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Try to reduce confusion about what is a lock method identifier, a lock

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method control structure, or a table of control structures.

. Use type LOCKMASK where an int is not a counter.

. Get rid of INVALID_TABLEID, use INVALID_LOCKMETHOD instead.

. Use INVALID_LOCKMETHOD instead of (LOCKMETHOD) NULL, because
  LOCKMETHOD is not a pointer.

. Define and use macro LockMethodIsValid.

. Rename LOCKMETHOD to LOCKMETHODID.

. Remove global variable LongTermTableId in lmgr.c, because it is
  never used.

. Make LockTableId static in lmgr.c, because it is used nowhere else.
  Why not remove it and use DEFAULT_LOCKMETHOD?

. Rename the lock method control structure from LOCKMETHODTABLE to
  LockMethodData.  Introduce a pointer type named LockMethod.

. Remove elog(FATAL) after InitLockTable() call in
  CreateSharedMemoryAndSemaphores(), because if something goes wrong,
  there is elog(FATAL) in LockMethodTableInit(), and if this doesn't
  help, an elog(ERROR) in InitLockTable() is promoted to FATAL.

. Make InitLockTable() void, because its only caller does not use its
  return value any more.

. Rename variables in lock.c to avoid statements like
        LockMethodTable[NumLockMethods] = lockMethodTable;
        lockMethodTable = LockMethodTable[lockmethod];

. Change LOCKMETHODID type to uint16 to fit into struct LOCKTAG.

. Remove static variables BITS_OFF and BITS_ON from lock.c, because
  I agree to this doubt:
 * XXX is a fetch from a static array really faster than a shift?

. Define and use macros LOCKBIT_ON/OFF.


Manfred Koizar
This commit is contained in:
Bruce Momjian
2003-12-01 21:59:25 +00:00
parent e2ac58c7bd
commit e7ca867485
8 changed files with 153 additions and 181 deletions
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56
src/include/storage/lock.h
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@@ -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 1.74 2003/11/29 22:41:13 pgsql Exp $
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.75 2003/12/01 21:59:25 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -42,22 +42,23 @@ extern bool Debug_deadlocks;
typedef int LOCKMASK;
typedef int LOCKMODE;
typedef int LOCKMETHOD;
/* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */
#define MAX_LOCKMODES 10
#define LOCKBIT_ON(lockmode) (1 << (lockmode))
#define LOCKBIT_OFF(lockmode) (~(1 << (lockmode)))
typedef uint16 LOCKMETHODID;
/* MAX_LOCK_METHODS is the number of distinct lock control tables allowed */
#define MAX_LOCK_METHODS 3
#define INVALID_TABLEID 0
#define INVALID_LOCKMETHOD INVALID_TABLEID
#define INVALID_LOCKMETHOD 0
#define DEFAULT_LOCKMETHOD 1
#define USER_LOCKMETHOD 2
#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.
@@ -83,15 +84,16 @@ typedef int LOCKMETHOD;
* masterLock -- synchronizes access to the table
*
*/
typedef struct LOCKMETHODTABLE
typedef struct LockMethodData
{
HTAB *lockHash;
HTAB *proclockHash;
LOCKMETHOD lockmethod;
int numLockModes;
int conflictTab[MAX_LOCKMODES];
LWLockId masterLock;
} LOCKMETHODTABLE;
HTAB *lockHash;
HTAB *proclockHash;
LOCKMETHODID lockmethodid;
int numLockModes;
LOCKMASK conflictTab[MAX_LOCKMODES];
LWLockId masterLock;
} LockMethodData;
typedef LockMethodData *LockMethod;
/*
@@ -115,7 +117,7 @@ typedef struct LOCKTAG
*/
OffsetNumber offnum;
uint16 lockmethod; /* needed by userlocks */
LOCKMETHODID lockmethodid; /* needed by userlocks */
} LOCKTAG;
@@ -139,8 +141,8 @@ typedef struct LOCK
LOCKTAG tag; /* unique identifier of lockable object */
/* data */
int grantMask; /* bitmask for lock types already granted */
int waitMask; /* bitmask for lock types awaited */
LOCKMASK grantMask; /* bitmask for lock types already granted */
LOCKMASK waitMask; /* bitmask for lock types awaited */
SHM_QUEUE lockHolders; /* list of PROCLOCK objects assoc. with
* lock */
PROC_QUEUE waitProcs; /* list of PGPROC objects waiting on lock */
@@ -151,7 +153,7 @@ typedef struct LOCK
int nGranted; /* total of granted[] array */
} LOCK;
#define LOCK_LOCKMETHOD(lock) ((lock).tag.lockmethod)
#define LOCK_LOCKMETHOD(lock) ((lock).tag.lockmethodid)
/*
@@ -204,7 +206,7 @@ typedef struct PROCLOCK
} PROCLOCK;
#define PROCLOCK_LOCKMETHOD(proclock) \
(((LOCK *) MAKE_PTR((proclock).tag.lock))->tag.lockmethod)
(((LOCK *) MAKE_PTR((proclock).tag.lock))->tag.lockmethodid)
/*
* This struct holds information passed from lmgr internals to the lock
@@ -227,17 +229,17 @@ typedef struct
* function prototypes
*/
extern void InitLocks(void);
extern LOCKMETHODTABLE *GetLocksMethodTable(LOCK *lock);
extern LOCKMETHOD LockMethodTableInit(char *tabName, LOCKMASK *conflictsP,
extern LockMethod GetLocksMethodTable(LOCK *lock);
extern LOCKMETHODID LockMethodTableInit(char *tabName, LOCKMASK *conflictsP,
int numModes, int maxBackends);
extern LOCKMETHOD LockMethodTableRename(LOCKMETHOD lockmethod);
extern bool LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
extern LOCKMETHODID LockMethodTableRename(LOCKMETHODID lockmethodid);
extern bool LockAcquire(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
TransactionId xid, LOCKMODE lockmode, bool dontWait);
extern bool LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
extern bool LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
TransactionId xid, LOCKMODE lockmode);
extern bool LockReleaseAll(LOCKMETHOD lockmethod, PGPROC *proc,
extern bool LockReleaseAll(LOCKMETHODID lockmethodid, PGPROC *proc,
bool allxids, TransactionId xid);
extern int LockCheckConflicts(LOCKMETHODTABLE *lockMethodTable,
extern int LockCheckConflicts(LockMethod lockMethodTable,
LOCKMODE lockmode,
LOCK *lock, PROCLOCK *proclock, PGPROC *proc,
int *myHolding);