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Improve LockAcquire API per my recent proposal. All error conditions

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are now reported via elog, eliminating the need to test the result code
at most call sites.  Make it possible for the caller to distinguish a
freshly acquired lock from one already held in the current transaction.
Use that capability to avoid redundant AcceptInvalidationMessages() calls
in LockRelation().
This commit is contained in:
Tom Lane
2005-05-29 22:45:02 +00:00
parent 299c442077
commit 140b078d2a
4 changed files with 81 additions and 69 deletions
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13
src/include/storage/lock.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.86 2005/05/19 23:30:18 tgl Exp $
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.87 2005/05/29 22:45:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -348,6 +348,15 @@ typedef struct
} LockData;
/* Result codes for LockAcquire() */
typedef enum
{
LOCKACQUIRE_NOT_AVAIL, /* lock not available, and dontWait=true */
LOCKACQUIRE_OK, /* lock successfully acquired */
LOCKACQUIRE_ALREADY_HELD /* incremented count for lock already held */
} LockAcquireResult;
/*
* function prototypes
*/
@@ -357,7 +366,7 @@ extern LOCKMETHODID LockMethodTableInit(const char *tabName,
const LOCKMASK *conflictsP,
int numModes, int maxBackends);
extern LOCKMETHODID LockMethodTableRename(LOCKMETHODID lockmethodid);
extern bool LockAcquire(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
extern LockAcquireResult LockAcquire(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
TransactionId xid, LOCKMODE lockmode, bool dontWait);
extern bool LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
TransactionId xid, LOCKMODE lockmode);