src/include/storage/lwlock.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * lwlock.h
   4  *        Lightweight lock manager
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef LWLOCK_H
  15 #define LWLOCK_H
  16
  17 /*
  18  * It's a bit odd to declare NUM_BUFFER_PARTITIONS and NUM_LOCK_PARTITIONS
  19  * here, but we need them to set up enum LWLockId correctly, and having
  20  * this file include lock.h or bufmgr.h would be backwards.
  21  */
  22
  23 /* Number of partitions of the shared buffer mapping hashtable */
  24 #define NUM_BUFFER_PARTITIONS  16
  25
  26 /* Number of partitions the shared lock tables are divided into */
  27 #define LOG2_NUM_LOCK_PARTITIONS  4
  28 #define NUM_LOCK_PARTITIONS  (1 << LOG2_NUM_LOCK_PARTITIONS)
  29
  30 /*
  31  * We have a number of predefined LWLocks, plus a bunch of LWLocks that are
  32  * dynamically assigned (e.g., for shared buffers).  The LWLock structures
  33  * live in shared memory (since they contain shared data) and are identified
  34  * by values of this enumerated type.  We abuse the notion of an enum somewhat
  35  * by allowing values not listed in the enum declaration to be assigned.
  36  * The extra value MaxDynamicLWLock is there to keep the compiler from
  37  * deciding that the enum can be represented as char or short ...
  38  *
  39  * If you remove a lock, please replace it with a placeholder. This retains
  40  * the lock numbering, which is helpful for DTrace and other external
  41  * debugging scripts.
  42  */
  43 typedef enum LWLockId
  44 {
  45         BufFreelistLock,
  46         ShmemIndexLock,
  47         OidGenLock,
  48         XidGenLock,
  49         ProcArrayLock,
  50         SInvalReadLock,
  51         SInvalWriteLock,
  52         WALInsertLock,
  53         WALWriteLock,
  54         ControlFileLock,
  55         CheckpointLock,
  56         CLogControlLock,
  57         SubtransControlLock,
  58         MultiXactGenLock,
  59         MultiXactOffsetControlLock,
  60         MultiXactMemberControlLock,
  61         RelCacheInitLock,
  62         BgWriterCommLock,
  63         TwoPhaseStateLock,
  64         TablespaceCreateLock,
  65         BtreeVacuumLock,
  66         AddinShmemInitLock,
  67         AutovacuumLock,
  68         AutovacuumScheduleLock,
  69         SyncScanLock,
  70         /* Individual lock IDs end here */
  71         FirstBufMappingLock,
  72         FirstLockMgrLock = FirstBufMappingLock + NUM_BUFFER_PARTITIONS,
  73
  74         /* must be last except for MaxDynamicLWLock: */
  75         NumFixedLWLocks = FirstLockMgrLock + NUM_LOCK_PARTITIONS,
  76
  77         MaxDynamicLWLock = 1000000000
  78 } LWLockId;
  79
  80
  81 typedef enum LWLockMode
  82 {
  83         LW_EXCLUSIVE,
  84         LW_SHARED
  85 } LWLockMode;
  86
  87
  88 #ifdef LOCK_DEBUG
  89 extern bool Trace_lwlocks;
  90 #endif
  91
  92 extern LWLockId LWLockAssign(void);
  93 extern void LWLockAcquire(LWLockId lockid, LWLockMode mode);
  94 extern bool LWLockConditionalAcquire(LWLockId lockid, LWLockMode mode);
  95 extern void LWLockRelease(LWLockId lockid);
  96 extern void LWLockReleaseAll(void);
  97 extern bool LWLockHeldByMe(LWLockId lockid);
  98
  99 extern int      NumLWLocks(void);
 100 extern Size LWLockShmemSize(void);
 101 extern void CreateLWLocks(void);
 102
 103 extern void RequestAddinLWLocks(int n);
 104
 105 #endif   /* LWLOCK_H */