[sql] Import reference version of SQLite 3.10.2.

third_party/sqlite/sqlite-src-3100200/src/mutex.c

 /*
 ** 2007 August 14
 **
 ** The author disclaims copyright to this source code.  In place of
 ** a legal notice, here is a blessing:
 **
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
 ** This file contains the C functions that implement mutexes.
 **
 ** This file contains code that is common across all mutex implementations.
 */
 #include "sqliteInt.h"
 
 #if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT)
 /*
 ** For debugging purposes, record when the mutex subsystem is initialized
 ** and uninitialized so that we can assert() if there is an attempt to
 ** allocate a mutex while the system is uninitialized.
 */
 static SQLITE_WSD int mutexIsInit = 0;
-#endif /* SQLITE_DEBUG */
+#endif /* SQLITE_DEBUG && !defined(SQLITE_MUTEX_OMIT) */
 
 
 #ifndef SQLITE_MUTEX_OMIT
 /*
 ** Initialize the mutex system.
 */
 int sqlite3MutexInit(void){ 
   int rc = SQLITE_OK;
   if( !sqlite3GlobalConfig.mutex.xMutexAlloc ){
     /* If the xMutexAlloc method has not been set, then the user did not
     ** install a mutex implementation via sqlite3_config() prior to 
     ** sqlite3_initialize() being called. This block copies pointers to
     ** the default implementation into the sqlite3GlobalConfig structure.
     */
     sqlite3_mutex_methods const *pFrom;
     sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;
 
     if( sqlite3GlobalConfig.bCoreMutex ){
       pFrom = sqlite3DefaultMutex();
     }else{
       pFrom = sqlite3NoopMutex();
     }
-    memcpy(pTo, pFrom, offsetof(sqlite3_mutex_methods, xMutexAlloc));
-    memcpy(&pTo->xMutexFree, &pFrom->xMutexFree,
-           sizeof(*pTo) - offsetof(sqlite3_mutex_methods, xMutexFree));
+    pTo->xMutexInit = pFrom->xMutexInit;
+    pTo->xMutexEnd = pFrom->xMutexEnd;
+    pTo->xMutexFree = pFrom->xMutexFree;
+    pTo->xMutexEnter = pFrom->xMutexEnter;
+    pTo->xMutexTry = pFrom->xMutexTry;
+    pTo->xMutexLeave = pFrom->xMutexLeave;
+    pTo->xMutexHeld = pFrom->xMutexHeld;
+    pTo->xMutexNotheld = pFrom->xMutexNotheld;
+    sqlite3MemoryBarrier();
     pTo->xMutexAlloc = pFrom->xMutexAlloc;
   }
+  assert( sqlite3GlobalConfig.mutex.xMutexInit );
   rc = sqlite3GlobalConfig.mutex.xMutexInit();
 
 #ifdef SQLITE_DEBUG
   GLOBAL(int, mutexIsInit) = 1;
 #endif
 
   return rc;
 }
 
 /*
@@ skipping 12 matching lines @@
 
   return rc;
 }
 
 /*
 ** Retrieve a pointer to a static mutex or allocate a new dynamic one.
 */
 sqlite3_mutex *sqlite3_mutex_alloc(int id){
 #ifndef SQLITE_OMIT_AUTOINIT
   if( id<=SQLITE_MUTEX_RECURSIVE && sqlite3_initialize() ) return 0;
+  if( id>SQLITE_MUTEX_RECURSIVE && sqlite3MutexInit() ) return 0;
 #endif
+  assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
   return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
 }
 
 sqlite3_mutex *sqlite3MutexAlloc(int id){
   if( !sqlite3GlobalConfig.bCoreMutex ){
     return 0;
   }
   assert( GLOBAL(int, mutexIsInit) );
+  assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
   return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
 }
 
 /*
 ** Free a dynamic mutex.
 */
 void sqlite3_mutex_free(sqlite3_mutex *p){
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexFree );
     sqlite3GlobalConfig.mutex.xMutexFree(p);
   }
 }
 
 /*
 ** Obtain the mutex p. If some other thread already has the mutex, block
 ** until it can be obtained.
 */
 void sqlite3_mutex_enter(sqlite3_mutex *p){
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexEnter );
     sqlite3GlobalConfig.mutex.xMutexEnter(p);
   }
 }
 
 /*
 ** Obtain the mutex p. If successful, return SQLITE_OK. Otherwise, if another
 ** thread holds the mutex and it cannot be obtained, return SQLITE_BUSY.
 */
 int sqlite3_mutex_try(sqlite3_mutex *p){
   int rc = SQLITE_OK;
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexTry );
     return sqlite3GlobalConfig.mutex.xMutexTry(p);
   }
   return rc;
 }
 
 /*
 ** The sqlite3_mutex_leave() routine exits a mutex that was previously
 ** entered by the same thread.  The behavior is undefined if the mutex 
 ** is not currently entered. If a NULL pointer is passed as an argument
 ** this function is a no-op.
 */
 void sqlite3_mutex_leave(sqlite3_mutex *p){
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexLeave );
     sqlite3GlobalConfig.mutex.xMutexLeave(p);
   }
 }
 
 #ifndef NDEBUG
 /*
 ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
 ** intended for use inside assert() statements.
 */
 int sqlite3_mutex_held(sqlite3_mutex *p){
+  assert( p==0 || sqlite3GlobalConfig.mutex.xMutexHeld );
   return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p);
 }
 int sqlite3_mutex_notheld(sqlite3_mutex *p){
+  assert( p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld );
   return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p);
 }
 #endif
 
 #endif /* !defined(SQLITE_MUTEX_OMIT) */