diff options
Diffstat (limited to 'src/backend/storage/buffer/bufmgr.c')
| -rw-r--r-- | src/backend/storage/buffer/bufmgr.c | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 2da3b4e364d..1be30d30e2b 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.139 2003/08/04 02:40:03 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.140 2003/08/10 19:48:08 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1937,6 +1937,37 @@ LockBuffer(Buffer buffer, int mode) } /* + * Acquire the cntx_lock for the buffer, but only if we don't have to wait. + * + * This assumes the caller wants BUFFER_LOCK_EXCLUSIVE mode. + */ +bool +ConditionalLockBuffer(Buffer buffer) +{ + BufferDesc *buf; + + Assert(BufferIsValid(buffer)); + if (BufferIsLocal(buffer)) + return true; /* act as though we got it */ + + buf = &(BufferDescriptors[buffer - 1]); + + if (LWLockConditionalAcquire(buf->cntx_lock, LW_EXCLUSIVE)) + { + /* + * This is not the best place to set cntxDirty flag (eg indices do + * not always change buffer they lock in excl mode). But please + * remember that it's critical to set cntxDirty *before* logging + * changes with XLogInsert() - see comments in BufferSync(). + */ + buf->cntxDirty = true; + + return true; + } + return false; +} + +/* * LockBufferForCleanup - lock a buffer in preparation for deleting items * * Items may be deleted from a disk page only when the caller (a) holds an |