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| 1 /* | |
| 2 ** 2007 August 14 | |
| 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 ** This file contains the C functions that implement mutexes. | |
| 13 ** | |
| 14 ** This file contains code that is common across all mutex implementations. | |
| 15 | |
| 16 ** | |
| 17 ** $Id: mutex.c,v 1.31 2009/07/16 18:21:18 drh Exp $ | |
| 18 */ | |
| 19 #include "sqliteInt.h" | |
| 20 | |
| 21 #if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT) | |
| 22 /* | |
| 23 ** For debugging purposes, record when the mutex subsystem is initialized | |
| 24 ** and uninitialized so that we can assert() if there is an attempt to | |
| 25 ** allocate a mutex while the system is uninitialized. | |
| 26 */ | |
| 27 static SQLITE_WSD int mutexIsInit = 0; | |
| 28 #endif /* SQLITE_DEBUG */ | |
| 29 | |
| 30 | |
| 31 #ifndef SQLITE_MUTEX_OMIT | |
| 32 /* | |
| 33 ** Initialize the mutex system. | |
| 34 */ | |
| 35 int sqlite3MutexInit(void){ | |
| 36 int rc = SQLITE_OK; | |
| 37 if( sqlite3GlobalConfig.bCoreMutex ){ | |
| 38 if( !sqlite3GlobalConfig.mutex.xMutexAlloc ){ | |
| 39 /* If the xMutexAlloc method has not been set, then the user did not | |
| 40 ** install a mutex implementation via sqlite3_config() prior to | |
| 41 ** sqlite3_initialize() being called. This block copies pointers to | |
| 42 ** the default implementation into the sqlite3GlobalConfig structure. | |
| 43 */ | |
| 44 sqlite3_mutex_methods *pFrom = sqlite3DefaultMutex(); | |
| 45 sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex; | |
| 46 | |
| 47 memcpy(pTo, pFrom, offsetof(sqlite3_mutex_methods, xMutexAlloc)); | |
| 48 memcpy(&pTo->xMutexFree, &pFrom->xMutexFree, | |
| 49 sizeof(*pTo) - offsetof(sqlite3_mutex_methods, xMutexFree)); | |
| 50 pTo->xMutexAlloc = pFrom->xMutexAlloc; | |
| 51 } | |
| 52 rc = sqlite3GlobalConfig.mutex.xMutexInit(); | |
| 53 } | |
| 54 | |
| 55 #ifdef SQLITE_DEBUG | |
| 56 GLOBAL(int, mutexIsInit) = 1; | |
| 57 #endif | |
| 58 | |
| 59 return rc; | |
| 60 } | |
| 61 | |
| 62 /* | |
| 63 ** Shutdown the mutex system. This call frees resources allocated by | |
| 64 ** sqlite3MutexInit(). | |
| 65 */ | |
| 66 int sqlite3MutexEnd(void){ | |
| 67 int rc = SQLITE_OK; | |
| 68 if( sqlite3GlobalConfig.mutex.xMutexEnd ){ | |
| 69 rc = sqlite3GlobalConfig.mutex.xMutexEnd(); | |
| 70 } | |
| 71 | |
| 72 #ifdef SQLITE_DEBUG | |
| 73 GLOBAL(int, mutexIsInit) = 0; | |
| 74 #endif | |
| 75 | |
| 76 return rc; | |
| 77 } | |
| 78 | |
| 79 /* | |
| 80 ** Retrieve a pointer to a static mutex or allocate a new dynamic one. | |
| 81 */ | |
| 82 sqlite3_mutex *sqlite3_mutex_alloc(int id){ | |
| 83 #ifndef SQLITE_OMIT_AUTOINIT | |
| 84 if( sqlite3_initialize() ) return 0; | |
| 85 #endif | |
| 86 return sqlite3GlobalConfig.mutex.xMutexAlloc(id); | |
| 87 } | |
| 88 | |
| 89 sqlite3_mutex *sqlite3MutexAlloc(int id){ | |
| 90 if( !sqlite3GlobalConfig.bCoreMutex ){ | |
| 91 return 0; | |
| 92 } | |
| 93 assert( GLOBAL(int, mutexIsInit) ); | |
| 94 return sqlite3GlobalConfig.mutex.xMutexAlloc(id); | |
| 95 } | |
| 96 | |
| 97 /* | |
| 98 ** Free a dynamic mutex. | |
| 99 */ | |
| 100 void sqlite3_mutex_free(sqlite3_mutex *p){ | |
| 101 if( p ){ | |
| 102 sqlite3GlobalConfig.mutex.xMutexFree(p); | |
| 103 } | |
| 104 } | |
| 105 | |
| 106 /* | |
| 107 ** Obtain the mutex p. If some other thread already has the mutex, block | |
| 108 ** until it can be obtained. | |
| 109 */ | |
| 110 void sqlite3_mutex_enter(sqlite3_mutex *p){ | |
| 111 if( p ){ | |
| 112 sqlite3GlobalConfig.mutex.xMutexEnter(p); | |
| 113 } | |
| 114 } | |
| 115 | |
| 116 /* | |
| 117 ** Obtain the mutex p. If successful, return SQLITE_OK. Otherwise, if another | |
| 118 ** thread holds the mutex and it cannot be obtained, return SQLITE_BUSY. | |
| 119 */ | |
| 120 int sqlite3_mutex_try(sqlite3_mutex *p){ | |
| 121 int rc = SQLITE_OK; | |
| 122 if( p ){ | |
| 123 return sqlite3GlobalConfig.mutex.xMutexTry(p); | |
| 124 } | |
| 125 return rc; | |
| 126 } | |
| 127 | |
| 128 /* | |
| 129 ** The sqlite3_mutex_leave() routine exits a mutex that was previously | |
| 130 ** entered by the same thread. The behavior is undefined if the mutex | |
| 131 ** is not currently entered. If a NULL pointer is passed as an argument | |
| 132 ** this function is a no-op. | |
| 133 */ | |
| 134 void sqlite3_mutex_leave(sqlite3_mutex *p){ | |
| 135 if( p ){ | |
| 136 sqlite3GlobalConfig.mutex.xMutexLeave(p); | |
| 137 } | |
| 138 } | |
| 139 | |
| 140 #ifndef NDEBUG | |
| 141 /* | |
| 142 ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are | |
| 143 ** intended for use inside assert() statements. | |
| 144 */ | |
| 145 int sqlite3_mutex_held(sqlite3_mutex *p){ | |
| 146 return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p); | |
| 147 } | |
| 148 int sqlite3_mutex_notheld(sqlite3_mutex *p){ | |
| 149 return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p); | |
| 150 } | |
| 151 #endif | |
| 152 | |
| 153 #endif /* SQLITE_OMIT_MUTEX */ | |
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Chromium Code Reviews
Issue 3108030:
Move bundled copy of sqlite one level deeper to better separate it... (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src/