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synced 2024-12-21 08:29:39 +08:00
The rolled-back flag on serializable xacts was pointless and redundant with
the marked-for-death flag. It was only set for a fleeting moment while a transaction was being cleaned up at rollback. All the places that checked for the rolled-back flag should also check the marked-for-death flag, as both flags mean that the transaction will roll back. I also renamed the marked-for-death into "doomed", which is a lot shorter name.
This commit is contained in:
Heikki Linnakangas
parent
0a0e2b52a5
commit
264a6b127a
@ -244,9 +244,9 @@
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#define SxactIsOnFinishedList(sxact) (!SHMQueueIsDetached(&((sxact)->finishedLink)))
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#define SxactIsPrepared(sxact) (((sxact)->flags & SXACT_FLAG_PREPARED) != 0)
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#define SxactIsCommitted(sxact) (((sxact)->flags & SXACT_FLAG_COMMITTED) != 0)
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#define SxactIsRolledBack(sxact) (((sxact)->flags & SXACT_FLAG_ROLLED_BACK) != 0)
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#define SxactIsPrepared(sxact) (((sxact)->flags & SXACT_FLAG_PREPARED) != 0)
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#define SxactIsDoomed(sxact) (((sxact)->flags & SXACT_FLAG_DOOMED) != 0)
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#define SxactIsReadOnly(sxact) (((sxact)->flags & SXACT_FLAG_READ_ONLY) != 0)
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#define SxactHasSummaryConflictIn(sxact) (((sxact)->flags & SXACT_FLAG_SUMMARY_CONFLICT_IN) != 0)
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#define SxactHasSummaryConflictOut(sxact) (((sxact)->flags & SXACT_FLAG_SUMMARY_CONFLICT_OUT) != 0)
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@ -259,7 +259,6 @@
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#define SxactIsDeferrableWaiting(sxact) (((sxact)->flags & SXACT_FLAG_DEFERRABLE_WAITING) != 0)
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#define SxactIsROSafe(sxact) (((sxact)->flags & SXACT_FLAG_RO_SAFE) != 0)
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#define SxactIsROUnsafe(sxact) (((sxact)->flags & SXACT_FLAG_RO_UNSAFE) != 0)
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#define SxactIsMarkedForDeath(sxact) (((sxact)->flags & SXACT_FLAG_MARKED_FOR_DEATH) != 0)
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/*
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* Compute the hash code associated with a PREDICATELOCKTARGETTAG.
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@ -609,8 +608,8 @@ RWConflictExists(const SERIALIZABLEXACT *reader, const SERIALIZABLEXACT *writer)
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Assert(reader != writer);
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/* Check the ends of the purported conflict first. */
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if (SxactIsRolledBack(reader)
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|| SxactIsRolledBack(writer)
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if (SxactIsDoomed(reader)
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|| SxactIsDoomed(writer)
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|| SHMQueueEmpty(&reader->outConflicts)
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|| SHMQueueEmpty(&writer->inConflicts))
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return false;
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@ -3048,7 +3047,7 @@ SetNewSxactGlobalXmin(void)
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for (sxact = FirstPredXact(); sxact != NULL; sxact = NextPredXact(sxact))
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{
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if (!SxactIsRolledBack(sxact)
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if (!SxactIsDoomed(sxact)
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&& !SxactIsCommitted(sxact)
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&& sxact != OldCommittedSxact)
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{
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@ -3113,7 +3112,7 @@ ReleasePredicateLocks(const bool isCommit)
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}
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Assert(!isCommit || SxactIsPrepared(MySerializableXact));
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Assert(!SxactIsRolledBack(MySerializableXact));
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Assert(!isCommit || !SxactIsDoomed(MySerializableXact));
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Assert(!SxactIsCommitted(MySerializableXact));
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/* may not be serializable during COMMIT/ROLLBACK PREPARED */
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@ -3153,9 +3152,7 @@ ReleasePredicateLocks(const bool isCommit)
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MySerializableXact->flags |= SXACT_FLAG_READ_ONLY;
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}
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else
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{
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MySerializableXact->flags |= SXACT_FLAG_ROLLED_BACK;
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}
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MySerializableXact->flags |= SXACT_FLAG_DOOMED;
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if (!topLevelIsDeclaredReadOnly)
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{
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@ -3531,7 +3528,7 @@ ReleaseOneSerializableXact(SERIALIZABLEXACT *sxact, bool partial,
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nextConflict;
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Assert(sxact != NULL);
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Assert(SxactIsRolledBack(sxact) || SxactIsCommitted(sxact));
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Assert(SxactIsDoomed(sxact) || SxactIsCommitted(sxact));
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Assert(LWLockHeldByMe(SerializableFinishedListLock));
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/*
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@ -3736,7 +3733,8 @@ CheckForSerializableConflictOut(const bool visible, const Relation relation,
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if (!SerializationNeededForRead(relation, snapshot))
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return;
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if (SxactIsMarkedForDeath(MySerializableXact))
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/* Check if someone else has already decided that we need to die */
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if (SxactIsDoomed(MySerializableXact))
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{
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ereport(ERROR,
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(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
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@ -3850,11 +3848,9 @@ CheckForSerializableConflictOut(const bool visible, const Relation relation,
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}
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sxact = sxid->myXact;
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Assert(TransactionIdEquals(sxact->topXid, xid));
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if (sxact == MySerializableXact
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|| SxactIsRolledBack(sxact)
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|| SxactIsMarkedForDeath(sxact))
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if (sxact == MySerializableXact || SxactIsDoomed(sxact))
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{
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/* We can't conflict with our own transaction or one rolled back. */
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/* Can't conflict with ourself or a transaction that will roll back. */
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LWLockRelease(SerializableXactHashLock);
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return;
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}
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@ -3869,7 +3865,7 @@ CheckForSerializableConflictOut(const bool visible, const Relation relation,
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{
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if (!SxactIsPrepared(sxact))
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{
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sxact->flags |= SXACT_FLAG_MARKED_FOR_DEATH;
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sxact->flags |= SXACT_FLAG_DOOMED;
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LWLockRelease(SerializableXactHashLock);
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return;
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}
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@ -3996,7 +3992,7 @@ CheckTargetForConflictsIn(PREDICATELOCKTARGETTAG *targettag)
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mypredlocktag = predlock->tag;
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}
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}
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else if (!SxactIsRolledBack(sxact)
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else if (!SxactIsDoomed(sxact)
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&& (!SxactIsCommitted(sxact)
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|| TransactionIdPrecedes(GetTransactionSnapshot()->xmin,
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sxact->finishedBefore))
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@ -4009,7 +4005,7 @@ CheckTargetForConflictsIn(PREDICATELOCKTARGETTAG *targettag)
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* Re-check after getting exclusive lock because the other
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* transaction may have flagged a conflict.
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*/
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if (!SxactIsRolledBack(sxact)
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if (!SxactIsDoomed(sxact)
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&& (!SxactIsCommitted(sxact)
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|| TransactionIdPrecedes(GetTransactionSnapshot()->xmin,
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sxact->finishedBefore))
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@ -4113,7 +4109,8 @@ CheckForSerializableConflictIn(const Relation relation, const HeapTuple tuple,
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if (!SerializationNeededForWrite(relation))
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return;
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if (SxactIsMarkedForDeath(MySerializableXact))
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/* Check if someone else has already decided that we need to die */
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if (SxactIsDoomed(MySerializableXact))
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ereport(ERROR,
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(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
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errmsg("could not serialize access due to read/write dependencies among transactions"),
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@ -4417,7 +4414,7 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
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{
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SERIALIZABLEXACT *t0 = conflict->sxactOut;
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if (!SxactIsRolledBack(t0)
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if (!SxactIsDoomed(t0)
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&& (!SxactIsCommitted(t0)
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|| t0->commitSeqNo >= writer->commitSeqNo)
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&& (!SxactIsReadOnly(t0)
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@ -4464,7 +4461,7 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
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errdetail("Cancelled on conflict out to pivot %u, during read.", writer->topXid),
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errhint("The transaction might succeed if retried.")));
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}
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writer->flags |= SXACT_FLAG_MARKED_FOR_DEATH;
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writer->flags |= SXACT_FLAG_DOOMED;
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}
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}
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@ -4496,7 +4493,8 @@ PreCommit_CheckForSerializationFailure(void)
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LWLockAcquire(SerializableXactHashLock, LW_EXCLUSIVE);
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if (SxactIsMarkedForDeath(MySerializableXact))
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/* Check if someone else has already decided that we need to die */
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if (SxactIsDoomed(MySerializableXact))
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{
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LWLockRelease(SerializableXactHashLock);
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ereport(ERROR,
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@ -4513,8 +4511,7 @@ PreCommit_CheckForSerializationFailure(void)
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while (nearConflict)
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{
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if (!SxactIsCommitted(nearConflict->sxactOut)
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&& !SxactIsRolledBack(nearConflict->sxactOut)
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&& !SxactIsMarkedForDeath(nearConflict->sxactOut))
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&& !SxactIsDoomed(nearConflict->sxactOut))
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{
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RWConflict farConflict;
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@ -4527,10 +4524,9 @@ PreCommit_CheckForSerializationFailure(void)
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if (farConflict->sxactOut == MySerializableXact
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|| (!SxactIsCommitted(farConflict->sxactOut)
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&& !SxactIsReadOnly(farConflict->sxactOut)
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&& !SxactIsRolledBack(farConflict->sxactOut)
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&& !SxactIsMarkedForDeath(farConflict->sxactOut)))
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&& !SxactIsDoomed(farConflict->sxactOut)))
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{
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nearConflict->sxactOut->flags |= SXACT_FLAG_MARKED_FOR_DEATH;
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nearConflict->sxactOut->flags |= SXACT_FLAG_DOOMED;
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break;
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}
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farConflict = (RWConflict)
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@ -90,22 +90,21 @@ typedef struct SERIALIZABLEXACT
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int pid; /* pid of associated process */
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} SERIALIZABLEXACT;
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#define SXACT_FLAG_ROLLED_BACK 0x00000001
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#define SXACT_FLAG_COMMITTED 0x00000002
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#define SXACT_FLAG_COMMITTED 0x00000001 /* already committed */
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#define SXACT_FLAG_PREPARED 0x00000002 /* about to commit */
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#define SXACT_FLAG_DOOMED 0x00000004 /* will roll back */
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/*
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* The following flag actually means that the flagged transaction has a
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* conflict out *to a transaction which committed ahead of it*. It's hard
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* to get that into a name of a reasonable length.
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*/
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#define SXACT_FLAG_CONFLICT_OUT 0x00000004
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#define SXACT_FLAG_READ_ONLY 0x00000008
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#define SXACT_FLAG_MARKED_FOR_DEATH 0x00000010
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#define SXACT_FLAG_CONFLICT_OUT 0x00000008
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#define SXACT_FLAG_READ_ONLY 0x00000010
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#define SXACT_FLAG_DEFERRABLE_WAITING 0x00000020
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#define SXACT_FLAG_RO_SAFE 0x00000040
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#define SXACT_FLAG_RO_UNSAFE 0x00000080
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#define SXACT_FLAG_SUMMARY_CONFLICT_IN 0x00000100
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#define SXACT_FLAG_SUMMARY_CONFLICT_OUT 0x00000200
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#define SXACT_FLAG_PREPARED 0x00000400
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/*
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* The following types are used to provide an ad hoc list for holding
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