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Overview
Comment: | Added experimental mutex implementation using interlocked ops and spin locks. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | experimental |
Files: | files | file ages | folders |
SHA1: |
f3676b243d94229fe6b646ef47066cd7 |
User & Date: | shaneh 2010-02-12 22:43:48.000 |
Context
2010-02-12
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22:43 | Added experimental mutex implementation using interlocked ops and spin locks. (Closed-Leaf check-in: f3676b243d user: shaneh tags: experimental) | |
2010-02-05
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16:28 | Avoid truncating non-in-memory sub-journals when releasing a savepoint for a small performance improvement. (check-in: 27dc5b1c52 user: shaneh tags: trunk) | |
Changes
Changes to src/mutex_w32.c.
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19 20 21 22 23 24 25 26 27 | */ #ifdef SQLITE_MUTEX_W32 /* ** Each recursive mutex is an instance of the following structure. */ struct sqlite3_mutex { CRITICAL_SECTION mutex; /* Mutex controlling the lock */ int id; /* Mutex type */ | > > > > | > > > > > > > > > > > > > | 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | */ #ifdef SQLITE_MUTEX_W32 /* ** Each recursive mutex is an instance of the following structure. */ struct sqlite3_mutex { #ifdef SQLITE_W32_INTERLOCK_MUTEX LONG lock; #else CRITICAL_SECTION mutex; /* Mutex controlling the lock */ #endif int id; /* Mutex type */ LONG nRef; /* Number of enterances */ DWORD owner; /* Thread holding this mutex */ #ifdef SQLITE_DEBUG int trace; /* True to trace changes */ #endif }; #ifdef SQLITE_W32_INTERLOCK_MUTEX #define SQLITE_W32_MUTEX_INITIALIZER 0L #else #define SQLITE_W32_MUTEX_INITIALIZER { 0 } #endif #ifdef SQLITE_DEBUG #define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)0, 0 } #else #define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)0 } #endif /* ** Return true (non-zero) if we are running under WinNT, Win2K, WinXP, ** or WinCE. Return false (zero) for Win95, Win98, or WinME. ** ** Here is an interesting observation: Win95, Win98, and WinME lack ** the LockFileEx() API. But we can still statically link against that |
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66 67 68 69 70 71 72 73 | #ifdef SQLITE_DEBUG /* ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are ** intended for use only inside assert() statements. */ static int winMutexHeld(sqlite3_mutex *p){ return p->nRef!=0 && p->owner==GetCurrentThreadId(); } | | | > > > > | > > > > > > > > > > > > > | 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 | #ifdef SQLITE_DEBUG /* ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are ** intended for use only inside assert() statements. */ static int winMutexHeld(sqlite3_mutex *p){ return p->nRef!=0 && p->owner==GetCurrentThreadId(); } static int winMutexNotheld2(sqlite3_mutex *p, DWORD tid){ return p->nRef==0 || p->owner!=tid; } static int winMutexNotheld(sqlite3_mutex *p){ DWORD tid = GetCurrentThreadId(); return winMutexNotheld2(p, tid); } #endif /* ** Initialize and deinitialize the mutex subsystem. */ static sqlite3_mutex winMutex_staticMutexes[6] = { SQLITE3_MUTEX_INITIALIZER, SQLITE3_MUTEX_INITIALIZER, SQLITE3_MUTEX_INITIALIZER, SQLITE3_MUTEX_INITIALIZER, SQLITE3_MUTEX_INITIALIZER, SQLITE3_MUTEX_INITIALIZER }; #ifndef SQLITE_W32_INTERLOCK_MUTEX static int winMutex_isInit = 0; /* As winMutexInit() and winMutexEnd() are called as part ** of the sqlite3_initialize and sqlite3_shutdown() ** processing, the "interlocked" magic is probably not ** strictly necessary. */ static long winMutex_lock = 0; #endif static int winMutexInit(void){ #ifndef SQLITE_W32_INTERLOCK_MUTEX /* The first to increment to 1 does actual initialization */ if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){ int i; for(i=0; i<ArraySize(winMutex_staticMutexes); i++){ InitializeCriticalSection(&winMutex_staticMutexes[i].mutex); } winMutex_isInit = 1; }else{ /* Someone else is in the process of initing the static mutexes */ while( !winMutex_isInit ){ Sleep(1); } } #endif return SQLITE_OK; } static int winMutexEnd(void){ #ifndef SQLITE_W32_INTERLOCK_MUTEX /* The first to decrement to 0 does actual shutdown ** (which should be the last to shutdown.) */ if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){ if( winMutex_isInit==1 ){ int i; for(i=0; i<ArraySize(winMutex_staticMutexes); i++){ DeleteCriticalSection(&winMutex_staticMutexes[i].mutex); } winMutex_isInit = 0; } } #endif 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. SQLite |
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168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 | switch( iType ){ case SQLITE_MUTEX_FAST: case SQLITE_MUTEX_RECURSIVE: { p = sqlite3MallocZero( sizeof(*p) ); if( p ){ p->id = iType; InitializeCriticalSection(&p->mutex); } break; } default: { assert( winMutex_isInit==1 ); assert( iType-2 >= 0 ); assert( iType-2 < ArraySize(winMutex_staticMutexes) ); p = &winMutex_staticMutexes[iType-2]; p->id = iType; break; } } return p; } /* ** This routine deallocates a previously ** allocated mutex. SQLite is careful to deallocate every ** mutex that it allocates. */ static void winMutexFree(sqlite3_mutex *p){ assert( p ); assert( p->nRef==0 ); assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE ); DeleteCriticalSection(&p->mutex); 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 | > > > > > > | > | > > > > > > > > > > > > > > > > | > > > > | > > > | > > > > > > > > > > > | > > > > > > > | > > > > > > > > > > > > > > | 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 | switch( iType ){ case SQLITE_MUTEX_FAST: case SQLITE_MUTEX_RECURSIVE: { p = sqlite3MallocZero( sizeof(*p) ); if( p ){ p->id = iType; #ifndef SQLITE_W32_INTERLOCK_MUTEX InitializeCriticalSection(&p->mutex); #endif } break; } default: { #ifndef SQLITE_W32_INTERLOCK_MUTEX assert( winMutex_isInit==1 ); #endif assert( iType-2 >= 0 ); assert( iType-2 < ArraySize(winMutex_staticMutexes) ); p = &winMutex_staticMutexes[iType-2]; p->id = iType; break; } } return p; } /* ** This routine deallocates a previously ** allocated mutex. SQLite is careful to deallocate every ** mutex that it allocates. */ static void winMutexFree(sqlite3_mutex *p){ assert( p ); assert( p->nRef==0 ); assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE ); #ifndef SQLITE_W32_INTERLOCK_MUTEX DeleteCriticalSection(&p->mutex); #endif 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 o(1ther kind of mutex ** more than once, the behavior is undefined. */ static void winMutexEnter(sqlite3_mutex *p){ DWORD tid = GetCurrentThreadId(); assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) ); #ifdef SQLITE_W32_INTERLOCK_MUTEX while( 1 ) { /* get exclusive access to mutex struct (using spinlock) */ while( InterlockedCompareExchange(&p->lock, 1, 0)!=0 ) Sleep(0); /* if not held or already held by us */ if ((p->owner == 0) || (p->owner == tid) ){ p->owner = tid; p->nRef++; p->lock = 0; /* release lock */ break; } else { p->lock = 0; /* release lock */ /* and wait some more... */ } } #else EnterCriticalSection(&p->mutex); p->owner = tid; p->nRef++; #endif #ifdef SQLITE_DEBUG if( p->trace ){ printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef); } #endif } static int winMutexTry(sqlite3_mutex *p){ DWORD tid = GetCurrentThreadId(); int rc = SQLITE_BUSY; assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) ); #ifdef SQLITE_W32_INTERLOCK_MUTEX /* get exclusive access to mutex struct (using spinlock) */ while( InterlockedCompareExchange(&p->lock, 1, 0)!=0 ) Sleep(0); /* if not held or already held by us */ if ((p->owner == 0) || (p->owner == tid) ){ p->owner = tid; p->nRef++; rc = SQLITE_OK; } p->lock = 0; /* release lock */ #else /* ** The sqlite3_mutex_try() routine is very rarely used, and when it ** is used it is merely an optimization. So it is OK for it to always ** fail. ** ** The TryEnterCriticalSection() interface is only available on WinNT. ** And some windows compilers complain if you try to use it without ** first doing some #defines that prevent SQLite from building on Win98. ** For that reason, we will omit this optimization for now. See ** ticket #2685. */ #if 0 if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){ p->owner = tid; p->nRef++; rc = SQLITE_OK; } #else UNUSED_PARAMETER(p); #endif #endif #ifdef SQLITE_DEBUG if( rc==SQLITE_OK && p->trace ){ printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef); } #endif 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 or ** is not currently allocated. SQLite will never do either. */ static void winMutexLeave(sqlite3_mutex *p){ DWORD tid = GetCurrentThreadId(); assert( p->nRef>0 ); assert( p->owner==tid ); #ifdef SQLITE_W32_INTERLOCK_MUTEX /* get exclusive access to mutex struct (using spinlock) */ while( InterlockedCompareExchange(&p->lock, 1L, 0L)!=0L ) Sleep(0); p->nRef--; assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE ); if( p->nRef==0 ) p->owner=0; p->lock = 0; /* release lock */ #else p->nRef--; assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE ); LeaveCriticalSection(&p->mutex); #endif #ifdef SQLITE_DEBUG if( p->trace ){ printf("leave mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef); } #endif } sqlite3_mutex_methods *sqlite3DefaultMutex(void){ static sqlite3_mutex_methods sMutex = { winMutexInit, winMutexEnd, winMutexAlloc, |
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