1 /* 2 ** 2012 July 21 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 ** 13 ** This file presents a simple cross-platform threading interface for 14 ** use internally by SQLite. 15 ** 16 ** A "thread" can be created using sqlite3ThreadCreate(). This thread 17 ** runs independently of its creator until it is joined using 18 ** sqlite3ThreadJoin(), at which point it terminates. 19 ** 20 ** Threads do not have to be real. It could be that the work of the 21 ** "thread" is done by the main thread at either the sqlite3ThreadCreate() 22 ** or sqlite3ThreadJoin() call. This is, in fact, what happens in 23 ** single threaded systems. Nothing in SQLite requires multiple threads. 24 ** This interface exists so that applications that want to take advantage 25 ** of multiple cores can do so, while also allowing applications to stay 26 ** single-threaded if desired. 27 */ 28 #include "sqliteInt.h" 29 30 #if SQLITE_MAX_WORKER_THREADS>0 31 32 /********************************* Unix Pthreads ****************************/ 33 #if SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) && SQLITE_THREADSAFE>0 34 35 #define SQLITE_THREADS_IMPLEMENTED 1 /* Prevent the single-thread code below */ 36 #include <pthread.h> 37 38 /* A running thread */ 39 struct SQLiteThread { 40 pthread_t tid; /* Thread ID */ 41 int done; /* Set to true when thread finishes */ 42 void *pOut; /* Result returned by the thread */ 43 void *(*xTask)(void*); /* The thread routine */ 44 void *pIn; /* Argument to the thread */ 45 }; 46 47 /* Create a new thread */ 48 int sqlite3ThreadCreate( 49 SQLiteThread **ppThread, /* OUT: Write the thread object here */ 50 void *(*xTask)(void*), /* Routine to run in a separate thread */ 51 void *pIn /* Argument passed into xTask() */ 52 ){ 53 SQLiteThread *p; 54 55 assert( ppThread!=0 ); 56 assert( xTask!=0 ); 57 /* This routine is never used in single-threaded mode */ 58 assert( sqlite3GlobalConfig.bCoreMutex!=0 ); 59 60 *ppThread = 0; 61 p = sqlite3Malloc(sizeof(*p)); 62 if( p==0 ) return SQLITE_NOMEM; 63 memset(p, 0, sizeof(*p)); 64 p->xTask = xTask; 65 p->pIn = pIn; 66 if( sqlite3FaultSim(200) ? 1 : pthread_create(&p->tid, 0, xTask, pIn) ){ 67 p->done = 1; 68 p->pOut = xTask(pIn); 69 } 70 *ppThread = p; 71 return SQLITE_OK; 72 } 73 74 /* Get the results of the thread */ 75 int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){ 76 int rc; 77 78 assert( ppOut!=0 ); 79 if( p==0 ) return SQLITE_NOMEM; 80 if( p->done ){ 81 *ppOut = p->pOut; 82 rc = SQLITE_OK; 83 }else{ 84 rc = pthread_join(p->tid, ppOut) ? SQLITE_ERROR : SQLITE_OK; 85 } 86 sqlite3_free(p); 87 return rc; 88 } 89 90 #endif /* SQLITE_OS_UNIX && defined(SQLITE_MUTEX_PTHREADS) */ 91 /******************************** End Unix Pthreads *************************/ 92 93 94 /********************************* Win32 Threads ****************************/ 95 #if SQLITE_OS_WIN && !SQLITE_OS_WINRT && SQLITE_THREADSAFE>0 96 97 #define SQLITE_THREADS_IMPLEMENTED 1 /* Prevent the single-thread code below */ 98 #include <process.h> 99 100 /* A running thread */ 101 struct SQLiteThread { 102 uintptr_t tid; /* The thread handle */ 103 void *(*xTask)(void*); /* The routine to run as a thread */ 104 void *pIn; /* Argument to xTask */ 105 void *pResult; /* Result of xTask */ 106 }; 107 108 /* Thread procedure Win32 compatibility shim */ 109 static void sqlite3ThreadProc( 110 void *pArg /* IN: Pointer to the SQLiteThread structure */ 111 ){ 112 SQLiteThread *p = (SQLiteThread *)pArg; 113 114 assert( p!=0 ); 115 assert( p->xTask!=0 ); 116 p->pResult = p->xTask(p->pIn); 117 _endthread(); 118 } 119 120 /* Create a new thread */ 121 int sqlite3ThreadCreate( 122 SQLiteThread **ppThread, /* OUT: Write the thread object here */ 123 void *(*xTask)(void*), /* Routine to run in a separate thread */ 124 void *pIn /* Argument passed into xTask() */ 125 ){ 126 SQLiteThread *p; 127 128 assert( ppThread!=0 ); 129 assert( xTask!=0 ); 130 *ppThread = 0; 131 p = sqlite3Malloc(sizeof(*p)); 132 if( p==0 ) return SQLITE_NOMEM; 133 if( sqlite3GlobalConfig.bCoreMutex==0 ){ 134 memset(p, 0, sizeof(*p)); 135 }else{ 136 p->xTask = xTask; 137 p->pIn = pIn; 138 p->tid = _beginthread(sqlite3ThreadProc, 0, p); 139 if( p->tid==(uintptr_t)-1 ){ 140 memset(p, 0, sizeof(*p)); 141 } 142 } 143 if( p->xTask==0 ){ 144 p->pResult = xTask(pIn); 145 } 146 *ppThread = p; 147 return SQLITE_OK; 148 } 149 150 /* Get the results of the thread */ 151 int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){ 152 DWORD rc; 153 154 assert( ppOut!=0 ); 155 if( p==0 ) return SQLITE_NOMEM; 156 if( p->xTask==0 ){ 157 rc = WAIT_OBJECT_0; 158 }else{ 159 rc = sqlite3Win32Wait((HANDLE)p->tid); 160 assert( rc!=WAIT_IO_COMPLETION ); 161 } 162 if( rc==WAIT_OBJECT_0 ) *ppOut = p->pResult; 163 sqlite3_free(p); 164 return (rc==WAIT_OBJECT_0) ? SQLITE_OK : SQLITE_ERROR; 165 } 166 167 #endif /* SQLITE_OS_WIN && !SQLITE_OS_WINRT */ 168 /******************************** End Win32 Threads *************************/ 169 170 171 /********************************* Single-Threaded **************************/ 172 #ifndef SQLITE_THREADS_IMPLEMENTED 173 /* 174 ** This implementation does not actually create a new thread. It does the 175 ** work of the thread in the main thread, when either the thread is created 176 ** or when it is joined 177 */ 178 179 /* A running thread */ 180 struct SQLiteThread { 181 void *(*xTask)(void*); /* The routine to run as a thread */ 182 void *pIn; /* Argument to xTask */ 183 void *pResult; /* Result of xTask */ 184 }; 185 186 /* Create a new thread */ 187 int sqlite3ThreadCreate( 188 SQLiteThread **ppThread, /* OUT: Write the thread object here */ 189 void *(*xTask)(void*), /* Routine to run in a separate thread */ 190 void *pIn /* Argument passed into xTask() */ 191 ){ 192 SQLiteThread *p; 193 194 assert( ppThread!=0 ); 195 assert( xTask!=0 ); 196 *ppThread = 0; 197 p = sqlite3Malloc(sizeof(*p)); 198 if( p==0 ) return SQLITE_NOMEM; 199 if( (SQLITE_PTR_TO_INT(p)/17)&1 ){ 200 p->xTask = xTask; 201 p->pIn = pIn; 202 }else{ 203 p->xTask = 0; 204 p->pResult = xTask(pIn); 205 } 206 *ppThread = p; 207 return SQLITE_OK; 208 } 209 210 /* Get the results of the thread */ 211 int sqlite3ThreadJoin(SQLiteThread *p, void **ppOut){ 212 213 assert( ppOut!=0 ); 214 if( p==0 ) return SQLITE_NOMEM; 215 if( p->xTask ){ 216 *ppOut = p->xTask(p->pIn); 217 }else{ 218 *ppOut = p->pResult; 219 } 220 sqlite3_free(p); 221 222 #if defined(SQLITE_TEST) 223 { 224 void *pTstAlloc = sqlite3Malloc(10); 225 if (!pTstAlloc) return SQLITE_NOMEM; 226 sqlite3_free(pTstAlloc); 227 } 228 #endif 229 230 return SQLITE_OK; 231 } 232 233 #endif /* !defined(SQLITE_THREADS_IMPLEMENTED) */ 234 /****************************** End Single-Threaded *************************/ 235 #endif /* SQLITE_MAX_WORKER_THREADS>0 */ 236