Esempio n. 1
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/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
void sqlite3_mutex_enter(sqlite3_mutex *p){
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
  EnterCriticalSection(&p->mutex);
  p->owner = GetCurrentThreadId(); 
  p->nRef++;
}
Esempio n. 2
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/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no
** such buffer exists or there is no space left in it, this function falls
** back to sqlite3Malloc().
**
** Multiple threads can run this routine at the same time.  Global variables
** in pcache1 need to be protected via mutex.
*/
static void *pcache1Alloc(int nByte){
  void *p = 0;
  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
  if( nByte<=pcache1.szSlot ){
    sqlite3_mutex_enter(pcache1.mutex);
    p = (PgHdr1 *)pcache1.pFree;
    if( p ){
      pcache1.pFree = pcache1.pFree->pNext;
      pcache1.nFreeSlot--;
      pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
      assert( pcache1.nFreeSlot>=0 );
      sqlite3StatusHighwater(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
      sqlite3StatusUp(SQLITE_STATUS_PAGECACHE_USED, 1);
    }
    sqlite3_mutex_leave(pcache1.mutex);
  }
  if( p==0 ){
    /* Memory is not available in the SQLITE_CONFIG_PAGECACHE pool.  Get
    ** it from sqlite3Malloc instead.
    */
    p = sqlite3Malloc(nByte);
#ifndef SQLITE_DISABLE_PAGECACHE_OVERFLOW_STATS
    if( p ){
      int sz = sqlite3MallocSize(p);
      sqlite3_mutex_enter(pcache1.mutex);
      sqlite3StatusHighwater(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
      sqlite3StatusUp(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
      sqlite3_mutex_leave(pcache1.mutex);
    }
#endif
    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
  }
  return p;
}
Esempio n. 3
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void *sqlite3ScratchMalloc(int n){
  void *p;
  assert( n>0 );

  sqlite3_mutex_enter(mem0.mutex);
  if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
    p = mem0.pScratchFree;
    mem0.pScratchFree = mem0.pScratchFree->pNext;
    mem0.nScratchFree--;
    sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);
    sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    if( sqlite3GlobalConfig.bMemstat ){
      sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
      n = mallocWithAlarm(n, &p);
      if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
      sqlite3_mutex_leave(mem0.mutex);
    }else{
      sqlite3_mutex_leave(mem0.mutex);
      p = sqlite3GlobalConfig.m.xMalloc(n);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
  }
  assert( sqlite3_mutex_notheld(mem0.mutex) );


#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  assert( scratchAllocOut<=1 );
  if( p ) scratchAllocOut++;
#endif

  return p;
}
/*
** Obtain the BtShared mutex associated with B-Tree handle p. Also,
** set BtShared.db to the database handle associated with p and the
** p->locked boolean to true.
*/
static void lockBtreeMutex(Btree *p){
  assert( p->locked==0 );
  assert( sqlite3_mutex_notheld(p->pBt->mutex) );
  assert( sqlite3_mutex_held(p->db->mutex) );

  sqlite3_mutex_enter(p->pBt->mutex);
  p->pBt->db = p->db;
  p->locked = 1;
}
Esempio n. 5
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/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
void sqlite3_mutex_enter(sqlite3_mutex *p){
  TID tid;
  PID holder1;
  ULONG holder2;
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
  DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);
  DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
  p->owner = tid;
  p->nRef++;
}
Esempio n. 6
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/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
void sqlite3_mutex_enter(sqlite3_mutex *p){
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
  pthread_mutex_lock(&p->mutex);
  p->owner = pthread_self();
  p->nRef++;
#ifdef SQLITE_DEBUG
  if( p->trace ){
    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }
#endif
}
Esempio n. 7
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int sqlite3_mutex_try(sqlite3_mutex *p){
  int rc;
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
  //if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){
  //  p->owner = GetCurrentThreadId();
  //  p->nRef++;
  //  rc = SQLITE_OK;
  //}else{
    rc = SQLITE_BUSY;
  //}
  return rc;
}
Esempio n. 8
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int sqlite3_mutex_try(sqlite3_mutex *p){
  int rc;
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );

#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
  /* If recursive mutexes are not available, then we have to grow
  ** our own.  This implementation assumes that pthread_equal()
  ** is atomic - that it cannot be deceived into thinking self
  ** and p->owner are equal if p->owner changes between two values
  ** that are not equal to self while the comparison is taking place.
  ** This implementation also assumes a coherent cache - that 
  ** separate processes cannot read different values from the same
  ** address at the same time.  If either of these two conditions
  ** are not met, then the mutexes will fail and problems will result.
  */
  {
    pthread_t self = pthread_self();
    if( p->nRef>0 && pthread_equal(p->owner, self) ){
      p->nRef++;
      rc = SQLITE_OK;
    }else if( pthread_mutex_lock(&p->mutex)==0 ){
      assert( p->nRef==0 );
      p->owner = self;
      p->nRef = 1;
      rc = SQLITE_OK;
    }else{
      rc = SQLITE_BUSY;
    }
  }
#else
  /* Use the built-in recursive mutexes if they are available.
  */
  if( pthread_mutex_trylock(&p->mutex)==0 ){
    p->owner = pthread_self();
    p->nRef++;
    rc = SQLITE_OK;
  }else{
    rc = SQLITE_BUSY;
  }
#endif

#ifdef SQLITE_DEBUG
  if( rc==SQLITE_OK && p->trace ){
    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }
#endif
  return rc;
}
Esempio n. 9
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int sqlite3_mutex_try(sqlite3_mutex *p){
  int rc;
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
  if( pthread_mutex_trylock(&p->mutex)==0 ){
    p->owner = pthread_self();
    p->nRef++;
    rc = SQLITE_OK;
#ifdef SQLITE_DEBUG
    if( p->trace ){
      printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
    }
#endif
  }else{
    rc = SQLITE_BUSY;
  }
  return rc;
}
Esempio n. 10
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int sqlite3_mutex_try(sqlite3_mutex *p){
  int rc;
  TID tid;
  PID holder1;
  ULONG holder2;
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
  if( DosRequestMutexSem(p->mutex, SEM_IMMEDIATE_RETURN) == NO_ERROR) {
    DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
    p->owner = tid;
    p->nRef++;
    rc = SQLITE_OK;
  } else {
    rc = SQLITE_BUSY;
  }

  return rc;
}
Esempio n. 11
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/*
** Allocate memory that is to be used and released right away.
** This routine is similar to alloca() in that it is not intended
** for situations where the memory might be held long-term.  This
** routine is intended to get memory to old large transient data
** structures that would not normally fit on the stack of an
** embedded processor.
*/
void *sqlite3ScratchMalloc(int n){
  void *p;
  assert( n>0 );

  sqlite3_mutex_enter(mem0.mutex);
  if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
    p = mem0.pScratchFree;
    mem0.pScratchFree = mem0.pScratchFree->pNext;
    mem0.nScratchFree--;
    sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);
    sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    if( sqlite3GlobalConfig.bMemstat ){
      sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
      n = mallocWithAlarm(n, &p);
      if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
      sqlite3_mutex_leave(mem0.mutex);
    }else{
      sqlite3_mutex_leave(mem0.mutex);
      p = sqlite3GlobalConfig.m.xMalloc(n);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
  }
  assert( sqlite3_mutex_notheld(mem0.mutex) );


#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  /* Verify that no more than two scratch allocations per thread
  ** are outstanding at one time.  (This is only checked in the
  ** single-threaded case since checking in the multi-threaded case
  ** would be much more complicated.) */
  assert( scratchAllocOut<=1 );
  if( p ) scratchAllocOut++;
#endif

  return p;
}
Esempio n. 12
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/*
** Allocate memory that is to be used and released right away.
** This routine is similar to alloca() in that it is not intended
** for situations where the memory might be held long-term.  This
** routine is intended to get memory to old large transient data
** structures that would not normally fit on the stack of an
** embedded processor.
*/
void *sqlite3ScratchMalloc(int n){
  void *p;
  assert( n>0 );

  sqlite3_mutex_enter(mem0.mutex);
  sqlite3StatusHighwater(SQLITE_STATUS_SCRATCH_SIZE, n);
  if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
    p = mem0.pScratchFree;
    mem0.pScratchFree = mem0.pScratchFree->pNext;
    mem0.nScratchFree--;
    sqlite3StatusUp(SQLITE_STATUS_SCRATCH_USED, 1);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    sqlite3_mutex_leave(mem0.mutex);
    p = sqlite3Malloc(n);
    if( sqlite3GlobalConfig.bMemstat && p ){
      sqlite3_mutex_enter(mem0.mutex);
      sqlite3StatusUp(SQLITE_STATUS_SCRATCH_OVERFLOW, sqlite3MallocSize(p));
      sqlite3_mutex_leave(mem0.mutex);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
  }
  assert( sqlite3_mutex_notheld(mem0.mutex) );


#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  /* EVIDENCE-OF: R-12970-05880 SQLite will not use more than one scratch
  ** buffers per thread.
  **
  ** This can only be checked in single-threaded mode.
  */
  assert( scratchAllocOut==0 );
  if( p ) scratchAllocOut++;
#endif

  return p;
}
Esempio n. 13
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int sqlite3_mutex_try(sqlite3_mutex *p){
  int rc = SQLITE_BUSY;
  assert( p );
  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
  /*
  ** The sqlite3_mutex_try() routine is very rarely used, and when it
  ** is used it is merely an optimization.  So it is OK for it to always
  ** fail.  
  **
  ** The TryEnterCriticalSection() interface is only available on WinNT.
  ** And some windows compilers complain if you try to use it without
  ** first doing some #defines that prevent SQLite from building on Win98.
  ** For that reason, we will omit this optimization for now.  See
  ** ticket #2685.
  */
#if 0
  if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){
    p->owner = GetCurrentThreadId();
    p->nRef++;
    rc = SQLITE_OK;
  }
#endif
  return rc;
}