWLockAcquireOrWait ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1435 of file lwlock.c.

References Assert, elog, ERROR, HOLD_INTERRUPTS, LWLockHandle::lock, LOG_LWDEBUG, LW_EXCLUSIVE, LW_SHARED, LW_WAIT_UNTIL_FREE, LWLockAttemptLock(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MAX_SIMUL_LWLOCKS, LWLockHandle::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().

1436 {
1437  PGPROC *proc = MyProc;
1438  bool mustwait;
1439  int extraWaits = 0;
1440 #ifdef LWLOCK_STATS
1441  lwlock_stats *lwstats;
1442 
1443  lwstats = get_lwlock_stats_entry(lock);
1444 #endif
1445 
1447 
1448  PRINT_LWDEBUG("LWLockAcquireOrWait", lock, mode);
1449 
1450  /* Ensure we will have room to remember the lock */
1452  elog(ERROR, "too many LWLocks taken");
1453 
1454  /*
1455  * Lock out cancel/die interrupts until we exit the code section protected
1456  * by the LWLock. This ensures that interrupts will not interfere with
1457  * manipulations of data structures in shared memory.
1458  */
1459  HOLD_INTERRUPTS();
1460 
1461  /*
1462  * NB: We're using nearly the same twice-in-a-row lock acquisition
1463  * protocol as LWLockAcquire(). Check its comments for details.
1464  */
1465  mustwait = LWLockAttemptLock(lock, mode);
1466 
1467  if (mustwait)
1468  {
1470 
1471  mustwait = LWLockAttemptLock(lock, mode);
1472 
1473  if (mustwait)
1474  {
1475  /*
1476  * Wait until awakened. Like in LWLockAcquire, be prepared for
1477  * bogus wakeups, because we share the semaphore with
1478  * ProcWaitForSignal.
1479  */
1480  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "waiting");
1481 
1482 #ifdef LWLOCK_STATS
1483  lwstats->block_count++;
1484 #endif
1485 
1486  LWLockReportWaitStart(lock);
1487  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
1488 
1489  for (;;)
1490  {
1491  PGSemaphoreLock(proc->sem);
1492  if (!proc->lwWaiting)
1493  break;
1494  extraWaits++;
1495  }
1496 
1497 #ifdef LOCK_DEBUG
1498  {
1499  /* not waiting anymore */
1500  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1501 
1502  Assert(nwaiters < MAX_BACKENDS);
1503  }
1504 #endif
1505  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
1507 
1508  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened");
1509  }
1510  else
1511  {
1512  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "acquired, undoing queue");
1513 
1514  /*
1515  * Got lock in the second attempt, undo queueing. We need to treat
1516  * this as having successfully acquired the lock, otherwise we'd
1517  * not necessarily wake up people we've prevented from acquiring
1518  * the lock.
1519  */
1520  LWLockDequeueSelf(lock);
1521  }
1522  }
1523 
1524  /*
1525  * Fix the process wait semaphore's count for any absorbed wakeups.
1526  */
1527  while (extraWaits-- > 0)
1528  PGSemaphoreUnlock(proc->sem);
1529 
1530  if (mustwait)
1531  {
1532  /* Failed to get lock, so release interrupt holdoff */
1534  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed");
1535  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode);
1536  }
1537  else
1538  {
1539  LOG_LWDEBUG("LWLockAcquireOrWait", lock, "succeeded");
1540  /* Add lock to list of locks held by this backend */
1543  TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode);
1544  }
1545 
1546  return !mustwait;
1547 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:343
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:826
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:161
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:208
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:118
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:43
#define MAX_BACKENDS
Definition: postmaster.h:75
LWLockMode mode
Definition: lwlock.c:214
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:772
unsigned int uint32
Definition: c.h:375
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1113
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:763
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1069
static int num_held_lwlocks
Definition: lwlock.c:217
#define Assert(condition)
Definition: c.h:746
LWLock * lock
Definition: lwlock.c:213
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:320
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:116
#define elog(elevel,...)
Definition: elog.h:214
PGSemaphore sem
Definition: proc.h:118
Definition: proc.h:112
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:122
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockConditionalAcquire()

bool LWLockConditionalAcquire ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1380 of file lwlock.c.

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

Referenced by BufferAlloc(), ConditionalLockBuffer(), ProcArrayEndTransaction(), SimpleLruWaitIO(), ss_report_location(), TransactionIdSetPageStatus(), and XLogNeedsFlush().

1381 {
1382  bool mustwait;
1383 
1385 
1386  PRINT_LWDEBUG("LWLockConditionalAcquire", lock, mode);
1387 
1388  /* Ensure we will have room to remember the lock */
1390  elog(ERROR, "too many LWLocks taken");
1391 
1392  /*
1393  * Lock out cancel/die interrupts until we exit the code section protected
1394  * by the LWLock. This ensures that interrupts will not interfere with
1395  * manipulations of data structures in shared memory.
1396  */
1397  HOLD_INTERRUPTS();
1398 
1399  /* Check for the lock */
1400  mustwait = LWLockAttemptLock(lock, mode);
1401 
1402  if (mustwait)
1403  {
1404  /* Failed to get lock, so release interrupt holdoff */
1406 
1407  LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed");
1408  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode);
1409  }
1410  else
1411  {
1412  /* Add lock to list of locks held by this backend */
1415  TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode);
1416  }
1417  return !mustwait;
1418 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
static bool LWLockAttemptLock(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:826
#define MAX_SIMUL_LWLOCKS
Definition: lwlock.c:208
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:118
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:43
LWLockMode mode
Definition: lwlock.c:214
#define AssertArg(condition)
Definition: c.h:748
static int num_held_lwlocks
Definition: lwlock.c:217
LWLock * lock
Definition: lwlock.c:213
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:116
#define elog(elevel,...)
Definition: elog.h:214
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockHeldByMe()

◆ LWLockHeldByMeInMode()

bool LWLockHeldByMeInMode ( LWLock lock,
LWLockMode  mode 
)

Definition at line 1946 of file lwlock.c.

References i, and num_held_lwlocks.

Referenced by DeleteLockTarget(), dshash_delete_entry(), dshash_release_lock(), IsBufferCleanupOK(), logicalrep_worker_cleanup(), MarkAsPreparingGuts(), MarkBufferDirty(), PrepareRedoAdd(), PrepareRedoRemove(), ProcessTwoPhaseBuffer(), RemoveGXact(), SearchNamedReplicationSlot(), SyncRepWakeQueue(), TransactionIdSetPageStatusInternal(), and TransferPredicateLocksToNewTarget().

1947 {
1948  int i;
1949 
1950  for (i = 0; i < num_held_lwlocks; i++)
1951  {
1952  if (held_lwlocks[i].lock == l && held_lwlocks[i].mode == mode)
1953  return true;
1954  }
1955  return false;
1956 }
static PgChecksumMode mode
Definition: pg_checksums.c:61
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
static int num_held_lwlocks
Definition: lwlock.c:217
int i

◆ LWLockInitialize()

void LWLockInitialize ( LWLock lock,
int  tranche_id 
)

Definition at line 745 of file lwlock.c.

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

Referenced by apw_init_shmem(), create_internal(), dshash_create(), ExecAppendInitializeDSM(), ExecHashJoinInitializeDSM(), InitBufferPool(), InitializeLWLocks(), InitPredicateLocks(), InitProcGlobal(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), SimpleLruInit(), sts_initialize(), tbm_prepare_shared_iterate(), and XLOGShmemInit().

746 {
748 #ifdef LOCK_DEBUG
749  pg_atomic_init_u32(&lock->nwaiters, 0);
750 #endif
751  lock->tranche = tranche_id;
752  proclist_init(&lock->waiters);
753 }
proclist_head waiters
Definition: lwlock.h:35
pg_atomic_uint32 state
Definition: lwlock.h:34
uint16 tranche
Definition: lwlock.h:33
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
static void proclist_init(proclist_head *list)
Definition: proclist.h:29
static void pg_atomic_init_u32(volatile pg_atomic_uint32 *ptr, uint32 val)
Definition: atomics.h:223

◆ LWLockNewTrancheId()

int LWLockNewTrancheId ( void  )

Definition at line 629 of file lwlock.c.

References ShmemLock, SpinLockAcquire, and SpinLockRelease.

Referenced by apw_init_shmem(), and InitializeLWLocks().

630 {
631  int result;
632  int *LWLockCounter;
633 
634  LWLockCounter = (int *) ((char *) MainLWLockArray - sizeof(int));
636  result = (*LWLockCounter)++;
638 
639  return result;
640 }
#define SpinLockAcquire(lock)
Definition: spin.h:62
#define SpinLockRelease(lock)
Definition: spin.h:64
slock_t * ShmemLock
Definition: shmem.c:88
LWLockPadded * MainLWLockArray
Definition: lwlock.c:200

◆ LWLockRegisterTranche()

void LWLockRegisterTranche ( int  tranche_id,
const char *  tranche_name 
)

Definition at line 653 of file lwlock.c.

References LWLockTrancheNames, LWLockTrancheNamesAllocated, LWTRANCHE_FIRST_USER_DEFINED, Max, MemoryContextAllocZero(), repalloc(), and TopMemoryContext.

Referenced by apw_init_shmem(), and CreateLWLocks().

654 {
655  /* This should only be called for user-defined tranches. */
656  if (tranche_id < LWTRANCHE_FIRST_USER_DEFINED)
657  return;
658 
659  /* Convert to array index. */
660  tranche_id -= LWTRANCHE_FIRST_USER_DEFINED;
661 
662  /* If necessary, create or enlarge array. */
663  if (tranche_id >= LWLockTrancheNamesAllocated)
664  {
665  int newalloc;
666 
667  newalloc = Max(LWLockTrancheNamesAllocated, 8);
668  while (newalloc <= tranche_id)
669  newalloc *= 2;
670 
671  if (LWLockTrancheNames == NULL)
672  LWLockTrancheNames = (const char **)
674  newalloc * sizeof(char *));
675  else
676  {
677  LWLockTrancheNames = (const char **)
678  repalloc(LWLockTrancheNames, newalloc * sizeof(char *));
680  0,
681  (newalloc - LWLockTrancheNamesAllocated) * sizeof(char *));
682  }
683  LWLockTrancheNamesAllocated = newalloc;
684  }
685 
686  LWLockTrancheNames[tranche_id] = tranche_name;
687 }
static int LWLockTrancheNamesAllocated
Definition: lwlock.c:193
MemoryContext TopMemoryContext
Definition: mcxt.c:44
void * MemoryContextAllocZero(MemoryContext context, Size size)
Definition: mcxt.c:840
#define Max(x, y)
Definition: c.h:922
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1070
static const char ** LWLockTrancheNames
Definition: lwlock.c:192

◆ LWLockRelease()

void LWLockRelease ( LWLock lock)

Definition at line 1812 of file lwlock.c.

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

Referenced by _bt_end_vacuum(), _bt_start_vacuum(), _bt_vacuum_cycleid(), AbsorbSyncRequests(), ActivateCommitTs(), AdvanceNextFullTransactionIdPastXid(), AdvanceOldestClogXid(), AdvanceOldestCommitTsXid(), AdvanceXLInsertBuffer(), alloc_object(), AlterSystemSetConfigFile(), ApplyLauncherMain(), apw_detach_shmem(), apw_dump_now(), apw_init_shmem(), apw_load_buffers(), asyncQueueAddEntries(), asyncQueueAdvanceTail(), asyncQueueReadAllNotifications(), asyncQueueUnregister(), AtAbort_Twophase(), AtPrepare_PredicateLocks(), attach_internal(), autoprewarm_main(), autoprewarm_start_worker(), AutoVacLauncherMain(), AutoVacuumRequestWork(), AutoVacWorkerMain(), BackendIdGetProc(), BackendIdGetTransactionIds(), BackendPidGetProc(), BackendXidGetPid(), BecomeLockGroupLeader(), BecomeLockGroupMember(), BootStrapCLOG(), BootStrapMultiXact(), BootStrapSUBTRANS(), BufferAlloc(), CancelDBBackends(), CancelVirtualTransaction(), check_for_freed_segments(), CheckBuffer(), CheckDeadLock(), CheckForSerializableConflictOut(), CheckPointPredicate(), CheckPointRelationMap(), CheckPointReplicationOrigin(), CheckPointReplicationSlots(), CheckPointTwoPhase(), CheckRecoveryConsistency(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), choose_next_subplan_for_leader(), choose_next_subplan_for_worker(), CleanupInvalidationState(), ClearOldPredicateLocks(), clog_redo(), commit_ts_redo(), ComputeXidHorizons(), copy_replication_slot(), CountDBBackends(), CountDBConnections(), CountOtherDBBackends(), CountUserBackends(), CreateCheckPoint(), CreateEndOfRecoveryRecord(), CreateInitDecodingContext(), CreatePredicateLock(), CreateRestartPoint(), DeactivateCommitTs(), DeleteChildTargetLocks(), DeleteLockTarget(), destroy_superblock(), do_autovacuum(), do_pg_start_backup(), do_pg_stop_backup(), do_start_worker(), DropAllPredicateLocksFromTable(), DropSubscription(), DropTableSpace(), dsa_allocate_extended(), dsa_dump(), dsa_free(), 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(), dshash_release_lock(), dsm_attach(), dsm_create(), dsm_detach(), dsm_pin_segment(), dsm_unpin_segment(), ensure_active_superblock(), entry_reset(), Exec_ListenPreCommit(), ExecParallelHashMergeCounters(), ExecParallelHashPopChunkQueue(), ExecParallelHashTupleAlloc(), ExecParallelHashTuplePrealloc(), ExpireAllKnownAssignedTransactionIds(), ExpireOldKnownAssignedTransactionIds(), ExpireTreeKnownAssignedTransactionIds(), ExtendCLOG(), ExtendCommitTs(), ExtendMultiXactMember(), ExtendMultiXactOffset(), ExtendSUBTRANS(), FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), find_multixact_start(), FinishPreparedTransaction(), FlushDatabaseBuffers(), FlushRelationBuffers(), FlushRelationsAllBuffers(), ForceTransactionIdLimitUpdate(), ForwardSyncRequest(), FreeWorkerInfo(), get_xid_status(), GetBackgroundWorkerPid(), GetBackgroundWorkerTypeByPid(), GetBlockerStatusData(), GetConflictingVirtualXIDs(), GetCurrentVirtualXIDs(), GetLastImportantRecPtr(), GetLastSegSwitchData(), GetLatestCommitTsData(), GetLockConflicts(), GetLockStatusData(), GetMultiXactIdMembers(), GetNewMultiXactId(), GetNewObjectId(), GetNewTransactionId(), GetOldestActiveTransactionId(), GetOldestMultiXactId(), GetOldestRestartPoint(), GetOldestSafeDecodingTransactionId(), GetOldSnapshotFromTimeMapping(), GetOldSnapshotTimeMapping(), GetPredicateLockStatusData(), GetPreparedTransactionList(), GetRunningTransactionLocks(), GetSafeSnapshot(), GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), GetSnapshotData(), GetVirtualXIDsDelayingChkpt(), HandleAutoVacLauncherInterrupts(), HaveVirtualXIDsDelayingChkpt(), InstallXLogFileSegment(), InvalidateBuffer(), InvalidateObsoleteReplicationSlots(), KnownAssignedXidsAdd(), KnownAssignedXidsReset(), lock_twophase_recover(), LockAcquireExtended(), LockBuffer(), LockErrorCleanup(), LockGXact(), LockHasWaiters(), LockRefindAndRelease(), LockRelease(), LockReleaseAll(), LockWaiterCount(), logicalrep_worker_attach(), logicalrep_worker_detach(), logicalrep_worker_launch(), logicalrep_worker_stop(), logicalrep_worker_wakeup(), LogStandbySnapshot(), LWLockReleaseAll(), LWLockReleaseClearVar(), MaintainOldSnapshotTimeMapping(), MarkAsPrepared(), MarkAsPreparing(), MaybeExtendOffsetSlru(), multixact_redo(), MultiXactAdvanceNextMXact(), MultiXactGetCheckptMulti(), MultiXactIdSetOldestMember(), MultiXactIdSetOldestVisible(), MultiXactSetNextMXact(), OnConflict_CheckForSerializationFailure(), PageIsPredicateLocked(), perform_relmap_update(), pg_get_replication_slots(), pg_get_shmem_allocations(), pg_notification_queue_usage(), pg_show_replication_origin_status(), pg_stat_get_subscription(), pg_stat_statements_internal(), pg_xact_status(), pgss_shmem_startup(), pgss_store(), pgstat_reset_replslot_counter(), 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(), process_syncing_tables_for_apply(), ProcKill(), ProcSleep(), ReadMultiXactCounts(), ReadMultiXactIdRange(), ReadNextFullTransactionId(), ReadNextMultiXactId(), ReadRecord(), RecordNewMultiXact(), RecoverPreparedTransactions(), RegisterDynamicBackgroundWorker(), RegisterPredicateLockingXid(), RelationCacheInitFilePostInvalidate(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), RemoveScratchTarget(), ReplicationOriginExitCleanup(), ReplicationSlotAcquireInternal(), ReplicationSlotCleanup(), ReplicationSlotCreate(), ReplicationSlotDropPtr(), ReplicationSlotRelease(), ReplicationSlotsComputeLogicalRestartLSN(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotsCountDBSlots(), ReplicationSlotsDropDBSlots(), replorigin_advance(), replorigin_drop(), replorigin_get_progress(), replorigin_session_advance(), replorigin_session_get_progress(), replorigin_session_reset(), replorigin_session_setup(), resize(), RestoreScratchTarget(), restoreTwoPhaseData(), SaveSlotToPath(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), SerialSetActiveSerXmin(), SetCommitTsLimit(), SetMultiXactIdLimit(), SetOffsetVacuumLimit(), SetTransactionIdLimit(), SetXidCommitTsInPage(), SharedInvalBackendInit(), ShmemInitStruct(), SICleanupQueue(), SIGetDataEntries(), SignalBackends(), SIInsertDataEntries(), SimpleLruReadPage(), SimpleLruReadPage_ReadOnly(), SimpleLruTruncate(), SimpleLruWaitIO(), SimpleLruWriteAll(), SlruDeleteSegment(), SlruInternalWritePage(), SnapBuildInitialSnapshot(), ss_get_location(), ss_report_location(), StandbyRecoverPreparedTransactions(), StartBufferIO(), StartupCLOG(), StartupDecodingContext(), StartupSUBTRANS(), StartupXLOG(), sts_parallel_scan_next(), SubTransGetParent(), SubTransSetParent(), SummarizeOldestCommittedSxact(), SyncOneBuffer(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepReleaseWaiters(), SyncRepUpdateSyncStandbysDefined(), SyncRepWaitForLSN(), TablespaceCreateDbspace(), tbm_shared_iterate(), TerminateBackgroundWorker(), TerminateBufferIO(), TerminateOtherDBBackends(), TransactionGroupUpdateXidStatus(), TransactionIdGetCommitTsData(), TransactionIdGetStatus(), TransactionIdIsActive(), TransactionIdIsInProgress(), TransactionIdSetPageStatus(), TransactionTreeSetCommitTsData(), TransferPredicateLocksToNewTarget(), TrimCLOG(), TrimMultiXact(), TruncateMultiXact(), TwoPhaseGetGXact(), update_cached_xid_range(), UpdateMinRecoveryPoint(), vac_truncate_clog(), vacuum_rel(), VirtualXactLock(), VirtualXactLockTableCleanup(), VirtualXactLockTableInsert(), wait_for_relation_state_change(), wait_for_worker_state_change(), WaitForReplicationWorkerAttach(), WaitIO(), WaitOnLock(), write_relcache_init_file(), xact_redo(), XidCacheRemoveRunningXids(), xlog_redo(), XLogBackgroundFlush(), XLogFlush(), XLogNeedsFlush(), and XLogReportParameters().

1813 {
1814  LWLockMode mode;
1815  uint32 oldstate;
1816  bool check_waiters;
1817  int i;
1818 
1819  /*
1820  * Remove lock from list of locks held. Usually, but not always, it will
1821  * be the latest-acquired lock; so search array backwards.
1822  */
1823  for (i = num_held_lwlocks; --i >= 0;)
1824  if (lock == held_lwlocks[i].lock)
1825  break;
1826 
1827  if (i < 0)
1828  elog(ERROR, "lock %s is not held", T_NAME(lock));
1829 
1830  mode = held_lwlocks[i].mode;
1831 
1832  num_held_lwlocks--;
1833  for (; i < num_held_lwlocks; i++)
1834  held_lwlocks[i] = held_lwlocks[i + 1];
1835 
1836  PRINT_LWDEBUG("LWLockRelease", lock, mode);
1837 
1838  /*
1839  * Release my hold on lock, after that it can immediately be acquired by
1840  * others, even if we still have to wakeup other waiters.
1841  */
1842  if (mode == LW_EXCLUSIVE)
1843  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_EXCLUSIVE);
1844  else
1845  oldstate = pg_atomic_sub_fetch_u32(&lock->state, LW_VAL_SHARED);
1846 
1847  /* nobody else can have that kind of lock */
1848  Assert(!(oldstate & LW_VAL_EXCLUSIVE));
1849 
1850 
1851  /*
1852  * We're still waiting for backends to get scheduled, don't wake them up
1853  * again.
1854  */
1855  if ((oldstate & (LW_FLAG_HAS_WAITERS | LW_FLAG_RELEASE_OK)) ==
1857  (oldstate & LW_LOCK_MASK) == 0)
1858  check_waiters = true;
1859  else
1860  check_waiters = false;
1861 
1862  /*
1863  * As waking up waiters requires the spinlock to be acquired, only do so
1864  * if necessary.
1865  */
1866  if (check_waiters)
1867  {
1868  /* XXX: remove before commit? */
1869  LOG_LWDEBUG("LWLockRelease", lock, "releasing waiters");
1870  LWLockWakeup(lock);
1871  }
1872 
1873  TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
1874 
1875  /*
1876  * Now okay to allow cancel/die interrupts.
1877  */
1879 }
#define T_NAME(lock)
Definition: lwlock.c:248
static PgChecksumMode mode
Definition: pg_checksums.c:61
LWLockMode
Definition: lwlock.h:130
#define LW_FLAG_HAS_WAITERS
Definition: lwlock.c:99
static uint32 pg_atomic_sub_fetch_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:401
#define LW_LOCK_MASK
Definition: lwlock.c:106
#define LW_VAL_SHARED
Definition: lwlock.c:104
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:118
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
#define ERROR
Definition: elog.h:43
LWLockMode mode
Definition: lwlock.c:214
static void LWLockWakeup(LWLock *lock)
Definition: lwlock.c:962
unsigned int uint32
Definition: c.h:375
static int num_held_lwlocks
Definition: lwlock.c:217
#define Assert(condition)
Definition: c.h:746
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
#define elog(elevel,...)
Definition: elog.h:214
int i
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ LWLockReleaseAll()

void LWLockReleaseAll ( void  )

Definition at line 1911 of file lwlock.c.

References HOLD_INTERRUPTS, LWLockRelease(), and num_held_lwlocks.

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

1912 {
1913  while (num_held_lwlocks > 0)
1914  {
1915  HOLD_INTERRUPTS(); /* match the upcoming RESUME_INTERRUPTS */
1916 
1918  }
1919 }
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
static LWLockHandle held_lwlocks[MAX_SIMUL_LWLOCKS]
Definition: lwlock.c:218
static int num_held_lwlocks
Definition: lwlock.c:217
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:116

◆ LWLockReleaseClearVar()

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

Definition at line 1885 of file lwlock.c.

References LWLockRelease(), LWLockWaitListLock(), LWLockWaitListUnlock(), and val.

Referenced by WALInsertLockRelease().

1886 {
1887  LWLockWaitListLock(lock);
1888 
1889  /*
1890  * Set the variable's value before releasing the lock, that prevents race
1891  * a race condition wherein a new locker acquires the lock, but hasn't yet
1892  * set the variables value.
1893  */
1894  *valptr = val;
1895  LWLockWaitListUnlock(lock);
1896 
1897  LWLockRelease(lock);
1898 }
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:949
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1812
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:897
long val
Definition: informix.c:664

◆ LWLockShmemSize()

Size LWLockShmemSize ( void  )

Definition at line 435 of file lwlock.c.

References add_size(), i, lock_named_request_allowed, LWLOCK_PADDED_SIZE, mul_size(), NamedLWLockTrancheRequests, NUM_FIXED_LWLOCKS, and NumLWLocksForNamedTranches().

Referenced by CreateLWLocks(), and CreateSharedMemoryAndSemaphores().

436 {
437  Size size;
438  int i;
439  int numLocks = NUM_FIXED_LWLOCKS;
440 
441  /* Calculate total number of locks needed in the main array. */
442  numLocks += NumLWLocksForNamedTranches();
443 
444  /* Space for the LWLock array. */
445  size = mul_size(numLocks, sizeof(LWLockPadded));
446 
447  /* Space for dynamic allocation counter, plus room for alignment. */
448  size = add_size(size, sizeof(int) + LWLOCK_PADDED_SIZE);
449 
450  /* space for named tranches. */
452 
453  /* space for name of each tranche. */
454  for (i = 0; i < NamedLWLockTrancheRequests; i++)
455  size = add_size(size, strlen(NamedLWLockTrancheRequestArray[i].tranche_name) + 1);
456 
457  /* Disallow adding any more named tranches. */
459 
460  return size;
461 }
static bool lock_named_request_allowed
Definition: lwlock.c:241
#define NUM_FIXED_LWLOCKS
Definition: lwlock.h:127
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
static int NumLWLocksForNamedTranches(void)
Definition: lwlock.c:420
Size mul_size(Size s1, Size s2)
Definition: shmem.c:515
Size add_size(Size s1, Size s2)
Definition: shmem.c:498
size_t Size
Definition: c.h:474
static NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:227
int i
#define LWLOCK_PADDED_SIZE
Definition: lwlock.h:72

◆ LWLockUpdateVar()

void LWLockUpdateVar ( LWLock lock,
uint64 *  valptr,
uint64  value 
)

Definition at line 1758 of file lwlock.c.

References Assert, proclist_mutable_iter::cur, GetPGProcByNumber, LW_EXCLUSIVE, LW_VAL_EXCLUSIVE, LW_WAIT_UNTIL_FREE, LWLockWaitListLock(), LWLockWaitListUnlock(), PGPROC::lwWaiting, PGPROC::lwWaitMode, 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, and LWLock::waiters.

Referenced by WALInsertLockAcquireExclusive(), and WALInsertLockUpdateInsertingAt().

1759 {
1760  proclist_head wakeup;
1761  proclist_mutable_iter iter;
1762 
1763  PRINT_LWDEBUG("LWLockUpdateVar", lock, LW_EXCLUSIVE);
1764 
1765  proclist_init(&wakeup);
1766 
1767  LWLockWaitListLock(lock);
1768 
1770 
1771  /* Update the lock's value */
1772  *valptr = val;
1773 
1774  /*
1775  * See if there are any LW_WAIT_UNTIL_FREE waiters that need to be woken
1776  * up. They are always in the front of the queue.
1777  */
1778  proclist_foreach_modify(iter, &lock->waiters, lwWaitLink)
1779  {
1780  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1781 
1782  if (waiter->lwWaitMode != LW_WAIT_UNTIL_FREE)
1783  break;
1784 
1785  proclist_delete(&lock->waiters, iter.cur, lwWaitLink);
1786  proclist_push_tail(&wakeup, iter.cur, lwWaitLink);
1787  }
1788 
1789  /* We are done updating shared state of the lock itself. */
1790  LWLockWaitListUnlock(lock);
1791 
1792  /*
1793  * Awaken any waiters I removed from the queue.
1794  */
1795  proclist_foreach_modify(iter, &wakeup, lwWaitLink)
1796  {
1797  PGPROC *waiter = GetPGProcByNumber(iter.cur);
1798 
1799  proclist_delete(&wakeup, iter.cur, lwWaitLink);
1800  /* check comment in LWLockWakeup() about this barrier */
1801  pg_write_barrier();
1802  waiter->lwWaiting = false;
1803  PGSemaphoreUnlock(waiter->sem);
1804  }
1805 }
#define GetPGProcByNumber(n)
Definition: proc.h:355
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
proclist_head waiters
Definition: lwlock.h:35
bool lwWaiting
Definition: proc.h:161
static void LWLockWaitListUnlock(LWLock *lock)
Definition: lwlock.c:949
#define proclist_foreach_modify(iter, lhead, link_member)
Definition: proclist.h:206
uint8 lwWaitMode
Definition: proc.h:162
pg_atomic_uint32 state
Definition: lwlock.h:34
#define proclist_delete(list, procno, link_member)
Definition: proclist.h:187
#define Assert(condition)
Definition: c.h:746
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define proclist_push_tail(list, procno, link_member)
Definition: proclist.h:191
static void LWLockWaitListLock(LWLock *lock)
Definition: lwlock.c:897
#define LW_VAL_EXCLUSIVE
Definition: lwlock.c:103
static void proclist_init(proclist_head *list)
Definition: proclist.h:29
#define pg_write_barrier()
Definition: atomics.h:159
PGSemaphore sem
Definition: proc.h:118
Definition: proc.h:112
long val
Definition: informix.c:664
static uint32 pg_atomic_read_u32(volatile pg_atomic_uint32 *ptr)
Definition: atomics.h:241

◆ LWLockWaitForVar()

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

Definition at line 1619 of file lwlock.c.

References Assert, HOLD_INTERRUPTS, LOG_LWDEBUG, LW_EXCLUSIVE, LW_FLAG_RELEASE_OK, LW_WAIT_UNTIL_FREE, LWLockConflictsWithVar(), LWLockDequeueSelf(), LWLockQueueSelf(), LWLockReportWaitEnd(), LWLockReportWaitStart(), PGPROC::lwWaiting, MAX_BACKENDS, MyProc, pg_atomic_fetch_or_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().

1620 {
1621  PGPROC *proc = MyProc;
1622  int extraWaits = 0;
1623  bool result = false;
1624 #ifdef LWLOCK_STATS
1625  lwlock_stats *lwstats;
1626 
1627  lwstats = get_lwlock_stats_entry(lock);
1628 #endif
1629 
1630  PRINT_LWDEBUG("LWLockWaitForVar", lock, LW_WAIT_UNTIL_FREE);
1631 
1632  /*
1633  * Lock out cancel/die interrupts while we sleep on the lock. There is no
1634  * cleanup mechanism to remove us from the wait queue if we got
1635  * interrupted.
1636  */
1637  HOLD_INTERRUPTS();
1638 
1639  /*
1640  * Loop here to check the lock's status after each time we are signaled.
1641  */
1642  for (;;)
1643  {
1644  bool mustwait;
1645 
1646  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1647  &result);
1648 
1649  if (!mustwait)
1650  break; /* the lock was free or value didn't match */
1651 
1652  /*
1653  * Add myself to wait queue. Note that this is racy, somebody else
1654  * could wakeup before we're finished queuing. NB: We're using nearly
1655  * the same twice-in-a-row lock acquisition protocol as
1656  * LWLockAcquire(). Check its comments for details. The only
1657  * difference is that we also have to check the variable's values when
1658  * checking the state of the lock.
1659  */
1661 
1662  /*
1663  * Set RELEASE_OK flag, to make sure we get woken up as soon as the
1664  * lock is released.
1665  */
1667 
1668  /*
1669  * We're now guaranteed to be woken up if necessary. Recheck the lock
1670  * and variables state.
1671  */
1672  mustwait = LWLockConflictsWithVar(lock, valptr, oldval, newval,
1673  &result);
1674 
1675  /* Ok, no conflict after we queued ourselves. Undo queueing. */
1676  if (!mustwait)
1677  {
1678  LOG_LWDEBUG("LWLockWaitForVar", lock, "free, undoing queue");
1679 
1680  LWLockDequeueSelf(lock);
1681  break;
1682  }
1683 
1684  /*
1685  * Wait until awakened.
1686  *
1687  * Since we share the process wait semaphore with the regular lock
1688  * manager and ProcWaitForSignal, and we may need to acquire an LWLock
1689  * while one of those is pending, it is possible that we get awakened
1690  * for a reason other than being signaled by LWLockRelease. If so,
1691  * loop back and wait again. Once we've gotten the LWLock,
1692  * re-increment the sema by the number of additional signals received,
1693  * so that the lock manager or signal manager will see the received
1694  * signal when it next waits.
1695  */
1696  LOG_LWDEBUG("LWLockWaitForVar", lock, "waiting");
1697 
1698 #ifdef LWLOCK_STATS
1699  lwstats->block_count++;
1700 #endif
1701 
1702  LWLockReportWaitStart(lock);
1703  TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE);
1704 
1705  for (;;)
1706  {
1707  PGSemaphoreLock(proc->sem);
1708  if (!proc->lwWaiting)
1709  break;
1710  extraWaits++;
1711  }
1712 
1713 #ifdef LOCK_DEBUG
1714  {
1715  /* not waiting anymore */
1716  uint32 nwaiters PG_USED_FOR_ASSERTS_ONLY = pg_atomic_fetch_sub_u32(&lock->nwaiters, 1);
1717 
1718  Assert(nwaiters < MAX_BACKENDS);
1719  }
1720 #endif
1721 
1722  TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE);
1724 
1725  LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened");
1726 
1727  /* Now loop back and check the status of the lock again. */
1728  }
1729 
1730  TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), LW_EXCLUSIVE);
1731 
1732  /*
1733  * Fix the process wait semaphore's count for any absorbed wakeups.
1734  */
1735  while (extraWaits-- > 0)
1736  PGSemaphoreUnlock(proc->sem);
1737 
1738  /*
1739  * Now okay to allow cancel/die interrupts.
1740  */
1742 
1743  return result;
1744 }
#define T_NAME(lock)
Definition: lwlock.c:248
static uint32 pg_atomic_fetch_sub_u32(volatile pg_atomic_uint32 *ptr, int32 sub_)
Definition: atomics.h:343
void PGSemaphoreUnlock(PGSemaphore sema)
Definition: posix_sema.c:340
PGPROC * MyProc
Definition: proc.c:67
bool lwWaiting
Definition: proc.h:161
pg_atomic_uint32 state
Definition: lwlock.h:34
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:118
#define MAX_BACKENDS
Definition: postmaster.h:75
static void LWLockReportWaitEnd(void)
Definition: lwlock.c:772
unsigned int uint32
Definition: c.h:375
static void LWLockDequeueSelf(LWLock *lock)
Definition: lwlock.c:1113
static void LWLockReportWaitStart(LWLock *lock)
Definition: lwlock.c:763
static void LWLockQueueSelf(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1069
#define Assert(condition)
Definition: c.h:746
#define newval
#define PRINT_LWDEBUG(a, b, c)
Definition: lwlock.c:312
#define LW_FLAG_RELEASE_OK
Definition: lwlock.c:100
void PGSemaphoreLock(PGSemaphore sema)
Definition: posix_sema.c:320
static bool LWLockConflictsWithVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval, bool *result)
Definition: lwlock.c:1559
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:116
static uint32 pg_atomic_fetch_or_u32(volatile pg_atomic_uint32 *ptr, uint32 or_)
Definition: atomics.h:372
PGSemaphore sem
Definition: proc.h:118
Definition: proc.h:112
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:122
#define LOG_LWDEBUG(a, b, c)
Definition: lwlock.c:313

◆ RequestNamedLWLockTranche()

void RequestNamedLWLockTranche ( const char *  tranche_name,
int  num_lwlocks 
)

Definition at line 705 of file lwlock.c.

References Assert, i, IsUnderPostmaster, lock_named_request_allowed, MemoryContextAlloc(), NAMEDATALEN, NamedLWLockTrancheRequests, NamedLWLockTrancheRequestsAllocated, NamedLWLockTrancheRequest::num_lwlocks, repalloc(), strlcpy(), TopMemoryContext, and NamedLWLockTrancheRequest::tranche_name.

Referenced by _PG_init().

706 {
707  NamedLWLockTrancheRequest *request;
708 
710  return; /* too late */
711 
712  if (NamedLWLockTrancheRequestArray == NULL)
713  {
718  * sizeof(NamedLWLockTrancheRequest));
719  }
720 
722  {
724 
725  while (i <= NamedLWLockTrancheRequests)
726  i *= 2;
727 
730  i * sizeof(NamedLWLockTrancheRequest));
732  }
733 
735  Assert(strlen(tranche_name) + 1 <= NAMEDATALEN);
736  strlcpy(request->tranche_name, tranche_name, NAMEDATALEN);
737  request->num_lwlocks = num_lwlocks;
739 }
static bool lock_named_request_allowed
Definition: lwlock.c:241
char tranche_name[NAMEDATALEN]
Definition: lwlock.c:223
#define NAMEDATALEN
int NamedLWLockTrancheRequests
Definition: lwlock.c:236
bool IsUnderPostmaster
Definition: globals.c:109
MemoryContext TopMemoryContext
Definition: mcxt.c:44
static int NamedLWLockTrancheRequestsAllocated
Definition: lwlock.c:228
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
#define Assert(condition)
Definition: c.h:746
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1070
static NamedLWLockTrancheRequest * NamedLWLockTrancheRequestArray
Definition: lwlock.c:227
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:797
int i

Variable Documentation

◆ MainLWLockArray

PGDLLIMPORT LWLockPadded* MainLWLockArray

Definition at line 200 of file lwlock.c.

Referenced by PostmasterMarkPIDForWorkerNotify().

◆ NamedLWLockTrancheArray

PGDLLIMPORT NamedLWLockTranche* NamedLWLockTrancheArray

Definition at line 239 of file lwlock.c.

Referenced by PostmasterMarkPIDForWorkerNotify().

◆ NamedLWLockTrancheRequests