diff options
Diffstat (limited to 'src/backend/storage/lmgr/predicate.c')
| -rw-r--r-- | src/backend/storage/lmgr/predicate.c | 38 |
1 files changed, 35 insertions, 3 deletions
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index 1707a746646..f0c8ee48c34 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -244,6 +244,14 @@ #define SxactIsOnFinishedList(sxact) (!SHMQueueIsDetached(&((sxact)->finishedLink))) +/* + * Note that a sxact is marked "prepared" once it has passed + * PreCommit_CheckForSerializationFailure, even if it isn't using + * 2PC. This is the point at which it can no longer be aborted. + * + * The PREPARED flag remains set after commit, so SxactIsCommitted + * implies SxactIsPrepared. + */ #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) @@ -3165,6 +3173,13 @@ ReleasePredicateLocks(bool isCommit) */ MySerializableXact->flags |= SXACT_FLAG_DOOMED; MySerializableXact->flags |= SXACT_FLAG_ROLLED_BACK; + /* + * If the transaction was previously prepared, but is now failing due + * to a ROLLBACK PREPARED or (hopefully very rare) error after the + * prepare, clear the prepared flag. This simplifies conflict + * checking. + */ + MySerializableXact->flags &= ~SXACT_FLAG_PREPARED; } if (!topLevelIsDeclaredReadOnly) @@ -4363,6 +4378,11 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader, * - 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) @@ -4381,7 +4401,12 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader, { SERIALIZABLEXACT *t2 = conflict->sxactIn; - if (SxactIsCommitted(t2) + /* + * Note that if T2 is merely prepared but not yet committed, we + * rely on t->commitSeqNo being InvalidSerCommitSeqNo, which is + * larger than any valid commit sequence number. + */ + if (SxactIsPrepared(t2) && (!SxactIsCommitted(reader) || t2->commitSeqNo <= reader->commitSeqNo) && (!SxactIsCommitted(writer) @@ -4400,7 +4425,8 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader, } /*------------------------------------------------------------------------ - * Check whether the reader has become a pivot with a committed writer: + * Check whether the reader has become a pivot with a writer + * that's committed (or prepared): * * T0 ------> R ------> W * rw rw @@ -4411,7 +4437,7 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader, * - T0 is READ ONLY, and overlaps the writer *------------------------------------------------------------------------ */ - if (!failure && SxactIsCommitted(writer) && !SxactIsReadOnly(reader)) + if (!failure && SxactIsPrepared(writer) && !SxactIsReadOnly(reader)) { if (SxactHasSummaryConflictIn(reader)) { @@ -4427,6 +4453,12 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader, { SERIALIZABLEXACT *t0 = conflict->sxactOut; + /* + * Note that if the writer is merely prepared but not yet + * committed, we rely on writer->commitSeqNo being + * InvalidSerCommitSeqNo, which is larger than any valid commit + * sequence number. + */ if (!SxactIsDoomed(t0) && (!SxactIsCommitted(t0) || t0->commitSeqNo >= writer->commitSeqNo) |