predicate.c File Reference

#include "postgres.h"
#include "access/parallel.h"
#include "access/slru.h"
#include "access/subtrans.h"
#include "access/transam.h"
#include "access/twophase.h"
#include "access/twophase_rmgr.h"
#include "access/xact.h"
#include "access/xlog.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/bufmgr.h"
#include "storage/predicate.h"
#include "storage/predicate_internals.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"

Include dependency graph for predicate.c:

Go to the source code of this file.

Data Structures
struct	SerialControlData

Macros
#define	TargetTagIsCoveredBy(covered_target, covering_target)
#define	PredicateLockHashPartition(hashcode)   ((hashcode) % NUM_PREDICATELOCK_PARTITIONS)
#define	PredicateLockHashPartitionLock(hashcode)
#define	PredicateLockHashPartitionLockByIndex(i)   (&MainLWLockArray[PREDICATELOCK_MANAGER_LWLOCK_OFFSET + (i)].lock)
#define	NPREDICATELOCKTARGETENTS()   mul_size(max_predicate_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
#define	SxactIsOnFinishedList(sxact)   (!SHMQueueIsDetached(&((sxact)->finishedLink)))
#define	SxactIsCommitted(sxact)   (((sxact)->flags & SXACT_FLAG_COMMITTED) != 0)
#define	SxactIsPrepared(sxact)   (((sxact)->flags & SXACT_FLAG_PREPARED) != 0)
#define	SxactIsRolledBack(sxact)   (((sxact)->flags & SXACT_FLAG_ROLLED_BACK) != 0)
#define	SxactIsDoomed(sxact)   (((sxact)->flags & SXACT_FLAG_DOOMED) != 0)
#define	SxactIsReadOnly(sxact)   (((sxact)->flags & SXACT_FLAG_READ_ONLY) != 0)
#define	SxactHasSummaryConflictIn(sxact)   (((sxact)->flags & SXACT_FLAG_SUMMARY_CONFLICT_IN) != 0)
#define	SxactHasSummaryConflictOut(sxact)   (((sxact)->flags & SXACT_FLAG_SUMMARY_CONFLICT_OUT) != 0)
#define	SxactHasConflictOut(sxact)   (((sxact)->flags & SXACT_FLAG_CONFLICT_OUT) != 0)
#define	SxactIsDeferrableWaiting(sxact)   (((sxact)->flags & SXACT_FLAG_DEFERRABLE_WAITING) != 0)
#define	SxactIsROSafe(sxact)   (((sxact)->flags & SXACT_FLAG_RO_SAFE) != 0)
#define	SxactIsROUnsafe(sxact)   (((sxact)->flags & SXACT_FLAG_RO_UNSAFE) != 0)
#define	SxactIsPartiallyReleased(sxact)   (((sxact)->flags & SXACT_FLAG_PARTIALLY_RELEASED) != 0)
#define	PredicateLockTargetTagHashCode(predicatelocktargettag)   get_hash_value(PredicateLockTargetHash, predicatelocktargettag)
#define	PredicateLockHashCodeFromTargetHashCode(predicatelocktag, targethash)
#define	SerialSlruCtl   (&SerialSlruCtlData)
#define	SERIAL_PAGESIZE   BLCKSZ
#define	SERIAL_ENTRYSIZE   sizeof(SerCommitSeqNo)
#define	SERIAL_ENTRIESPERPAGE   (SERIAL_PAGESIZE / SERIAL_ENTRYSIZE)
#define	SERIAL_MAX_PAGE   (MaxTransactionId / SERIAL_ENTRIESPERPAGE)
#define	SerialNextPage(page)   (((page) >= SERIAL_MAX_PAGE) ? 0 : (page) + 1)
#define	SerialValue(slotno, xid)
#define	SerialPage(xid)   (((uint32) (xid)) / SERIAL_ENTRIESPERPAGE)

Typedefs
typedef struct SerialControlData	SerialControlData
typedef struct SerialControlData *	SerialControl

Functions
static SERIALIZABLEXACT *	CreatePredXact (void)
static void	ReleasePredXact (SERIALIZABLEXACT *sxact)
static SERIALIZABLEXACT *	FirstPredXact (void)
static SERIALIZABLEXACT *	NextPredXact (SERIALIZABLEXACT *sxact)
static bool	RWConflictExists (const SERIALIZABLEXACT *reader, const SERIALIZABLEXACT *writer)
static void	SetRWConflict (SERIALIZABLEXACT *reader, SERIALIZABLEXACT *writer)
static void	SetPossibleUnsafeConflict (SERIALIZABLEXACT *roXact, SERIALIZABLEXACT *activeXact)
static void	ReleaseRWConflict (RWConflict conflict)
static void	FlagSxactUnsafe (SERIALIZABLEXACT *sxact)
static bool	SerialPagePrecedesLogically (int page1, int page2)
static void	SerialInit (void)
static void	SerialAdd (TransactionId xid, SerCommitSeqNo minConflictCommitSeqNo)
static SerCommitSeqNo	SerialGetMinConflictCommitSeqNo (TransactionId xid)
static void	SerialSetActiveSerXmin (TransactionId xid)
static uint32	predicatelock_hash (const void *key, Size keysize)
static void	SummarizeOldestCommittedSxact (void)
static Snapshot	GetSafeSnapshot (Snapshot snapshot)
static Snapshot	GetSerializableTransactionSnapshotInt (Snapshot snapshot, VirtualTransactionId *sourcevxid, int sourcepid)
static bool	PredicateLockExists (const PREDICATELOCKTARGETTAG *targettag)
static bool	GetParentPredicateLockTag (const PREDICATELOCKTARGETTAG *tag, PREDICATELOCKTARGETTAG *parent)
static bool	CoarserLockCovers (const PREDICATELOCKTARGETTAG *newtargettag)
static void	RemoveScratchTarget (bool lockheld)
static void	RestoreScratchTarget (bool lockheld)
static void	RemoveTargetIfNoLongerUsed (PREDICATELOCKTARGET *target, uint32 targettaghash)
static void	DeleteChildTargetLocks (const PREDICATELOCKTARGETTAG *newtargettag)
static int	MaxPredicateChildLocks (const PREDICATELOCKTARGETTAG *tag)
static bool	CheckAndPromotePredicateLockRequest (const PREDICATELOCKTARGETTAG *reqtag)
static void	DecrementParentLocks (const PREDICATELOCKTARGETTAG *targettag)
static void	CreatePredicateLock (const PREDICATELOCKTARGETTAG *targettag, uint32 targettaghash, SERIALIZABLEXACT *sxact)
static void	DeleteLockTarget (PREDICATELOCKTARGET *target, uint32 targettaghash)
static bool	TransferPredicateLocksToNewTarget (PREDICATELOCKTARGETTAG oldtargettag, PREDICATELOCKTARGETTAG newtargettag, bool removeOld)
static void	PredicateLockAcquire (const PREDICATELOCKTARGETTAG *targettag)
static void	DropAllPredicateLocksFromTable (Relation relation, bool transfer)
static void	SetNewSxactGlobalXmin (void)
static void	ClearOldPredicateLocks (void)
static void	ReleaseOneSerializableXact (SERIALIZABLEXACT *sxact, bool partial, bool summarize)
static bool	XidIsConcurrent (TransactionId xid)
static void	CheckTargetForConflictsIn (PREDICATELOCKTARGETTAG *targettag)
static void	FlagRWConflict (SERIALIZABLEXACT *reader, SERIALIZABLEXACT *writer)
static void	OnConflict_CheckForSerializationFailure (const SERIALIZABLEXACT *reader, SERIALIZABLEXACT *writer)
static void	CreateLocalPredicateLockHash (void)
static void	ReleasePredicateLocksLocal (void)
static bool	PredicateLockingNeededForRelation (Relation relation)
static bool	SerializationNeededForRead (Relation relation, Snapshot snapshot)
static bool	SerializationNeededForWrite (Relation relation)
void	CheckPointPredicate (void)
void	InitPredicateLocks (void)
Size	PredicateLockShmemSize (void)
PredicateLockData *	GetPredicateLockStatusData (void)
int	GetSafeSnapshotBlockingPids (int blocked_pid, int *output, int output_size)
Snapshot	GetSerializableTransactionSnapshot (Snapshot snapshot)
void	SetSerializableTransactionSnapshot (Snapshot snapshot, VirtualTransactionId *sourcevxid, int sourcepid)
void	RegisterPredicateLockingXid (TransactionId xid)
bool	PageIsPredicateLocked (Relation relation, BlockNumber blkno)
void	PredicateLockRelation (Relation relation, Snapshot snapshot)
void	PredicateLockPage (Relation relation, BlockNumber blkno, Snapshot snapshot)
void	PredicateLockTID (Relation relation, ItemPointer tid, Snapshot snapshot, TransactionId tuple_xid)
void	TransferPredicateLocksToHeapRelation (Relation relation)
void	PredicateLockPageSplit (Relation relation, BlockNumber oldblkno, BlockNumber newblkno)
void	PredicateLockPageCombine (Relation relation, BlockNumber oldblkno, BlockNumber newblkno)
void	ReleasePredicateLocks (bool isCommit, bool isReadOnlySafe)
bool	CheckForSerializableConflictOutNeeded (Relation relation, Snapshot snapshot)
void	CheckForSerializableConflictOut (Relation relation, TransactionId xid, Snapshot snapshot)
void	CheckForSerializableConflictIn (Relation relation, ItemPointer tid, BlockNumber blkno)
void	CheckTableForSerializableConflictIn (Relation relation)
void	PreCommit_CheckForSerializationFailure (void)
void	AtPrepare_PredicateLocks (void)
void	PostPrepare_PredicateLocks (TransactionId xid)
void	PredicateLockTwoPhaseFinish (TransactionId xid, bool isCommit)
void	predicatelock_twophase_recover (TransactionId xid, uint16 info, void *recdata, uint32 len)
SerializableXactHandle	ShareSerializableXact (void)
void	AttachSerializableXact (SerializableXactHandle handle)

Variables
static SlruCtlData	SerialSlruCtlData
static SerialControl	serialControl
static SERIALIZABLEXACT *	OldCommittedSxact
int	max_predicate_locks_per_xact
int	max_predicate_locks_per_relation
int	max_predicate_locks_per_page
static PredXactList	PredXact
static RWConflictPoolHeader	RWConflictPool
static HTAB *	SerializableXidHash
static HTAB *	PredicateLockTargetHash
static HTAB *	PredicateLockHash
static SHM_QUEUE *	FinishedSerializableTransactions
static const PREDICATELOCKTARGETTAG	ScratchTargetTag = {0, 0, 0, 0}
static uint32	ScratchTargetTagHash
static LWLock *	ScratchPartitionLock
static HTAB *	LocalPredicateLockHash = NULL
static SERIALIZABLEXACT *	MySerializableXact = InvalidSerializableXact
static bool	MyXactDidWrite = false
static SERIALIZABLEXACT *	SavedSerializableXact = InvalidSerializableXact

Macro Definition Documentation

NPREDICATELOCKTARGETENTS

#define NPREDICATELOCKTARGETENTS

(

)

mul_size(max_predicate_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))

Definition at line 259 of file predicate.c.

Referenced by InitPredicateLocks(), and PredicateLockShmemSize().

PredicateLockHashCodeFromTargetHashCode

#define PredicateLockHashCodeFromTargetHashCode	(		predicatelocktag,
			targethash
	)

Value:

((targethash) ^ ((uint32) PointerGetDatum((predicatelocktag)->myXact)) \
     << LOG2_NUM_PREDICATELOCK_PARTITIONS)

Definition at line 311 of file predicate.c.

Referenced by CheckTargetForConflictsIn(), ClearOldPredicateLocks(), CreatePredicateLock(), DeleteChildTargetLocks(), DeleteLockTarget(), DropAllPredicateLocksFromTable(), predicatelock_hash(), ReleaseOneSerializableXact(), and TransferPredicateLocksToNewTarget().

PredicateLockHashPartition

#define PredicateLockHashPartition

(

hashcode

)

((hashcode) % NUM_PREDICATELOCK_PARTITIONS)

Definition at line 251 of file predicate.c.

PredicateLockHashPartitionLock

#define PredicateLockHashPartitionLock

(

hashcode

)

Value:

(&MainLWLockArray[PREDICATELOCK_MANAGER_LWLOCK_OFFSET + \
        PredicateLockHashPartition(hashcode)].lock)

Definition at line 253 of file predicate.c.

Referenced by CheckTargetForConflictsIn(), ClearOldPredicateLocks(), CreatePredicateLock(), DeleteChildTargetLocks(), DeleteLockTarget(), InitPredicateLocks(), PageIsPredicateLocked(), ReleaseOneSerializableXact(), and TransferPredicateLocksToNewTarget().

PredicateLockHashPartitionLockByIndex

#define PredicateLockHashPartitionLockByIndex

(

i

)

(&MainLWLockArray[PREDICATELOCK_MANAGER_LWLOCK_OFFSET + (i)].lock)

Definition at line 256 of file predicate.c.

Referenced by CheckTableForSerializableConflictIn(), DropAllPredicateLocksFromTable(), and GetPredicateLockStatusData().

PredicateLockTargetTagHashCode

#define PredicateLockTargetTagHashCode

(

predicatelocktargettag

)

get_hash_value(PredicateLockTargetHash, predicatelocktargettag)

Definition at line 298 of file predicate.c.

Referenced by CheckTargetForConflictsIn(), ClearOldPredicateLocks(), DecrementParentLocks(), DeleteChildTargetLocks(), DropAllPredicateLocksFromTable(), InitPredicateLocks(), PageIsPredicateLocked(), predicatelock_hash(), predicatelock_twophase_recover(), PredicateLockAcquire(), ReleaseOneSerializableXact(), and TransferPredicateLocksToNewTarget().

SERIAL_ENTRIESPERPAGE

#define SERIAL_ENTRIESPERPAGE   (SERIAL_PAGESIZE / SERIAL_ENTRYSIZE)

Definition at line 325 of file predicate.c.

Referenced by SerialInit(), and SerialPagePrecedesLogically().

SERIAL_ENTRYSIZE

#define SERIAL_ENTRYSIZE   sizeof(SerCommitSeqNo)

Definition at line 324 of file predicate.c.

SERIAL_MAX_PAGE

#define SERIAL_MAX_PAGE   (MaxTransactionId / SERIAL_ENTRIESPERPAGE)

Definition at line 330 of file predicate.c.

SERIAL_PAGESIZE

#define SERIAL_PAGESIZE   BLCKSZ

Definition at line 323 of file predicate.c.

SerialNextPage

#define SerialNextPage

(

page

)

(((page) >= SERIAL_MAX_PAGE) ? 0 : (page) + 1)

Definition at line 332 of file predicate.c.

Referenced by SerialAdd().

SerialPage

#define SerialPage

(

xid

)

(((uint32) (xid)) / SERIAL_ENTRIESPERPAGE)

Definition at line 338 of file predicate.c.

Referenced by CheckPointPredicate(), SerialAdd(), and SerialGetMinConflictCommitSeqNo().

SerialSlruCtl

#define SerialSlruCtl   (&SerialSlruCtlData)

Definition at line 321 of file predicate.c.

Referenced by CheckPointPredicate(), SerialAdd(), SerialGetMinConflictCommitSeqNo(), and SerialInit().

SerialValue

#define SerialValue	(		slotno,
			xid
	)

Value:

(*((SerCommitSeqNo *) \
    (SerialSlruCtl->shared->page_buffer[slotno] + \
    ((((uint32) (xid)) % SERIAL_ENTRIESPERPAGE) * SERIAL_ENTRYSIZE))))

Definition at line 334 of file predicate.c.

Referenced by SerialAdd(), and SerialGetMinConflictCommitSeqNo().

SxactHasConflictOut

#define SxactHasConflictOut

(

sxact

)

(((sxact)->flags & SXACT_FLAG_CONFLICT_OUT) != 0)

Definition at line 284 of file predicate.c.

Referenced by CheckForSerializableConflictOut(), OnConflict_CheckForSerializationFailure(), ReleasePredicateLocks(), and SummarizeOldestCommittedSxact().

SxactHasSummaryConflictIn

#define SxactHasSummaryConflictIn

(

sxact

)

(((sxact)->flags & SXACT_FLAG_SUMMARY_CONFLICT_IN) != 0)

Definition at line 277 of file predicate.c.

Referenced by CheckForSerializableConflictOut(), and OnConflict_CheckForSerializationFailure().

SxactHasSummaryConflictOut

#define SxactHasSummaryConflictOut

(

sxact

)

(((sxact)->flags & SXACT_FLAG_SUMMARY_CONFLICT_OUT) != 0)

Definition at line 278 of file predicate.c.

Referenced by CheckForSerializableConflictOut(), OnConflict_CheckForSerializationFailure(), and ReleasePredicateLocks().

SxactIsCommitted

#define SxactIsCommitted

(

sxact

)

(((sxact)->flags & SXACT_FLAG_COMMITTED) != 0)

Definition at line 272 of file predicate.c.

Referenced by CheckForSerializableConflictOut(), CheckTargetForConflictsIn(), GetSerializableTransactionSnapshotInt(), OnConflict_CheckForSerializationFailure(), PreCommit_CheckForSerializationFailure(), ReleaseOneSerializableXact(), ReleasePredicateLocks(), and SetNewSxactGlobalXmin().

SxactIsDeferrableWaiting

#define SxactIsDeferrableWaiting

(

sxact

)

(((sxact)->flags & SXACT_FLAG_DEFERRABLE_WAITING) != 0)

Definition at line 285 of file predicate.c.

Referenced by GetSafeSnapshotBlockingPids(), and ReleasePredicateLocks().

SxactIsDoomed

#define SxactIsDoomed

(

sxact

)

(((sxact)->flags & SXACT_FLAG_DOOMED) != 0)

Definition at line 275 of file predicate.c.

Referenced by CheckForSerializableConflictIn(), CheckForSerializableConflictOut(), CheckForSerializableConflictOutNeeded(), CheckTargetForConflictsIn(), GetSerializableTransactionSnapshotInt(), OnConflict_CheckForSerializationFailure(), PreCommit_CheckForSerializationFailure(), ReleasePredicateLocks(), and RWConflictExists().

SxactIsOnFinishedList

#define SxactIsOnFinishedList

(

sxact

)

(!SHMQueueIsDetached(&((sxact)->finishedLink)))

Definition at line 262 of file predicate.c.

Referenced by ReleaseOneSerializableXact(), and ReleasePredicateLocks().

SxactIsPartiallyReleased

#define SxactIsPartiallyReleased

(

sxact

)

(((sxact)->flags & SXACT_FLAG_PARTIALLY_RELEASED) != 0)

Definition at line 288 of file predicate.c.

Referenced by PreCommit_CheckForSerializationFailure(), and ReleasePredicateLocks().

SxactIsPrepared

#define SxactIsPrepared

(

sxact

)

(((sxact)->flags & SXACT_FLAG_PREPARED) != 0)

Definition at line 273 of file predicate.c.

Referenced by CheckForSerializableConflictOut(), OnConflict_CheckForSerializationFailure(), PostPrepare_PredicateLocks(), PreCommit_CheckForSerializationFailure(), predicatelock_twophase_recover(), and ReleasePredicateLocks().

SxactIsReadOnly

#define SxactIsReadOnly

(

sxact

)

(((sxact)->flags & SXACT_FLAG_READ_ONLY) != 0)

Definition at line 276 of file predicate.c.

Referenced by CheckForSerializableConflictOut(), ClearOldPredicateLocks(), FlagSxactUnsafe(), GetSerializableTransactionSnapshotInt(), OnConflict_CheckForSerializationFailure(), PreCommit_CheckForSerializationFailure(), predicatelock_twophase_recover(), ReleasePredicateLocks(), SetPossibleUnsafeConflict(), and SummarizeOldestCommittedSxact().

SxactIsRolledBack

#define SxactIsRolledBack

(

sxact

)

(((sxact)->flags & SXACT_FLAG_ROLLED_BACK) != 0)

Definition at line 274 of file predicate.c.

Referenced by ReleaseOneSerializableXact(), ReleasePredicateLocks(), and SetNewSxactGlobalXmin().

SxactIsROSafe

#define SxactIsROSafe

(

sxact

)

(((sxact)->flags & SXACT_FLAG_RO_SAFE) != 0)

Definition at line 286 of file predicate.c.

Referenced by FlagSxactUnsafe(), GetSafeSnapshot(), ReleasePredicateLocks(), and SerializationNeededForRead().

SxactIsROUnsafe

#define SxactIsROUnsafe

(

sxact

)

(((sxact)->flags & SXACT_FLAG_RO_UNSAFE) != 0)

Definition at line 287 of file predicate.c.

Referenced by GetSafeSnapshot(), and ReleasePredicateLocks().

TargetTagIsCoveredBy

#define TargetTagIsCoveredBy	(		covered_target,
			covering_target
	)

Value:

((GET_PREDICATELOCKTARGETTAG_RELATION(covered_target) == /* (2) */  \
      GET_PREDICATELOCKTARGETTAG_RELATION(covering_target))             \
     && (GET_PREDICATELOCKTARGETTAG_OFFSET(covering_target) ==          \
         InvalidOffsetNumber)                                /* (3) */  \
     && (((GET_PREDICATELOCKTARGETTAG_OFFSET(covered_target) !=         \
           InvalidOffsetNumber)                              /* (4a) */ \
          && (GET_PREDICATELOCKTARGETTAG_PAGE(covering_target) ==       \
              GET_PREDICATELOCKTARGETTAG_PAGE(covered_target)))         \
         || ((GET_PREDICATELOCKTARGETTAG_PAGE(covering_target) ==       \
              InvalidBlockNumber)                            /* (4b) */ \
             && (GET_PREDICATELOCKTARGETTAG_PAGE(covered_target)        \
                 != InvalidBlockNumber)))                               \
     && (GET_PREDICATELOCKTARGETTAG_DB(covered_target) ==    /* (1) */  \
         GET_PREDICATELOCKTARGETTAG_DB(covering_target)))

Definition at line 228 of file predicate.c.

Referenced by DeleteChildTargetLocks().

Typedef Documentation

SerialControl

typedef struct SerialControlData* SerialControl

Definition at line 347 of file predicate.c.

SerialControlData

typedef struct SerialControlData SerialControlData

Function Documentation

AtPrepare_PredicateLocks()

void AtPrepare_PredicateLocks

(

void

)

Definition at line 4925 of file predicate.c.

References Assert, TwoPhasePredicateRecord::data, SERIALIZABLEXACT::flags, TwoPhasePredicateXactRecord::flags, InvalidSerializableXact, IsParallelWorker, TwoPhasePredicateRecord::lockRecord, LW_SHARED, LWLockAcquire(), LWLockRelease(), MySerializableXact, PREDICATELOCKTAG::myTarget, offsetof, ParallelContextActive(), SERIALIZABLEXACT::predicateLocks, RegisterTwoPhaseRecord(), SHMQueueNext(), PREDICATELOCKTARGET::tag, PREDICATELOCK::tag, TwoPhasePredicateLockRecord::target, TWOPHASE_RM_PREDICATELOCK_ID, TWOPHASEPREDICATERECORD_LOCK, TWOPHASEPREDICATERECORD_XACT, TwoPhasePredicateRecord::type, PREDICATELOCK::xactLink, TwoPhasePredicateRecord::xactRecord, SERIALIZABLEXACT::xmin, and TwoPhasePredicateXactRecord::xmin.

Referenced by PrepareTransaction().

{
    PREDICATELOCK *predlock;
    SERIALIZABLEXACT *sxact;
    TwoPhasePredicateRecord record;
    TwoPhasePredicateXactRecord *xactRecord;
    TwoPhasePredicateLockRecord *lockRecord;

    sxact = MySerializableXact;
    xactRecord = &(record.data.xactRecord);
    lockRecord = &(record.data.lockRecord);

    if (MySerializableXact == InvalidSerializableXact)
        return;

    /* Generate an xact record for our SERIALIZABLEXACT */
    record.type = TWOPHASEPREDICATERECORD_XACT;
    xactRecord->xmin = MySerializableXact->xmin;
    xactRecord->flags = MySerializableXact->flags;

    /*
     * Note that we don't include the list of conflicts in our out in the
     * statefile, because new conflicts can be added even after the
     * transaction prepares. We'll just make a conservative assumption during
     * recovery instead.
     */

    RegisterTwoPhaseRecord(TWOPHASE_RM_PREDICATELOCK_ID, 0,
                           &record, sizeof(record));

    /*
     * Generate a lock record for each lock.
     *
     * To do this, we need to walk the predicate lock list in our sxact rather
     * than using the local predicate lock table because the latter is not
     * guaranteed to be accurate.
     */
    LWLockAcquire(SerializablePredicateListLock, LW_SHARED);

    /*
     * No need to take sxact->perXactPredicateListLock in parallel mode
     * because there cannot be any parallel workers running while we are
     * preparing a transaction.
     */
    Assert(!IsParallelWorker() && !ParallelContextActive());

    predlock = (PREDICATELOCK *)
        SHMQueueNext(&(sxact->predicateLocks),
                     &(sxact->predicateLocks),
                     offsetof(PREDICATELOCK, xactLink));

    while (predlock != NULL)
    {
        record.type = TWOPHASEPREDICATERECORD_LOCK;
        lockRecord->target = predlock->tag.myTarget->tag;

        RegisterTwoPhaseRecord(TWOPHASE_RM_PREDICATELOCK_ID, 0,
                               &record, sizeof(record));

        predlock = (PREDICATELOCK *)
            SHMQueueNext(&(sxact->predicateLocks),
                         &(predlock->xactLink),
                         offsetof(PREDICATELOCK, xactLink));
    }

    LWLockRelease(SerializablePredicateListLock);
}

AttachSerializableXact()

void AttachSerializableXact

(

SerializableXactHandle

handle

)

Definition at line 5195 of file predicate.c.

References Assert, CreateLocalPredicateLockHash(), and InvalidSerializableXact.

Referenced by ParallelWorkerMain().

{

    Assert(MySerializableXact == InvalidSerializableXact);

    MySerializableXact = (SERIALIZABLEXACT *) handle;
    if (MySerializableXact != InvalidSerializableXact)
        CreateLocalPredicateLockHash();
}

CheckAndPromotePredicateLockRequest()

static bool CheckAndPromotePredicateLockRequest ( const PREDICATELOCKTARGETTAG *  reqtag )

static

Definition at line 2318 of file predicate.c.

References LOCALPREDICATELOCK::childLocks, GetParentPredicateLockTag(), HASH_ENTER, hash_search(), LOCALPREDICATELOCK::held, MaxPredicateChildLocks(), and PredicateLockAcquire().

Referenced by PredicateLockAcquire().

{
    PREDICATELOCKTARGETTAG targettag,
                nexttag,
                promotiontag;
    LOCALPREDICATELOCK *parentlock;
    bool        found,
                promote;

    promote = false;

    targettag = *reqtag;

    /* check parents iteratively */
    while (GetParentPredicateLockTag(&targettag, &nexttag))
    {
        targettag = nexttag;
        parentlock = (LOCALPREDICATELOCK *) hash_search(LocalPredicateLockHash,
                                                        &targettag,
                                                        HASH_ENTER,
                                                        &found);
        if (!found)
        {
            parentlock->held = false;
            parentlock->childLocks = 1;
        }
        else
            parentlock->childLocks++;

        if (parentlock->childLocks >
            MaxPredicateChildLocks(&targettag))
        {
            /*
             * We should promote to this parent lock. Continue to check its
             * ancestors, however, both to get their child counts right and to
             * check whether we should just go ahead and promote to one of
             * them.
             */
            promotiontag = targettag;
            promote = true;
        }
    }

    if (promote)
    {
        /* acquire coarsest ancestor eligible for promotion */
        PredicateLockAcquire(&promotiontag);
        return true;
    }
    else
        return false;
}

CheckForSerializableConflictIn()

void CheckForSerializableConflictIn	(	Relation	relation,
		ItemPointer	tid,
		BlockNumber	blkno
	)

Definition at line 4446 of file predicate.c.

References CheckTargetForConflictsIn(), RelFileNode::dbNode, ereport, errcode(), errdetail_internal(), errhint(), errmsg(), ERROR, InvalidBlockNumber, ItemPointerGetBlockNumber, ItemPointerGetOffsetNumber, MyXactDidWrite, RelationData::rd_id, RelationData::rd_node, SerializationNeededForWrite(), SET_PREDICATELOCKTARGETTAG_PAGE, SET_PREDICATELOCKTARGETTAG_RELATION, SET_PREDICATELOCKTARGETTAG_TUPLE, and SxactIsDoomed.

Referenced by _bt_check_unique(), _bt_doinsert(), _hash_doinsert(), ginEntryInsert(), ginFindLeafPage(), ginHeapTupleFastInsert(), gistinserttuples(), heap_delete(), heap_insert(), heap_multi_insert(), heap_update(), and index_insert().

{
    PREDICATELOCKTARGETTAG targettag;

    if (!SerializationNeededForWrite(relation))
        return;

    /* Check if someone else has already decided that we need to die */
    if (SxactIsDoomed(MySerializableXact))
        ereport(ERROR,
                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                 errmsg("could not serialize access due to read/write dependencies among transactions"),
                 errdetail_internal("Reason code: Canceled on identification as a pivot, during conflict in checking."),
                 errhint("The transaction might succeed if retried.")));

    /*
     * We're doing a write which might cause rw-conflicts now or later.
     * Memorize that fact.
     */
    MyXactDidWrite = true;

    /*
     * It is important that we check for locks from the finest granularity to
     * the coarsest granularity, so that granularity promotion doesn't cause
     * us to miss a lock.  The new (coarser) lock will be acquired before the
     * old (finer) locks are released.
     *
     * It is not possible to take and hold a lock across the checks for all
     * granularities because each target could be in a separate partition.
     */
    if (tid != NULL)
    {
        SET_PREDICATELOCKTARGETTAG_TUPLE(targettag,
                                         relation->rd_node.dbNode,
                                         relation->rd_id,
                                         ItemPointerGetBlockNumber(tid),
                                         ItemPointerGetOffsetNumber(tid));
        CheckTargetForConflictsIn(&targettag);
    }

    if (blkno != InvalidBlockNumber)
    {
        SET_PREDICATELOCKTARGETTAG_PAGE(targettag,
                                        relation->rd_node.dbNode,
                                        relation->rd_id,
                                        blkno);
        CheckTargetForConflictsIn(&targettag);
    }

    SET_PREDICATELOCKTARGETTAG_RELATION(targettag,
                                        relation->rd_node.dbNode,
                                        relation->rd_id);
    CheckTargetForConflictsIn(&targettag);
}

CheckForSerializableConflictOut()

void CheckForSerializableConflictOut	(	Relation	relation,
		TransactionId	xid,
		Snapshot	snapshot
	)

Definition at line 4121 of file predicate.c.

References Assert, SERIALIZABLEXACT::earliestOutConflictCommit, ereport, errcode(), errdetail_internal(), errhint(), errmsg(), ERROR, FlagRWConflict(), SERIALIZABLEXACT::flags, GetTopTransactionIdIfAny(), HASH_FIND, hash_search(), SERIALIZABLEXACT::inConflicts, InvalidSerCommitSeqNo, SERIALIZABLEXACT::lastCommitBeforeSnapshot, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SERIALIZABLEXID::myXact, RWConflictExists(), SERIALIZABLEXACT::SeqNo, SerialGetMinConflictCommitSeqNo(), SerializationNeededForRead(), SHMQueueEmpty(), SXACT_FLAG_DOOMED, SXACT_FLAG_SUMMARY_CONFLICT_OUT, SxactHasConflictOut, SxactHasSummaryConflictIn, SxactHasSummaryConflictOut, SxactIsCommitted, SxactIsDoomed, SxactIsPrepared, SxactIsReadOnly, SERIALIZABLEXACT::topXid, TransactionIdEquals, TransactionIdIsValid, SERIALIZABLEXIDTAG::xid, and XidIsConcurrent().

Referenced by HeapCheckForSerializableConflictOut().

{
    SERIALIZABLEXIDTAG sxidtag;
    SERIALIZABLEXID *sxid;
    SERIALIZABLEXACT *sxact;

    if (!SerializationNeededForRead(relation, snapshot))
        return;

    /* Check if someone else has already decided that we need to die */
    if (SxactIsDoomed(MySerializableXact))
    {
        ereport(ERROR,
                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                 errmsg("could not serialize access due to read/write dependencies among transactions"),
                 errdetail_internal("Reason code: Canceled on identification as a pivot, during conflict out checking."),
                 errhint("The transaction might succeed if retried.")));
    }
    Assert(TransactionIdIsValid(xid));

    if (TransactionIdEquals(xid, GetTopTransactionIdIfAny()))
        return;

    /*
     * Find sxact or summarized info for the top level xid.
     */
    sxidtag.xid = xid;
    LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
    sxid = (SERIALIZABLEXID *)
        hash_search(SerializableXidHash, &sxidtag, HASH_FIND, NULL);
    if (!sxid)
    {
        /*
         * Transaction not found in "normal" SSI structures.  Check whether it
         * got pushed out to SLRU storage for "old committed" transactions.
         */
        SerCommitSeqNo conflictCommitSeqNo;

        conflictCommitSeqNo = SerialGetMinConflictCommitSeqNo(xid);
        if (conflictCommitSeqNo != 0)
        {
            if (conflictCommitSeqNo != InvalidSerCommitSeqNo
                && (!SxactIsReadOnly(MySerializableXact)
                    || conflictCommitSeqNo
                    <= MySerializableXact->SeqNo.lastCommitBeforeSnapshot))
                ereport(ERROR,
                        (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                         errmsg("could not serialize access due to read/write dependencies among transactions"),
                         errdetail_internal("Reason code: Canceled on conflict out to old pivot %u.", xid),
                         errhint("The transaction might succeed if retried.")));

            if (SxactHasSummaryConflictIn(MySerializableXact)
                || !SHMQueueEmpty(&MySerializableXact->inConflicts))
                ereport(ERROR,
                        (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                         errmsg("could not serialize access due to read/write dependencies among transactions"),
                         errdetail_internal("Reason code: Canceled on identification as a pivot, with conflict out to old committed transaction %u.", xid),
                         errhint("The transaction might succeed if retried.")));

            MySerializableXact->flags |= SXACT_FLAG_SUMMARY_CONFLICT_OUT;
        }

        /* It's not serializable or otherwise not important. */
        LWLockRelease(SerializableXactHashLock);
        return;
    }
    sxact = sxid->myXact;
    Assert(TransactionIdEquals(sxact->topXid, xid));
    if (sxact == MySerializableXact || SxactIsDoomed(sxact))
    {
        /* Can't conflict with ourself or a transaction that will roll back. */
        LWLockRelease(SerializableXactHashLock);
        return;
    }

    /*
     * We have a conflict out to a transaction which has a conflict out to a
     * summarized transaction.  That summarized transaction must have
     * committed first, and we can't tell when it committed in relation to our
     * snapshot acquisition, so something needs to be canceled.
     */
    if (SxactHasSummaryConflictOut(sxact))
    {
        if (!SxactIsPrepared(sxact))
        {
            sxact->flags |= SXACT_FLAG_DOOMED;
            LWLockRelease(SerializableXactHashLock);
            return;
        }
        else
        {
            LWLockRelease(SerializableXactHashLock);
            ereport(ERROR,
                    (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                     errmsg("could not serialize access due to read/write dependencies among transactions"),
                     errdetail_internal("Reason code: Canceled on conflict out to old pivot."),
                     errhint("The transaction might succeed if retried.")));
        }
    }

    /*
     * If this is a read-only transaction and the writing transaction has
     * committed, and it doesn't have a rw-conflict to a transaction which
     * committed before it, no conflict.
     */
    if (SxactIsReadOnly(MySerializableXact)
        && SxactIsCommitted(sxact)
        && !SxactHasSummaryConflictOut(sxact)
        && (!SxactHasConflictOut(sxact)
            || MySerializableXact->SeqNo.lastCommitBeforeSnapshot < sxact->SeqNo.earliestOutConflictCommit))
    {
        /* Read-only transaction will appear to run first.  No conflict. */
        LWLockRelease(SerializableXactHashLock);
        return;
    }

    if (!XidIsConcurrent(xid))
    {
        /* This write was already in our snapshot; no conflict. */
        LWLockRelease(SerializableXactHashLock);
        return;
    }

    if (RWConflictExists(MySerializableXact, sxact))
    {
        /* We don't want duplicate conflict records in the list. */
        LWLockRelease(SerializableXactHashLock);
        return;
    }

    /*
     * Flag the conflict.  But first, if this conflict creates a dangerous
     * structure, ereport an error.
     */
    FlagRWConflict(MySerializableXact, sxact);
    LWLockRelease(SerializableXactHashLock);
}

CheckForSerializableConflictOutNeeded()

bool CheckForSerializableConflictOutNeeded	(	Relation	relation,
		Snapshot	snapshot
	)

Definition at line 4089 of file predicate.c.

References ereport, errcode(), errdetail_internal(), errhint(), errmsg(), ERROR, SerializationNeededForRead(), and SxactIsDoomed.

Referenced by HeapCheckForSerializableConflictOut().

{
    if (!SerializationNeededForRead(relation, snapshot))
        return false;

    /* Check if someone else has already decided that we need to die */
    if (SxactIsDoomed(MySerializableXact))
    {
        ereport(ERROR,
                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                 errmsg("could not serialize access due to read/write dependencies among transactions"),
                 errdetail_internal("Reason code: Canceled on identification as a pivot, during conflict out checking."),
                 errhint("The transaction might succeed if retried.")));
    }

    return true;
}

CheckPointPredicate()

void CheckPointPredicate

(

void

)

Definition at line 1069 of file predicate.c.

References SerialControlData::headPage, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SerialPage, SerialSlruCtl, SimpleLruTruncate(), SimpleLruWriteAll(), SerialControlData::tailXid, and TransactionIdIsValid.

Referenced by CheckPointGuts().

{
    int         tailPage;

    LWLockAcquire(SerialSLRULock, LW_EXCLUSIVE);

    /* Exit quickly if the SLRU is currently not in use. */
    if (serialControl->headPage < 0)
    {
        LWLockRelease(SerialSLRULock);
        return;
    }

    if (TransactionIdIsValid(serialControl->tailXid))
    {
        /* We can truncate the SLRU up to the page containing tailXid */
        tailPage = SerialPage(serialControl->tailXid);
    }
    else
    {
        /*----------
         * The SLRU is no longer needed. Truncate to head before we set head
         * invalid.
         *
         * XXX: It's possible that the SLRU is not needed again until XID
         * wrap-around has happened, so that the segment containing headPage
         * that we leave behind will appear to be new again. In that case it
         * won't be removed until XID horizon advances enough to make it
         * current again.
         *
         * XXX: This should happen in vac_truncate_clog(), not in checkpoints.
         * Consider this scenario, starting from a system with no in-progress
         * transactions and VACUUM FREEZE having maximized oldestXact:
         * - Start a SERIALIZABLE transaction.
         * - Start, finish, and summarize a SERIALIZABLE transaction, creating
         *   one SLRU page.
         * - Consume XIDs to reach xidStopLimit.
         * - Finish all transactions.  Due to the long-running SERIALIZABLE
         *   transaction, earlier checkpoints did not touch headPage.  The
         *   next checkpoint will change it, but that checkpoint happens after
         *   the end of the scenario.
         * - VACUUM to advance XID limits.
         * - Consume ~2M XIDs, crossing the former xidWrapLimit.
         * - Start, finish, and summarize a SERIALIZABLE transaction.
         *   SerialAdd() declines to create the targetPage, because headPage
         *   is not regarded as in the past relative to that targetPage.  The
         *   transaction instigating the summarize fails in
         *   SimpleLruReadPage().
         */
        tailPage = serialControl->headPage;
        serialControl->headPage = -1;
    }

    LWLockRelease(SerialSLRULock);

    /* Truncate away pages that are no longer required */
    SimpleLruTruncate(SerialSlruCtl, tailPage);

    /*
     * Write dirty SLRU pages to disk
     *
     * This is not actually necessary from a correctness point of view. We do
     * it merely as a debugging aid.
     *
     * We're doing this after the truncation to avoid writing pages right
     * before deleting the file in which they sit, which would be completely
     * pointless.
     */
    SimpleLruWriteAll(SerialSlruCtl, true);
}

CheckTableForSerializableConflictIn()

void CheckTableForSerializableConflictIn

(

Relation

relation

)

Definition at line 4529 of file predicate.c.

References Assert, RelFileNode::dbNode, FlagRWConflict(), GET_PREDICATELOCKTARGETTAG_DB, GET_PREDICATELOCKTARGETTAG_RELATION, hash_seq_init(), hash_seq_search(), i, LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), PREDICATELOCKTAG::myXact, MyXactDidWrite, NUM_PREDICATELOCK_PARTITIONS, offsetof, PredicateLockHashPartitionLockByIndex, PREDICATELOCKTARGET::predicateLocks, RelationData::rd_id, RelationData::rd_index, RelationData::rd_node, RWConflictExists(), SerializationNeededForWrite(), SHMQueueNext(), PredXactListData::SxactGlobalXmin, PREDICATELOCKTARGET::tag, PREDICATELOCK::tag, PREDICATELOCK::targetLink, and TransactionIdIsValid.

Referenced by ExecuteTruncateGuts(), and heap_drop_with_catalog().

{
    HASH_SEQ_STATUS seqstat;
    PREDICATELOCKTARGET *target;
    Oid         dbId;
    Oid         heapId;
    int         i;

    /*
     * Bail out quickly if there are no serializable transactions running.
     * It's safe to check this without taking locks because the caller is
     * holding an ACCESS EXCLUSIVE lock on the relation.  No new locks which
     * would matter here can be acquired while that is held.
     */
    if (!TransactionIdIsValid(PredXact->SxactGlobalXmin))
        return;

    if (!SerializationNeededForWrite(relation))
        return;

    /*
     * We're doing a write which might cause rw-conflicts now or later.
     * Memorize that fact.
     */
    MyXactDidWrite = true;

    Assert(relation->rd_index == NULL); /* not an index relation */

    dbId = relation->rd_node.dbNode;
    heapId = relation->rd_id;

    LWLockAcquire(SerializablePredicateListLock, LW_EXCLUSIVE);
    for (i = 0; i < NUM_PREDICATELOCK_PARTITIONS; i++)
        LWLockAcquire(PredicateLockHashPartitionLockByIndex(i), LW_SHARED);
    LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);

    /* Scan through target list */
    hash_seq_init(&seqstat, PredicateLockTargetHash);

    while ((target = (PREDICATELOCKTARGET *) hash_seq_search(&seqstat)))
    {
        PREDICATELOCK *predlock;

        /*
         * Check whether this is a target which needs attention.
         */
        if (GET_PREDICATELOCKTARGETTAG_RELATION(target->tag) != heapId)
            continue;           /* wrong relation id */
        if (GET_PREDICATELOCKTARGETTAG_DB(target->tag) != dbId)
            continue;           /* wrong database id */

        /*
         * Loop through locks for this target and flag conflicts.
         */
        predlock = (PREDICATELOCK *)
            SHMQueueNext(&(target->predicateLocks),
                         &(target->predicateLocks),
                         offsetof(PREDICATELOCK, targetLink));
        while (predlock)
        {
            PREDICATELOCK *nextpredlock;

            nextpredlock = (PREDICATELOCK *)
                SHMQueueNext(&(target->predicateLocks),
                             &(predlock->targetLink),
                             offsetof(PREDICATELOCK, targetLink));

            if (predlock->tag.myXact != MySerializableXact
                && !RWConflictExists(predlock->tag.myXact, MySerializableXact))
            {
                FlagRWConflict(predlock->tag.myXact, MySerializableXact);
            }

            predlock = nextpredlock;
        }
    }

    /* Release locks in reverse order */
    LWLockRelease(SerializableXactHashLock);
    for (i = NUM_PREDICATELOCK_PARTITIONS - 1; i >= 0; i--)
        LWLockRelease(PredicateLockHashPartitionLockByIndex(i));
    LWLockRelease(SerializablePredicateListLock);
}

CheckTargetForConflictsIn()

static void CheckTargetForConflictsIn ( PREDICATELOCKTARGETTAG *  targettag )

static

Definition at line 4264 of file predicate.c.

References Assert, DecrementParentLocks(), SERIALIZABLEXACT::finishedBefore, FlagRWConflict(), GET_PREDICATELOCKTARGETTAG_OFFSET, GetTransactionSnapshot(), HASH_FIND, HASH_REMOVE, hash_search_with_hash_value(), InvalidSerializableXact, IsInParallelMode(), IsSubTransaction(), LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), PREDICATELOCKTAG::myXact, offsetof, SERIALIZABLEXACT::perXactPredicateListLock, PredicateLockHashCodeFromTargetHashCode, PredicateLockHashPartitionLock, PREDICATELOCKTARGET::predicateLocks, PredicateLockTargetTagHashCode, RemoveTargetIfNoLongerUsed(), RWConflictExists(), SHMQueueDelete(), SHMQueueNext(), SxactIsCommitted, SxactIsDoomed, PREDICATELOCK::tag, PREDICATELOCK::targetLink, TransactionIdPrecedes(), and PREDICATELOCK::xactLink.

Referenced by CheckForSerializableConflictIn().

{
    uint32      targettaghash;
    LWLock     *partitionLock;
    PREDICATELOCKTARGET *target;
    PREDICATELOCK *predlock;
    PREDICATELOCK *mypredlock = NULL;
    PREDICATELOCKTAG mypredlocktag;

    Assert(MySerializableXact != InvalidSerializableXact);

    /*
     * The same hash and LW lock apply to the lock target and the lock itself.
     */
    targettaghash = PredicateLockTargetTagHashCode(targettag);
    partitionLock = PredicateLockHashPartitionLock(targettaghash);
    LWLockAcquire(partitionLock, LW_SHARED);
    target = (PREDICATELOCKTARGET *)
        hash_search_with_hash_value(PredicateLockTargetHash,
                                    targettag, targettaghash,
                                    HASH_FIND, NULL);
    if (!target)
    {
        /* Nothing has this target locked; we're done here. */
        LWLockRelease(partitionLock);
        return;
    }

    /*
     * Each lock for an overlapping transaction represents a conflict: a
     * rw-dependency in to this transaction.
     */
    predlock = (PREDICATELOCK *)
        SHMQueueNext(&(target->predicateLocks),
                     &(target->predicateLocks),
                     offsetof(PREDICATELOCK, targetLink));
    LWLockAcquire(SerializableXactHashLock, LW_SHARED);
    while (predlock)
    {
        SHM_QUEUE  *predlocktargetlink;
        PREDICATELOCK *nextpredlock;
        SERIALIZABLEXACT *sxact;

        predlocktargetlink = &(predlock->targetLink);
        nextpredlock = (PREDICATELOCK *)
            SHMQueueNext(&(target->predicateLocks),
                         predlocktargetlink,
                         offsetof(PREDICATELOCK, targetLink));

        sxact = predlock->tag.myXact;
        if (sxact == MySerializableXact)
        {
            /*
             * If we're getting a write lock on a tuple, we don't need a
             * predicate (SIREAD) lock on the same tuple. We can safely remove
             * our SIREAD lock, but we'll defer doing so until after the loop
             * because that requires upgrading to an exclusive partition lock.
             *
             * We can't use this optimization within a subtransaction because
             * the subtransaction could roll back, and we would be left
             * without any lock at the top level.
             */
            if (!IsSubTransaction()
                && GET_PREDICATELOCKTARGETTAG_OFFSET(*targettag))
            {
                mypredlock = predlock;
                mypredlocktag = predlock->tag;
            }
        }
        else if (!SxactIsDoomed(sxact)
                 && (!SxactIsCommitted(sxact)
                     || TransactionIdPrecedes(GetTransactionSnapshot()->xmin,
                                              sxact->finishedBefore))
                 && !RWConflictExists(sxact, MySerializableXact))
        {
            LWLockRelease(SerializableXactHashLock);
            LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);

            /*
             * Re-check after getting exclusive lock because the other
             * transaction may have flagged a conflict.
             */
            if (!SxactIsDoomed(sxact)
                && (!SxactIsCommitted(sxact)
                    || TransactionIdPrecedes(GetTransactionSnapshot()->xmin,
                                             sxact->finishedBefore))
                && !RWConflictExists(sxact, MySerializableXact))
            {
                FlagRWConflict(sxact, MySerializableXact);
            }

            LWLockRelease(SerializableXactHashLock);
            LWLockAcquire(SerializableXactHashLock, LW_SHARED);
        }

        predlock = nextpredlock;
    }
    LWLockRelease(SerializableXactHashLock);
    LWLockRelease(partitionLock);

    /*
     * If we found one of our own SIREAD locks to remove, remove it now.
     *
     * At this point our transaction already has a RowExclusiveLock on the
     * relation, so we are OK to drop the predicate lock on the tuple, if
     * found, without fearing that another write against the tuple will occur
     * before the MVCC information makes it to the buffer.
     */
    if (mypredlock != NULL)
    {
        uint32      predlockhashcode;
        PREDICATELOCK *rmpredlock;

        LWLockAcquire(SerializablePredicateListLock, LW_SHARED);
        if (IsInParallelMode())
            LWLockAcquire(&MySerializableXact->perXactPredicateListLock, LW_EXCLUSIVE);
        LWLockAcquire(partitionLock, LW_EXCLUSIVE);
        LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);

        /*
         * Remove the predicate lock from shared memory, if it wasn't removed
         * while the locks were released.  One way that could happen is from
         * autovacuum cleaning up an index.
         */
        predlockhashcode = PredicateLockHashCodeFromTargetHashCode
            (&mypredlocktag, targettaghash);
        rmpredlock = (PREDICATELOCK *)
            hash_search_with_hash_value(PredicateLockHash,
                                        &mypredlocktag,
                                        predlockhashcode,
                                        HASH_FIND, NULL);
        if (rmpredlock != NULL)
        {
            Assert(rmpredlock == mypredlock);

            SHMQueueDelete(&(mypredlock->targetLink));
            SHMQueueDelete(&(mypredlock->xactLink));

            rmpredlock = (PREDICATELOCK *)
                hash_search_with_hash_value(PredicateLockHash,
                                            &mypredlocktag,
                                            predlockhashcode,
                                            HASH_REMOVE, NULL);
            Assert(rmpredlock == mypredlock);

            RemoveTargetIfNoLongerUsed(target, targettaghash);
        }

        LWLockRelease(SerializableXactHashLock);
        LWLockRelease(partitionLock);
        if (IsInParallelMode())
            LWLockRelease(&MySerializableXact->perXactPredicateListLock);
        LWLockRelease(SerializablePredicateListLock);

        if (rmpredlock != NULL)
        {
            /*
             * Remove entry in local lock table if it exists. It's OK if it
             * doesn't exist; that means the lock was transferred to a new
             * target by a different backend.
             */
            hash_search_with_hash_value(LocalPredicateLockHash,
                                        targettag, targettaghash,
                                        HASH_REMOVE, NULL);

            DecrementParentLocks(targettag);
        }
    }
}

ClearOldPredicateLocks()

static void ClearOldPredicateLocks ( void  )

static

Definition at line 3743 of file predicate.c.

References Assert, PredXactListData::CanPartialClearThrough, SERIALIZABLEXACT::commitSeqNo, PREDICATELOCK::commitSeqNo, SERIALIZABLEXACT::finishedBefore, SERIALIZABLEXACT::finishedLink, HASH_REMOVE, hash_search_with_hash_value(), PredXactListData::HavePartialClearedThrough, InvalidSerCommitSeqNo, LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), PREDICATELOCKTAG::myTarget, offsetof, PredicateLockHashCodeFromTargetHashCode, PredicateLockHashPartitionLock, SERIALIZABLEXACT::predicateLocks, PredicateLockTargetTagHashCode, ReleaseOneSerializableXact(), RemoveTargetIfNoLongerUsed(), SHMQueueDelete(), SHMQueueNext(), PredXactListData::SxactGlobalXmin, SxactIsReadOnly, PREDICATELOCKTARGET::tag, PREDICATELOCK::tag, PREDICATELOCK::targetLink, TransactionIdIsValid, TransactionIdPrecedesOrEquals(), and PREDICATELOCK::xactLink.

Referenced by ReleasePredicateLocks().

{
    SERIALIZABLEXACT *finishedSxact;
    PREDICATELOCK *predlock;

    /*
     * Loop through finished transactions. They are in commit order, so we can
     * stop as soon as we find one that's still interesting.
     */
    LWLockAcquire(SerializableFinishedListLock, LW_EXCLUSIVE);
    finishedSxact = (SERIALIZABLEXACT *)
        SHMQueueNext(FinishedSerializableTransactions,
                     FinishedSerializableTransactions,
                     offsetof(SERIALIZABLEXACT, finishedLink));
    LWLockAcquire(SerializableXactHashLock, LW_SHARED);
    while (finishedSxact)
    {
        SERIALIZABLEXACT *nextSxact;

        nextSxact = (SERIALIZABLEXACT *)
            SHMQueueNext(FinishedSerializableTransactions,
                         &(finishedSxact->finishedLink),
                         offsetof(SERIALIZABLEXACT, finishedLink));
        if (!TransactionIdIsValid(PredXact->SxactGlobalXmin)
            || TransactionIdPrecedesOrEquals(finishedSxact->finishedBefore,
                                             PredXact->SxactGlobalXmin))
        {
            /*
             * This transaction committed before any in-progress transaction
             * took its snapshot. It's no longer interesting.
             */
            LWLockRelease(SerializableXactHashLock);
            SHMQueueDelete(&(finishedSxact->finishedLink));
            ReleaseOneSerializableXact(finishedSxact, false, false);
            LWLockAcquire(SerializableXactHashLock, LW_SHARED);
        }
        else if (finishedSxact->commitSeqNo > PredXact->HavePartialClearedThrough
                 && finishedSxact->commitSeqNo <= PredXact->CanPartialClearThrough)
        {
            /*
             * Any active transactions that took their snapshot before this
             * transaction committed are read-only, so we can clear part of
             * its state.
             */
            LWLockRelease(SerializableXactHashLock);

            if (SxactIsReadOnly(finishedSxact))
            {
                /* A read-only transaction can be removed entirely */
                SHMQueueDelete(&(finishedSxact->finishedLink));
                ReleaseOneSerializableXact(finishedSxact, false, false);
            }
            else
            {
                /*
                 * A read-write transaction can only be partially cleared. We
                 * need to keep the SERIALIZABLEXACT but can release the
                 * SIREAD locks and conflicts in.
                 */
                ReleaseOneSerializableXact(finishedSxact, true, false);
            }

            PredXact->HavePartialClearedThrough = finishedSxact->commitSeqNo;
            LWLockAcquire(SerializableXactHashLock, LW_SHARED);
        }
        else
        {
            /* Still interesting. */
            break;
        }
        finishedSxact = nextSxact;
    }
    LWLockRelease(SerializableXactHashLock);

    /*
     * Loop through predicate locks on dummy transaction for summarized data.
     */
    LWLockAcquire(SerializablePredicateListLock, LW_SHARED);
    predlock = (PREDICATELOCK *)
        SHMQueueNext(&OldCommittedSxact->predicateLocks,
                     &OldCommittedSxact->predicateLocks,
                     offsetof(PREDICATELOCK, xactLink));
    while (predlock)
    {
        PREDICATELOCK *nextpredlock;
        bool        canDoPartialCleanup;

        nextpredlock = (PREDICATELOCK *)
            SHMQueueNext(&OldCommittedSxact->predicateLocks,
                         &predlock->xactLink,
                         offsetof(PREDICATELOCK, xactLink));

        LWLockAcquire(SerializableXactHashLock, LW_SHARED);
        Assert(predlock->commitSeqNo != 0);
        Assert(predlock->commitSeqNo != InvalidSerCommitSeqNo);
        canDoPartialCleanup = (predlock->commitSeqNo <= PredXact->CanPartialClearThrough);
        LWLockRelease(SerializableXactHashLock);

        /*
         * If this lock originally belonged to an old enough transaction, we
         * can release it.
         */
        if (canDoPartialCleanup)
        {
            PREDICATELOCKTAG tag;
            PREDICATELOCKTARGET *target;
            PREDICATELOCKTARGETTAG targettag;
            uint32      targettaghash;
            LWLock     *partitionLock;

            tag = predlock->tag;
            target = tag.myTarget;
            targettag = target->tag;
            targettaghash = PredicateLockTargetTagHashCode(&targettag);
            partitionLock = PredicateLockHashPartitionLock(targettaghash);

            LWLockAcquire(partitionLock, LW_EXCLUSIVE);

            SHMQueueDelete(&(predlock->targetLink));
            SHMQueueDelete(&(predlock->xactLink));

            hash_search_with_hash_value(PredicateLockHash, &tag,
                                        PredicateLockHashCodeFromTargetHashCode(&tag,
                                                                                targettaghash),
                                        HASH_REMOVE, NULL);
            RemoveTargetIfNoLongerUsed(target, targettaghash);

            LWLockRelease(partitionLock);
        }

        predlock = nextpredlock;
    }

    LWLockRelease(SerializablePredicateListLock);
    LWLockRelease(SerializableFinishedListLock);
}

CoarserLockCovers()

static bool CoarserLockCovers ( const PREDICATELOCKTARGETTAG *  newtargettag )

static

Definition at line 2093 of file predicate.c.

References GetParentPredicateLockTag(), and PredicateLockExists().

Referenced by PredicateLockAcquire().

{
    PREDICATELOCKTARGETTAG targettag,
                parenttag;

    targettag = *newtargettag;

    /* check parents iteratively until no more */
    while (GetParentPredicateLockTag(&targettag, &parenttag))
    {
        targettag = parenttag;
        if (PredicateLockExists(&targettag))
            return true;
    }

    /* no more parents to check; lock is not covered */
    return false;
}

CreateLocalPredicateLockHash()

static void CreateLocalPredicateLockHash ( void  )

static

Definition at line 1922 of file predicate.c.

References Assert, HASHCTL::entrysize, HASH_BLOBS, hash_create(), HASH_ELEM, HASHCTL::keysize, and max_predicate_locks_per_xact.

Referenced by AttachSerializableXact(), and GetSerializableTransactionSnapshotInt().

{
    HASHCTL     hash_ctl;

    /* Initialize the backend-local hash table of parent locks */
    Assert(LocalPredicateLockHash == NULL);
    hash_ctl.keysize = sizeof(PREDICATELOCKTARGETTAG);
    hash_ctl.entrysize = sizeof(LOCALPREDICATELOCK);
    LocalPredicateLockHash = hash_create("Local predicate lock",
                                         max_predicate_locks_per_xact,
                                         &hash_ctl,
                                         HASH_ELEM | HASH_BLOBS);
}

CreatePredicateLock()

static void CreatePredicateLock ( const PREDICATELOCKTARGETTAG *  targettag, uint32  targettaghash, SERIALIZABLEXACT *  sxact  )

static

Definition at line 2445 of file predicate.c.

References PREDICATELOCK::commitSeqNo, ereport, errcode(), errhint(), errmsg(), ERROR, HASH_ENTER_NULL, hash_search_with_hash_value(), InvalidSerCommitSeqNo, IsInParallelMode(), LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), PREDICATELOCKTAG::myTarget, PREDICATELOCKTAG::myXact, SERIALIZABLEXACT::perXactPredicateListLock, PredicateLockHashCodeFromTargetHashCode, PredicateLockHashPartitionLock, SERIALIZABLEXACT::predicateLocks, PREDICATELOCKTARGET::predicateLocks, SHMQueueInit(), SHMQueueInsertBefore(), PREDICATELOCK::targetLink, and PREDICATELOCK::xactLink.

Referenced by predicatelock_twophase_recover(), and PredicateLockAcquire().

{
    PREDICATELOCKTARGET *target;
    PREDICATELOCKTAG locktag;
    PREDICATELOCK *lock;
    LWLock     *partitionLock;
    bool        found;

    partitionLock = PredicateLockHashPartitionLock(targettaghash);

    LWLockAcquire(SerializablePredicateListLock, LW_SHARED);
    if (IsInParallelMode())
        LWLockAcquire(&sxact->perXactPredicateListLock, LW_EXCLUSIVE);
    LWLockAcquire(partitionLock, LW_EXCLUSIVE);

    /* Make sure that the target is represented. */
    target = (PREDICATELOCKTARGET *)
        hash_search_with_hash_value(PredicateLockTargetHash,
                                    targettag, targettaghash,
                                    HASH_ENTER_NULL, &found);
    if (!target)
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory"),
                 errhint("You might need to increase max_pred_locks_per_transaction.")));
    if (!found)
        SHMQueueInit(&(target->predicateLocks));

    /* We've got the sxact and target, make sure they're joined. */
    locktag.myTarget = target;
    locktag.myXact = sxact;
    lock = (PREDICATELOCK *)
        hash_search_with_hash_value(PredicateLockHash, &locktag,
                                    PredicateLockHashCodeFromTargetHashCode(&locktag, targettaghash),
                                    HASH_ENTER_NULL, &found);
    if (!lock)
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory"),
                 errhint("You might need to increase max_pred_locks_per_transaction.")));

    if (!found)
    {
        SHMQueueInsertBefore(&(target->predicateLocks), &(lock->targetLink));
        SHMQueueInsertBefore(&(sxact->predicateLocks),
                             &(lock->xactLink));
        lock->commitSeqNo = InvalidSerCommitSeqNo;
    }

    LWLockRelease(partitionLock);
    if (IsInParallelMode())
        LWLockRelease(&sxact->perXactPredicateListLock);
    LWLockRelease(SerializablePredicateListLock);
}

CreatePredXact()

static SERIALIZABLEXACT * CreatePredXact ( void  )

static

Definition at line 580 of file predicate.c.

References PredXactListData::activeList, PredXactListData::availableList, PredXactListElementData::link, offsetof, SHMQueueDelete(), SHMQueueInsertBefore(), SHMQueueNext(), and PredXactListElementData::sxact.

Referenced by GetSerializableTransactionSnapshotInt(), InitPredicateLocks(), and predicatelock_twophase_recover().

{
    PredXactListElement ptle;

    ptle = (PredXactListElement)
        SHMQueueNext(&PredXact->availableList,
                     &PredXact->availableList,
                     offsetof(PredXactListElementData, link));
    if (!ptle)
        return NULL;

    SHMQueueDelete(&ptle->link);
    SHMQueueInsertBefore(&PredXact->activeList, &ptle->link);
    return &ptle->sxact;
}

DecrementParentLocks()

static void DecrementParentLocks ( const PREDICATELOCKTARGETTAG *  targettag )

static

Definition at line 2383 of file predicate.c.

References Assert, LOCALPREDICATELOCK::childLocks, GetParentPredicateLockTag(), HASH_FIND, HASH_REMOVE, hash_search_with_hash_value(), LOCALPREDICATELOCK::held, PG_USED_FOR_ASSERTS_ONLY, and PredicateLockTargetTagHashCode.

Referenced by CheckTargetForConflictsIn(), and DeleteChildTargetLocks().

{
    PREDICATELOCKTARGETTAG parenttag,
                nexttag;

    parenttag = *targettag;

    while (GetParentPredicateLockTag(&parenttag, &nexttag))
    {
        uint32      targettaghash;
        LOCALPREDICATELOCK *parentlock,
                   *rmlock PG_USED_FOR_ASSERTS_ONLY;

        parenttag = nexttag;
        targettaghash = PredicateLockTargetTagHashCode(&parenttag);
        parentlock = (LOCALPREDICATELOCK *)
            hash_search_with_hash_value(LocalPredicateLockHash,
                                        &parenttag, targettaghash,
                                        HASH_FIND, NULL);

        /*
         * There's a small chance the parent lock doesn't exist in the lock
         * table. This can happen if we prematurely removed it because an
         * index split caused the child refcount to be off.
         */
        if (parentlock == NULL)
            continue;

        parentlock->childLocks--;

        /*
         * Under similar circumstances the parent lock's refcount might be
         * zero. This only happens if we're holding that lock (otherwise we
         * would have removed the entry).
         */
        if (parentlock->childLocks < 0)
        {
            Assert(parentlock->held);
            parentlock->childLocks = 0;
        }

        if ((parentlock->childLocks == 0) && (!parentlock->held))
        {
            rmlock = (LOCALPREDICATELOCK *)
                hash_search_with_hash_value(LocalPredicateLockHash,
                                            &parenttag, targettaghash,
                                            HASH_REMOVE, NULL);
            Assert(rmlock == parentlock);
        }
    }
}

DeleteChildTargetLocks()

static void DeleteChildTargetLocks ( const PREDICATELOCKTARGETTAG *  newtargettag )

static

Definition at line 2196 of file predicate.c.

References Assert, DecrementParentLocks(), HASH_REMOVE, hash_search_with_hash_value(), IsInParallelMode(), LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), MySerializableXact, PREDICATELOCKTAG::myTarget, PREDICATELOCKTAG::myXact, offsetof, SERIALIZABLEXACT::perXactPredicateListLock, PG_USED_FOR_ASSERTS_ONLY, PredicateLockHashCodeFromTargetHashCode, PredicateLockHashPartitionLock, SERIALIZABLEXACT::predicateLocks, PredicateLockTargetTagHashCode, RemoveTargetIfNoLongerUsed(), SHMQueueDelete(), SHMQueueNext(), PREDICATELOCKTARGET::tag, PREDICATELOCK::tag, PREDICATELOCK::targetLink, TargetTagIsCoveredBy, and PREDICATELOCK::xactLink.

Referenced by PredicateLockAcquire().

{
    SERIALIZABLEXACT *sxact;
    PREDICATELOCK *predlock;

    LWLockAcquire(SerializablePredicateListLock, LW_SHARED);
    sxact = MySerializableXact;
    if (IsInParallelMode())
        LWLockAcquire(&sxact->perXactPredicateListLock, LW_EXCLUSIVE);
    predlock = (PREDICATELOCK *)
        SHMQueueNext(&(sxact->predicateLocks),
                     &(sxact->predicateLocks),
                     offsetof(PREDICATELOCK, xactLink));
    while (predlock)
    {
        SHM_QUEUE  *predlocksxactlink;
        PREDICATELOCK *nextpredlock;
        PREDICATELOCKTAG oldlocktag;
        PREDICATELOCKTARGET *oldtarget;
        PREDICATELOCKTARGETTAG oldtargettag;

        predlocksxactlink = &(predlock->xactLink);
        nextpredlock = (PREDICATELOCK *)
            SHMQueueNext(&(sxact->predicateLocks),
                         predlocksxactlink,
                         offsetof(PREDICATELOCK, xactLink));

        oldlocktag = predlock->tag;
        Assert(oldlocktag.myXact == sxact);
        oldtarget = oldlocktag.myTarget;
        oldtargettag = oldtarget->tag;

        if (TargetTagIsCoveredBy(oldtargettag, *newtargettag))
        {
            uint32      oldtargettaghash;
            LWLock     *partitionLock;
            PREDICATELOCK *rmpredlock PG_USED_FOR_ASSERTS_ONLY;

            oldtargettaghash = PredicateLockTargetTagHashCode(&oldtargettag);
            partitionLock = PredicateLockHashPartitionLock(oldtargettaghash);

            LWLockAcquire(partitionLock, LW_EXCLUSIVE);

            SHMQueueDelete(predlocksxactlink);
            SHMQueueDelete(&(predlock->targetLink));
            rmpredlock = hash_search_with_hash_value
                (PredicateLockHash,
                 &oldlocktag,
                 PredicateLockHashCodeFromTargetHashCode(&oldlocktag,
                                                         oldtargettaghash),
                 HASH_REMOVE, NULL);
            Assert(rmpredlock == predlock);

            RemoveTargetIfNoLongerUsed(oldtarget, oldtargettaghash);

            LWLockRelease(partitionLock);

            DecrementParentLocks(&oldtargettag);
        }

        predlock = nextpredlock;
    }
    if (IsInParallelMode())
        LWLockRelease(&sxact->perXactPredicateListLock);
    LWLockRelease(SerializablePredicateListLock);
}

DeleteLockTarget()

static void DeleteLockTarget ( PREDICATELOCKTARGET *  target, uint32  targettaghash  )

static

Definition at line 2662 of file predicate.c.

References Assert, HASH_REMOVE, hash_search_with_hash_value(), LW_EXCLUSIVE, LWLockAcquire(), LWLockHeldByMe(), LWLockHeldByMeInMode(), LWLockRelease(), offsetof, PredicateLockHashCodeFromTargetHashCode, PredicateLockHashPartitionLock, PREDICATELOCKTARGET::predicateLocks, RemoveTargetIfNoLongerUsed(), SHMQueueDelete(), SHMQueueNext(), PREDICATELOCK::tag, PREDICATELOCK::targetLink, and PREDICATELOCK::xactLink.

Referenced by TransferPredicateLocksToNewTarget().

{
    PREDICATELOCK *predlock;
    SHM_QUEUE  *predlocktargetlink;
    PREDICATELOCK *nextpredlock;
    bool        found;

    Assert(LWLockHeldByMeInMode(SerializablePredicateListLock,
                                LW_EXCLUSIVE));
    Assert(LWLockHeldByMe(PredicateLockHashPartitionLock(targettaghash)));

    predlock = (PREDICATELOCK *)
        SHMQueueNext(&(target->predicateLocks),
                     &(target->predicateLocks),
                     offsetof(PREDICATELOCK, targetLink));
    LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
    while (predlock)
    {
        predlocktargetlink = &(predlock->targetLink);
        nextpredlock = (PREDICATELOCK *)
            SHMQueueNext(&(target->predicateLocks),
                         predlocktargetlink,
                         offsetof(PREDICATELOCK, targetLink));

        SHMQueueDelete(&(predlock->xactLink));
        SHMQueueDelete(&(predlock->targetLink));

        hash_search_with_hash_value
            (PredicateLockHash,
             &predlock->tag,
             PredicateLockHashCodeFromTargetHashCode(&predlock->tag,
                                                     targettaghash),
             HASH_REMOVE, &found);
        Assert(found);

        predlock = nextpredlock;
    }
    LWLockRelease(SerializableXactHashLock);

    /* Remove the target itself, if possible. */
    RemoveTargetIfNoLongerUsed(target, targettaghash);
}

DropAllPredicateLocksFromTable()

static void DropAllPredicateLocksFromTable ( Relation  relation, bool  transfer  )

static

Definition at line 2950 of file predicate.c.

References Assert, PREDICATELOCK::commitSeqNo, RelFileNode::dbNode, GET_PREDICATELOCKTARGETTAG_DB, GET_PREDICATELOCKTARGETTAG_RELATION, GET_PREDICATELOCKTARGETTAG_TYPE, HASH_ENTER, HASH_REMOVE, hash_search(), hash_search_with_hash_value(), hash_seq_init(), hash_seq_search(), i, InvalidOid, InvalidSerCommitSeqNo, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), PREDICATELOCKTAG::myTarget, PREDICATELOCKTAG::myXact, NUM_PREDICATELOCK_PARTITIONS, offsetof, PredicateLockHashCodeFromTargetHashCode, PredicateLockHashPartitionLockByIndex, PredicateLockingNeededForRelation(), SERIALIZABLEXACT::predicateLocks, PREDICATELOCKTARGET::predicateLocks, PredicateLockTargetTagHashCode, PREDLOCKTAG_RELATION, RelationData::rd_id, RelationData::rd_index, RelationData::rd_node, RemoveScratchTarget(), RestoreScratchTarget(), SET_PREDICATELOCKTARGETTAG_RELATION, SHMQueueDelete(), SHMQueueInit(), SHMQueueInsertBefore(), SHMQueueNext(), PredXactListData::SxactGlobalXmin, PREDICATELOCKTARGET::tag, PREDICATELOCK::tag, PREDICATELOCK::targetLink, TransactionIdIsValid, and PREDICATELOCK::xactLink.

Referenced by TransferPredicateLocksToHeapRelation().

{
    HASH_SEQ_STATUS seqstat;
    PREDICATELOCKTARGET *oldtarget;
    PREDICATELOCKTARGET *heaptarget;
    Oid         dbId;
    Oid         relId;
    Oid         heapId;
    int         i;
    bool        isIndex;
    bool        found;
    uint32      heaptargettaghash;

    /*
     * Bail out quickly if there are no serializable transactions running.
     * It's safe to check this without taking locks because the caller is
     * holding an ACCESS EXCLUSIVE lock on the relation.  No new locks which
     * would matter here can be acquired while that is held.
     */
    if (!TransactionIdIsValid(PredXact->SxactGlobalXmin))
        return;

    if (!PredicateLockingNeededForRelation(relation))
        return;

    dbId = relation->rd_node.dbNode;
    relId = relation->rd_id;
    if (relation->rd_index == NULL)
    {
        isIndex = false;
        heapId = relId;
    }
    else
    {
        isIndex = true;
        heapId = relation->rd_index->indrelid;
    }
    Assert(heapId != InvalidOid);
    Assert(transfer || !isIndex);   /* index OID only makes sense with
                                     * transfer */

    /* Retrieve first time needed, then keep. */
    heaptargettaghash = 0;
    heaptarget = NULL;

    /* Acquire locks on all lock partitions */
    LWLockAcquire(SerializablePredicateListLock, LW_EXCLUSIVE);
    for (i = 0; i < NUM_PREDICATELOCK_PARTITIONS; i++)
        LWLockAcquire(PredicateLockHashPartitionLockByIndex(i), LW_EXCLUSIVE);
    LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);

    /*
     * Remove the dummy entry to give us scratch space, so we know we'll be
     * able to create the new lock target.
     */
    if (transfer)
        RemoveScratchTarget(true);

    /* Scan through target map */
    hash_seq_init(&seqstat, PredicateLockTargetHash);

    while ((oldtarget = (PREDICATELOCKTARGET *) hash_seq_search(&seqstat)))
    {
        PREDICATELOCK *oldpredlock;

        /*
         * Check whether this is a target which needs attention.
         */
        if (GET_PREDICATELOCKTARGETTAG_RELATION(oldtarget->tag) != relId)
            continue;           /* wrong relation id */
        if (GET_PREDICATELOCKTARGETTAG_DB(oldtarget->tag) != dbId)
            continue;           /* wrong database id */
        if (transfer && !isIndex
            && GET_PREDICATELOCKTARGETTAG_TYPE(oldtarget->tag) == PREDLOCKTAG_RELATION)
            continue;           /* already the right lock */

        /*
         * If we made it here, we have work to do.  We make sure the heap
         * relation lock exists, then we walk the list of predicate locks for
         * the old target we found, moving all locks to the heap relation lock
         * -- unless they already hold that.
         */

        /*
         * First make sure we have the heap relation target.  We only need to
         * do this once.
         */
        if (transfer && heaptarget == NULL)
        {
            PREDICATELOCKTARGETTAG heaptargettag;

            SET_PREDICATELOCKTARGETTAG_RELATION(heaptargettag, dbId, heapId);
            heaptargettaghash = PredicateLockTargetTagHashCode(&heaptargettag);
            heaptarget = hash_search_with_hash_value(PredicateLockTargetHash,
                                                     &heaptargettag,
                                                     heaptargettaghash,
                                                     HASH_ENTER, &found);
            if (!found)
                SHMQueueInit(&heaptarget->predicateLocks);
        }

        /*
         * Loop through all the locks on the old target, replacing them with
         * locks on the new target.
         */
        oldpredlock = (PREDICATELOCK *)
            SHMQueueNext(&(oldtarget->predicateLocks),
                         &(oldtarget->predicateLocks),
                         offsetof(PREDICATELOCK, targetLink));
        while (oldpredlock)
        {
            PREDICATELOCK *nextpredlock;
            PREDICATELOCK *newpredlock;
            SerCommitSeqNo oldCommitSeqNo;
            SERIALIZABLEXACT *oldXact;

            nextpredlock = (PREDICATELOCK *)
                SHMQueueNext(&(oldtarget->predicateLocks),
                             &(oldpredlock->targetLink),
                             offsetof(PREDICATELOCK, targetLink));

            /*
             * Remove the old lock first. This avoids the chance of running
             * out of lock structure entries for the hash table.
             */
            oldCommitSeqNo = oldpredlock->commitSeqNo;
            oldXact = oldpredlock->tag.myXact;

            SHMQueueDelete(&(oldpredlock->xactLink));

            /*
             * No need for retail delete from oldtarget list, we're removing
             * the whole target anyway.
             */
            hash_search(PredicateLockHash,
                        &oldpredlock->tag,
                        HASH_REMOVE, &found);
            Assert(found);

            if (transfer)
            {
                PREDICATELOCKTAG newpredlocktag;

                newpredlocktag.myTarget = heaptarget;
                newpredlocktag.myXact = oldXact;
                newpredlock = (PREDICATELOCK *)
                    hash_search_with_hash_value(PredicateLockHash,
                                                &newpredlocktag,
                                                PredicateLockHashCodeFromTargetHashCode(&newpredlocktag,
                                                                                        heaptargettaghash),
                                                HASH_ENTER,
                                                &found);
                if (!found)
                {
                    SHMQueueInsertBefore(&(heaptarget->predicateLocks),
                                         &(newpredlock->targetLink));
                    SHMQueueInsertBefore(&(newpredlocktag.myXact->predicateLocks),
                                         &(newpredlock->xactLink));
                    newpredlock->commitSeqNo = oldCommitSeqNo;
                }
                else
                {
                    if (newpredlock->commitSeqNo < oldCommitSeqNo)
                        newpredlock->commitSeqNo = oldCommitSeqNo;
                }

                Assert(newpredlock->commitSeqNo != 0);
                Assert((newpredlock->commitSeqNo == InvalidSerCommitSeqNo)
                       || (newpredlock->tag.myXact == OldCommittedSxact));
            }

            oldpredlock = nextpredlock;
        }

        hash_search(PredicateLockTargetHash, &oldtarget->tag, HASH_REMOVE,
                    &found);
        Assert(found);
    }

    /* Put the scratch entry back */
    if (transfer)
        RestoreScratchTarget(true);

    /* Release locks in reverse order */
    LWLockRelease(SerializableXactHashLock);
    for (i = NUM_PREDICATELOCK_PARTITIONS - 1; i >= 0; i--)
        LWLockRelease(PredicateLockHashPartitionLockByIndex(i));
    LWLockRelease(SerializablePredicateListLock);
}

FirstPredXact()

static SERIALIZABLEXACT * FirstPredXact ( void  )

static

Definition at line 612 of file predicate.c.

References PredXactListData::activeList, offsetof, SHMQueueNext(), and PredXactListElementData::sxact.

Referenced by GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), and SetNewSxactGlobalXmin().

{
    PredXactListElement ptle;

    ptle = (PredXactListElement)
        SHMQueueNext(&PredXact->activeList,
                     &PredXact->activeList,
                     offsetof(PredXactListElementData, link));
    if (!ptle)
        return NULL;

    return &ptle->sxact;
}

FlagRWConflict()

static void FlagRWConflict ( SERIALIZABLEXACT *  reader, SERIALIZABLEXACT *  writer  )

static

Definition at line 4621 of file predicate.c.

References Assert, SERIALIZABLEXACT::flags, OnConflict_CheckForSerializationFailure(), SetRWConflict(), SXACT_FLAG_SUMMARY_CONFLICT_IN, and SXACT_FLAG_SUMMARY_CONFLICT_OUT.

Referenced by CheckForSerializableConflictOut(), CheckTableForSerializableConflictIn(), and CheckTargetForConflictsIn().

{
    Assert(reader != writer);

    /* First, see if this conflict causes failure. */
    OnConflict_CheckForSerializationFailure(reader, writer);

    /* Actually do the conflict flagging. */
    if (reader == OldCommittedSxact)
        writer->flags |= SXACT_FLAG_SUMMARY_CONFLICT_IN;
    else if (writer == OldCommittedSxact)
        reader->flags |= SXACT_FLAG_SUMMARY_CONFLICT_OUT;
    else
        SetRWConflict(reader, writer);
}

FlagSxactUnsafe()

static void FlagSxactUnsafe ( SERIALIZABLEXACT *  sxact )

static

Definition at line 750 of file predicate.c.

References Assert, SERIALIZABLEXACT::flags, RWConflictData::inLink, offsetof, SERIALIZABLEXACT::possibleUnsafeConflicts, ReleaseRWConflict(), SHMQueueNext(), SXACT_FLAG_RO_UNSAFE, RWConflictData::sxactIn, SxactIsReadOnly, SxactIsROSafe, and RWConflictData::sxactOut.

Referenced by ReleasePredicateLocks().

{
    RWConflict  conflict,
                nextConflict;

    Assert(SxactIsReadOnly(sxact));
    Assert(!SxactIsROSafe(sxact));

    sxact->flags |= SXACT_FLAG_RO_UNSAFE;

    /*
     * We know this isn't a safe snapshot, so we can stop looking for other
     * potential conflicts.
     */
    conflict = (RWConflict)
        SHMQueueNext(&sxact->possibleUnsafeConflicts,
                     &sxact->possibleUnsafeConflicts,
                     offsetof(RWConflictData, inLink));
    while (conflict)
    {
        nextConflict = (RWConflict)
            SHMQueueNext(&sxact->possibleUnsafeConflicts,
                         &conflict->inLink,
                         offsetof(RWConflictData, inLink));

        Assert(!SxactIsReadOnly(conflict->sxactOut));
        Assert(sxact == conflict->sxactIn);

        ReleaseRWConflict(conflict);

        conflict = nextConflict;
    }
}

GetParentPredicateLockTag()

static bool GetParentPredicateLockTag ( const PREDICATELOCKTARGETTAG *  tag, PREDICATELOCKTARGETTAG *  parent  )

static

Definition at line 2054 of file predicate.c.

References Assert, GET_PREDICATELOCKTARGETTAG_DB, GET_PREDICATELOCKTARGETTAG_PAGE, GET_PREDICATELOCKTARGETTAG_RELATION, GET_PREDICATELOCKTARGETTAG_TYPE, PREDLOCKTAG_PAGE, PREDLOCKTAG_RELATION, PREDLOCKTAG_TUPLE, SET_PREDICATELOCKTARGETTAG_PAGE, and SET_PREDICATELOCKTARGETTAG_RELATION.

Referenced by CheckAndPromotePredicateLockRequest(), CoarserLockCovers(), DecrementParentLocks(), and PredicateLockPageSplit().

{
    switch (GET_PREDICATELOCKTARGETTAG_TYPE(*tag))
    {
        case PREDLOCKTAG_RELATION:
            /* relation locks have no parent lock */
            return false;

        case PREDLOCKTAG_PAGE:
            /* parent lock is relation lock */
            SET_PREDICATELOCKTARGETTAG_RELATION(*parent,
                                                GET_PREDICATELOCKTARGETTAG_DB(*tag),
                                                GET_PREDICATELOCKTARGETTAG_RELATION(*tag));

            return true;

        case PREDLOCKTAG_TUPLE:
            /* parent lock is page lock */
            SET_PREDICATELOCKTARGETTAG_PAGE(*parent,
                                            GET_PREDICATELOCKTARGETTAG_DB(*tag),
                                            GET_PREDICATELOCKTARGETTAG_RELATION(*tag),
                                            GET_PREDICATELOCKTARGETTAG_PAGE(*tag));
            return true;
    }

    /* not reachable */
    Assert(false);
    return false;
}

GetPredicateLockStatusData()

PredicateLockData* GetPredicateLockStatusData

(

void

)

Definition at line 1443 of file predicate.c.

References Assert, hash_get_num_entries(), hash_seq_init(), hash_seq_search(), i, PredicateLockData::locktags, LW_SHARED, LWLockAcquire(), LWLockRelease(), PREDICATELOCKTAG::myTarget, PREDICATELOCKTAG::myXact, PredicateLockData::nelements, NUM_PREDICATELOCK_PARTITIONS, palloc(), PredicateLockHashPartitionLockByIndex, PREDICATELOCKTARGET::tag, PREDICATELOCK::tag, and PredicateLockData::xacts.

Referenced by pg_lock_status().

{
    PredicateLockData *data;
    int         i;
    int         els,
                el;
    HASH_SEQ_STATUS seqstat;
    PREDICATELOCK *predlock;

    data = (PredicateLockData *) palloc(sizeof(PredicateLockData));

    /*
     * To ensure consistency, take simultaneous locks on all partition locks
     * in ascending order, then SerializableXactHashLock.
     */
    for (i = 0; i < NUM_PREDICATELOCK_PARTITIONS; i++)
        LWLockAcquire(PredicateLockHashPartitionLockByIndex(i), LW_SHARED);
    LWLockAcquire(SerializableXactHashLock, LW_SHARED);

    /* Get number of locks and allocate appropriately-sized arrays. */
    els = hash_get_num_entries(PredicateLockHash);
    data->nelements = els;
    data->locktags = (PREDICATELOCKTARGETTAG *)
        palloc(sizeof(PREDICATELOCKTARGETTAG) * els);
    data->xacts = (SERIALIZABLEXACT *)
        palloc(sizeof(SERIALIZABLEXACT) * els);


    /* Scan through PredicateLockHash and copy contents */
    hash_seq_init(&seqstat, PredicateLockHash);

    el = 0;

    while ((predlock = (PREDICATELOCK *) hash_seq_search(&seqstat)))
    {
        data->locktags[el] = predlock->tag.myTarget->tag;
        data->xacts[el] = *predlock->tag.myXact;
        el++;
    }

    Assert(el == els);

    /* Release locks in reverse order */
    LWLockRelease(SerializableXactHashLock);
    for (i = NUM_PREDICATELOCK_PARTITIONS - 1; i >= 0; i--)
        LWLockRelease(PredicateLockHashPartitionLockByIndex(i));

    return data;
}

GetSafeSnapshot()

static Snapshot GetSafeSnapshot ( Snapshot  snapshot )

static

Definition at line 1558 of file predicate.c.

References Assert, DEBUG2, ereport, errcode(), errmsg_internal(), SERIALIZABLEXACT::flags, GetSerializableTransactionSnapshotInt(), InvalidPid, InvalidSerializableXact, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), SERIALIZABLEXACT::possibleUnsafeConflicts, ProcWaitForSignal(), ReleasePredicateLocks(), SHMQueueEmpty(), SXACT_FLAG_DEFERRABLE_WAITING, SxactIsROSafe, SxactIsROUnsafe, WAIT_EVENT_SAFE_SNAPSHOT, XactDeferrable, and XactReadOnly.

Referenced by GetSerializableTransactionSnapshot().

{
    Snapshot    snapshot;

    Assert(XactReadOnly && XactDeferrable);

    while (true)
    {
        /*
         * GetSerializableTransactionSnapshotInt is going to call
         * GetSnapshotData, so we need to provide it the static snapshot area
         * our caller passed to us.  The pointer returned is actually the same
         * one passed to it, but we avoid assuming that here.
         */
        snapshot = GetSerializableTransactionSnapshotInt(origSnapshot,
                                                         NULL, InvalidPid);

        if (MySerializableXact == InvalidSerializableXact)
            return snapshot;    /* no concurrent r/w xacts; it's safe */

        LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);

        /*
         * Wait for concurrent transactions to finish. Stop early if one of
         * them marked us as conflicted.
         */
        MySerializableXact->flags |= SXACT_FLAG_DEFERRABLE_WAITING;
        while (!(SHMQueueEmpty(&MySerializableXact->possibleUnsafeConflicts) ||
                 SxactIsROUnsafe(MySerializableXact)))
        {
            LWLockRelease(SerializableXactHashLock);
            ProcWaitForSignal(WAIT_EVENT_SAFE_SNAPSHOT);
            LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
        }
        MySerializableXact->flags &= ~SXACT_FLAG_DEFERRABLE_WAITING;

        if (!SxactIsROUnsafe(MySerializableXact))
        {
            LWLockRelease(SerializableXactHashLock);
            break;              /* success */
        }

        LWLockRelease(SerializableXactHashLock);

        /* else, need to retry... */
        ereport(DEBUG2,
                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                 errmsg_internal("deferrable snapshot was unsafe; trying a new one")));
        ReleasePredicateLocks(false, false);
    }

    /*
     * Now we have a safe snapshot, so we don't need to do any further checks.
     */
    Assert(SxactIsROSafe(MySerializableXact));
    ReleasePredicateLocks(false, true);

    return snapshot;
}

GetSafeSnapshotBlockingPids()

int GetSafeSnapshotBlockingPids	(	int	blocked_pid,
		int *	output,
		int	output_size
	)

Definition at line 1628 of file predicate.c.

References FirstPredXact(), RWConflictData::inLink, LW_SHARED, LWLockAcquire(), LWLockRelease(), NextPredXact(), offsetof, SERIALIZABLEXACT::pid, SERIALIZABLEXACT::possibleUnsafeConflicts, SHMQueueNext(), SxactIsDeferrableWaiting, and RWConflictData::sxactOut.

Referenced by pg_isolation_test_session_is_blocked(), and pg_safe_snapshot_blocking_pids().

{
    int         num_written = 0;
    SERIALIZABLEXACT *sxact;

    LWLockAcquire(SerializableXactHashLock, LW_SHARED);

    /* Find blocked_pid's SERIALIZABLEXACT by linear search. */
    for (sxact = FirstPredXact(); sxact != NULL; sxact = NextPredXact(sxact))
    {
        if (sxact->pid == blocked_pid)
            break;
    }

    /* Did we find it, and is it currently waiting in GetSafeSnapshot? */
    if (sxact != NULL && SxactIsDeferrableWaiting(sxact))
    {
        RWConflict  possibleUnsafeConflict;

        /* Traverse the list of possible unsafe conflicts collecting PIDs. */
        possibleUnsafeConflict = (RWConflict)
            SHMQueueNext(&sxact->possibleUnsafeConflicts,
                         &sxact->possibleUnsafeConflicts,
                         offsetof(RWConflictData, inLink));

        while (possibleUnsafeConflict != NULL && num_written < output_size)
        {
            output[num_written++] = possibleUnsafeConflict->sxactOut->pid;
            possibleUnsafeConflict = (RWConflict)
                SHMQueueNext(&sxact->possibleUnsafeConflicts,
                             &possibleUnsafeConflict->inLink,
                             offsetof(RWConflictData, inLink));
        }
    }

    LWLockRelease(SerializableXactHashLock);

    return num_written;
}

GetSerializableTransactionSnapshot()

Snapshot GetSerializableTransactionSnapshot

(

Snapshot

snapshot

)

Definition at line 1680 of file predicate.c.

References Assert, ereport, errcode(), errdetail(), errhint(), errmsg(), ERROR, GetSafeSnapshot(), GetSerializableTransactionSnapshotInt(), InvalidPid, IsolationIsSerializable, RecoveryInProgress(), XactDeferrable, and XactReadOnly.

Referenced by GetTransactionSnapshot().

{
    Assert(IsolationIsSerializable());

    /*
     * Can't use serializable mode while recovery is still active, as it is,
     * for example, on a hot standby.  We could get here despite the check in
     * check_XactIsoLevel() if default_transaction_isolation is set to
     * serializable, so phrase the hint accordingly.
     */
    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("cannot use serializable mode in a hot standby"),
                 errdetail("\"default_transaction_isolation\" is set to \"serializable\"."),
                 errhint("You can use \"SET default_transaction_isolation = 'repeatable read'\" to change the default.")));

    /*
     * A special optimization is available for SERIALIZABLE READ ONLY
     * DEFERRABLE transactions -- we can wait for a suitable snapshot and
     * thereby avoid all SSI overhead once it's running.
     */
    if (XactReadOnly && XactDeferrable)
        return GetSafeSnapshot(snapshot);

    return GetSerializableTransactionSnapshotInt(snapshot,
                                                 NULL, InvalidPid);
}

GetSerializableTransactionSnapshotInt()

static Snapshot GetSerializableTransactionSnapshotInt ( Snapshot  snapshot, VirtualTransactionId *  sourcevxid, int  sourcepid  )

static

Definition at line 1762 of file predicate.c.

References Assert, SERIALIZABLEXACT::commitSeqNo, CreateLocalPredicateLockHash(), CreatePredXact(), elog, ereport, errcode(), errdetail(), errmsg(), ERROR, SERIALIZABLEXACT::finishedBefore, SERIALIZABLEXACT::finishedLink, FirstPredXact(), SERIALIZABLEXACT::flags, GET_VXID_FROM_PGPROC, GetSnapshotData(), GetTopTransactionIdIfAny(), SERIALIZABLEXACT::inConflicts, InvalidSerCommitSeqNo, InvalidSerializableXact, InvalidTransactionId, IsInParallelMode(), SERIALIZABLEXACT::lastCommitBeforeSnapshot, PredXactListData::LastSxactCommitSeqNo, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), max_prepared_xacts, MaxBackends, MyProc, MyProcPid, MyXactDidWrite, NextPredXact(), SERIALIZABLEXACT::outConflicts, SERIALIZABLEXACT::pid, SERIALIZABLEXACT::possibleUnsafeConflicts, SERIALIZABLEXACT::predicateLocks, SERIALIZABLEXACT::prepareSeqNo, ProcArrayInstallImportedXmin(), RecoveryInProgress(), ReleasePredXact(), SERIALIZABLEXACT::SeqNo, SerialSetActiveSerXmin(), SetPossibleUnsafeConflict(), SHMQueueElemInit(), SHMQueueInit(), SummarizeOldestCommittedSxact(), SXACT_FLAG_READ_ONLY, PredXactListData::SxactGlobalXmin, PredXactListData::SxactGlobalXminCount, SxactIsCommitted, SxactIsDoomed, SxactIsReadOnly, SERIALIZABLEXACT::topXid, TransactionIdEquals, TransactionIdFollows(), TransactionIdIsValid, SERIALIZABLEXACT::vxid, PredXactListData::WritableSxactCount, XactReadOnly, SERIALIZABLEXACT::xmin, and SnapshotData::xmin.

Referenced by GetSafeSnapshot(), GetSerializableTransactionSnapshot(), and SetSerializableTransactionSnapshot().

{
    PGPROC     *proc;
    VirtualTransactionId vxid;
    SERIALIZABLEXACT *sxact,
               *othersxact;

    /* We only do this for serializable transactions.  Once. */
    Assert(MySerializableXact == InvalidSerializableXact);

    Assert(!RecoveryInProgress());

    /*
     * Since all parts of a serializable transaction must use the same
     * snapshot, it is too late to establish one after a parallel operation
     * has begun.
     */
    if (IsInParallelMode())
        elog(ERROR, "cannot establish serializable snapshot during a parallel operation");

    proc = MyProc;
    Assert(proc != NULL);
    GET_VXID_FROM_PGPROC(vxid, *proc);

    /*
     * First we get the sxact structure, which may involve looping and access
     * to the "finished" list to free a structure for use.
     *
     * We must hold SerializableXactHashLock when taking/checking the snapshot
     * to avoid race conditions, for much the same reasons that
     * GetSnapshotData takes the ProcArrayLock.  Since we might have to
     * release SerializableXactHashLock to call SummarizeOldestCommittedSxact,
     * this means we have to create the sxact first, which is a bit annoying
     * (in particular, an elog(ERROR) in procarray.c would cause us to leak
     * the sxact).  Consider refactoring to avoid this.
     */
#ifdef TEST_SUMMARIZE_SERIAL
    SummarizeOldestCommittedSxact();
#endif
    LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
    do
    {
        sxact = CreatePredXact();
        /* If null, push out committed sxact to SLRU summary & retry. */
        if (!sxact)
        {
            LWLockRelease(SerializableXactHashLock);
            SummarizeOldestCommittedSxact();
            LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
        }
    } while (!sxact);

    /* Get the snapshot, or check that it's safe to use */
    if (!sourcevxid)
        snapshot = GetSnapshotData(snapshot);
    else if (!ProcArrayInstallImportedXmin(snapshot->xmin, sourcevxid))
    {
        ReleasePredXact(sxact);
        LWLockRelease(SerializableXactHashLock);
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("could not import the requested snapshot"),
                 errdetail("The source process with PID %d is not running anymore.",
                           sourcepid)));
    }

    /*
     * If there are no serializable transactions which are not read-only, we
     * can "opt out" of predicate locking and conflict checking for a
     * read-only transaction.
     *
     * The reason this is safe is that a read-only transaction can only become
     * part of a dangerous structure if it overlaps a writable transaction
     * which in turn overlaps a writable transaction which committed before
     * the read-only transaction started.  A new writable transaction can
     * overlap this one, but it can't meet the other condition of overlapping
     * a transaction which committed before this one started.
     */
    if (XactReadOnly && PredXact->WritableSxactCount == 0)
    {
        ReleasePredXact(sxact);
        LWLockRelease(SerializableXactHashLock);
        return snapshot;
    }

    /* Maintain serializable global xmin info. */
    if (!TransactionIdIsValid(PredXact->SxactGlobalXmin))
    {
        Assert(PredXact->SxactGlobalXminCount == 0);
        PredXact->SxactGlobalXmin = snapshot->xmin;
        PredXact->SxactGlobalXminCount = 1;
        SerialSetActiveSerXmin(snapshot->xmin);
    }
    else if (TransactionIdEquals(snapshot->xmin, PredXact->SxactGlobalXmin))
    {
        Assert(PredXact->SxactGlobalXminCount > 0);
        PredXact->SxactGlobalXminCount++;
    }
    else
    {
        Assert(TransactionIdFollows(snapshot->xmin, PredXact->SxactGlobalXmin));
    }

    /* Initialize the structure. */
    sxact->vxid = vxid;
    sxact->SeqNo.lastCommitBeforeSnapshot = PredXact->LastSxactCommitSeqNo;
    sxact->prepareSeqNo = InvalidSerCommitSeqNo;
    sxact->commitSeqNo = InvalidSerCommitSeqNo;
    SHMQueueInit(&(sxact->outConflicts));
    SHMQueueInit(&(sxact->inConflicts));
    SHMQueueInit(&(sxact->possibleUnsafeConflicts));
    sxact->topXid = GetTopTransactionIdIfAny();
    sxact->finishedBefore = InvalidTransactionId;
    sxact->xmin = snapshot->xmin;
    sxact->pid = MyProcPid;
    SHMQueueInit(&(sxact->predicateLocks));
    SHMQueueElemInit(&(sxact->finishedLink));
    sxact->flags = 0;
    if (XactReadOnly)
    {
        sxact->flags |= SXACT_FLAG_READ_ONLY;

        /*
         * Register all concurrent r/w transactions as possible conflicts; if
         * all of them commit without any outgoing conflicts to earlier
         * transactions then this snapshot can be deemed safe (and we can run
         * without tracking predicate locks).
         */
        for (othersxact = FirstPredXact();
             othersxact != NULL;
             othersxact = NextPredXact(othersxact))
        {
            if (!SxactIsCommitted(othersxact)
                && !SxactIsDoomed(othersxact)
                && !SxactIsReadOnly(othersxact))
            {
                SetPossibleUnsafeConflict(sxact, othersxact);
            }
        }
    }
    else
    {
        ++(PredXact->WritableSxactCount);
        Assert(PredXact->WritableSxactCount <=
               (MaxBackends + max_prepared_xacts));
    }

    MySerializableXact = sxact;
    MyXactDidWrite = false;     /* haven't written anything yet */

    LWLockRelease(SerializableXactHashLock);

    CreateLocalPredicateLockHash();

    return snapshot;
}

InitPredicateLocks()

void InitPredicateLocks

(

void

)

Definition at line 1153 of file predicate.c.

References PredXactListData::activeList, Assert, PredXactListData::availableList, RWConflictPoolHeaderData::availableList, PredXactListData::CanPartialClearThrough, SERIALIZABLEXACT::commitSeqNo, CreatePredXact(), PredXactListData::element, RWConflictPoolHeaderData::element, HASHCTL::entrysize, SERIALIZABLEXACT::finishedBefore, SERIALIZABLEXACT::finishedLink, FirstNormalSerCommitSeqNo, SERIALIZABLEXACT::flags, HASHCTL::hash, HASH_BLOBS, HASH_ELEM, HASH_ENTER, HASH_FIXED_SIZE, HASH_FUNCTION, HASH_PARTITION, hash_search(), PredXactListData::HavePartialClearedThrough, i, SERIALIZABLEXACT::inConflicts, InvalidTransactionId, IsUnderPostmaster, HASHCTL::keysize, SERIALIZABLEXACT::lastCommitBeforeSnapshot, PredXactListData::LastSxactCommitSeqNo, PredXactListElementData::link, LWLockInitialize(), LWTRANCHE_PER_XACT_PREDICATE_LIST, max_prepared_xacts, MaxBackends, mul_size(), NPREDICATELOCKTARGETENTS, HASHCTL::num_partitions, NUM_PREDICATELOCK_PARTITIONS, PredXactListData::OldCommittedSxact, SERIALIZABLEXACT::outConflicts, RWConflictData::outLink, SERIALIZABLEXACT::perXactPredicateListLock, SERIALIZABLEXACT::pid, SERIALIZABLEXACT::possibleUnsafeConflicts, predicatelock_hash(), PredicateLockHashPartitionLock, SERIALIZABLEXACT::predicateLocks, PredicateLockTargetTagHashCode, PredXactListDataSize, PredXactListElementDataSize, SERIALIZABLEXACT::prepareSeqNo, RWConflictDataSize, RWConflictPoolHeaderDataSize, ScratchTargetTagHash, SERIALIZABLEXACT::SeqNo, SerialInit(), SetInvalidVirtualTransactionId, ShmemAlloc(), ShmemInitHash(), ShmemInitStruct(), SHMQueueInit(), SHMQueueInsertBefore(), PredXactListElementData::sxact, SXACT_FLAG_COMMITTED, PredXactListData::SxactGlobalXmin, PredXactListData::SxactGlobalXminCount, SERIALIZABLEXACT::topXid, SERIALIZABLEXACT::vxid, PredXactListData::WritableSxactCount, and SERIALIZABLEXACT::xmin.

Referenced by CreateSharedMemoryAndSemaphores().

{
    HASHCTL     info;
    long        max_table_size;
    Size        requestSize;
    bool        found;

#ifndef EXEC_BACKEND
    Assert(!IsUnderPostmaster);
#endif

    /*
     * Compute size of predicate lock target hashtable. Note these
     * calculations must agree with PredicateLockShmemSize!
     */
    max_table_size = NPREDICATELOCKTARGETENTS();

    /*
     * Allocate hash table for PREDICATELOCKTARGET structs.  This stores
     * per-predicate-lock-target information.
     */
    info.keysize = sizeof(PREDICATELOCKTARGETTAG);
    info.entrysize = sizeof(PREDICATELOCKTARGET);
    info.num_partitions = NUM_PREDICATELOCK_PARTITIONS;

    PredicateLockTargetHash = ShmemInitHash("PREDICATELOCKTARGET hash",
                                            max_table_size,
                                            max_table_size,
                                            &info,
                                            HASH_ELEM | HASH_BLOBS |
                                            HASH_PARTITION | HASH_FIXED_SIZE);

    /*
     * Reserve a dummy entry in the hash table; we use it to make sure there's
     * always one entry available when we need to split or combine a page,
     * because running out of space there could mean aborting a
     * non-serializable transaction.
     */
    if (!IsUnderPostmaster)
    {
        (void) hash_search(PredicateLockTargetHash, &ScratchTargetTag,
                           HASH_ENTER, &found);
        Assert(!found);
    }

    /* Pre-calculate the hash and partition lock of the scratch entry */
    ScratchTargetTagHash = PredicateLockTargetTagHashCode(&ScratchTargetTag);
    ScratchPartitionLock = PredicateLockHashPartitionLock(ScratchTargetTagHash);

    /*
     * Allocate hash table for PREDICATELOCK structs.  This stores per
     * xact-lock-of-a-target information.
     */
    info.keysize = sizeof(PREDICATELOCKTAG);
    info.entrysize = sizeof(PREDICATELOCK);
    info.hash = predicatelock_hash;
    info.num_partitions = NUM_PREDICATELOCK_PARTITIONS;

    /* Assume an average of 2 xacts per target */
    max_table_size *= 2;

    PredicateLockHash = ShmemInitHash("PREDICATELOCK hash",
                                      max_table_size,
                                      max_table_size,
                                      &info,
                                      HASH_ELEM | HASH_FUNCTION |
                                      HASH_PARTITION | HASH_FIXED_SIZE);

    /*
     * Compute size for serializable transaction hashtable. Note these
     * calculations must agree with PredicateLockShmemSize!
     */
    max_table_size = (MaxBackends + max_prepared_xacts);

    /*
     * Allocate a list to hold information on transactions participating in
     * predicate locking.
     *
     * Assume an average of 10 predicate locking transactions per backend.
     * This allows aggressive cleanup while detail is present before data must
     * be summarized for storage in SLRU and the "dummy" transaction.
     */
    max_table_size *= 10;

    PredXact = ShmemInitStruct("PredXactList",
                               PredXactListDataSize,
                               &found);
    Assert(found == IsUnderPostmaster);
    if (!found)
    {
        int         i;

        SHMQueueInit(&PredXact->availableList);
        SHMQueueInit(&PredXact->activeList);
        PredXact->SxactGlobalXmin = InvalidTransactionId;
        PredXact->SxactGlobalXminCount = 0;
        PredXact->WritableSxactCount = 0;
        PredXact->LastSxactCommitSeqNo = FirstNormalSerCommitSeqNo - 1;
        PredXact->CanPartialClearThrough = 0;
        PredXact->HavePartialClearedThrough = 0;
        requestSize = mul_size((Size) max_table_size,
                               PredXactListElementDataSize);
        PredXact->element = ShmemAlloc(requestSize);
        /* Add all elements to available list, clean. */
        memset(PredXact->element, 0, requestSize);
        for (i = 0; i < max_table_size; i++)
        {
            LWLockInitialize(&PredXact->element[i].sxact.perXactPredicateListLock,
                             LWTRANCHE_PER_XACT_PREDICATE_LIST);
            SHMQueueInsertBefore(&(PredXact->availableList),
                                 &(PredXact->element[i].link));
        }
        PredXact->OldCommittedSxact = CreatePredXact();
        SetInvalidVirtualTransactionId(PredXact->OldCommittedSxact->vxid);
        PredXact->OldCommittedSxact->prepareSeqNo = 0;
        PredXact->OldCommittedSxact->commitSeqNo = 0;
        PredXact->OldCommittedSxact->SeqNo.lastCommitBeforeSnapshot = 0;
        SHMQueueInit(&PredXact->OldCommittedSxact->outConflicts);
        SHMQueueInit(&PredXact->OldCommittedSxact->inConflicts);
        SHMQueueInit(&PredXact->OldCommittedSxact->predicateLocks);
        SHMQueueInit(&PredXact->OldCommittedSxact->finishedLink);
        SHMQueueInit(&PredXact->OldCommittedSxact->possibleUnsafeConflicts);
        PredXact->OldCommittedSxact->topXid = InvalidTransactionId;
        PredXact->OldCommittedSxact->finishedBefore = InvalidTransactionId;
        PredXact->OldCommittedSxact->xmin = InvalidTransactionId;
        PredXact->OldCommittedSxact->flags = SXACT_FLAG_COMMITTED;
        PredXact->OldCommittedSxact->pid = 0;
    }
    /* This never changes, so let's keep a local copy. */
    OldCommittedSxact = PredXact->OldCommittedSxact;

    /*
     * Allocate hash table for SERIALIZABLEXID structs.  This stores per-xid
     * information for serializable transactions which have accessed data.
     */
    info.keysize = sizeof(SERIALIZABLEXIDTAG);
    info.entrysize = sizeof(SERIALIZABLEXID);

    SerializableXidHash = ShmemInitHash("SERIALIZABLEXID hash",
                                        max_table_size,
                                        max_table_size,
                                        &info,
                                        HASH_ELEM | HASH_BLOBS |
                                        HASH_FIXED_SIZE);

    /*
     * Allocate space for tracking rw-conflicts in lists attached to the
     * transactions.
     *
     * Assume an average of 5 conflicts per transaction.  Calculations suggest
     * that this will prevent resource exhaustion in even the most pessimal
     * loads up to max_connections = 200 with all 200 connections pounding the
     * database with serializable transactions.  Beyond that, there may be
     * occasional transactions canceled when trying to flag conflicts. That's
     * probably OK.
     */
    max_table_size *= 5;

    RWConflictPool = ShmemInitStruct("RWConflictPool",
                                     RWConflictPoolHeaderDataSize,
                                     &found);
    Assert(found == IsUnderPostmaster);
    if (!found)
    {
        int         i;

        SHMQueueInit(&RWConflictPool->availableList);
        requestSize = mul_size((Size) max_table_size,
                               RWConflictDataSize);
        RWConflictPool->element = ShmemAlloc(requestSize);
        /* Add all elements to available list, clean. */
        memset(RWConflictPool->element, 0, requestSize);
        for (i = 0; i < max_table_size; i++)
        {
            SHMQueueInsertBefore(&(RWConflictPool->availableList),
                                 &(RWConflictPool->element[i].outLink));
        }
    }

    /*
     * Create or attach to the header for the list of finished serializable
     * transactions.
     */
    FinishedSerializableTransactions = (SHM_QUEUE *)
        ShmemInitStruct("FinishedSerializableTransactions",
                        sizeof(SHM_QUEUE),
                        &found);
    Assert(found == IsUnderPostmaster);
    if (!found)
        SHMQueueInit(FinishedSerializableTransactions);

    /*
     * Initialize the SLRU storage for old committed serializable
     * transactions.
     */
    SerialInit();
}

MaxPredicateChildLocks()

static int MaxPredicateChildLocks ( const PREDICATELOCKTARGETTAG *  tag )

static

Definition at line 2281 of file predicate.c.

References Assert, GET_PREDICATELOCKTARGETTAG_TYPE, max_predicate_locks_per_page, max_predicate_locks_per_relation, max_predicate_locks_per_xact, PREDLOCKTAG_PAGE, PREDLOCKTAG_RELATION, and PREDLOCKTAG_TUPLE.

Referenced by CheckAndPromotePredicateLockRequest().

{
    switch (GET_PREDICATELOCKTARGETTAG_TYPE(*tag))
    {
        case PREDLOCKTAG_RELATION:
            return max_predicate_locks_per_relation < 0
                ? (max_predicate_locks_per_xact
                   / (-max_predicate_locks_per_relation)) - 1
                : max_predicate_locks_per_relation;

        case PREDLOCKTAG_PAGE:
            return max_predicate_locks_per_page;

        case PREDLOCKTAG_TUPLE:

            /*
             * not reachable: nothing is finer-granularity than a tuple, so we
             * should never try to promote to it.
             */
            Assert(false);
            return 0;
    }

    /* not reachable */
    Assert(false);
    return 0;
}

NextPredXact()

static SERIALIZABLEXACT * NextPredXact ( SERIALIZABLEXACT *  sxact )

static

Definition at line 627 of file predicate.c.

References PredXactListData::activeList, Assert, PredXactListElementData::link, offsetof, ShmemAddrIsValid(), SHMQueueNext(), and PredXactListElementData::sxact.

Referenced by GetSafeSnapshotBlockingPids(), GetSerializableTransactionSnapshotInt(), and SetNewSxactGlobalXmin().

{
    PredXactListElement ptle;

    Assert(ShmemAddrIsValid(sxact));

    ptle = (PredXactListElement)
        (((char *) sxact)
         - offsetof(PredXactListElementData, sxact)
         + offsetof(PredXactListElementData, link));
    ptle = (PredXactListElement)
        SHMQueueNext(&PredXact->activeList,
                     &ptle->link,
                     offsetof(PredXactListElementData, link));
    if (!ptle)
        return NULL;

    return &ptle->sxact;
}

OnConflict_CheckForSerializationFailure()

static void OnConflict_CheckForSerializationFailure ( const SERIALIZABLEXACT *  reader, SERIALIZABLEXACT *  writer  )

static

Definition at line 4656 of file predicate.c.

References Assert, SERIALIZABLEXACT::commitSeqNo, ereport, errcode(), errdetail_internal(), errhint(), errmsg(), ERROR, SERIALIZABLEXACT::flags, SERIALIZABLEXACT::inConflicts, RWConflictData::inLink, SERIALIZABLEXACT::lastCommitBeforeSnapshot, LWLockHeldByMe(), LWLockRelease(), offsetof, SERIALIZABLEXACT::outConflicts, RWConflictData::outLink, SERIALIZABLEXACT::prepareSeqNo, SERIALIZABLEXACT::SeqNo, SHMQueueNext(), SXACT_FLAG_DOOMED, SxactHasConflictOut, SxactHasSummaryConflictIn, SxactHasSummaryConflictOut, RWConflictData::sxactIn, SxactIsCommitted, SxactIsDoomed, SxactIsPrepared, SxactIsReadOnly, RWConflictData::sxactOut, and SERIALIZABLEXACT::topXid.

Referenced by FlagRWConflict().

{
    bool        failure;
    RWConflict  conflict;

    Assert(LWLockHeldByMe(SerializableXactHashLock));

    failure = false;

    /*------------------------------------------------------------------------
     * Check for already-committed writer with rw-conflict out flagged
     * (conflict-flag on W means that T2 committed before W):
     *
     *      R ------> W ------> T2
     *          rw        rw
     *
     * That is a dangerous structure, so we must abort. (Since the writer
     * has already committed, we must be the reader)
     *------------------------------------------------------------------------
     */
    if (SxactIsCommitted(writer)
        && (SxactHasConflictOut(writer) || SxactHasSummaryConflictOut(writer)))
        failure = true;

    /*------------------------------------------------------------------------
     * Check whether the writer has become a pivot with an out-conflict
     * committed transaction (T2), and T2 committed first:
     *
     *      R ------> W ------> T2
     *          rw        rw
     *
     * Because T2 must've committed first, there is no anomaly if:
     * - the reader committed before T2
     * - the writer committed before T2
     * - the reader is a READ ONLY transaction and the reader was concurrent
     *   with T2 (= reader acquired its snapshot before T2 committed)
     *
     * We also handle the case that T2 is prepared but not yet committed
     * here. In that case T2 has already checked for conflicts, so if it
     * commits first, making the above conflict real, it's too late for it
     * to abort.
     *------------------------------------------------------------------------
     */
    if (!failure)
    {
        if (SxactHasSummaryConflictOut(writer))
        {
            failure = true;
            conflict = NULL;
        }
        else
            conflict = (RWConflict)
                SHMQueueNext(&writer->outConflicts,
                             &writer->outConflicts,
                             offsetof(RWConflictData, outLink));
        while (conflict)
        {
            SERIALIZABLEXACT *t2 = conflict->sxactIn;

            if (SxactIsPrepared(t2)
                && (!SxactIsCommitted(reader)
                    || t2->prepareSeqNo <= reader->commitSeqNo)
                && (!SxactIsCommitted(writer)
                    || t2->prepareSeqNo <= writer->commitSeqNo)
                && (!SxactIsReadOnly(reader)
                    || t2->prepareSeqNo <= reader->SeqNo.lastCommitBeforeSnapshot))
            {
                failure = true;
                break;
            }
            conflict = (RWConflict)
                SHMQueueNext(&writer->outConflicts,
                             &conflict->outLink,
                             offsetof(RWConflictData, outLink));
        }
    }

    /*------------------------------------------------------------------------
     * Check whether the reader has become a pivot with a writer
     * that's committed (or prepared):
     *
     *      T0 ------> R ------> W
     *           rw        rw
     *
     * Because W must've committed first for an anomaly to occur, there is no
     * anomaly if:
     * - T0 committed before the writer
     * - T0 is READ ONLY, and overlaps the writer
     *------------------------------------------------------------------------
     */
    if (!failure && SxactIsPrepared(writer) && !SxactIsReadOnly(reader))
    {
        if (SxactHasSummaryConflictIn(reader))
        {
            failure = true;
            conflict = NULL;
        }
        else
            conflict = (RWConflict)
                SHMQueueNext(&reader->inConflicts,
                             &reader->inConflicts,
                             offsetof(RWConflictData, inLink));
        while (conflict)
        {
            SERIALIZABLEXACT *t0 = conflict->sxactOut;

            if (!SxactIsDoomed(t0)
                && (!SxactIsCommitted(t0)
                    || t0->commitSeqNo >= writer->prepareSeqNo)
                && (!SxactIsReadOnly(t0)
                    || t0->SeqNo.lastCommitBeforeSnapshot >= writer->prepareSeqNo))
            {
                failure = true;
                break;
            }
            conflict = (RWConflict)
                SHMQueueNext(&reader->inConflicts,
                             &conflict->inLink,
                             offsetof(RWConflictData, inLink));
        }
    }

    if (failure)
    {
        /*
         * We have to kill a transaction to avoid a possible anomaly from
         * occurring. If the writer is us, we can just ereport() to cause a
         * transaction abort. Otherwise we flag the writer for termination,
         * causing it to abort when it tries to commit. However, if the writer
         * is a prepared transaction, already prepared, we can't abort it
         * anymore, so we have to kill the reader instead.
         */
        if (MySerializableXact == writer)
        {
            LWLockRelease(SerializableXactHashLock);
            ereport(ERROR,
                    (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                     errmsg("could not serialize access due to read/write dependencies among transactions"),
                     errdetail_internal("Reason code: Canceled on identification as a pivot, during write."),
                     errhint("The transaction might succeed if retried.")));
        }
        else if (SxactIsPrepared(writer))
        {
            LWLockRelease(SerializableXactHashLock);

            /* if we're not the writer, we have to be the reader */
            Assert(MySerializableXact == reader);
            ereport(ERROR,
                    (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                     errmsg("could not serialize access due to read/write dependencies among transactions"),
                     errdetail_internal("Reason code: Canceled on conflict out to pivot %u, during read.", writer->topXid),
                     errhint("The transaction might succeed if retried.")));
        }
        writer->flags |= SXACT_FLAG_DOOMED;
    }
}

PageIsPredicateLocked()

bool PageIsPredicateLocked	(	Relation	relation,
		BlockNumber	blkno
	)

Definition at line 1990 of file predicate.c.

References RelFileNode::dbNode, HASH_FIND, hash_search_with_hash_value(), LW_SHARED, LWLockAcquire(), LWLockRelease(), PredicateLockHashPartitionLock, PredicateLockTargetTagHashCode, RelationData::rd_id, RelationData::rd_node, and SET_PREDICATELOCKTARGETTAG_PAGE.

{
    PREDICATELOCKTARGETTAG targettag;
    uint32      targettaghash;
    LWLock     *partitionLock;
    PREDICATELOCKTARGET *target;

    SET_PREDICATELOCKTARGETTAG_PAGE(targettag,
                                    relation->rd_node.dbNode,
                                    relation->rd_id,
                                    blkno);

    targettaghash = PredicateLockTargetTagHashCode(&targettag);
    partitionLock = PredicateLockHashPartitionLock(targettaghash);
    LWLockAcquire(partitionLock, LW_SHARED);
    target = (PREDICATELOCKTARGET *)
        hash_search_with_hash_value(PredicateLockTargetHash,
                                    &targettag, targettaghash,
                                    HASH_FIND, NULL);
    LWLockRelease(partitionLock);

    return (target != NULL);
}

PostPrepare_PredicateLocks()

void PostPrepare_PredicateLocks

(

TransactionId

xid

)

Definition at line 5001 of file predicate.c.

References Assert, hash_destroy(), InvalidSerializableXact, MyXactDidWrite, SERIALIZABLEXACT::pid, and SxactIsPrepared.

Referenced by PrepareTransaction().

{
    if (MySerializableXact == InvalidSerializableXact)
        return;

    Assert(SxactIsPrepared(MySerializableXact));

    MySerializableXact->pid = 0;

    hash_destroy(LocalPredicateLockHash);
    LocalPredicateLockHash = NULL;

    MySerializableXact = InvalidSerializableXact;
    MyXactDidWrite = false;
}

PreCommit_CheckForSerializationFailure()

void PreCommit_CheckForSerializationFailure

(

void

)

Definition at line 4831 of file predicate.c.

References Assert, ereport, errcode(), errdetail_internal(), errhint(), errmsg(), ERROR, SERIALIZABLEXACT::flags, SERIALIZABLEXACT::inConflicts, RWConflictData::inLink, InvalidSerializableXact, IsolationIsSerializable, PredXactListData::LastSxactCommitSeqNo, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), offsetof, SERIALIZABLEXACT::prepareSeqNo, SHMQueueNext(), SXACT_FLAG_DOOMED, SXACT_FLAG_PREPARED, SxactIsCommitted, SxactIsDoomed, SxactIsPartiallyReleased, SxactIsPrepared, SxactIsReadOnly, and RWConflictData::sxactOut.

Referenced by CommitTransaction(), and PrepareTransaction().

{
    RWConflict  nearConflict;

    if (MySerializableXact == InvalidSerializableXact)
        return;

    Assert(IsolationIsSerializable());

    LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);

    /* Check if someone else has already decided that we need to die */
    if (SxactIsDoomed(MySerializableXact))
    {
        Assert(!SxactIsPartiallyReleased(MySerializableXact));
        LWLockRelease(SerializableXactHashLock);
        ereport(ERROR,
                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                 errmsg("could not serialize access due to read/write dependencies among transactions"),
                 errdetail_internal("Reason code: Canceled on identification as a pivot, during commit attempt."),
                 errhint("The transaction might succeed if retried.")));
    }

    nearConflict = (RWConflict)
        SHMQueueNext(&MySerializableXact->inConflicts,
                     &MySerializableXact->inConflicts,
                     offsetof(RWConflictData, inLink));
    while (nearConflict)
    {
        if (!SxactIsCommitted(nearConflict->sxactOut)
            && !SxactIsDoomed(nearConflict->sxactOut))
        {
            RWConflict  farConflict;

            farConflict = (RWConflict)
                SHMQueueNext(&nearConflict->sxactOut->inConflicts,
                             &nearConflict->sxactOut->inConflicts,
                             offsetof(RWConflictData, inLink));
            while (farConflict)
            {
                if (farConflict->sxactOut == MySerializableXact
                    || (!SxactIsCommitted(farConflict->sxactOut)
                        && !SxactIsReadOnly(farConflict->sxactOut)
                        && !SxactIsDoomed(farConflict->sxactOut)))
                {
                    /*
                     * Normally, we kill the pivot transaction to make sure we
                     * make progress if the failing transaction is retried.
                     * However, we can't kill it if it's already prepared, so
                     * in that case we commit suicide instead.
                     */
                    if (SxactIsPrepared(nearConflict->sxactOut))
                    {
                        LWLockRelease(SerializableXactHashLock);
                        ereport(ERROR,
                                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                                 errmsg("could not serialize access due to read/write dependencies among transactions"),
                                 errdetail_internal("Reason code: Canceled on commit attempt with conflict in from prepared pivot."),
                                 errhint("The transaction might succeed if retried.")));
                    }
                    nearConflict->sxactOut->flags |= SXACT_FLAG_DOOMED;
                    break;
                }
                farConflict = (RWConflict)
                    SHMQueueNext(&nearConflict->sxactOut->inConflicts,
                                 &farConflict->inLink,
                                 offsetof(RWConflictData, inLink));
            }
        }

        nearConflict = (RWConflict)
            SHMQueueNext(&MySerializableXact->inConflicts,
                         &nearConflict->inLink,
                         offsetof(RWConflictData, inLink));
    }

    MySerializableXact->prepareSeqNo = ++(PredXact->LastSxactCommitSeqNo);
    MySerializableXact->flags |= SXACT_FLAG_PREPARED;

    LWLockRelease(SerializableXactHashLock);
}

predicatelock_hash()

static uint32 predicatelock_hash ( const void *  key, Size  keysize  )

static

Definition at line 1417 of file predicate.c.

References Assert, PREDICATELOCKTAG::myTarget, PredicateLockHashCodeFromTargetHashCode, PredicateLockTargetTagHashCode, and PREDICATELOCKTARGET::tag.

Referenced by InitPredicateLocks().

{
    const PREDICATELOCKTAG *predicatelocktag = (const PREDICATELOCKTAG *) key;
    uint32      targethash;

    Assert(keysize == sizeof(PREDICATELOCKTAG));

    /* Look into the associated target object, and compute its hash code */
    targethash = PredicateLockTargetTagHashCode(&predicatelocktag->myTarget->tag);

    return PredicateLockHashCodeFromTargetHashCode(predicatelocktag, targethash);
}

predicatelock_twophase_recover()

void predicatelock_twophase_recover	(	TransactionId	xid,
		uint16	info,
		void *	recdata,
		uint32	len
	)

Definition at line 5050 of file predicate.c.

References Assert, VirtualTransactionId::backendId, SERIALIZABLEXACT::commitSeqNo, CreatePredicateLock(), CreatePredXact(), TwoPhasePredicateRecord::data, ereport, errcode(), errmsg(), ERROR, SERIALIZABLEXACT::finishedBefore, SERIALIZABLEXACT::finishedLink, SERIALIZABLEXACT::flags, TwoPhasePredicateXactRecord::flags, HASH_ENTER, HASH_FIND, hash_search(), SERIALIZABLEXACT::inConflicts, InvalidBackendId, InvalidSerCommitSeqNo, InvalidSerializableXact, InvalidTransactionId, SERIALIZABLEXACT::lastCommitBeforeSnapshot, VirtualTransactionId::localTransactionId, TwoPhasePredicateRecord::lockRecord, LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), max_prepared_xacts, MaxBackends, SERIALIZABLEXID::myXact, SERIALIZABLEXACT::outConflicts, SERIALIZABLEXACT::pid, SERIALIZABLEXACT::possibleUnsafeConflicts, SERIALIZABLEXACT::predicateLocks, PredicateLockTargetTagHashCode, SERIALIZABLEXACT::prepareSeqNo, RecoverySerCommitSeqNo, SERIALIZABLEXACT::SeqNo, SerialSetActiveSerXmin(), SHMQueueElemInit(), SHMQueueInit(), SXACT_FLAG_SUMMARY_CONFLICT_IN, SXACT_FLAG_SUMMARY_CONFLICT_OUT, PredXactListData::SxactGlobalXmin, PredXactListData::SxactGlobalXminCount, SxactIsPrepared, SxactIsReadOnly, TwoPhasePredicateLockRecord::target, SERIALIZABLEXACT::topXid, TransactionIdEquals, TransactionIdFollows(), TransactionIdIsValid, TWOPHASEPREDICATERECORD_LOCK, TWOPHASEPREDICATERECORD_XACT, TwoPhasePredicateRecord::type, SERIALIZABLEXACT::vxid, PredXactListData::WritableSxactCount, TwoPhasePredicateRecord::xactRecord, SERIALIZABLEXIDTAG::xid, SERIALIZABLEXACT::xmin, and TwoPhasePredicateXactRecord::xmin.

{
    TwoPhasePredicateRecord *record;

    Assert(len == sizeof(TwoPhasePredicateRecord));

    record = (TwoPhasePredicateRecord *) recdata;

    Assert((record->type == TWOPHASEPREDICATERECORD_XACT) ||
           (record->type == TWOPHASEPREDICATERECORD_LOCK));

    if (record->type == TWOPHASEPREDICATERECORD_XACT)
    {
        /* Per-transaction record. Set up a SERIALIZABLEXACT. */
        TwoPhasePredicateXactRecord *xactRecord;
        SERIALIZABLEXACT *sxact;
        SERIALIZABLEXID *sxid;
        SERIALIZABLEXIDTAG sxidtag;
        bool        found;

        xactRecord = (TwoPhasePredicateXactRecord *) &record->data.xactRecord;

        LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
        sxact = CreatePredXact();
        if (!sxact)
            ereport(ERROR,
                    (errcode(ERRCODE_OUT_OF_MEMORY),
                     errmsg("out of shared memory")));

        /* vxid for a prepared xact is InvalidBackendId/xid; no pid */
        sxact->vxid.backendId = InvalidBackendId;
        sxact->vxid.localTransactionId = (LocalTransactionId) xid;
        sxact->pid = 0;

        /* a prepared xact hasn't committed yet */
        sxact->prepareSeqNo = RecoverySerCommitSeqNo;
        sxact->commitSeqNo = InvalidSerCommitSeqNo;
        sxact->finishedBefore = InvalidTransactionId;

        sxact->SeqNo.lastCommitBeforeSnapshot = RecoverySerCommitSeqNo;

        /*
         * Don't need to track this; no transactions running at the time the
         * recovered xact started are still active, except possibly other
         * prepared xacts and we don't care whether those are RO_SAFE or not.
         */
        SHMQueueInit(&(sxact->possibleUnsafeConflicts));

        SHMQueueInit(&(sxact->predicateLocks));
        SHMQueueElemInit(&(sxact->finishedLink));

        sxact->topXid = xid;
        sxact->xmin = xactRecord->xmin;
        sxact->flags = xactRecord->flags;
        Assert(SxactIsPrepared(sxact));
        if (!SxactIsReadOnly(sxact))
        {
            ++(PredXact->WritableSxactCount);
            Assert(PredXact->WritableSxactCount <=
                   (MaxBackends + max_prepared_xacts));
        }

        /*
         * We don't know whether the transaction had any conflicts or not, so
         * we'll conservatively assume that it had both a conflict in and a
         * conflict out, and represent that with the summary conflict flags.
         */
        SHMQueueInit(&(sxact->outConflicts));
        SHMQueueInit(&(sxact->inConflicts));
        sxact->flags |= SXACT_FLAG_SUMMARY_CONFLICT_IN;
        sxact->flags |= SXACT_FLAG_SUMMARY_CONFLICT_OUT;

        /* Register the transaction's xid */
        sxidtag.xid = xid;
        sxid = (SERIALIZABLEXID *) hash_search(SerializableXidHash,
                                               &sxidtag,
                                               HASH_ENTER, &found);
        Assert(sxid != NULL);
        Assert(!found);
        sxid->myXact = (SERIALIZABLEXACT *) sxact;

        /*
         * Update global xmin. Note that this is a special case compared to
         * registering a normal transaction, because the global xmin might go
         * backwards. That's OK, because until recovery is over we're not
         * going to complete any transactions or create any non-prepared
         * transactions, so there's no danger of throwing away.
         */
        if ((!TransactionIdIsValid(PredXact->SxactGlobalXmin)) ||
            (TransactionIdFollows(PredXact->SxactGlobalXmin, sxact->xmin)))
        {
            PredXact->SxactGlobalXmin = sxact->xmin;
            PredXact->SxactGlobalXminCount = 1;
            SerialSetActiveSerXmin(sxact->xmin);
        }
        else if (TransactionIdEquals(sxact->xmin, PredXact->SxactGlobalXmin))
        {
            Assert(PredXact->SxactGlobalXminCount > 0);
            PredXact->SxactGlobalXminCount++;
        }

        LWLockRelease(SerializableXactHashLock);
    }
    else if (record->type == TWOPHASEPREDICATERECORD_LOCK)
    {
        /* Lock record. Recreate the PREDICATELOCK */
        TwoPhasePredicateLockRecord *lockRecord;
        SERIALIZABLEXID *sxid;
        SERIALIZABLEXACT *sxact;
        SERIALIZABLEXIDTAG sxidtag;
        uint32      targettaghash;

        lockRecord = (TwoPhasePredicateLockRecord *) &record->data.lockRecord;
        targettaghash = PredicateLockTargetTagHashCode(&lockRecord->target);

        LWLockAcquire(SerializableXactHashLock, LW_SHARED);
        sxidtag.xid = xid;
        sxid = (SERIALIZABLEXID *)
            hash_search(SerializableXidHash, &sxidtag, HASH_FIND, NULL);
        LWLockRelease(SerializableXactHashLock);

        Assert(sxid != NULL);
        sxact = sxid->myXact;
        Assert(sxact != InvalidSerializableXact);

        CreatePredicateLock(&lockRecord->target, targettaghash, sxact);
    }
}

PredicateLockAcquire()

static void PredicateLockAcquire ( const PREDICATELOCKTARGETTAG *  targettag )

static

Definition at line 2510 of file predicate.c.

References CheckAndPromotePredicateLockRequest(), LOCALPREDICATELOCK::childLocks, CoarserLockCovers(), CreatePredicateLock(), DeleteChildTargetLocks(), GET_PREDICATELOCKTARGETTAG_TYPE, HASH_ENTER, hash_search_with_hash_value(), LOCALPREDICATELOCK::held, PredicateLockExists(), PredicateLockTargetTagHashCode, and PREDLOCKTAG_TUPLE.

Referenced by CheckAndPromotePredicateLockRequest(), PredicateLockPage(), PredicateLockRelation(), and PredicateLockTID().

{
    uint32      targettaghash;
    bool        found;
    LOCALPREDICATELOCK *locallock;

    /* Do we have the lock already, or a covering lock? */
    if (PredicateLockExists(targettag))
        return;

    if (CoarserLockCovers(targettag))
        return;

    /* the same hash and LW lock apply to the lock target and the local lock. */
    targettaghash = PredicateLockTargetTagHashCode(targettag);

    /* Acquire lock in local table */
    locallock = (LOCALPREDICATELOCK *)
        hash_search_with_hash_value(LocalPredicateLockHash,
                                    targettag, targettaghash,
                                    HASH_ENTER, &found);
    locallock->held = true;
    if (!found)
        locallock->childLocks = 0;

    /* Actually create the lock */
    CreatePredicateLock(targettag, targettaghash, MySerializableXact);

    /*
     * Lock has been acquired. Check whether it should be promoted to a
     * coarser granularity, or whether there are finer-granularity locks to
     * clean up.
     */
    if (CheckAndPromotePredicateLockRequest(targettag))
    {
        /*
         * Lock request was promoted to a coarser-granularity lock, and that
         * lock was acquired. It will delete this lock and any of its
         * children, so we're done.
         */
    }
    else
    {
        /* Clean up any finer-granularity locks */
        if (GET_PREDICATELOCKTARGETTAG_TYPE(*targettag) != PREDLOCKTAG_TUPLE)
            DeleteChildTargetLocks(targettag);
    }
}

PredicateLockExists()

static bool PredicateLockExists ( const PREDICATELOCKTARGETTAG *  targettag )

static

Definition at line 2027 of file predicate.c.

References HASH_FIND, hash_search(), and LOCALPREDICATELOCK::held.

Referenced by CoarserLockCovers(), PredicateLockAcquire(), and PredicateLockTID().

{
    LOCALPREDICATELOCK *lock;

    /* check local hash table */
    lock = (LOCALPREDICATELOCK *) hash_search(LocalPredicateLockHash,
                                              targettag,
                                              HASH_FIND, NULL);

    if (!lock)
        return false;

    /*
     * Found entry in the table, but still need to check whether it's actually
     * held -- it could just be a parent of some held lock.
     */
    return lock->held;
}

PredicateLockingNeededForRelation()

static bool PredicateLockingNeededForRelation ( Relation  relation )

inlinestatic

Definition at line 495 of file predicate.c.

References FirstBootstrapObjectId, RelationData::rd_id, RelationData::rd_rel, and RelationUsesLocalBuffers.

Referenced by DropAllPredicateLocksFromTable(), PredicateLockPageSplit(), SerializationNeededForRead(), and SerializationNeededForWrite().

{
    return !(relation->rd_id < FirstBootstrapObjectId ||
             RelationUsesLocalBuffers(relation) ||
             relation->rd_rel->relkind == RELKIND_MATVIEW);
}

PredicateLockPage()

void PredicateLockPage	(	Relation	relation,
		BlockNumber	blkno,
		Snapshot	snapshot
	)

Definition at line 2592 of file predicate.c.

References RelFileNode::dbNode, PredicateLockAcquire(), RelationData::rd_id, RelationData::rd_node, SerializationNeededForRead(), and SET_PREDICATELOCKTARGETTAG_PAGE.

Referenced by _bt_endpoint(), _bt_first(), _bt_readnextpage(), _hash_first(), _hash_readnext(), collectMatchBitmap(), gistScanPage(), IndexOnlyNext(), moveRightIfItNeeded(), scanPendingInsert(), and startScanEntry().

{
    PREDICATELOCKTARGETTAG tag;

    if (!SerializationNeededForRead(relation, snapshot))
        return;

    SET_PREDICATELOCKTARGETTAG_PAGE(tag,
                                    relation->rd_node.dbNode,
                                    relation->rd_id,
                                    blkno);
    PredicateLockAcquire(&tag);
}

PredicateLockPageCombine()

void PredicateLockPageCombine	(	Relation	relation,
		BlockNumber	oldblkno,
		BlockNumber	newblkno
	)

Definition at line 3252 of file predicate.c.

References PredicateLockPageSplit().

Referenced by _bt_mark_page_halfdead(), and ginDeletePage().

{
    /*
     * Page combines differ from page splits in that we ought to be able to
     * remove the locks on the old page after transferring them to the new
     * page, instead of duplicating them. However, because we can't edit other
     * backends' local lock tables, removing the old lock would leave them
     * with an entry in their LocalPredicateLockHash for a lock they're not
     * holding, which isn't acceptable. So we wind up having to do the same
     * work as a page split, acquiring a lock on the new page and keeping the
     * old page locked too. That can lead to some false positives, but should
     * be rare in practice.
     */
    PredicateLockPageSplit(relation, oldblkno, newblkno);
}

PredicateLockPageSplit()

void PredicateLockPageSplit	(	Relation	relation,
		BlockNumber	oldblkno,
		BlockNumber	newblkno
	)

Definition at line 3167 of file predicate.c.

References Assert, BlockNumberIsValid, RelFileNode::dbNode, GetParentPredicateLockTag(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), PredicateLockingNeededForRelation(), RelationData::rd_id, RelationData::rd_node, SET_PREDICATELOCKTARGETTAG_PAGE, success, PredXactListData::SxactGlobalXmin, TransactionIdIsValid, and TransferPredicateLocksToNewTarget().

Referenced by _bt_insertonpg(), _hash_splitbucket(), createPostingTree(), ginPlaceToPage(), gistplacetopage(), and PredicateLockPageCombine().

{
    PREDICATELOCKTARGETTAG oldtargettag;
    PREDICATELOCKTARGETTAG newtargettag;
    bool        success;

    /*
     * Bail out quickly if there are no serializable transactions running.
     *
     * It's safe to do this check without taking any additional locks. Even if
     * a serializable transaction starts concurrently, we know it can't take
     * any SIREAD locks on the page being split because the caller is holding
     * the associated buffer page lock. Memory reordering isn't an issue; the
     * memory barrier in the LWLock acquisition guarantees that this read
     * occurs while the buffer page lock is held.
     */
    if (!TransactionIdIsValid(PredXact->SxactGlobalXmin))
        return;

    if (!PredicateLockingNeededForRelation(relation))
        return;

    Assert(oldblkno != newblkno);
    Assert(BlockNumberIsValid(oldblkno));
    Assert(BlockNumberIsValid(newblkno));

    SET_PREDICATELOCKTARGETTAG_PAGE(oldtargettag,
                                    relation->rd_node.dbNode,
                                    relation->rd_id,
                                    oldblkno);
    SET_PREDICATELOCKTARGETTAG_PAGE(newtargettag,
                                    relation->rd_node.dbNode,
                                    relation->rd_id,
                                    newblkno);

    LWLockAcquire(SerializablePredicateListLock, LW_EXCLUSIVE);

    /*
     * Try copying the locks over to the new page's tag, creating it if
     * necessary.
     */
    success = TransferPredicateLocksToNewTarget(oldtargettag,
                                                newtargettag,
                                                false);

    if (!success)
    {
        /*
         * No more predicate lock entries are available. Failure isn't an
         * option here, so promote the page lock to a relation lock.
         */

        /* Get the parent relation lock's lock tag */
        success = GetParentPredicateLockTag(&oldtargettag,
                                            &newtargettag);
        Assert(success);

        /*
         * Move the locks to the parent. This shouldn't fail.
         *
         * Note that here we are removing locks held by other backends,
         * leading to a possible inconsistency in their local lock hash table.
         * This is OK because we're replacing it with a lock that covers the
         * old one.
         */
        success = TransferPredicateLocksToNewTarget(oldtargettag,
                                                    newtargettag,
                                                    true);
        Assert(success);
    }

    LWLockRelease(SerializablePredicateListLock);
}