shmem.h File Reference

#include "utils/hsearch.h"

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Data Structures
struct	SHM_QUEUE
struct	ShmemIndexEnt

Macros
#define	SHMEM_INDEX_KEYSIZE   (48)
#define	SHMEM_INDEX_SIZE   (64)

Typedefs
typedef struct SHM_QUEUE	SHM_QUEUE

Functions
void	InitShmemAccess (void *seghdr)
void	InitShmemAllocation (void)
void *	ShmemAlloc (Size size)
void *	ShmemAllocNoError (Size size)
void *	ShmemAllocUnlocked (Size size)
bool	ShmemAddrIsValid (const void *addr)
void	InitShmemIndex (void)
HTAB *	ShmemInitHash (const char *name, long init_size, long max_size, HASHCTL *infoP, int hash_flags)
void *	ShmemInitStruct (const char *name, Size size, bool *foundPtr)
Size	add_size (Size s1, Size s2)
Size	mul_size (Size s1, Size s2)
void	RequestAddinShmemSpace (Size size)
void	SHMQueueInit (SHM_QUEUE *queue)
void	SHMQueueElemInit (SHM_QUEUE *queue)
void	SHMQueueDelete (SHM_QUEUE *queue)
void	SHMQueueInsertBefore (SHM_QUEUE *queue, SHM_QUEUE *elem)
void	SHMQueueInsertAfter (SHM_QUEUE *queue, SHM_QUEUE *elem)
Pointer	SHMQueueNext (const SHM_QUEUE *queue, const SHM_QUEUE *curElem, Size linkOffset)
Pointer	SHMQueuePrev (const SHM_QUEUE *queue, const SHM_QUEUE *curElem, Size linkOffset)
bool	SHMQueueEmpty (const SHM_QUEUE *queue)
bool	SHMQueueIsDetached (const SHM_QUEUE *queue)

Macro Definition Documentation

SHMEM_INDEX_KEYSIZE

#define SHMEM_INDEX_KEYSIZE   (48)

Definition at line 53 of file shmem.h.

Referenced by InitShmemIndex().

SHMEM_INDEX_SIZE

#define SHMEM_INDEX_SIZE   (64)

Definition at line 55 of file shmem.h.

Referenced by CreateSharedMemoryAndSemaphores(), and InitShmemIndex().

Typedef Documentation

SHM_QUEUE

typedef struct SHM_QUEUE SHM_QUEUE

Function Documentation

add_size()

Size add_size	(	Size	s1,
		Size	s2
	)

Definition at line 498 of file shmem.c.

References ereport, errcode(), errmsg(), ERROR, and s2.

Referenced by _bt_parallel_estimate_shared(), ApplyLauncherShmemSize(), AsyncShmemInit(), AsyncShmemSize(), AutoVacuumShmemSize(), BackendStatusShmemSize(), BackgroundWorkerShmemSize(), begin_parallel_vacuum(), BTreeShmemSize(), BufferShmemSize(), CheckpointerShmemSize(), CreateSharedMemoryAndSemaphores(), CreateSharedProcArray(), estimate_variable_size(), EstimateComboCIDStateSpace(), EstimateGUCStateSpace(), EstimateLibraryStateSpace(), EstimateParamExecSpace(), EstimateParamListSpace(), EstimateSnapshotSpace(), EstimateTransactionStateSpace(), ExecAppendEstimate(), ExecBitmapHeapEstimate(), ExecHashEstimate(), ExecSortEstimate(), expand_planner_arrays(), hash_estimate_size(), index_parallelscan_estimate(), index_parallelscan_initialize(), LockShmemSize(), LWLockShmemSize(), MultiXactShmemSize(), pgss_memsize(), PMSignalShmemSize(), PredicateLockShmemSize(), ProcArrayShmemSize(), ProcGlobalShmemSize(), ProcSignalShmemSize(), ReplicationOriginShmemSize(), ReplicationSlotsShmemSize(), RequestAddinShmemSpace(), SerializeTransactionState(), shm_toc_estimate(), SInvalShmemSize(), SnapMgrShmemSize(), StrategyShmemSize(), table_parallelscan_estimate(), tuplesort_estimate_shared(), TwoPhaseShmemSize(), WalRcvShmemSize(), WalSndShmemSize(), and XLOGShmemSize().

{
    Size        result;

    result = s1 + s2;
    /* We are assuming Size is an unsigned type here... */
    if (result < s1 || result < s2)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("requested shared memory size overflows size_t")));
    return result;
}

InitShmemAccess()

void InitShmemAccess

(

void *

seghdr

)

Definition at line 101 of file shmem.c.

References ShmemBase, ShmemEnd, and PGShmemHeader::totalsize.

Referenced by BackendRun(), and CreateSharedMemoryAndSemaphores().

{
    PGShmemHeader *shmhdr = (PGShmemHeader *) seghdr;

    ShmemSegHdr = shmhdr;
    ShmemBase = (void *) shmhdr;
    ShmemEnd = (char *) ShmemBase + shmhdr->totalsize;
}

InitShmemAllocation()

void InitShmemAllocation

(

void

)

Definition at line 116 of file shmem.c.

References Assert, CACHELINEALIGN, ShmemAlloc(), ShmemAllocUnlocked(), ShmemLock, ShmemSegHdr, ShmemVariableCache, and SpinLockInit.

Referenced by CreateSharedMemoryAndSemaphores().

{
    PGShmemHeader *shmhdr = ShmemSegHdr;
    char       *aligned;

    Assert(shmhdr != NULL);

    /*
     * Initialize the spinlock used by ShmemAlloc.  We must use
     * ShmemAllocUnlocked, since obviously ShmemAlloc can't be called yet.
     */
    ShmemLock = (slock_t *) ShmemAllocUnlocked(sizeof(slock_t));

    SpinLockInit(ShmemLock);

    /*
     * Allocations after this point should go through ShmemAlloc, which
     * expects to allocate everything on cache line boundaries.  Make sure the
     * first allocation begins on a cache line boundary.
     */
    aligned = (char *)
        (CACHELINEALIGN((((char *) shmhdr) + shmhdr->freeoffset)));
    shmhdr->freeoffset = aligned - (char *) shmhdr;

    /* ShmemIndex can't be set up yet (need LWLocks first) */
    shmhdr->index = NULL;
    ShmemIndex = (HTAB *) NULL;

    /*
     * Initialize ShmemVariableCache for transaction manager. (This doesn't
     * really belong here, but not worth moving.)
     */
    ShmemVariableCache = (VariableCache)
        ShmemAlloc(sizeof(*ShmemVariableCache));
    memset(ShmemVariableCache, 0, sizeof(*ShmemVariableCache));
}

InitShmemIndex()

void InitShmemIndex

(

void

)

Definition at line 292 of file shmem.c.

References HASHCTL::entrysize, HASH_ELEM, HASHCTL::keysize, SHMEM_INDEX_KEYSIZE, SHMEM_INDEX_SIZE, and ShmemInitHash().

Referenced by CreateSharedMemoryAndSemaphores().

{
    HASHCTL     info;
    int         hash_flags;

    /*
     * Create the shared memory shmem index.
     *
     * Since ShmemInitHash calls ShmemInitStruct, which expects the ShmemIndex
     * hashtable to exist already, we have a bit of a circularity problem in
     * initializing the ShmemIndex itself.  The special "ShmemIndex" hash
     * table name will tell ShmemInitStruct to fake it.
     */
    info.keysize = SHMEM_INDEX_KEYSIZE;
    info.entrysize = sizeof(ShmemIndexEnt);
    hash_flags = HASH_ELEM;

    ShmemIndex = ShmemInitHash("ShmemIndex",
                               SHMEM_INDEX_SIZE, SHMEM_INDEX_SIZE,
                               &info, hash_flags);
}

mul_size()

Size mul_size	(	Size	s1,
		Size	s2
	)

Definition at line 515 of file shmem.c.

References ereport, errcode(), errmsg(), ERROR, and s2.

Referenced by ApplyLauncherShmemSize(), AsyncShmemInit(), AsyncShmemSize(), AutoVacuumShmemSize(), BackendStatusShmemSize(), BackgroundWorkerShmemSize(), BTreeShmemSize(), BufferShmemSize(), CheckpointerShmemSize(), CreateSharedBackendStatus(), CreateSharedProcArray(), EstimateComboCIDStateSpace(), EstimateReindexStateSpace(), EstimateSnapshotSpace(), EstimateTransactionStateSpace(), ExecHashEstimate(), ExecInitParallelPlan(), ExecParallelRetrieveInstrumentation(), ExecParallelRetrieveJitInstrumentation(), ExecParallelSetupTupleQueues(), ExecSortEstimate(), hash_estimate_size(), InitializeParallelDSM(), InitPredicateLocks(), LWLockShmemSize(), PGSemaphoreShmemSize(), PMSignalShmemSize(), PostmasterMarkPIDForWorkerNotify(), PredicateLockShmemSize(), ProcArrayShmemSize(), ProcGlobalShmemSize(), ProcSignalShmemSize(), ReplicationOriginShmemSize(), ReplicationSlotsShmemSize(), shm_toc_estimate(), SInvalShmemSize(), SnapMgrShmemSize(), tuplesort_estimate_shared(), TwoPhaseShmemSize(), WalSndShmemSize(), and XLOGShmemSize().

{
    Size        result;

    if (s1 == 0 || s2 == 0)
        return 0;
    result = s1 * s2;
    /* We are assuming Size is an unsigned type here... */
    if (result / s2 != s1)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("requested shared memory size overflows size_t")));
    return result;
}

RequestAddinShmemSpace()

void RequestAddinShmemSpace

(

Size

size

)

Definition at line 70 of file ipci.c.

References add_size(), addin_request_allowed, IsUnderPostmaster, and total_addin_request.

Referenced by _PG_init().

{
    if (IsUnderPostmaster || !addin_request_allowed)
        return;                 /* too late */
    total_addin_request = add_size(total_addin_request, size);
}

ShmemAddrIsValid()

bool ShmemAddrIsValid

(

const void *

addr

)

Definition at line 283 of file shmem.c.

References ShmemBase, and ShmemEnd.

Referenced by NextPredXact(), ReleasePredXact(), ShmemInitStruct(), SHMQueueDelete(), SHMQueueElemInit(), SHMQueueEmpty(), SHMQueueInit(), SHMQueueInsertAfter(), SHMQueueInsertBefore(), SHMQueueIsDetached(), SHMQueueNext(), and SHMQueuePrev().

{
    return (addr >= ShmemBase) && (addr < ShmemEnd);
}

ShmemAlloc()

void* ShmemAlloc

(

Size

size

)

Definition at line 161 of file shmem.c.

References ereport, errcode(), errmsg(), ERROR, and ShmemAllocRaw().

Referenced by CreateLWLocks(), InitPredicateLocks(), InitProcGlobal(), InitShmemAllocation(), PostmasterMarkPIDForWorkerNotify(), and ShmemInitStruct().

{
    void       *newSpace;
    Size        allocated_size;

    newSpace = ShmemAllocRaw(size, &allocated_size);
    if (!newSpace)
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory (%zu bytes requested)",
                        size)));
    return newSpace;
}

ShmemAllocNoError()

void* ShmemAllocNoError

(

Size

size

)

Definition at line 181 of file shmem.c.

References ShmemAllocRaw().

Referenced by ShmemInitHash().

{
    Size        allocated_size;

    return ShmemAllocRaw(size, &allocated_size);
}

ShmemAllocUnlocked()

void* ShmemAllocUnlocked

(

Size

size

)

Definition at line 247 of file shmem.c.

References Assert, ereport, errcode(), errmsg(), ERROR, PGShmemHeader::freeoffset, MAXALIGN, ShmemBase, and PGShmemHeader::totalsize.

Referenced by InitShmemAllocation(), PGReserveSemaphores(), and SpinlockSemaInit().

{
    Size        newStart;
    Size        newFree;
    void       *newSpace;

    /*
     * Ensure allocated space is adequately aligned.
     */
    size = MAXALIGN(size);

    Assert(ShmemSegHdr != NULL);

    newStart = ShmemSegHdr->freeoffset;

    newFree = newStart + size;
    if (newFree > ShmemSegHdr->totalsize)
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory (%zu bytes requested)",
                        size)));
    ShmemSegHdr->freeoffset = newFree;

    newSpace = (void *) ((char *) ShmemBase + newStart);

    Assert(newSpace == (void *) MAXALIGN(newSpace));

    return newSpace;
}

ShmemInitHash()

HTAB* ShmemInitHash	(	const char *	name,
		long	init_size,
		long	max_size,
		HASHCTL *	infoP,
		int	hash_flags
	)

Definition at line 337 of file shmem.c.

References HASHCTL::alloc, HASHCTL::dsize, HASH_ALLOC, HASH_ATTACH, hash_create(), HASH_DIRSIZE, hash_get_shared_size(), hash_select_dirsize(), HASH_SHARED_MEM, HASHCTL::hctl, HASHCTL::max_dsize, ShmemAllocNoError(), and ShmemInitStruct().

Referenced by InitBufTable(), InitLocks(), InitPredicateLocks(), InitShmemIndex(), and pgss_shmem_startup().

{
    bool        found;
    void       *location;

    /*
     * Hash tables allocated in shared memory have a fixed directory; it can't
     * grow or other backends wouldn't be able to find it. So, make sure we
     * make it big enough to start with.
     *
     * The shared memory allocator must be specified too.
     */
    infoP->dsize = infoP->max_dsize = hash_select_dirsize(max_size);
    infoP->alloc = ShmemAllocNoError;
    hash_flags |= HASH_SHARED_MEM | HASH_ALLOC | HASH_DIRSIZE;

    /* look it up in the shmem index */
    location = ShmemInitStruct(name,
                               hash_get_shared_size(infoP, hash_flags),
                               &found);

    /*
     * if it already exists, attach to it rather than allocate and initialize
     * new space
     */
    if (found)
        hash_flags |= HASH_ATTACH;

    /* Pass location of hashtable header to hash_create */
    infoP->hctl = (HASHHDR *) location;

    return hash_create(name, init_size, infoP, hash_flags);
}

ShmemInitStruct()

void* ShmemInitStruct	(	const char *	name,
		Size	size,
		bool *	foundPtr
	)

Definition at line 392 of file shmem.c.

References ShmemIndexEnt::allocated_size, Assert, CACHELINEALIGN, ereport, errcode(), errmsg(), ERROR, HASH_ENTER_NULL, HASH_REMOVE, hash_search(), PGShmemHeader::index, IsUnderPostmaster, ShmemIndexEnt::location, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), ShmemAddrIsValid(), ShmemAlloc(), ShmemAllocRaw(), ShmemSegHdr, and ShmemIndexEnt::size.

Referenced by ApplyLauncherShmemInit(), apw_init_shmem(), AsyncShmemInit(), AutoVacuumShmemInit(), AuxiliaryPidGetProc(), BackgroundWorkerShmemInit(), BTreeShmemInit(), CheckpointerShmemInit(), CommitTsShmemInit(), CreateSharedBackendStatus(), CreateSharedInvalidationState(), CreateSharedProcArray(), InitBufferPool(), InitLocks(), InitPredicateLocks(), InitProcGlobal(), MultiXactShmemInit(), OldSerXidInit(), pgss_shmem_startup(), PMSignalShmemInit(), ProcSignalShmemInit(), ReplicationOriginShmemInit(), ReplicationSlotsShmemInit(), ShmemInitHash(), SimpleLruInit(), SnapMgrInit(), StrategyInitialize(), SyncScanShmemInit(), TwoPhaseShmemInit(), WalRcvShmemInit(), WalSndShmemInit(), and XLOGShmemInit().

{
    ShmemIndexEnt *result;
    void       *structPtr;

    LWLockAcquire(ShmemIndexLock, LW_EXCLUSIVE);

    if (!ShmemIndex)
    {
        PGShmemHeader *shmemseghdr = ShmemSegHdr;

        /* Must be trying to create/attach to ShmemIndex itself */
        Assert(strcmp(name, "ShmemIndex") == 0);

        if (IsUnderPostmaster)
        {
            /* Must be initializing a (non-standalone) backend */
            Assert(shmemseghdr->index != NULL);
            structPtr = shmemseghdr->index;
            *foundPtr = true;
        }
        else
        {
            /*
             * If the shmem index doesn't exist, we are bootstrapping: we must
             * be trying to init the shmem index itself.
             *
             * Notice that the ShmemIndexLock is released before the shmem
             * index has been initialized.  This should be OK because no other
             * process can be accessing shared memory yet.
             */
            Assert(shmemseghdr->index == NULL);
            structPtr = ShmemAlloc(size);
            shmemseghdr->index = structPtr;
            *foundPtr = false;
        }
        LWLockRelease(ShmemIndexLock);
        return structPtr;
    }

    /* look it up in the shmem index */
    result = (ShmemIndexEnt *)
        hash_search(ShmemIndex, name, HASH_ENTER_NULL, foundPtr);

    if (!result)
    {
        LWLockRelease(ShmemIndexLock);
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("could not create ShmemIndex entry for data structure \"%s\"",
                        name)));
    }

    if (*foundPtr)
    {
        /*
         * Structure is in the shmem index so someone else has allocated it
         * already.  The size better be the same as the size we are trying to
         * initialize to, or there is a name conflict (or worse).
         */
        if (result->size != size)
        {
            LWLockRelease(ShmemIndexLock);
            ereport(ERROR,
                    (errmsg("ShmemIndex entry size is wrong for data structure"
                            " \"%s\": expected %zu, actual %zu",
                            name, size, result->size)));
        }
        structPtr = result->location;
    }
    else
    {
        Size    allocated_size;

        /* It isn't in the table yet. allocate and initialize it */
        structPtr = ShmemAllocRaw(size, &allocated_size);
        if (structPtr == NULL)
        {
            /* out of memory; remove the failed ShmemIndex entry */
            hash_search(ShmemIndex, name, HASH_REMOVE, NULL);
            LWLockRelease(ShmemIndexLock);
            ereport(ERROR,
                    (errcode(ERRCODE_OUT_OF_MEMORY),
                     errmsg("not enough shared memory for data structure"
                            " \"%s\" (%zu bytes requested)",
                            name, size)));
        }
        result->size = size;
        result->allocated_size = allocated_size;
        result->location = structPtr;
    }

    LWLockRelease(ShmemIndexLock);

    Assert(ShmemAddrIsValid(structPtr));

    Assert(structPtr == (void *) CACHELINEALIGN(structPtr));

    return structPtr;
}

SHMQueueDelete()

void SHMQueueDelete

(

SHM_QUEUE *

queue

)

Definition at line 68 of file shmqueue.c.

References Assert, SHM_QUEUE::next, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by CheckTargetForConflictsIn(), CleanUpLock(), ClearOldPredicateLocks(), CreatePredXact(), DeleteChildTargetLocks(), DeleteLockTarget(), DropAllPredicateLocksFromTable(), LockAcquireExtended(), PostPrepare_Locks(), ProcWakeup(), ReleaseOneSerializableXact(), ReleasePredXact(), ReleaseRWConflict(), RemoveFromWaitQueue(), SetPossibleUnsafeConflict(), SetRWConflict(), SummarizeOldestCommittedSxact(), SyncRepCancelWait(), SyncRepCleanupAtProcExit(), SyncRepWakeQueue(), and TransferPredicateLocksToNewTarget().

{
    SHM_QUEUE  *nextElem = queue->next;
    SHM_QUEUE  *prevElem = queue->prev;

    Assert(ShmemAddrIsValid(queue));
    Assert(ShmemAddrIsValid(nextElem));
    Assert(ShmemAddrIsValid(prevElem));

    prevElem->next = queue->next;
    nextElem->prev = queue->prev;

    queue->prev = queue->next = NULL;
}

SHMQueueElemInit()

void SHMQueueElemInit

(

SHM_QUEUE *

queue

)

Definition at line 57 of file shmqueue.c.

References Assert, SHM_QUEUE::next, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by GetSerializableTransactionSnapshotInt(), InitAuxiliaryProcess(), InitProcess(), MarkAsPreparingGuts(), and predicatelock_twophase_recover().

{
    Assert(ShmemAddrIsValid(queue));
    queue->prev = queue->next = NULL;
}

SHMQueueEmpty()

bool SHMQueueEmpty

(

const SHM_QUEUE *

queue

)

Definition at line 180 of file shmqueue.c.

References Assert, SHM_QUEUE::next, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by CheckForSerializableConflictOut(), CleanUpLock(), GetSafeSnapshot(), InitAuxiliaryProcess(), InitProcess(), lock_twophase_recover(), ProcKill(), ReleasePredicateLocks(), RemoveTargetIfNoLongerUsed(), RWConflictExists(), SetupLockInTable(), SummarizeOldestCommittedSxact(), and TransferPredicateLocksToNewTarget().

{
    Assert(ShmemAddrIsValid(queue));

    if (queue->prev == queue)
    {
        Assert(queue->next == queue);
        return true;
    }
    return false;
}

SHMQueueInit()

void SHMQueueInit

(

SHM_QUEUE *

queue

)

Definition at line 36 of file shmqueue.c.

References Assert, SHM_QUEUE::next, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by CreatePredicateLock(), DropAllPredicateLocksFromTable(), GetSerializableTransactionSnapshotInt(), InitPredicateLocks(), InitProcGlobal(), lock_twophase_recover(), MarkAsPreparingGuts(), predicatelock_twophase_recover(), ProcQueueInit(), ReleaseOneSerializableXact(), SetupLockInTable(), TransferPredicateLocksToNewTarget(), and WalSndShmemInit().

{
    Assert(ShmemAddrIsValid(queue));
    queue->prev = queue->next = queue;
}

SHMQueueInsertAfter()

void SHMQueueInsertAfter	(	SHM_QUEUE *	queue,
		SHM_QUEUE *	elem
	)

Definition at line 108 of file shmqueue.c.

References Assert, SHM_QUEUE::next, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by SyncRepQueueInsert().

{
    SHM_QUEUE  *nextPtr = queue->next;

    Assert(ShmemAddrIsValid(queue));
    Assert(ShmemAddrIsValid(elem));

    elem->prev = nextPtr->prev;
    elem->next = queue->next;
    queue->next = elem;
    nextPtr->prev = elem;
}

SHMQueueInsertBefore()

void SHMQueueInsertBefore	(	SHM_QUEUE *	queue,
		SHM_QUEUE *	elem
	)

Definition at line 89 of file shmqueue.c.

References Assert, SHM_QUEUE::next, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by CreatePredicateLock(), CreatePredXact(), DeadLockCheck(), DropAllPredicateLocksFromTable(), InitPredicateLocks(), lock_twophase_recover(), PostPrepare_Locks(), ProcSleep(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), ReleasePredXact(), ReleaseRWConflict(), SetPossibleUnsafeConflict(), SetRWConflict(), SetupLockInTable(), and TransferPredicateLocksToNewTarget().

{
    SHM_QUEUE  *prevPtr = queue->prev;

    Assert(ShmemAddrIsValid(queue));
    Assert(ShmemAddrIsValid(elem));

    elem->next = prevPtr->next;
    elem->prev = queue->prev;
    queue->prev = elem;
    prevPtr->next = elem;
}

SHMQueueIsDetached()

bool SHMQueueIsDetached

(

const SHM_QUEUE *

queue

)

Definition at line 47 of file shmqueue.c.

References Assert, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by SyncRepCancelWait(), SyncRepCleanupAtProcExit(), and SyncRepWaitForLSN().

{
    Assert(ShmemAddrIsValid(queue));
    return (queue->prev == NULL);
}

SHMQueueNext()

Pointer SHMQueueNext	(	const SHM_QUEUE *	queue,
		const SHM_QUEUE *	curElem,
		Size	linkOffset
	)

Definition at line 145 of file shmqueue.c.

References Assert, SHM_QUEUE::next, and ShmemAddrIsValid().

Referenced by AtPrepare_PredicateLocks(), CheckTableForSerializableConflictIn(), CheckTargetForConflictsIn(), ClearOldPredicateLocks(), CreatePredXact(), DeleteChildTargetLocks(), DeleteLockTarget(), DropAllPredicateLocksFromTable(), FindLockCycleRecurseMember(), FirstPredXact(), FlagSxactUnsafe(), GetLockConflicts(), GetLockmodeName(), GetSafeSnapshotBlockingPids(), GetSingleProcBlockerStatusData(), LockCheckConflicts(), LockReleaseAll(), NextPredXact(), OnConflict_CheckForSerializationFailure(), PostPrepare_Locks(), PreCommit_CheckForSerializationFailure(), ProcSleep(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), RWConflictExists(), SetPossibleUnsafeConflict(), SetRWConflict(), SummarizeOldestCommittedSxact(), SyncRepUpdateSyncStandbysDefined(), SyncRepWakeQueue(), and TransferPredicateLocksToNewTarget().

{
    SHM_QUEUE  *elemPtr = curElem->next;

    Assert(ShmemAddrIsValid(curElem));

    if (elemPtr == queue)       /* back to the queue head? */
        return NULL;

    return (Pointer) (((char *) elemPtr) - linkOffset);
}

SHMQueuePrev()

Pointer SHMQueuePrev	(	const SHM_QUEUE *	queue,
		const SHM_QUEUE *	curElem,
		Size	linkOffset
	)

Definition at line 164 of file shmqueue.c.

References Assert, SHM_QUEUE::prev, and ShmemAddrIsValid().

Referenced by SyncRepQueueInsert().

{
    SHM_QUEUE  *elemPtr = curElem->prev;

    Assert(ShmemAddrIsValid(curElem));

    if (elemPtr == queue)       /* back to the queue head? */
        return NULL;

    return (Pointer) (((char *) elemPtr) - linkOffset);
}