granicus.if.org Git - postgresql/blob - src/include/storage/lwlock.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * lwlock.h
   4  *        Lightweight lock manager
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.24 2005/12/11 21:02:18 tgl Exp $
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef LWLOCK_H
  15 #define LWLOCK_H
  16
  17 /*
  18  * We have a number of predefined LWLocks, plus a bunch of LWLocks that are
  19  * dynamically assigned (e.g., for shared buffers).  The LWLock structures
  20  * live in shared memory (since they contain shared data) and are identified
  21  * by values of this enumerated type.  We abuse the notion of an enum somewhat
  22  * by allowing values not listed in the enum declaration to be assigned.
  23  * The extra value MaxDynamicLWLock is there to keep the compiler from
  24  * deciding that the enum can be represented as char or short ...
  25  */
  26 typedef enum LWLockId
  27 {
  28         BufMappingLock,
  29         BufFreelistLock,
  30         OidGenLock,
  31         XidGenLock,
  32         ProcArrayLock,
  33         SInvalLock,
  34         FreeSpaceLock,
  35         WALInsertLock,
  36         WALWriteLock,
  37         ControlFileLock,
  38         CheckpointLock,
  39         CheckpointStartLock,
  40         CLogControlLock,
  41         SubtransControlLock,
  42         MultiXactGenLock,
  43         MultiXactOffsetControlLock,
  44         MultiXactMemberControlLock,
  45         RelCacheInitLock,
  46         BgWriterCommLock,
  47         TwoPhaseStateLock,
  48         FirstLockMgrLock,                       /* must be last except for MaxDynamicLWLock */
  49
  50         MaxDynamicLWLock = 1000000000
  51 } LWLockId;
  52
  53
  54 typedef enum LWLockMode
  55 {
  56         LW_EXCLUSIVE,
  57         LW_SHARED
  58 } LWLockMode;
  59
  60
  61 #ifdef LOCK_DEBUG
  62 extern bool Trace_lwlocks;
  63 #endif
  64
  65 extern LWLockId LWLockAssign(void);
  66 extern void LWLockAcquire(LWLockId lockid, LWLockMode mode);
  67 extern bool LWLockConditionalAcquire(LWLockId lockid, LWLockMode mode);
  68 extern void LWLockRelease(LWLockId lockid);
  69 extern void LWLockReleaseAll(void);
  70 extern bool LWLockHeldByMe(LWLockId lockid);
  71
  72 extern int      NumLWLocks(void);
  73 extern Size LWLockShmemSize(void);
  74 extern void CreateLWLocks(void);
  75
  76 #endif   /* LWLOCK_H */