/*-------------------------------------------------------------------------
*
* lwlock.h
* Lightweight lock manager
*
*
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.42 2009/03/03 08:11:24 heikki Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef LWLOCK_H
#define LWLOCK_H
/*
* It's a bit odd to declare NUM_BUFFER_PARTITIONS and NUM_LOCK_PARTITIONS
* here, but we need them to set up enum LWLockId correctly, and having
* this file include lock.h or bufmgr.h would be backwards.
*/
/* Number of partitions of the shared buffer mapping hashtable */
#define NUM_BUFFER_PARTITIONS 16
/* Number of partitions the shared lock tables are divided into */
#define LOG2_NUM_LOCK_PARTITIONS 4
#define NUM_LOCK_PARTITIONS (1 << LOG2_NUM_LOCK_PARTITIONS)
/*
* We have a number of predefined LWLocks, plus a bunch of LWLocks that are
* dynamically assigned (e.g., for shared buffers). The LWLock structures
* live in shared memory (since they contain shared data) and are identified
* by values of this enumerated type. We abuse the notion of an enum somewhat
* by allowing values not listed in the enum declaration to be assigned.
* The extra value MaxDynamicLWLock is there to keep the compiler from
* deciding that the enum can be represented as char or short ...
*
* If you remove a lock, please replace it with a placeholder. This retains
* the lock numbering, which is helpful for DTrace and other external
* debugging scripts.
*/
typedef enum LWLockId
{
BufFreelistLock,
ShmemIndexLock,
OidGenLock,
XidGenLock,
ProcArrayLock,
SInvalReadLock,
SInvalWriteLock,
WALInsertLock,
WALWriteLock,
ControlFileLock,
CheckpointLock,
CLogControlLock,
SubtransControlLock,
MultiXactGenLock,
MultiXactOffsetControlLock,
MultiXactMemberControlLock,
RelCacheInitLock,
BgWriterCommLock,
TwoPhaseStateLock,
TablespaceCreateLock,
BtreeVacuumLock,
AddinShmemInitLock,
AutovacuumLock,
AutovacuumScheduleLock,
SyncScanLock,
/* Individual lock IDs end here */
FirstBufMappingLock,
FirstLockMgrLock = FirstBufMappingLock + NUM_BUFFER_PARTITIONS,
/* must be last except for MaxDynamicLWLock: */
NumFixedLWLocks = FirstLockMgrLock + NUM_LOCK_PARTITIONS,
MaxDynamicLWLock = 1000000000
} LWLockId;
typedef enum LWLockMode
{
LW_EXCLUSIVE,
LW_SHARED
} LWLockMode;
#ifdef LOCK_DEBUG
extern bool Trace_lwlocks;
#endif
extern LWLockId LWLockAssign(void);
extern void LWLockAcquire(LWLockId lockid, LWLockMode mode);
extern bool LWLockConditionalAcquire(LWLockId lockid, LWLockMode mode);
extern void LWLockRelease(LWLockId lockid);
extern void LWLockReleaseAll(void);
extern bool LWLockHeldByMe(LWLockId lockid);
extern int NumLWLocks(void);
extern Size LWLockShmemSize(void);
extern void CreateLWLocks(void);
extern void RequestAddinLWLocks(int n);
#endif /* LWLOCK_H */
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