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| 1 /* | |
| 2 ** 2008 August 05 | |
| 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 implements that page cache. | |
| 13 ** | |
| 14 ** @(#) $Id: pcache.c,v 1.47 2009/07/25 11:46:49 danielk1977 Exp $ | |
| 15 */ | |
| 16 #include "sqliteInt.h" | |
| 17 | |
| 18 /* | |
| 19 ** A complete page cache is an instance of this structure. | |
| 20 */ | |
| 21 struct PCache { | |
| 22 PgHdr *pDirty, *pDirtyTail; /* List of dirty pages in LRU order */ | |
| 23 PgHdr *pSynced; /* Last synced page in dirty page list */ | |
| 24 int nRef; /* Number of referenced pages */ | |
| 25 int nMax; /* Configured cache size */ | |
| 26 int szPage; /* Size of every page in this cache */ | |
| 27 int szExtra; /* Size of extra space for each page */ | |
| 28 int bPurgeable; /* True if pages are on backing store */ | |
| 29 int (*xStress)(void*,PgHdr*); /* Call to try make a page clean */ | |
| 30 void *pStress; /* Argument to xStress */ | |
| 31 sqlite3_pcache *pCache; /* Pluggable cache module */ | |
| 32 PgHdr *pPage1; /* Reference to page 1 */ | |
| 33 }; | |
| 34 | |
| 35 /* | |
| 36 ** Some of the assert() macros in this code are too expensive to run | |
| 37 ** even during normal debugging. Use them only rarely on long-running | |
| 38 ** tests. Enable the expensive asserts using the | |
| 39 ** -DSQLITE_ENABLE_EXPENSIVE_ASSERT=1 compile-time option. | |
| 40 */ | |
| 41 #ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT | |
| 42 # define expensive_assert(X) assert(X) | |
| 43 #else | |
| 44 # define expensive_assert(X) | |
| 45 #endif | |
| 46 | |
| 47 /********************************** Linked List Management ********************/ | |
| 48 | |
| 49 #if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT) | |
| 50 /* | |
| 51 ** Check that the pCache->pSynced variable is set correctly. If it | |
| 52 ** is not, either fail an assert or return zero. Otherwise, return | |
| 53 ** non-zero. This is only used in debugging builds, as follows: | |
| 54 ** | |
| 55 ** expensive_assert( pcacheCheckSynced(pCache) ); | |
| 56 */ | |
| 57 static int pcacheCheckSynced(PCache *pCache){ | |
| 58 PgHdr *p; | |
| 59 for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pDirtyPrev){ | |
| 60 assert( p->nRef || (p->flags&PGHDR_NEED_SYNC) ); | |
| 61 } | |
| 62 return (p==0 || p->nRef || (p->flags&PGHDR_NEED_SYNC)==0); | |
| 63 } | |
| 64 #endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */ | |
| 65 | |
| 66 /* | |
| 67 ** Remove page pPage from the list of dirty pages. | |
| 68 */ | |
| 69 static void pcacheRemoveFromDirtyList(PgHdr *pPage){ | |
| 70 PCache *p = pPage->pCache; | |
| 71 | |
| 72 assert( pPage->pDirtyNext || pPage==p->pDirtyTail ); | |
| 73 assert( pPage->pDirtyPrev || pPage==p->pDirty ); | |
| 74 | |
| 75 /* Update the PCache1.pSynced variable if necessary. */ | |
| 76 if( p->pSynced==pPage ){ | |
| 77 PgHdr *pSynced = pPage->pDirtyPrev; | |
| 78 while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){ | |
| 79 pSynced = pSynced->pDirtyPrev; | |
| 80 } | |
| 81 p->pSynced = pSynced; | |
| 82 } | |
| 83 | |
| 84 if( pPage->pDirtyNext ){ | |
| 85 pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev; | |
| 86 }else{ | |
| 87 assert( pPage==p->pDirtyTail ); | |
| 88 p->pDirtyTail = pPage->pDirtyPrev; | |
| 89 } | |
| 90 if( pPage->pDirtyPrev ){ | |
| 91 pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext; | |
| 92 }else{ | |
| 93 assert( pPage==p->pDirty ); | |
| 94 p->pDirty = pPage->pDirtyNext; | |
| 95 } | |
| 96 pPage->pDirtyNext = 0; | |
| 97 pPage->pDirtyPrev = 0; | |
| 98 | |
| 99 expensive_assert( pcacheCheckSynced(p) ); | |
| 100 } | |
| 101 | |
| 102 /* | |
| 103 ** Add page pPage to the head of the dirty list (PCache1.pDirty is set to | |
| 104 ** pPage). | |
| 105 */ | |
| 106 static void pcacheAddToDirtyList(PgHdr *pPage){ | |
| 107 PCache *p = pPage->pCache; | |
| 108 | |
| 109 assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage ); | |
| 110 | |
| 111 pPage->pDirtyNext = p->pDirty; | |
| 112 if( pPage->pDirtyNext ){ | |
| 113 assert( pPage->pDirtyNext->pDirtyPrev==0 ); | |
| 114 pPage->pDirtyNext->pDirtyPrev = pPage; | |
| 115 } | |
| 116 p->pDirty = pPage; | |
| 117 if( !p->pDirtyTail ){ | |
| 118 p->pDirtyTail = pPage; | |
| 119 } | |
| 120 if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){ | |
| 121 p->pSynced = pPage; | |
| 122 } | |
| 123 expensive_assert( pcacheCheckSynced(p) ); | |
| 124 } | |
| 125 | |
| 126 /* | |
| 127 ** Wrapper around the pluggable caches xUnpin method. If the cache is | |
| 128 ** being used for an in-memory database, this function is a no-op. | |
| 129 */ | |
| 130 static void pcacheUnpin(PgHdr *p){ | |
| 131 PCache *pCache = p->pCache; | |
| 132 if( pCache->bPurgeable ){ | |
| 133 if( p->pgno==1 ){ | |
| 134 pCache->pPage1 = 0; | |
| 135 } | |
| 136 sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 0); | |
| 137 } | |
| 138 } | |
| 139 | |
| 140 /*************************************************** General Interfaces ****** | |
| 141 ** | |
| 142 ** Initialize and shutdown the page cache subsystem. Neither of these | |
| 143 ** functions are threadsafe. | |
| 144 */ | |
| 145 int sqlite3PcacheInitialize(void){ | |
| 146 if( sqlite3GlobalConfig.pcache.xInit==0 ){ | |
| 147 sqlite3PCacheSetDefault(); | |
| 148 } | |
| 149 return sqlite3GlobalConfig.pcache.xInit(sqlite3GlobalConfig.pcache.pArg); | |
| 150 } | |
| 151 void sqlite3PcacheShutdown(void){ | |
| 152 if( sqlite3GlobalConfig.pcache.xShutdown ){ | |
| 153 sqlite3GlobalConfig.pcache.xShutdown(sqlite3GlobalConfig.pcache.pArg); | |
| 154 } | |
| 155 } | |
| 156 | |
| 157 /* | |
| 158 ** Return the size in bytes of a PCache object. | |
| 159 */ | |
| 160 int sqlite3PcacheSize(void){ return sizeof(PCache); } | |
| 161 | |
| 162 /* | |
| 163 ** Create a new PCache object. Storage space to hold the object | |
| 164 ** has already been allocated and is passed in as the p pointer. | |
| 165 ** The caller discovers how much space needs to be allocated by | |
| 166 ** calling sqlite3PcacheSize(). | |
| 167 */ | |
| 168 void sqlite3PcacheOpen( | |
| 169 int szPage, /* Size of every page */ | |
| 170 int szExtra, /* Extra space associated with each page */ | |
| 171 int bPurgeable, /* True if pages are on backing store */ | |
| 172 int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */ | |
| 173 void *pStress, /* Argument to xStress */ | |
| 174 PCache *p /* Preallocated space for the PCache */ | |
| 175 ){ | |
| 176 memset(p, 0, sizeof(PCache)); | |
| 177 p->szPage = szPage; | |
| 178 p->szExtra = szExtra; | |
| 179 p->bPurgeable = bPurgeable; | |
| 180 p->xStress = xStress; | |
| 181 p->pStress = pStress; | |
| 182 p->nMax = 100; | |
| 183 } | |
| 184 | |
| 185 /* | |
| 186 ** Change the page size for PCache object. The caller must ensure that there | |
| 187 ** are no outstanding page references when this function is called. | |
| 188 */ | |
| 189 void sqlite3PcacheSetPageSize(PCache *pCache, int szPage){ | |
| 190 assert( pCache->nRef==0 && pCache->pDirty==0 ); | |
| 191 if( pCache->pCache ){ | |
| 192 sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache); | |
| 193 pCache->pCache = 0; | |
| 194 } | |
| 195 pCache->szPage = szPage; | |
| 196 } | |
| 197 | |
| 198 /* | |
| 199 ** Try to obtain a page from the cache. | |
| 200 */ | |
| 201 int sqlite3PcacheFetch( | |
| 202 PCache *pCache, /* Obtain the page from this cache */ | |
| 203 Pgno pgno, /* Page number to obtain */ | |
| 204 int createFlag, /* If true, create page if it does not exist already */ | |
| 205 PgHdr **ppPage /* Write the page here */ | |
| 206 ){ | |
| 207 PgHdr *pPage = 0; | |
| 208 int eCreate; | |
| 209 | |
| 210 assert( pCache!=0 ); | |
| 211 assert( createFlag==1 || createFlag==0 ); | |
| 212 assert( pgno>0 ); | |
| 213 | |
| 214 /* If the pluggable cache (sqlite3_pcache*) has not been allocated, | |
| 215 ** allocate it now. | |
| 216 */ | |
| 217 if( !pCache->pCache && createFlag ){ | |
| 218 sqlite3_pcache *p; | |
| 219 int nByte; | |
| 220 nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr); | |
| 221 p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable); | |
| 222 if( !p ){ | |
| 223 return SQLITE_NOMEM; | |
| 224 } | |
| 225 sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax); | |
| 226 pCache->pCache = p; | |
| 227 } | |
| 228 | |
| 229 eCreate = createFlag * (1 + (!pCache->bPurgeable || !pCache->pDirty)); | |
| 230 if( pCache->pCache ){ | |
| 231 pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, eCreate); | |
| 232 } | |
| 233 | |
| 234 if( !pPage && eCreate==1 ){ | |
| 235 PgHdr *pPg; | |
| 236 | |
| 237 /* Find a dirty page to write-out and recycle. First try to find a | |
| 238 ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC | |
| 239 ** cleared), but if that is not possible settle for any other | |
| 240 ** unreferenced dirty page. | |
| 241 */ | |
| 242 expensive_assert( pcacheCheckSynced(pCache) ); | |
| 243 for(pPg=pCache->pSynced; | |
| 244 pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); | |
| 245 pPg=pPg->pDirtyPrev | |
| 246 ); | |
| 247 if( !pPg ){ | |
| 248 for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev); | |
| 249 } | |
| 250 if( pPg ){ | |
| 251 int rc; | |
| 252 rc = pCache->xStress(pCache->pStress, pPg); | |
| 253 if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){ | |
| 254 return rc; | |
| 255 } | |
| 256 } | |
| 257 | |
| 258 pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2); | |
| 259 } | |
| 260 | |
| 261 if( pPage ){ | |
| 262 if( !pPage->pData ){ | |
| 263 memset(pPage, 0, sizeof(PgHdr) + pCache->szExtra); | |
| 264 pPage->pExtra = (void*)&pPage[1]; | |
| 265 pPage->pData = (void *)&((char *)pPage)[sizeof(PgHdr) + pCache->szExtra]; | |
| 266 pPage->pCache = pCache; | |
| 267 pPage->pgno = pgno; | |
| 268 } | |
| 269 assert( pPage->pCache==pCache ); | |
| 270 assert( pPage->pgno==pgno ); | |
| 271 assert( pPage->pExtra==(void *)&pPage[1] ); | |
| 272 | |
| 273 if( 0==pPage->nRef ){ | |
| 274 pCache->nRef++; | |
| 275 } | |
| 276 pPage->nRef++; | |
| 277 if( pgno==1 ){ | |
| 278 pCache->pPage1 = pPage; | |
| 279 } | |
| 280 } | |
| 281 *ppPage = pPage; | |
| 282 return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK; | |
| 283 } | |
| 284 | |
| 285 /* | |
| 286 ** Decrement the reference count on a page. If the page is clean and the | |
| 287 ** reference count drops to 0, then it is made elible for recycling. | |
| 288 */ | |
| 289 void sqlite3PcacheRelease(PgHdr *p){ | |
| 290 assert( p->nRef>0 ); | |
| 291 p->nRef--; | |
| 292 if( p->nRef==0 ){ | |
| 293 PCache *pCache = p->pCache; | |
| 294 pCache->nRef--; | |
| 295 if( (p->flags&PGHDR_DIRTY)==0 ){ | |
| 296 pcacheUnpin(p); | |
| 297 }else{ | |
| 298 /* Move the page to the head of the dirty list. */ | |
| 299 pcacheRemoveFromDirtyList(p); | |
| 300 pcacheAddToDirtyList(p); | |
| 301 } | |
| 302 } | |
| 303 } | |
| 304 | |
| 305 /* | |
| 306 ** Increase the reference count of a supplied page by 1. | |
| 307 */ | |
| 308 void sqlite3PcacheRef(PgHdr *p){ | |
| 309 assert(p->nRef>0); | |
| 310 p->nRef++; | |
| 311 } | |
| 312 | |
| 313 /* | |
| 314 ** Drop a page from the cache. There must be exactly one reference to the | |
| 315 ** page. This function deletes that reference, so after it returns the | |
| 316 ** page pointed to by p is invalid. | |
| 317 */ | |
| 318 void sqlite3PcacheDrop(PgHdr *p){ | |
| 319 PCache *pCache; | |
| 320 assert( p->nRef==1 ); | |
| 321 if( p->flags&PGHDR_DIRTY ){ | |
| 322 pcacheRemoveFromDirtyList(p); | |
| 323 } | |
| 324 pCache = p->pCache; | |
| 325 pCache->nRef--; | |
| 326 if( p->pgno==1 ){ | |
| 327 pCache->pPage1 = 0; | |
| 328 } | |
| 329 sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 1); | |
| 330 } | |
| 331 | |
| 332 /* | |
| 333 ** Make sure the page is marked as dirty. If it isn't dirty already, | |
| 334 ** make it so. | |
| 335 */ | |
| 336 void sqlite3PcacheMakeDirty(PgHdr *p){ | |
| 337 p->flags &= ~PGHDR_DONT_WRITE; | |
| 338 assert( p->nRef>0 ); | |
| 339 if( 0==(p->flags & PGHDR_DIRTY) ){ | |
| 340 p->flags |= PGHDR_DIRTY; | |
| 341 pcacheAddToDirtyList( p); | |
| 342 } | |
| 343 } | |
| 344 | |
| 345 /* | |
| 346 ** Make sure the page is marked as clean. If it isn't clean already, | |
| 347 ** make it so. | |
| 348 */ | |
| 349 void sqlite3PcacheMakeClean(PgHdr *p){ | |
| 350 if( (p->flags & PGHDR_DIRTY) ){ | |
| 351 pcacheRemoveFromDirtyList(p); | |
| 352 p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC); | |
| 353 if( p->nRef==0 ){ | |
| 354 pcacheUnpin(p); | |
| 355 } | |
| 356 } | |
| 357 } | |
| 358 | |
| 359 /* | |
| 360 ** Make every page in the cache clean. | |
| 361 */ | |
| 362 void sqlite3PcacheCleanAll(PCache *pCache){ | |
| 363 PgHdr *p; | |
| 364 while( (p = pCache->pDirty)!=0 ){ | |
| 365 sqlite3PcacheMakeClean(p); | |
| 366 } | |
| 367 } | |
| 368 | |
| 369 /* | |
| 370 ** Clear the PGHDR_NEED_SYNC flag from all dirty pages. | |
| 371 */ | |
| 372 void sqlite3PcacheClearSyncFlags(PCache *pCache){ | |
| 373 PgHdr *p; | |
| 374 for(p=pCache->pDirty; p; p=p->pDirtyNext){ | |
| 375 p->flags &= ~PGHDR_NEED_SYNC; | |
| 376 } | |
| 377 pCache->pSynced = pCache->pDirtyTail; | |
| 378 } | |
| 379 | |
| 380 /* | |
| 381 ** Change the page number of page p to newPgno. | |
| 382 */ | |
| 383 void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){ | |
| 384 PCache *pCache = p->pCache; | |
| 385 assert( p->nRef>0 ); | |
| 386 assert( newPgno>0 ); | |
| 387 sqlite3GlobalConfig.pcache.xRekey(pCache->pCache, p, p->pgno, newPgno); | |
| 388 p->pgno = newPgno; | |
| 389 if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){ | |
| 390 pcacheRemoveFromDirtyList(p); | |
| 391 pcacheAddToDirtyList(p); | |
| 392 } | |
| 393 } | |
| 394 | |
| 395 /* | |
| 396 ** Drop every cache entry whose page number is greater than "pgno". The | |
| 397 ** caller must ensure that there are no outstanding references to any pages | |
| 398 ** other than page 1 with a page number greater than pgno. | |
| 399 ** | |
| 400 ** If there is a reference to page 1 and the pgno parameter passed to this | |
| 401 ** function is 0, then the data area associated with page 1 is zeroed, but | |
| 402 ** the page object is not dropped. | |
| 403 */ | |
| 404 void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){ | |
| 405 if( pCache->pCache ){ | |
| 406 PgHdr *p; | |
| 407 PgHdr *pNext; | |
| 408 for(p=pCache->pDirty; p; p=pNext){ | |
| 409 pNext = p->pDirtyNext; | |
| 410 if( p->pgno>pgno ){ | |
| 411 assert( p->flags&PGHDR_DIRTY ); | |
| 412 sqlite3PcacheMakeClean(p); | |
| 413 } | |
| 414 } | |
| 415 if( pgno==0 && pCache->pPage1 ){ | |
| 416 memset(pCache->pPage1->pData, 0, pCache->szPage); | |
| 417 pgno = 1; | |
| 418 } | |
| 419 sqlite3GlobalConfig.pcache.xTruncate(pCache->pCache, pgno+1); | |
| 420 } | |
| 421 } | |
| 422 | |
| 423 /* | |
| 424 ** Close a cache. | |
| 425 */ | |
| 426 void sqlite3PcacheClose(PCache *pCache){ | |
| 427 if( pCache->pCache ){ | |
| 428 sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache); | |
| 429 } | |
| 430 } | |
| 431 | |
| 432 /* | |
| 433 ** Discard the contents of the cache. | |
| 434 */ | |
| 435 void sqlite3PcacheClear(PCache *pCache){ | |
| 436 sqlite3PcacheTruncate(pCache, 0); | |
| 437 } | |
| 438 | |
| 439 /* | |
| 440 ** Merge two lists of pages connected by pDirty and in pgno order. | |
| 441 ** Do not both fixing the pDirtyPrev pointers. | |
| 442 */ | |
| 443 static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){ | |
| 444 PgHdr result, *pTail; | |
| 445 pTail = &result; | |
| 446 while( pA && pB ){ | |
| 447 if( pA->pgno<pB->pgno ){ | |
| 448 pTail->pDirty = pA; | |
| 449 pTail = pA; | |
| 450 pA = pA->pDirty; | |
| 451 }else{ | |
| 452 pTail->pDirty = pB; | |
| 453 pTail = pB; | |
| 454 pB = pB->pDirty; | |
| 455 } | |
| 456 } | |
| 457 if( pA ){ | |
| 458 pTail->pDirty = pA; | |
| 459 }else if( pB ){ | |
| 460 pTail->pDirty = pB; | |
| 461 }else{ | |
| 462 pTail->pDirty = 0; | |
| 463 } | |
| 464 return result.pDirty; | |
| 465 } | |
| 466 | |
| 467 /* | |
| 468 ** Sort the list of pages in accending order by pgno. Pages are | |
| 469 ** connected by pDirty pointers. The pDirtyPrev pointers are | |
| 470 ** corrupted by this sort. | |
| 471 ** | |
| 472 ** Since there cannot be more than 2^31 distinct pages in a database, | |
| 473 ** there cannot be more than 31 buckets required by the merge sorter. | |
| 474 ** One extra bucket is added to catch overflow in case something | |
| 475 ** ever changes to make the previous sentence incorrect. | |
| 476 */ | |
| 477 #define N_SORT_BUCKET 32 | |
| 478 static PgHdr *pcacheSortDirtyList(PgHdr *pIn){ | |
| 479 PgHdr *a[N_SORT_BUCKET], *p; | |
| 480 int i; | |
| 481 memset(a, 0, sizeof(a)); | |
| 482 while( pIn ){ | |
| 483 p = pIn; | |
| 484 pIn = p->pDirty; | |
| 485 p->pDirty = 0; | |
| 486 for(i=0; ALWAYS(i<N_SORT_BUCKET-1); i++){ | |
| 487 if( a[i]==0 ){ | |
| 488 a[i] = p; | |
| 489 break; | |
| 490 }else{ | |
| 491 p = pcacheMergeDirtyList(a[i], p); | |
| 492 a[i] = 0; | |
| 493 } | |
| 494 } | |
| 495 if( NEVER(i==N_SORT_BUCKET-1) ){ | |
| 496 /* To get here, there need to be 2^(N_SORT_BUCKET) elements in | |
| 497 ** the input list. But that is impossible. | |
| 498 */ | |
| 499 a[i] = pcacheMergeDirtyList(a[i], p); | |
| 500 } | |
| 501 } | |
| 502 p = a[0]; | |
| 503 for(i=1; i<N_SORT_BUCKET; i++){ | |
| 504 p = pcacheMergeDirtyList(p, a[i]); | |
| 505 } | |
| 506 return p; | |
| 507 } | |
| 508 | |
| 509 /* | |
| 510 ** Return a list of all dirty pages in the cache, sorted by page number. | |
| 511 */ | |
| 512 PgHdr *sqlite3PcacheDirtyList(PCache *pCache){ | |
| 513 PgHdr *p; | |
| 514 for(p=pCache->pDirty; p; p=p->pDirtyNext){ | |
| 515 p->pDirty = p->pDirtyNext; | |
| 516 } | |
| 517 return pcacheSortDirtyList(pCache->pDirty); | |
| 518 } | |
| 519 | |
| 520 /* | |
| 521 ** Return the total number of referenced pages held by the cache. | |
| 522 */ | |
| 523 int sqlite3PcacheRefCount(PCache *pCache){ | |
| 524 return pCache->nRef; | |
| 525 } | |
| 526 | |
| 527 /* | |
| 528 ** Return the number of references to the page supplied as an argument. | |
| 529 */ | |
| 530 int sqlite3PcachePageRefcount(PgHdr *p){ | |
| 531 return p->nRef; | |
| 532 } | |
| 533 | |
| 534 /* | |
| 535 ** Return the total number of pages in the cache. | |
| 536 */ | |
| 537 int sqlite3PcachePagecount(PCache *pCache){ | |
| 538 int nPage = 0; | |
| 539 if( pCache->pCache ){ | |
| 540 nPage = sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache); | |
| 541 } | |
| 542 return nPage; | |
| 543 } | |
| 544 | |
| 545 /* | |
| 546 ** Get the suggested cache-size value. | |
| 547 */ | |
| 548 int sqlite3PcacheGetCachesize(PCache *pCache){ | |
| 549 return pCache->nMax; | |
| 550 } | |
| 551 | |
| 552 /* | |
| 553 ** Set the suggested cache-size value. | |
| 554 */ | |
| 555 void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){ | |
| 556 pCache->nMax = mxPage; | |
| 557 if( pCache->pCache ){ | |
| 558 sqlite3GlobalConfig.pcache.xCachesize(pCache->pCache, mxPage); | |
| 559 } | |
| 560 } | |
| 561 | |
| 562 #if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG) | |
| 563 /* | |
| 564 ** For all dirty pages currently in the cache, invoke the specified | |
| 565 ** callback. This is only used if the SQLITE_CHECK_PAGES macro is | |
| 566 ** defined. | |
| 567 */ | |
| 568 void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)){ | |
| 569 PgHdr *pDirty; | |
| 570 for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext){ | |
| 571 xIter(pDirty); | |
| 572 } | |
| 573 } | |
| 574 #endif | |
| OLD | NEW |
|---|
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/