src/include/storage/lwlock.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * lwlock.h
   4  *        Lightweight lock manager
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, 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 like was done
  40  * for FreeSpaceMapLock. This retains the lock numbering, which is helpful for
  41  * DTrace and other external debugging scripts.
  42  */
  43 typedef enum LWLockId
  44 {
  45         BufFreelistLock,
  46         ShmemIndexLock,
  47         OidGenLock,
  48         XidGenLock,
  49         ProcArrayLock,
  50         SInvalReadLock,
  51         SInvalWriteLock,
  52         UnusedLock1,                            /* FreeSpaceMapLock used to be here */
  53         WALInsertLock,
  54         WALWriteLock,
  55         ControlFileLock,
  56         CheckpointLock,
  57         CLogControlLock,
  58         SubtransControlLock,
  59         MultiXactGenLock,
  60         MultiXactOffsetControlLock,
  61         MultiXactMemberControlLock,
  62         RelCacheInitLock,
  63         BgWriterCommLock,
  64         TwoPhaseStateLock,
  65         TablespaceCreateLock,
  66         BtreeVacuumLock,
  67         AddinShmemInitLock,
  68         AutovacuumLock,
  69         AutovacuumScheduleLock,
  70         SyncScanLock,
  71         /* Individual lock IDs end here */
  72         FirstBufMappingLock,
  73         FirstLockMgrLock = FirstBufMappingLock + NUM_BUFFER_PARTITIONS,
  74
  75         /* must be last except for MaxDynamicLWLock: */
  76         NumFixedLWLocks = FirstLockMgrLock + NUM_LOCK_PARTITIONS,
  77
  78         MaxDynamicLWLock = 1000000000
  79 } LWLockId;
  80
  81
  82 typedef enum LWLockMode
  83 {
  84         LW_EXCLUSIVE,
  85         LW_SHARED
  86 } LWLockMode;
  87
  88
  89 #ifdef LOCK_DEBUG
  90 extern bool Trace_lwlocks;
  91 #endif
  92
  93 extern LWLockId LWLockAssign(void);
  94 extern void LWLockAcquire(LWLockId lockid, LWLockMode mode);
  95 extern bool LWLockConditionalAcquire(LWLockId lockid, LWLockMode mode);
  96 extern void LWLockRelease(LWLockId lockid);
  97 extern void LWLockReleaseAll(void);
  98 extern bool LWLockHeldByMe(LWLockId lockid);
  99
 100 extern int      NumLWLocks(void);
 101 extern Size LWLockShmemSize(void);
 102 extern void CreateLWLocks(void);
 103
 104 extern void RequestAddinLWLocks(int n);
 105
 106 #endif   /* LWLOCK_H */