ext/lsm1/lsm_mutex.c

   1 /*
   2 ** 2012-01-30
   3 **
   4 ** The author disclaims copyright to this source code.  In place of
   5 ** a legal notice, here is a blessing:
   6 **
   7 **    May you do good and not evil.
   8 **    May you find forgiveness for yourself and forgive others.
   9 **    May you share freely, never taking more than you give.
  10 **
  11 *************************************************************************
  12 **
  13 ** Mutex functions for LSM.
  14 */
  15 #include "lsmInt.h"
  16
  17 /*
  18 ** Allocate a new mutex.
  19 */
  20 int lsmMutexNew(lsm_env *pEnv, lsm_mutex **ppNew){
  21   return pEnv->xMutexNew(pEnv, ppNew);
  22 }
  23
  24 /*
  25 ** Return a handle for one of the static mutexes.
  26 */
  27 int lsmMutexStatic(lsm_env *pEnv, int iMutex, lsm_mutex **ppStatic){
  28   return pEnv->xMutexStatic(pEnv, iMutex, ppStatic);
  29 }
  30
  31 /*
  32 ** Free a mutex allocated by lsmMutexNew().
  33 */
  34 void lsmMutexDel(lsm_env *pEnv, lsm_mutex *pMutex){
  35   if( pMutex ) pEnv->xMutexDel(pMutex);
  36 }
  37
  38 /*
  39 ** Enter a mutex.
  40 */
  41 void lsmMutexEnter(lsm_env *pEnv, lsm_mutex *pMutex){
  42   pEnv->xMutexEnter(pMutex);
  43 }
  44
  45 /*
  46 ** Attempt to enter a mutex, but do not block. If successful, return zero.
  47 ** Otherwise, if the mutex is already held by some other thread and is not
  48 ** entered, return non zero.
  49 **
  50 ** Each successful call to this function must be matched by a call to
  51 ** lsmMutexLeave().
  52 */
  53 int lsmMutexTry(lsm_env *pEnv, lsm_mutex *pMutex){
  54   return pEnv->xMutexTry(pMutex);
  55 }
  56
  57 /*
  58 ** Leave a mutex.
  59 */
  60 void lsmMutexLeave(lsm_env *pEnv, lsm_mutex *pMutex){
  61   pEnv->xMutexLeave(pMutex);
  62 }
  63
  64 #ifndef NDEBUG
  65 /*
  66 ** Return non-zero if the mutex passed as the second argument is held
  67 ** by the calling thread, or zero otherwise. If the implementation is not
  68 ** able to tell if the mutex is held by the caller, it should return
  69 ** non-zero.
  70 **
  71 ** This function is only used as part of assert() statements.
  72 */
  73 int lsmMutexHeld(lsm_env *pEnv, lsm_mutex *pMutex){
  74   return pEnv->xMutexHeld ? pEnv->xMutexHeld(pMutex) : 1;
  75 }
  76
  77 /*
  78 ** Return non-zero if the mutex passed as the second argument is not
  79 ** held by the calling thread, or zero otherwise. If the implementation
  80 ** is not able to tell if the mutex is held by the caller, it should
  81 ** return non-zero.
  82 **
  83 ** This function is only used as part of assert() statements.
  84 */
  85 int lsmMutexNotHeld(lsm_env *pEnv, lsm_mutex *pMutex){
  86   return pEnv->xMutexNotHeld ? pEnv->xMutexNotHeld(pMutex) : 1;
  87 }
  88 #endif