diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/include/storage/lock.h | 45 |
1 files changed, 25 insertions, 20 deletions
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h index 1289fee7eca..0c0c66077f7 100644 --- a/src/include/storage/lock.h +++ b/src/include/storage/lock.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.79 2004/07/17 03:31:26 tgl Exp $ + * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.80 2004/08/26 17:22:28 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -26,10 +26,10 @@ typedef struct PROC_QUEUE int size; /* number of entries in list */ } PROC_QUEUE; -/* struct PGPROC is declared in storage/proc.h, but must forward-reference it */ +/* struct PGPROC is declared in proc.h, but must forward-reference it */ typedef struct PGPROC PGPROC; - +/* GUC variables */ extern int max_locks_per_xact; #ifdef LOCK_DEBUG @@ -41,6 +41,11 @@ extern bool Debug_deadlocks; #endif /* LOCK_DEBUG */ +/* + * LOCKMODE is an integer (1..N) indicating a lock type. LOCKMASK is a bit + * mask indicating a set of held or requested lock types (the bit 1<<mode + * corresponds to a particular lock mode). + */ typedef int LOCKMASK; typedef int LOCKMODE; /* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */ @@ -49,6 +54,11 @@ typedef int LOCKMODE; #define LOCKBIT_ON(lockmode) (1 << (lockmode)) #define LOCKBIT_OFF(lockmode) (~(1 << (lockmode))) +/* + * There is normally only one lock method, the default one. + * If user locks are enabled, an additional lock method is present. + * Lock methods are identified by LOCKMETHODID. + */ typedef uint16 LOCKMETHODID; /* MAX_LOCK_METHODS is the number of distinct lock control tables allowed */ #define MAX_LOCK_METHODS 3 @@ -60,18 +70,13 @@ typedef uint16 LOCKMETHODID; #define LockMethodIsValid(lockmethodid) ((lockmethodid) != INVALID_LOCKMETHOD) /* - * There is normally only one lock method, the default one. - * If user locks are enabled, an additional lock method is present. - * - * This is the control structure for a lock table. It - * lives in shared memory. This information is the same - * for all backends. + * This is the control structure for a lock table. It lives in shared + * memory. Currently, none of these fields change after startup. In addition + * to the LockMethodData, a lock table has a "lockHash" table holding + * per-locked-object lock information, and a "proclockHash" table holding + * per-lock-holder/waiter lock information. * - * lockHash -- hash table holding per-locked-object lock information - * - * proclockHash -- hash table holding per-lock-waiter/holder lock information - * - * lockmethod -- the handle used by the lock table's clients to + * lockmethodid -- the handle used by the lock table's clients to * refer to the type of lock table being used. * * numLockModes -- number of lock types (READ,WRITE,etc) that @@ -81,8 +86,7 @@ typedef uint16 LOCKMETHODID; * type conflicts. conflictTab[i] is a mask with the j-th bit * turned on if lock types i and j conflict. * - * masterLock -- synchronizes access to the table - * + * masterLock -- LWLock used to synchronize access to the table */ typedef struct LockMethodData { @@ -156,12 +160,13 @@ typedef struct LOCK /* * We may have several different transactions holding or awaiting locks - * on the same lockable object. We need to store some per-waiter/holder - * information for each such holder (or would-be holder). + * on the same lockable object. We need to store some per-holder/waiter + * information for each such holder (or would-be holder). This is kept in + * a PROCLOCK struct. * * PROCLOCKTAG is the key information needed to look up a PROCLOCK item in the - * proclock hashtable. A PROCLOCKTAG value uniquely identifies a lock - * holder/waiter. + * proclock hashtable. A PROCLOCKTAG value uniquely identifies the combination + * of a lockable object and a holder/waiter for that object. * * There are two possible kinds of proclock tags: a transaction (identified * both by the PGPROC of the backend running it, and the xact's own ID) and |