--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/persistentstorage/sqlite3api/SQLite/mutex.c Fri Jan 22 11:06:30 2010 +0200
@@ -0,0 +1,277 @@
+/*
+** 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.
+**
+** The implementation in this file does not provide any mutual
+** exclusion and is thus suitable for use only in applications
+** that use SQLite in a single thread. But this implementation
+** does do a lot of error checking on mutexes to make sure they
+** are called correctly and at appropriate times. Hence, this
+** implementation is suitable for testing.
+** debugging purposes
+**
+** $Id: mutex.c,v 1.28 2008/09/01 18:34:20 danielk1977 Exp $
+*/
+#include "sqliteInt.h"
+
+#ifndef SQLITE_MUTEX_NOOP
+/*
+** Initialize the mutex system.
+*/
+int sqlite3MutexInit(void){
+ int rc = SQLITE_OK;
+ if( sqlite3GlobalConfig.bCoreMutex ){
+ 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.
+ **
+ ** The danger is that although sqlite3_config() is not a threadsafe
+ ** API, sqlite3_initialize() is, and so multiple threads may be
+ ** attempting to run this function simultaneously. To guard write
+ ** access to the sqlite3GlobalConfig structure, the 'MASTER' static mutex
+ ** is obtained before modifying it.
+ */
+ sqlite3_mutex_methods *p = sqlite3DefaultMutex();
+ sqlite3_mutex *pMaster = 0;
+
+ rc = p->xMutexInit();
+ if( rc==SQLITE_OK ){
+ pMaster = p->xMutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+ assert(pMaster);
+ p->xMutexEnter(pMaster);
+ assert( sqlite3GlobalConfig.mutex.xMutexAlloc==0
+ || sqlite3GlobalConfig.mutex.xMutexAlloc==p->xMutexAlloc
+ );
+ if( !sqlite3GlobalConfig.mutex.xMutexAlloc ){
+ sqlite3GlobalConfig.mutex = *p;
+ }
+ p->xMutexLeave(pMaster);
+ }
+ }else{
+ rc = sqlite3GlobalConfig.mutex.xMutexInit();
+ }
+ }
+
+ return rc;
+}
+
+/*
+** Shutdown the mutex system. This call frees resources allocated by
+** sqlite3MutexInit().
+*/
+int sqlite3MutexEnd(void){
+ int rc = SQLITE_OK;
+ rc = sqlite3GlobalConfig.mutex.xMutexEnd();
+ return rc;
+}
+
+/*
+** Retrieve a pointer to a static mutex or allocate a new dynamic one.
+*/
+SQLITE_EXPORT sqlite3_mutex *sqlite3_mutex_alloc(int id){
+#ifndef SQLITE_OMIT_AUTOINIT
+ if( sqlite3_initialize() ) return 0;
+#endif
+ return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
+}
+
+sqlite3_mutex *sqlite3MutexAlloc(int id){
+ if( !sqlite3GlobalConfig.bCoreMutex ){
+ return 0;
+ }
+ return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
+}
+
+/*
+** Free a dynamic mutex.
+*/
+SQLITE_EXPORT void sqlite3_mutex_free(sqlite3_mutex *p){
+ if( p ){
+ sqlite3GlobalConfig.mutex.xMutexFree(p);
+ }
+}
+
+/*
+** Obtain the mutex p. If some other thread already has the mutex, block
+** until it can be obtained.
+*/
+SQLITE_EXPORT void sqlite3_mutex_enter(sqlite3_mutex *p){
+ if( p ){
+ 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.
+*/
+SQLITE_EXPORT int sqlite3_mutex_try(sqlite3_mutex *p){
+ int rc = SQLITE_OK;
+ if( p ){
+ 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.
+*/
+SQLITE_EXPORT void sqlite3_mutex_leave(sqlite3_mutex *p){
+ if( p ){
+ sqlite3GlobalConfig.mutex.xMutexLeave(p);
+ }
+}
+
+#ifndef NDEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+SQLITE_EXPORT int sqlite3_mutex_held(sqlite3_mutex *p){
+ return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p);
+}
+SQLITE_EXPORT int sqlite3_mutex_notheld(sqlite3_mutex *p){
+ return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p);
+}
+#else
+
+SQLITE_EXPORT int sqlite3_mutex_held(sqlite3_mutex *p){return 1;}
+SQLITE_EXPORT int sqlite3_mutex_notheld(sqlite3_mutex *p){return 1;}
+
+#endif
+#endif
+
+#ifdef SQLITE_MUTEX_NOOP_DEBUG
+/*
+** In this implementation, mutexes do not provide any mutual exclusion.
+** But the error checking is provided. This implementation is useful
+** for test purposes.
+*/
+
+/*
+** The mutex object
+*/
+struct sqlite3_mutex {
+ int id; /* The mutex type */
+ int cnt; /* Number of entries without a matching leave */
+};
+
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+static int noopMutexHeld(sqlite3_mutex *p){
+ return p==0 || p->cnt>0;
+}
+static int noopMutexNotheld(sqlite3_mutex *p){
+ return p==0 || p->cnt==0;
+}
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int noopMutexInit(void){ return SQLITE_OK; }
+static int noopMutexEnd(void){ return SQLITE_OK; }
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it. If it returns NULL
+** that means that a mutex could not be allocated.
+*/
+static sqlite3_mutex *noopMutexAlloc(int id){
+ static sqlite3_mutex aStatic[6];
+ sqlite3_mutex *pNew = 0;
+ switch( id ){
+ case SQLITE_MUTEX_FAST:
+ case SQLITE_MUTEX_RECURSIVE: {
+ pNew = sqlite3Malloc(sizeof(*pNew));
+ if( pNew ){
+ pNew->id = id;
+ pNew->cnt = 0;
+ }
+ break;
+ }
+ default: {
+ assert( id-2 >= 0 );
+ assert( id-2 < sizeof(aStatic)/sizeof(aStatic[0]) );
+ pNew = &aStatic[id-2];
+ pNew->id = id;
+ break;
+ }
+ }
+ return pNew;
+}
+
+/*
+** This routine deallocates a previously allocated mutex.
+*/
+static void noopMutexFree(sqlite3_mutex *p){
+ assert( p->cnt==0 );
+ assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+ sqlite3_free(p);
+}
+
+/*
+** 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.
+*/
+static void noopMutexEnter(sqlite3_mutex *p){
+ assert( p->id==SQLITE_MUTEX_RECURSIVE || noopMutexNotheld(p) );
+ p->cnt++;
+}
+static int noopMutexTry(sqlite3_mutex *p){
+ assert( p->id==SQLITE_MUTEX_RECURSIVE || noopMutexNotheld(p) );
+ p->cnt++;
+ return SQLITE_OK;
+}
+
+/*
+** 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 or
+** is not currently allocated. SQLite will never do either.
+*/
+static void noopMutexLeave(sqlite3_mutex *p){
+ assert( noopMutexHeld(p) );
+ p->cnt--;
+ assert( p->id==SQLITE_MUTEX_RECURSIVE || noopMutexNotheld(p) );
+}
+
+sqlite3_mutex_methods *sqlite3DefaultMutex(void){
+ static sqlite3_mutex_methods sMutex = {
+ noopMutexInit,
+ noopMutexEnd,
+ noopMutexAlloc,
+ noopMutexFree,
+ noopMutexEnter,
+ noopMutexTry,
+ noopMutexLeave,
+
+ noopMutexHeld,
+ noopMutexNotheld
+ };
+
+ return &sMutex;
+}
+#endif /* SQLITE_MUTEX_NOOP_DEBUG */