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Overview
| Comment: | Remove the BtreeMutexArray object - use the Vdbe.btreeMask field to accomplish the same result. Add a generation counter to btree mutexes in order to assert that mutexes are never temporarily dropped over a range of instructions in order to do deadlock avoidance in some subroutine. Lock all btrees in any Vdbe program that uses OP_ParseSchema. |
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| SHA1: |
d81708f7d1eee399bfe76f6b8dac950a |
| User & Date: | drh 2011-04-04 00:14:43 |
Context
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2011-04-04
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| 03:27 | Suppress unused parameter warnings in sqlite3VdbeEnter() and related routines. check-in: f8e98ab3 user: drh tags: trunk | |
| 00:14 | Remove the BtreeMutexArray object - use the Vdbe.btreeMask field to accomplish the same result. Add a generation counter to btree mutexes in order to assert that mutexes are never temporarily dropped over a range of instructions in order to do deadlock avoidance in some subroutine. Lock all btrees in any Vdbe program that uses OP_ParseSchema. check-in: d81708f7 user: drh tags: trunk | |
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2011-04-03
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| 18:19 | Make sure that the constant 1 is cast to yDbType before shifting to create an attached database mask. This check-in is a follow-up and fix to the [7aaf8772274422] change that increases the maximum number of attached databases from 30 to 62. check-in: e2a09ea7 user: drh tags: trunk | |
Changes
Changes to src/btmutex.c.
35 35 } 36 36 37 37 /* 38 38 ** Release the BtShared mutex associated with B-Tree handle p and 39 39 ** clear the p->locked boolean. 40 40 */ 41 41 static void unlockBtreeMutex(Btree *p){ 42 + BtShared *pBt = p->pBt; 42 43 assert( p->locked==1 ); 43 - assert( sqlite3_mutex_held(p->pBt->mutex) ); 44 + assert( sqlite3_mutex_held(pBt->mutex) ); 44 45 assert( sqlite3_mutex_held(p->db->mutex) ); 45 - assert( p->db==p->pBt->db ); 46 + assert( p->db==pBt->db ); 46 47 47 - sqlite3_mutex_leave(p->pBt->mutex); 48 + pBt->iMutexCounter++; 49 + sqlite3_mutex_leave(pBt->mutex); 48 50 p->locked = 0; 49 51 } 52 + 53 +#ifdef SQLITE_DEBUG 54 +/* 55 +** Return the number of times that the mutex has been exited for 56 +** the given btree. 57 +** 58 +** This is a small circular counter that wraps around to zero on 59 +** overflow. It is used only for sanity checking - to verify that 60 +** mutexes are held continously by asserting that the value of 61 +** this counter at the beginning of a region is the same as at 62 +** the end. 63 +*/ 64 +u32 sqlite3BtreeMutexCounter(Btree *p){ 65 + assert( p->locked==1 || p->sharable==0 ); 66 + return p->pBt->iMutexCounter; 67 +} 68 +#endif 50 69 51 70 /* 52 71 ** Enter a mutex on the given BTree object. 53 72 ** 54 73 ** If the object is not sharable, then no mutex is ever required 55 74 ** and this routine is a no-op. The underlying mutex is non-recursive. 56 75 ** But we keep a reference count in Btree.wantToLock so the behavior ................................................................................ 87 106 /* Unless the database is sharable and unlocked, then BtShared.db 88 107 ** should already be set correctly. */ 89 108 assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db ); 90 109 91 110 if( !p->sharable ) return; 92 111 p->wantToLock++; 93 112 if( p->locked ) return; 113 + 114 + /* Increment the mutex counter on all locked btrees in the same 115 + ** database connection. This simulates the unlocking that would 116 + ** occur on a worst-case mutex dead-lock avoidance scenario. 117 + */ 118 +#ifdef SQLITE_DEBUG 119 + { 120 + int ii; 121 + sqlite3 *db = p->db; 122 + Btree *pOther; 123 + for(ii=0; ii<db->nDb; ii++){ 124 + if( ii==1 ) continue; 125 + pOther = db->aDb[ii].pBt; 126 + if( pOther==0 || pOther->sharable==0 || pOther->locked==0 ) continue; 127 + pOther->pBt->iMutexCounter++; 128 + } 129 + } 130 +#endif 94 131 95 132 /* In most cases, we should be able to acquire the lock we 96 133 ** want without having to go throught the ascending lock 97 134 ** procedure that follows. Just be sure not to block. 98 135 */ 99 136 if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){ 100 137 p->pBt->db = p->db; ................................................................................ 247 284 return 0; 248 285 } 249 286 } 250 287 return 1; 251 288 } 252 289 #endif /* NDEBUG */ 253 290 291 +#else /* SQLITE_THREADSAFE>0 above. SQLITE_THREADSAFE==0 below */ 254 292 /* 255 -** Add a new Btree pointer to a BtreeMutexArray. 256 -** if the pointer can possibly be shared with 257 -** another database connection. 293 +** The following are special cases for mutex enter routines for use 294 +** in single threaded applications that use shared cache. Except for 295 +** these two routines, all mutex operations are no-ops in that case and 296 +** are null #defines in btree.h. 258 297 ** 259 -** The pointers are kept in sorted order by pBtree->pBt. That 260 -** way when we go to enter all the mutexes, we can enter them 261 -** in order without every having to backup and retry and without 262 -** worrying about deadlock. 263 -** 264 -** The number of shared btrees will always be small (usually 0 or 1) 265 -** so an insertion sort is an adequate algorithm here. 298 +** If shared cache is disabled, then all btree mutex routines, including 299 +** the ones below, are no-ops and are null #defines in btree.h. 266 300 */ 267 -void sqlite3BtreeMutexArrayInsert(BtreeMutexArray *pArray, Btree *pBtree){ 268 - int i, j; 269 - BtShared *pBt; 270 - if( pBtree==0 || pBtree->sharable==0 ) return; 271 -#ifndef NDEBUG 272 - { 273 - for(i=0; i<pArray->nMutex; i++){ 274 - assert( pArray->aBtree[i]!=pBtree ); 275 - } 276 - } 277 -#endif 278 - assert( pArray->nMutex>=0 ); 279 - assert( pArray->nMutex<ArraySize(pArray->aBtree)-1 ); 280 - pBt = pBtree->pBt; 281 - for(i=0; i<pArray->nMutex; i++){ 282 - assert( pArray->aBtree[i]!=pBtree ); 283 - if( pArray->aBtree[i]->pBt>pBt ){ 284 - for(j=pArray->nMutex; j>i; j--){ 285 - pArray->aBtree[j] = pArray->aBtree[j-1]; 286 - } 287 - pArray->aBtree[i] = pBtree; 288 - pArray->nMutex++; 289 - return; 290 - } 291 - } 292 - pArray->aBtree[pArray->nMutex++] = pBtree; 293 -} 294 301 295 -/* 296 -** Enter the mutex of every btree in the array. This routine is 297 -** called at the beginning of sqlite3VdbeExec(). The mutexes are 298 -** exited at the end of the same function. 299 -*/ 300 -void sqlite3BtreeMutexArrayEnter(BtreeMutexArray *pArray){ 301 - int i; 302 - for(i=0; i<pArray->nMutex; i++){ 303 - Btree *p = pArray->aBtree[i]; 304 - /* Some basic sanity checking */ 305 - assert( i==0 || pArray->aBtree[i-1]->pBt<p->pBt ); 306 - assert( !p->locked || p->wantToLock>0 ); 307 - 308 - /* We should already hold a lock on the database connection */ 309 - assert( sqlite3_mutex_held(p->db->mutex) ); 310 - 311 - /* The Btree is sharable because only sharable Btrees are entered 312 - ** into the array in the first place. */ 313 - assert( p->sharable ); 314 - 315 - p->wantToLock++; 316 - if( !p->locked ){ 317 - lockBtreeMutex(p); 318 - } 319 - } 320 -} 321 - 322 -/* 323 -** Leave the mutex of every btree in the group. 324 -*/ 325 -void sqlite3BtreeMutexArrayLeave(BtreeMutexArray *pArray){ 326 - int i; 327 - for(i=0; i<pArray->nMutex; i++){ 328 - Btree *p = pArray->aBtree[i]; 329 - /* Some basic sanity checking */ 330 - assert( i==0 || pArray->aBtree[i-1]->pBt<p->pBt ); 331 - assert( p->locked ); 332 - assert( p->wantToLock>0 ); 333 - 334 - /* We should already hold a lock on the database connection */ 335 - assert( sqlite3_mutex_held(p->db->mutex) ); 336 - 337 - p->wantToLock--; 338 - if( p->wantToLock==0 ){ 339 - unlockBtreeMutex(p); 340 - } 341 - } 342 -} 343 - 344 -#else 345 302 void sqlite3BtreeEnter(Btree *p){ 346 303 p->pBt->db = p->db; 347 304 } 348 305 void sqlite3BtreeEnterAll(sqlite3 *db){ 349 306 int i; 350 307 for(i=0; i<db->nDb; i++){ 351 308 Btree *p = db->aDb[i].pBt;
Changes to src/btree.h.
35 35 36 36 /* 37 37 ** Forward declarations of structure 38 38 */ 39 39 typedef struct Btree Btree; 40 40 typedef struct BtCursor BtCursor; 41 41 typedef struct BtShared BtShared; 42 -typedef struct BtreeMutexArray BtreeMutexArray; 43 - 44 -/* 45 -** This structure records all of the Btrees that need to hold 46 -** a mutex before we enter sqlite3VdbeExec(). The Btrees are 47 -** are placed in aBtree[] in order of aBtree[]->pBt. That way, 48 -** we can always lock and unlock them all quickly. 49 -*/ 50 -struct BtreeMutexArray { 51 - int nMutex; 52 - Btree *aBtree[SQLITE_MAX_ATTACHED+1]; 53 -}; 54 42 55 43 56 44 int sqlite3BtreeOpen( 57 45 const char *zFilename, /* Name of database file to open */ 58 46 sqlite3 *db, /* Associated database connection */ 59 47 Btree **ppBtree, /* Return open Btree* here */ 60 48 int flags, /* Flags */ ................................................................................ 224 212 #endif 225 213 226 214 #if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE 227 215 void sqlite3BtreeLeave(Btree*); 228 216 void sqlite3BtreeEnterCursor(BtCursor*); 229 217 void sqlite3BtreeLeaveCursor(BtCursor*); 230 218 void sqlite3BtreeLeaveAll(sqlite3*); 231 - void sqlite3BtreeMutexArrayEnter(BtreeMutexArray*); 232 - void sqlite3BtreeMutexArrayLeave(BtreeMutexArray*); 233 - void sqlite3BtreeMutexArrayInsert(BtreeMutexArray*, Btree*); 234 219 #ifndef NDEBUG 235 220 /* These routines are used inside assert() statements only. */ 236 221 int sqlite3BtreeHoldsMutex(Btree*); 237 222 int sqlite3BtreeHoldsAllMutexes(sqlite3*); 223 + u32 sqlite3BtreeMutexCounter(Btree*); 238 224 #endif 239 225 #else 240 226 241 227 # define sqlite3BtreeLeave(X) 228 +# define sqlite3BtreeMutexCounter(X) 0 242 229 # define sqlite3BtreeEnterCursor(X) 243 230 # define sqlite3BtreeLeaveCursor(X) 244 231 # define sqlite3BtreeLeaveAll(X) 245 -# define sqlite3BtreeMutexArrayEnter(X) 246 -# define sqlite3BtreeMutexArrayLeave(X) 247 -# define sqlite3BtreeMutexArrayInsert(X,Y) 248 232 249 233 # define sqlite3BtreeHoldsMutex(X) 1 250 234 # define sqlite3BtreeHoldsAllMutexes(X) 1 251 235 #endif 252 236 253 237 254 238 #endif /* _BTREE_H_ */
Changes to src/btreeInt.h.
422 422 u16 minLeaf; /* Minimum local payload in a LEAFDATA table */ 423 423 u32 pageSize; /* Total number of bytes on a page */ 424 424 u32 usableSize; /* Number of usable bytes on each page */ 425 425 int nTransaction; /* Number of open transactions (read + write) */ 426 426 u32 nPage; /* Number of pages in the database */ 427 427 void *pSchema; /* Pointer to space allocated by sqlite3BtreeSchema() */ 428 428 void (*xFreeSchema)(void*); /* Destructor for BtShared.pSchema */ 429 - sqlite3_mutex *mutex; /* Non-recursive mutex required to access this struct */ 429 + sqlite3_mutex *mutex; /* Non-recursive mutex required to access this object */ 430 430 Bitvec *pHasContent; /* Set of pages moved to free-list this transaction */ 431 431 #ifndef SQLITE_OMIT_SHARED_CACHE 432 432 int nRef; /* Number of references to this structure */ 433 433 BtShared *pNext; /* Next on a list of sharable BtShared structs */ 434 434 BtLock *pLock; /* List of locks held on this shared-btree struct */ 435 435 Btree *pWriter; /* Btree with currently open write transaction */ 436 436 u8 isExclusive; /* True if pWriter has an EXCLUSIVE lock on the db */ 437 437 u8 isPending; /* If waiting for read-locks to clear */ 438 + u16 iMutexCounter; /* The number of mutex_leave(mutex) calls */ 438 439 #endif 439 440 u8 *pTmpSpace; /* BtShared.pageSize bytes of space for tmp use */ 440 441 }; 441 442 442 443 /* 443 444 ** An instance of the following structure is used to hold information 444 445 ** about a cell. The parseCellPtr() function fills in this structure
Changes to src/vdbe.c.
567 567 #ifdef VDBE_PROFILE 568 568 u64 start; /* CPU clock count at start of opcode */ 569 569 int origPc; /* Program counter at start of opcode */ 570 570 #endif 571 571 /*** INSERT STACK UNION HERE ***/ 572 572 573 573 assert( p->magic==VDBE_MAGIC_RUN ); /* sqlite3_step() verifies this */ 574 - sqlite3VdbeMutexArrayEnter(p); 574 + sqlite3VdbeEnter(p); 575 575 if( p->rc==SQLITE_NOMEM ){ 576 576 /* This happens if a malloc() inside a call to sqlite3_column_text() or 577 577 ** sqlite3_column_text16() failed. */ 578 578 goto no_mem; 579 579 } 580 580 assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY ); 581 581 p->rc = SQLITE_OK; ................................................................................ 1390 1390 if( ctx.pFunc->flags & SQLITE_FUNC_NEEDCOLL ){ 1391 1391 assert( pOp>aOp ); 1392 1392 assert( pOp[-1].p4type==P4_COLLSEQ ); 1393 1393 assert( pOp[-1].opcode==OP_CollSeq ); 1394 1394 ctx.pColl = pOp[-1].p4.pColl; 1395 1395 } 1396 1396 (*ctx.pFunc->xFunc)(&ctx, n, apVal); /* IMP: R-24505-23230 */ 1397 + sqlite3VdbeMutexResync(p); 1397 1398 if( db->mallocFailed ){ 1398 1399 /* Even though a malloc() has failed, the implementation of the 1399 1400 ** user function may have called an sqlite3_result_XXX() function 1400 1401 ** to return a value. The following call releases any resources 1401 1402 ** associated with such a value. 1402 1403 */ 1403 1404 sqlite3VdbeMemRelease(&ctx.s); 1404 1405 goto no_mem; 1405 1406 } 1407 + 1408 + /* The app-defined function has done something that as caused this 1409 + ** statement to expire. (Perhaps the function called sqlite3_exec() 1410 + ** with a CREATE TABLE statement.) 1411 + */ 1412 +#if 0 1413 + if( p->expired ){ 1414 + rc = SQLITE_ABORT; 1415 + break; 1416 + } 1417 +#endif 1406 1418 1407 1419 /* If any auxiliary data functions have been called by this user function, 1408 1420 ** immediately call the destructor for any non-static values. 1409 1421 */ 1410 1422 if( ctx.pVdbeFunc ){ 1411 1423 sqlite3VdbeDeleteAuxData(ctx.pVdbeFunc, pOp->p1); 1412 1424 pOp->p4.pVdbeFunc = ctx.pVdbeFunc; ................................................................................ 2646 2658 if( rc!=SQLITE_OK ){ 2647 2659 goto abort_due_to_error; 2648 2660 } 2649 2661 } 2650 2662 if( p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){ 2651 2663 sqlite3ExpirePreparedStatements(db); 2652 2664 sqlite3ResetInternalSchema(db, 0); 2665 + sqlite3VdbeMutexResync(p); 2653 2666 db->flags = (db->flags | SQLITE_InternChanges); 2654 2667 } 2655 2668 } 2656 2669 2657 2670 /* Regardless of whether this is a RELEASE or ROLLBACK, destroy all 2658 2671 ** savepoints nested inside of the savepoint being operated on. */ 2659 2672 while( db->pSavepoint!=pSavepoint ){ ................................................................................ 2936 2949 ** discard the database schema, as the user code implementing the 2937 2950 ** v-table would have to be ready for the sqlite3_vtab structure itself 2938 2951 ** to be invalidated whenever sqlite3_step() is called from within 2939 2952 ** a v-table method. 2940 2953 */ 2941 2954 if( db->aDb[pOp->p1].pSchema->schema_cookie!=iMeta ){ 2942 2955 sqlite3ResetInternalSchema(db, pOp->p1); 2956 + sqlite3VdbeMutexResync(p); 2943 2957 } 2944 2958 2945 2959 p->expired = 1; 2946 2960 rc = SQLITE_SCHEMA; 2947 2961 } 2948 2962 break; 2949 2963 } ................................................................................ 4617 4631 ** then runs the new virtual machine. It is thus a re-entrant opcode. 4618 4632 */ 4619 4633 case OP_ParseSchema: { 4620 4634 int iDb; 4621 4635 const char *zMaster; 4622 4636 char *zSql; 4623 4637 InitData initData; 4638 + 4639 + /* Any prepared statement that invokes this opcode will hold mutexes 4640 + ** on every btree. This is a prerequisite for invoking 4641 + ** sqlite3InitCallback(). 4642 + */ 4643 +#ifdef SQLITE_DEBUG 4644 + for(iDb=0; iDb<db->nDb; iDb++){ 4645 + assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) ); 4646 + } 4647 +#endif 4648 + assert( p->btreeMask == ~(yDbMask)0 ); 4649 + 4624 4650 4625 4651 iDb = pOp->p1; 4626 4652 assert( iDb>=0 && iDb<db->nDb ); 4627 - 4628 - /* When this opcode is invoked, it is guaranteed that the b-tree mutex 4629 - ** is held and the schema is loaded for database iDb. However, at the 4630 - ** start of the sqlite3_exec() call below, SQLite will invoke 4631 - ** sqlite3BtreeEnterAll(). If all mutexes are not already held, the iDb 4632 - ** mutex may be temporarily released to avoid deadlock. If this happens, 4633 - ** then some other thread may delete the in-memory schema of database iDb 4634 - ** before the SQL statement runs. The schema will not be reloaded because 4635 - ** the db->init.busy flag is set. This can result in a "no such table: 4636 - ** sqlite_master" or "malformed database schema" error being returned to 4637 - ** the user. 4638 - ** 4639 - ** To avoid this, obtain all mutexes and check that no other thread has 4640 - ** deleted the schema before calling sqlite3_exec(). If we find that the 4641 - ** another thread has deleted the schema, there is no need to update it. 4642 - ** The updated schema will be loaded from disk when it is next required. 4643 - */ 4644 - assert( sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) ); 4645 4653 assert( DbHasProperty(db, iDb, DB_SchemaLoaded) ); 4646 - sqlite3BtreeEnterAll(db); 4647 - if( DbHasProperty(db, iDb, DB_SchemaLoaded) ){ 4654 + /* Used to be a conditional */ { 4648 4655 zMaster = SCHEMA_TABLE(iDb); 4649 4656 initData.db = db; 4650 4657 initData.iDb = pOp->p1; 4651 4658 initData.pzErrMsg = &p->zErrMsg; 4652 4659 zSql = sqlite3MPrintf(db, 4653 4660 "SELECT name, rootpage, sql FROM '%q'.%s WHERE %s ORDER BY rowid", 4654 4661 db->aDb[iDb].zName, zMaster, pOp->p4.z); ................................................................................ 4661 4668 assert( !db->mallocFailed ); 4662 4669 rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0); 4663 4670 if( rc==SQLITE_OK ) rc = initData.rc; 4664 4671 sqlite3DbFree(db, zSql); 4665 4672 db->init.busy = 0; 4666 4673 } 4667 4674 } 4668 - sqlite3BtreeLeaveAll(db); 4669 4675 if( rc==SQLITE_NOMEM ){ 4670 4676 goto no_mem; 4671 4677 } 4672 4678 break; 4673 4679 } 4674 4680 4675 4681 #if !defined(SQLITE_OMIT_ANALYZE) ................................................................................ 5186 5192 if( ctx.pFunc->flags & SQLITE_FUNC_NEEDCOLL ){ 5187 5193 assert( pOp>p->aOp ); 5188 5194 assert( pOp[-1].p4type==P4_COLLSEQ ); 5189 5195 assert( pOp[-1].opcode==OP_CollSeq ); 5190 5196 ctx.pColl = pOp[-1].p4.pColl; 5191 5197 } 5192 5198 (ctx.pFunc->xStep)(&ctx, n, apVal); /* IMP: R-24505-23230 */ 5199 + sqlite3VdbeMutexResync(p); 5193 5200 if( ctx.isError ){ 5194 5201 sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&ctx.s)); 5195 5202 rc = ctx.isError; 5196 5203 } 5204 + 5205 + /* The app-defined function has done something that as caused this 5206 + ** statement to expire. (Perhaps the function called sqlite3_exec() 5207 + ** with a CREATE TABLE statement.) 5208 + */ 5209 +#if 0 5210 + if( p->expired ){ 5211 + rc = SQLITE_ABORT; 5212 + break; 5213 + } 5214 +#endif 5215 + 5197 5216 sqlite3VdbeMemRelease(&ctx.s); 5217 + 5198 5218 break; 5199 5219 } 5200 5220 5201 5221 /* Opcode: AggFinal P1 P2 * P4 * 5202 5222 ** 5203 5223 ** Execute the finalizer function for an aggregate. P1 is 5204 5224 ** the memory location that is the accumulator for the aggregate. ................................................................................ 5212 5232 */ 5213 5233 case OP_AggFinal: { 5214 5234 Mem *pMem; 5215 5235 assert( pOp->p1>0 && pOp->p1<=p->nMem ); 5216 5236 pMem = &aMem[pOp->p1]; 5217 5237 assert( (pMem->flags & ~(MEM_Null|MEM_Agg))==0 ); 5218 5238 rc = sqlite3VdbeMemFinalize(pMem, pOp->p4.pFunc); 5239 + sqlite3VdbeMutexResync(p); 5219 5240 if( rc ){ 5220 5241 sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(pMem)); 5242 + }else if( p->expired ){ 5243 + rc = SQLITE_ABORT; 5221 5244 } 5222 5245 sqlite3VdbeChangeEncoding(pMem, encoding); 5223 5246 UPDATE_MAX_BLOBSIZE(pMem); 5224 5247 if( sqlite3VdbeMemTooBig(pMem) ){ 5225 5248 goto too_big; 5226 5249 } 5227 5250 break; ................................................................................ 5290 5313 || eNew==PAGER_JOURNALMODE_WAL 5291 5314 || eNew==PAGER_JOURNALMODE_QUERY 5292 5315 ); 5293 5316 assert( pOp->p1>=0 && pOp->p1<db->nDb ); 5294 5317 5295 5318 /* This opcode is used in two places: PRAGMA journal_mode and ATTACH. 5296 5319 ** In PRAGMA journal_mode, the sqlite3VdbeUsesBtree() routine is called 5297 - ** when the statment is prepared and so p->aMutex.nMutex>0. All mutexes 5320 + ** when the statement is prepared and so p->btreeMask!=0. All mutexes 5298 5321 ** are already acquired. But when used in ATTACH, sqlite3VdbeUsesBtree() 5299 5322 ** is not called when the statement is prepared because it requires the 5300 5323 ** iDb index of the database as a parameter, and the database has not 5301 5324 ** yet been attached so that index is unavailable. We have to wait 5302 5325 ** until runtime (now) to get the mutex on the newly attached database. 5303 5326 ** No other mutexes are required by the ATTACH command so this is safe 5304 5327 ** to do. 5305 5328 */ 5306 - assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 || p->aMutex.nMutex==0 ); 5307 - if( p->aMutex.nMutex==0 ){ 5329 + if( p->btreeMask==0 ){ 5308 5330 /* This occurs right after ATTACH. Get a mutex on the newly ATTACHed 5309 5331 ** database. */ 5310 5332 sqlite3VdbeUsesBtree(p, pOp->p1); 5311 - sqlite3VdbeMutexArrayEnter(p); 5333 + sqlite3VdbeEnter(p); 5312 5334 } 5313 5335 5314 5336 pBt = db->aDb[pOp->p1].pBt; 5315 5337 pPager = sqlite3BtreePager(pBt); 5316 5338 eOld = sqlite3PagerGetJournalMode(pPager); 5317 5339 if( eNew==PAGER_JOURNALMODE_QUERY ) eNew = eOld; 5318 5340 if( !sqlite3PagerOkToChangeJournalMode(pPager) ) eNew = eOld; ................................................................................ 5942 5964 p->rc = rc; 5943 5965 testcase( sqlite3GlobalConfig.xLog!=0 ); 5944 5966 sqlite3_log(rc, "statement aborts at %d: [%s] %s", 5945 5967 pc, p->zSql, p->zErrMsg); 5946 5968 sqlite3VdbeHalt(p); 5947 5969 if( rc==SQLITE_IOERR_NOMEM ) db->mallocFailed = 1; 5948 5970 rc = SQLITE_ERROR; 5949 - if( resetSchemaOnFault ) sqlite3ResetInternalSchema(db, 0); 5971 + if( resetSchemaOnFault ){ 5972 + sqlite3ResetInternalSchema(db, 0); 5973 + sqlite3VdbeMutexResync(p); 5974 + } 5950 5975 5951 5976 /* This is the only way out of this procedure. We have to 5952 5977 ** release the mutexes on btrees that were acquired at the 5953 5978 ** top. */ 5954 5979 vdbe_return: 5955 - sqlite3BtreeMutexArrayLeave(&p->aMutex); 5980 + sqlite3VdbeLeave(p); 5956 5981 return rc; 5957 5982 5958 5983 /* Jump to here if a string or blob larger than SQLITE_MAX_LENGTH 5959 5984 ** is encountered. 5960 5985 */ 5961 5986 too_big: 5962 5987 sqlite3SetString(&p->zErrMsg, db, "string or blob too big");
Changes to src/vdbeInt.h.
299 299 u8 minWriteFileFormat; /* Minimum file format for writable database files */ 300 300 u8 inVtabMethod; /* See comments above */ 301 301 u8 usesStmtJournal; /* True if uses a statement journal */ 302 302 u8 readOnly; /* True for read-only statements */ 303 303 u8 isPrepareV2; /* True if prepared with prepare_v2() */ 304 304 int nChange; /* Number of db changes made since last reset */ 305 305 yDbMask btreeMask; /* Bitmask of db->aDb[] entries referenced */ 306 + u32 iMutexCounter; /* Mutex counter upon sqlite3VdbeEnter() */ 306 307 int iStatement; /* Statement number (or 0 if has not opened stmt) */ 307 308 int aCounter[3]; /* Counters used by sqlite3_stmt_status() */ 308 - BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */ 309 309 #ifndef SQLITE_OMIT_TRACE 310 310 i64 startTime; /* Time when query started - used for profiling */ 311 311 #endif 312 312 i64 nFkConstraint; /* Number of imm. FK constraints this VM */ 313 313 i64 nStmtDefCons; /* Number of def. constraints when stmt started */ 314 314 char *zSql; /* Text of the SQL statement that generated this */ 315 315 void *pFree; /* Free this when deleting the vdbe */ ................................................................................ 383 383 int sqlite3VdbeMemFinalize(Mem*, FuncDef*); 384 384 const char *sqlite3OpcodeName(int); 385 385 int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve); 386 386 int sqlite3VdbeCloseStatement(Vdbe *, int); 387 387 void sqlite3VdbeFrameDelete(VdbeFrame*); 388 388 int sqlite3VdbeFrameRestore(VdbeFrame *); 389 389 void sqlite3VdbeMemStoreType(Mem *pMem); 390 +void sqlite3VdbeEnter(Vdbe*); 391 +void sqlite3VdbeLeave(Vdbe*); 392 +void sqlite3VdbeMutexResync(Vdbe*); 390 393 391 394 #ifdef SQLITE_DEBUG 392 395 void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*); 393 396 #endif 394 397 395 398 #ifndef SQLITE_OMIT_FOREIGN_KEY 396 399 int sqlite3VdbeCheckFk(Vdbe *, int); 397 400 #else 398 401 # define sqlite3VdbeCheckFk(p,i) 0 399 402 #endif 400 403 401 -#ifndef SQLITE_OMIT_SHARED_CACHE 402 -void sqlite3VdbeMutexArrayEnter(Vdbe *p); 403 -#else 404 -# define sqlite3VdbeMutexArrayEnter(p) 405 -#endif 406 - 407 404 int sqlite3VdbeMemTranslate(Mem*, u8); 408 405 #ifdef SQLITE_DEBUG 409 406 void sqlite3VdbePrintSql(Vdbe*); 410 407 void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf); 411 408 #endif 412 409 int sqlite3VdbeMemHandleBom(Mem *pMem); 413 410
Changes to src/vdbeaux.c.
153 153 pOp->p5 = 0; 154 154 pOp->p1 = p1; 155 155 pOp->p2 = p2; 156 156 pOp->p3 = p3; 157 157 pOp->p4.p = 0; 158 158 pOp->p4type = P4_NOTUSED; 159 159 p->expired = 0; 160 + if( op==OP_ParseSchema ){ 161 + /* Any program that uses the OP_ParseSchema opcode needs to lock 162 + ** all btrees. */ 163 + p->btreeMask = ~(yDbMask)0; 164 + } 160 165 #ifdef SQLITE_DEBUG 161 166 pOp->zComment = 0; 162 167 if( sqlite3VdbeAddopTrace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]); 163 168 #endif 164 169 #ifdef VDBE_PROFILE 165 170 pOp->cycles = 0; 166 171 pOp->cnt = 0; ................................................................................ 453 458 ** returned program. 454 459 */ 455 460 VdbeOp *sqlite3VdbeTakeOpArray(Vdbe *p, int *pnOp, int *pnMaxArg){ 456 461 VdbeOp *aOp = p->aOp; 457 462 assert( aOp && !p->db->mallocFailed ); 458 463 459 464 /* Check that sqlite3VdbeUsesBtree() was not called on this VM */ 460 - assert( p->aMutex.nMutex==0 ); 465 + assert( p->btreeMask==0 ); 461 466 462 467 resolveP2Values(p, pnMaxArg); 463 468 *pnOp = p->nOp; 464 469 p->aOp = 0; 465 470 return aOp; 466 471 } 467 472 ................................................................................ 941 946 return zP4; 942 947 } 943 948 #endif 944 949 945 950 /* 946 951 ** Declare to the Vdbe that the BTree object at db->aDb[i] is used. 947 952 ** 948 -** The prepared statement has to know in advance which Btree objects 949 -** will be used so that it can acquire mutexes on them all in sorted 950 -** order (via sqlite3VdbeMutexArrayEnter(). Mutexes are acquired 951 -** in order (and released in reverse order) to avoid deadlocks. 953 +** The prepared statements need to know in advance the complete set of 954 +** attached databases that they will be using. A mask of these databases 955 +** is maintained in p->btreeMask and is used for locking and other purposes. 952 956 */ 953 957 void sqlite3VdbeUsesBtree(Vdbe *p, int i){ 954 - yDbMask mask; 955 958 assert( i>=0 && i<p->db->nDb && i<sizeof(yDbMask)*8 ); 956 959 assert( i<(int)sizeof(p->btreeMask)*8 ); 957 - mask = ((yDbMask)1)<<i; 958 - if( (p->btreeMask & mask)==0 ){ 959 - p->btreeMask |= mask; 960 - sqlite3BtreeMutexArrayInsert(&p->aMutex, p->db->aDb[i].pBt); 961 - } 962 -} 963 - 960 + p->btreeMask |= ((yDbMask)1)<<i; 961 +} 962 + 963 +/* 964 +** Compute the sum of all mutex counters for all btrees in the 965 +** given prepared statement. 966 +*/ 967 +#ifndef SQLITE_OMIT_SHARED_CACHE 968 +static u32 mutexCounterSum(Vdbe *p){ 969 + u32 cntSum = 0; 970 +#ifdef SQLITE_DEBUG 971 + int i; 972 + yDbMask mask; 973 + sqlite3 *db = p->db; 974 + Db *aDb = db->aDb; 975 + int nDb = db->nDb; 976 + for(i=0, mask=1; i<nDb; i++, mask += mask){ 977 + if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){ 978 + cntSum += sqlite3BtreeMutexCounter(aDb[i].pBt); 979 + } 980 + } 981 +#endif 982 + return cntSum; 983 +} 984 +#endif 985 + 986 +/* 987 +** If SQLite is compiled to support shared-cache mode and to be threadsafe, 988 +** this routine obtains the mutex associated with each BtShared structure 989 +** that may be accessed by the VM passed as an argument. In doing so it also 990 +** sets the BtShared.db member of each of the BtShared structures, ensuring 991 +** that the correct busy-handler callback is invoked if required. 992 +** 993 +** If SQLite is not threadsafe but does support shared-cache mode, then 994 +** sqlite3BtreeEnter() is invoked to set the BtShared.db variables 995 +** of all of BtShared structures accessible via the database handle 996 +** associated with the VM. 997 +** 998 +** If SQLite is not threadsafe and does not support shared-cache mode, this 999 +** function is a no-op. 1000 +** 1001 +** The p->btreeMask field is a bitmask of all btrees that the prepared 1002 +** statement p will ever use. Let N be the number of bits in p->btreeMask 1003 +** corresponding to btrees that use shared cache. Then the runtime of 1004 +** this routine is N*N. But as N is rarely more than 1, this should not 1005 +** be a problem. 1006 +*/ 1007 +void sqlite3VdbeEnter(Vdbe *p){ 1008 +#ifndef SQLITE_OMIT_SHARED_CACHE 1009 + int i; 1010 + yDbMask mask; 1011 + sqlite3 *db = p->db; 1012 + Db *aDb = db->aDb; 1013 + int nDb = db->nDb; 1014 + for(i=0, mask=1; i<nDb; i++, mask += mask){ 1015 + if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){ 1016 + sqlite3BtreeEnter(aDb[i].pBt); 1017 + } 1018 + } 1019 + p->iMutexCounter = mutexCounterSum(p); 1020 +#endif 1021 +} 1022 + 1023 +/* 1024 +** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter(). 1025 +*/ 1026 +void sqlite3VdbeLeave(Vdbe *p){ 1027 +#ifndef SQLITE_OMIT_SHARED_CACHE 1028 + int i; 1029 + yDbMask mask; 1030 + sqlite3 *db = p->db; 1031 + Db *aDb = db->aDb; 1032 + int nDb = db->nDb; 1033 + 1034 + /* Assert that the all mutexes have been held continously since 1035 + ** the most recent sqlite3VdbeEnter() or sqlite3VdbeMutexResync(). 1036 + */ 1037 + assert( mutexCounterSum(p) == p->iMutexCounter ); 1038 + 1039 + for(i=0, mask=1; i<nDb; i++, mask += mask){ 1040 + if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){ 1041 + sqlite3BtreeLeave(aDb[i].pBt); 1042 + } 1043 + } 1044 +#endif 1045 +} 1046 + 1047 +/* 1048 +** Recompute the sum of the mutex counters on all btrees used by the 1049 +** prepared statement p. 1050 +** 1051 +** Call this routine while holding a sqlite3VdbeEnter() after doing something 1052 +** that might cause one or more of the individual mutexes held by the 1053 +** prepared statement to be released. Calling sqlite3BtreeEnter() on 1054 +** any BtShared mutex which is not used by the prepared statement is one 1055 +** way to cause one or more of the mutexes in the prepared statement 1056 +** to be temporarily released. The anti-deadlocking logic in 1057 +** sqlite3BtreeEnter() can cause mutexes to be released temporarily then 1058 +** reacquired. 1059 +** 1060 +** Calling this routine is an acknowledgement that some of the individual 1061 +** mutexes in the prepared statement might have been released and reacquired. 1062 +** So checks to verify that mutex-protected content did not change 1063 +** unexpectedly should accompany any call to this routine. 1064 +*/ 1065 +void sqlite3VdbeMutexResync(Vdbe *p){ 1066 +#if !defined(SQLITE_OMIT_SHARED_CACHE) && defined(SQLITE_DEBUG) 1067 + p->iMutexCounter = mutexCounterSum(p); 1068 +#endif 1069 +} 964 1070 965 1071 #if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG) 966 1072 /* 967 1073 ** Print a single opcode. This routine is used for debugging only. 968 1074 */ 969 1075 void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){ 970 1076 char *zP4; ................................................................................ 1955 2061 if( eOp==SAVEPOINT_ROLLBACK ){ 1956 2062 db->nDeferredCons = p->nStmtDefCons; 1957 2063 } 1958 2064 } 1959 2065 return rc; 1960 2066 } 1961 2067 1962 -/* 1963 -** If SQLite is compiled to support shared-cache mode and to be threadsafe, 1964 -** this routine obtains the mutex associated with each BtShared structure 1965 -** that may be accessed by the VM passed as an argument. In doing so it 1966 -** sets the BtShared.db member of each of the BtShared structures, ensuring 1967 -** that the correct busy-handler callback is invoked if required. 1968 -** 1969 -** If SQLite is not threadsafe but does support shared-cache mode, then 1970 -** sqlite3BtreeEnterAll() is invoked to set the BtShared.db variables 1971 -** of all of BtShared structures accessible via the database handle 1972 -** associated with the VM. Of course only a subset of these structures 1973 -** will be accessed by the VM, and we could use Vdbe.btreeMask to figure 1974 -** that subset out, but there is no advantage to doing so. 1975 -** 1976 -** If SQLite is not threadsafe and does not support shared-cache mode, this 1977 -** function is a no-op. 1978 -*/ 1979 -#ifndef SQLITE_OMIT_SHARED_CACHE 1980 -void sqlite3VdbeMutexArrayEnter(Vdbe *p){ 1981 -#if SQLITE_THREADSAFE 1982 - sqlite3BtreeMutexArrayEnter(&p->aMutex); 1983 -#else 1984 - sqlite3BtreeEnterAll(p->db); 1985 -#endif 1986 -} 1987 -#endif 1988 - 1989 2068 /* 1990 2069 ** This function is called when a transaction opened by the database 1991 2070 ** handle associated with the VM passed as an argument is about to be 1992 2071 ** committed. If there are outstanding deferred foreign key constraint 1993 2072 ** violations, return SQLITE_ERROR. Otherwise, SQLITE_OK. 1994 2073 ** 1995 2074 ** If there are outstanding FK violations and this function returns ................................................................................ 2054 2133 /* No commit or rollback needed if the program never started */ 2055 2134 if( p->pc>=0 ){ 2056 2135 int mrc; /* Primary error code from p->rc */ 2057 2136 int eStatementOp = 0; 2058 2137 int isSpecialError; /* Set to true if a 'special' error */ 2059 2138 2060 2139 /* Lock all btrees used by the statement */ 2061 - sqlite3VdbeMutexArrayEnter(p); 2140 + sqlite3VdbeEnter(p); 2062 2141 2063 2142 /* Check for one of the special errors */ 2064 2143 mrc = p->rc & 0xff; 2065 2144 assert( p->rc!=SQLITE_IOERR_BLOCKED ); /* This error no longer exists */ 2066 2145 isSpecialError = mrc==SQLITE_NOMEM || mrc==SQLITE_IOERR 2067 2146 || mrc==SQLITE_INTERRUPT || mrc==SQLITE_FULL; 2068 2147 if( isSpecialError ){ ................................................................................ 2108 2187 && db->autoCommit 2109 2188 && db->writeVdbeCnt==(p->readOnly==0) 2110 2189 ){ 2111 2190 if( p->rc==SQLITE_OK || (p->errorAction==OE_Fail && !isSpecialError) ){ 2112 2191 rc = sqlite3VdbeCheckFk(p, 1); 2113 2192 if( rc!=SQLITE_OK ){ 2114 2193 if( NEVER(p->readOnly) ){ 2115 - sqlite3BtreeMutexArrayLeave(&p->aMutex); 2194 + sqlite3VdbeLeave(p); 2116 2195 return SQLITE_ERROR; 2117 2196 } 2118 2197 rc = SQLITE_CONSTRAINT; 2119 2198 }else{ 2120 2199 /* The auto-commit flag is true, the vdbe program was successful 2121 2200 ** or hit an 'OR FAIL' constraint and there are no deferred foreign 2122 2201 ** key constraints to hold up the transaction. This means a commit 2123 2202 ** is required. */ 2124 2203 rc = vdbeCommit(db, p); 2125 2204 } 2126 2205 if( rc==SQLITE_BUSY && p->readOnly ){ 2127 - sqlite3BtreeMutexArrayLeave(&p->aMutex); 2206 + sqlite3VdbeLeave(p); 2128 2207 return SQLITE_BUSY; 2129 2208 }else if( rc!=SQLITE_OK ){ 2130 2209 p->rc = rc; 2131 2210 sqlite3RollbackAll(db); 2132 2211 }else{ 2133 2212 db->nDeferredCons = 0; 2134 2213 sqlite3CommitInternalChanges(db); ................................................................................ 2192 2271 /* Rollback or commit any schema changes that occurred. */ 2193 2272 if( p->rc!=SQLITE_OK && db->flags&SQLITE_InternChanges ){ 2194 2273 sqlite3ResetInternalSchema(db, 0); 2195 2274 db->flags = (db->flags | SQLITE_InternChanges); 2196 2275 } 2197 2276 2198 2277 /* Release the locks */ 2199 - sqlite3BtreeMutexArrayLeave(&p->aMutex); 2278 + sqlite3VdbeMutexResync(p); 2279 + sqlite3VdbeLeave(p); 2200 2280 } 2201 2281 2202 2282 /* We have successfully halted and closed the VM. Record this fact. */ 2203 2283 if( p->pc>=0 ){ 2204 2284 db->activeVdbeCnt--; 2205 2285 if( !p->readOnly ){ 2206 2286 db->writeVdbeCnt--;