diff options
Diffstat (limited to 'src/mutex.c')
| -rw-r--r-- | src/mutex.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/src/mutex.c b/src/mutex.c index 3eded653b..46bb82d71 100644 --- a/src/mutex.c +++ b/src/mutex.c @@ -19,7 +19,7 @@ ** implementation is suitable for testing. ** debugging purposes ** -** $Id: mutex.c,v 1.21 2008/06/17 17:21:18 danielk1977 Exp $ +** $Id: mutex.c,v 1.22 2008/06/17 18:57:49 danielk1977 Exp $ */ #include "sqliteInt.h" @@ -30,12 +30,24 @@ int sqlite3_mutex_init(void){ int rc; if( !sqlite3Config.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 sqlite3Config 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 sqlite3Config structure, the 'MASTER' static mutex + ** is obtained before modifying it. + */ sqlite3_mutex_methods *p = sqlite3DefaultMutex(); sqlite3_mutex *pMaster; rc = p->xMutexInit(); if( rc==SQLITE_OK ){ pMaster = p->xMutexAlloc(SQLITE_MUTEX_STATIC_MASTER); + assert(pMaster); p->xMutexEnter(pMaster); assert( sqlite3Config.mutex.xMutexAlloc==0 || sqlite3Config.mutex.xMutexAlloc==p->xMutexAlloc @@ -45,7 +57,6 @@ int sqlite3_mutex_init(void){ } p->xMutexLeave(pMaster); } - }else{ rc = sqlite3Config.mutex.xMutexInit(); } |