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 1.17 2005/03/04 20:21:07 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 (for shared buffers).  The LWLock structures live
  20  * in shared memory (since they contain shared data) and are identified by
  21  * 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         LockMgrLock,
  31         OidGenLock,
  32         XidGenLock,
  33         SInvalLock,
  34         FreeSpaceLock,
  35         MMCacheLock,
  36         WALInsertLock,
  37         WALWriteLock,
  38         ControlFileLock,
  39         CheckpointLock,
  40         CheckpointStartLock,
  41         CLogControlLock,
  42         SubtransControlLock,
  43         RelCacheInitLock,
  44         BgWriterCommLock,
  45
  46         NumFixedLWLocks,                        /* must be last except for
  47                                                                  * MaxDynamicLWLock */
  48
  49         MaxDynamicLWLock = 1000000000
  50 } LWLockId;
  51
  52
  53 typedef enum LWLockMode
  54 {
  55         LW_EXCLUSIVE,
  56         LW_SHARED
  57 } LWLockMode;
  58
  59
  60 #ifdef LOCK_DEBUG
  61 extern bool Trace_lwlocks;
  62 #endif
  63
  64 extern LWLockId LWLockAssign(void);
  65 extern void LWLockAcquire(LWLockId lockid, LWLockMode mode);
  66 extern bool LWLockConditionalAcquire(LWLockId lockid, LWLockMode mode);
  67 extern void LWLockRelease(LWLockId lockid);
  68 extern void LWLockReleaseAll(void);
  69 extern bool LWLockHeldByMe(LWLockId lockid);
  70
  71 extern int      NumLWLocks(void);
  72 extern int      LWLockShmemSize(void);
  73 extern void CreateLWLocks(void);
  74
  75 #endif   /* LWLOCK_H */