diff options
author | Tom Lane <tgl@sss.pgh.pa.us> | 2005-08-01 20:31:16 +0000 |
---|---|---|
committer | Tom Lane <tgl@sss.pgh.pa.us> | 2005-08-01 20:31:16 +0000 |
commit | 2a4fad1a0e43d6375ffa8eddb2d8dfa1ed36593f (patch) | |
tree | bb2bc2208507b0ab2403850e8dd01003a4ed73e9 /src/backend/access/transam/multixact.c | |
parent | ca7abcd89dbeecb82cde50fccf4f6c483244fdf7 (diff) | |
download | postgresql-2a4fad1a0e43d6375ffa8eddb2d8dfa1ed36593f.tar.gz postgresql-2a4fad1a0e43d6375ffa8eddb2d8dfa1ed36593f.zip |
Add NOWAIT option to SELECT FOR UPDATE/SHARE.
Original patch by Hans-Juergen Schoenig, revisions by Karel Zak
and Tom Lane.
Diffstat (limited to 'src/backend/access/transam/multixact.c')
-rw-r--r-- | src/backend/access/transam/multixact.c | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index 41773625af4..8f107d42c6e 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -42,7 +42,7 @@ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/access/transam/multixact.c,v 1.5 2005/06/08 15:50:25 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/multixact.c,v 1.6 2005/08/01 20:31:06 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -559,6 +559,43 @@ MultiXactIdWait(MultiXactId multi) } /* + * ConditionalMultiXactIdWait + * As above, but only lock if we can get the lock without blocking. + */ +bool +ConditionalMultiXactIdWait(MultiXactId multi) +{ + bool result = true; + TransactionId *members; + int nmembers; + + nmembers = GetMultiXactIdMembers(multi, &members); + + if (nmembers >= 0) + { + int i; + + for (i = 0; i < nmembers; i++) + { + TransactionId member = members[i]; + + debug_elog4(DEBUG2, "ConditionalMultiXactIdWait: trying %d (%u)", + i, member); + if (!TransactionIdIsCurrentTransactionId(member)) + { + result = ConditionalXactLockTableWait(member); + if (!result) + break; + } + } + + pfree(members); + } + + return result; +} + +/* * CreateMultiXactId * Make a new MultiXactId * @@ -590,7 +627,7 @@ CreateMultiXactId(int nxids, TransactionId *xids) */ multi = mXactCacheGetBySet(nxids, xids); if (MultiXactIdIsValid(multi)) - { + { debug_elog2(DEBUG2, "Create: in cache!"); return multi; } |