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Overview
Comment: | Fix an obscure race condition that can occur when multiple threads, shared cache and DDL statements are combined. Enhance notify2.test to test this scenario. (CVS 6373) |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
92ec5975123284aff3a69ee16c397d9e |
User & Date: | danielk1977 2009-03-23 17:11:27.000 |
Context
2009-03-23
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17:49 | Add asserts to make sure that database connection locks are held when accessing the lookaside memory allocation buffers. No defects were found. (CVS 6374) (check-in: 8a9f3e6606 user: drh tags: trunk) | |
17:11 | Fix an obscure race condition that can occur when multiple threads, shared cache and DDL statements are combined. Enhance notify2.test to test this scenario. (CVS 6373) (check-in: 92ec597512 user: danielk1977 tags: trunk) | |
04:33 | Use the ROUND8() macro to round an integer up to the nearest multiple of 8 and ROUNDDOWN8() macro to round down to the nearest multiple of 8. This is a cosmetic change. (CVS 6372) (check-in: db1d4d2f50 user: danielk1977 tags: trunk) | |
Changes
Changes to src/prepare.c.
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9 10 11 12 13 14 15 | ** May you share freely, never taking more than you give. ** ************************************************************************* ** This file contains the implementation of the sqlite3_prepare() ** interface, and routines that contribute to loading the database schema ** from disk. ** | | | 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | ** May you share freely, never taking more than you give. ** ************************************************************************* ** This file contains the implementation of the sqlite3_prepare() ** interface, and routines that contribute to loading the database schema ** from disk. ** ** $Id: prepare.c,v 1.112 2009/03/23 17:11:27 danielk1977 Exp $ */ #include "sqliteInt.h" /* ** Fill the InitData structure with an error message that indicates ** that the database is corrupt. */ |
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87 88 89 90 91 92 93 | db->init.iDb = 0; db->lookaside.bEnabled = lookasideEnabled; assert( rc!=SQLITE_OK || zErr==0 ); if( SQLITE_OK!=rc ){ pData->rc = rc; if( rc==SQLITE_NOMEM ){ db->mallocFailed = 1; | | | 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 | db->init.iDb = 0; db->lookaside.bEnabled = lookasideEnabled; assert( rc!=SQLITE_OK || zErr==0 ); if( SQLITE_OK!=rc ){ pData->rc = rc; if( rc==SQLITE_NOMEM ){ db->mallocFailed = 1; }else if( rc!=SQLITE_INTERRUPT && (rc&0xff)!=SQLITE_LOCKED ){ corruptSchema(pData, argv[0], zErr); } sqlite3DbFree(db, zErr); } }else if( argv[0]==0 ){ corruptSchema(pData, 0, 0); }else{ |
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Changes to src/test_thread.c.
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10 11 12 13 14 15 16 | ** ************************************************************************* ** ** This file contains the implementation of some Tcl commands used to ** test that sqlite3 database handles may be concurrently accessed by ** multiple threads. Right now this only works on unix. ** | | | 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | ** ************************************************************************* ** ** This file contains the implementation of some Tcl commands used to ** test that sqlite3 database handles may be concurrently accessed by ** multiple threads. Right now this only works on unix. ** ** $Id: test_thread.c,v 1.13 2009/03/23 17:11:27 danielk1977 Exp $ */ #include "sqliteInt.h" #include <tcl.h> #if SQLITE_THREADSAFE |
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113 114 115 116 117 118 119 | extern int Sqlitetest_mutex_Init(Tcl_Interp*); interp = Tcl_CreateInterp(); Tcl_CreateObjCommand(interp, "clock_seconds", clock_seconds_proc, 0, 0); Tcl_CreateObjCommand(interp, "sqlthread", sqlthread_proc, pSqlThread, 0); #if defined(OS_UNIX) && defined(SQLITE_ENABLE_UNLOCK_NOTIFY) Tcl_CreateObjCommand(interp, "sqlite3_blocking_step", blocking_step_proc,0,0); | | | > > | 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 | extern int Sqlitetest_mutex_Init(Tcl_Interp*); interp = Tcl_CreateInterp(); Tcl_CreateObjCommand(interp, "clock_seconds", clock_seconds_proc, 0, 0); Tcl_CreateObjCommand(interp, "sqlthread", sqlthread_proc, pSqlThread, 0); #if defined(OS_UNIX) && defined(SQLITE_ENABLE_UNLOCK_NOTIFY) Tcl_CreateObjCommand(interp, "sqlite3_blocking_step", blocking_step_proc,0,0); Tcl_CreateObjCommand(interp, "sqlite3_blocking_prepare_v2", blocking_prepare_v2_proc, (void *)1, 0); Tcl_CreateObjCommand(interp, "sqlite3_nonblocking_prepare_v2", blocking_prepare_v2_proc, 0, 0); #endif Sqlitetest1_Init(interp); Sqlitetest_mutex_Init(interp); rc = Tcl_Eval(interp, p->zScript); pRes = Tcl_GetObjResult(interp); pList = Tcl_NewObj(); |
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540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 | Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), 0); return TCL_OK; } /* ** Usage: sqlite3_blocking_prepare_v2 DB sql bytes ?tailvar? */ static int blocking_prepare_v2_proc( void * clientData, Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[] ){ sqlite3 *db; const char *zSql; int bytes; const char *zTail = 0; sqlite3_stmt *pStmt = 0; char zBuf[50]; int rc; if( objc!=5 && objc!=4 ){ Tcl_AppendResult(interp, "wrong # args: should be \"", Tcl_GetString(objv[0]), " DB sql bytes tailvar", 0); return TCL_ERROR; } if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR; zSql = Tcl_GetString(objv[2]); if( Tcl_GetIntFromObj(interp, objv[3], &bytes) ) return TCL_ERROR; | > > > | > > > > | 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 | Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), 0); return TCL_OK; } /* ** Usage: sqlite3_blocking_prepare_v2 DB sql bytes ?tailvar? ** Usage: sqlite3_nonblocking_prepare_v2 DB sql bytes ?tailvar? */ static int blocking_prepare_v2_proc( void * clientData, Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[] ){ sqlite3 *db; const char *zSql; int bytes; const char *zTail = 0; sqlite3_stmt *pStmt = 0; char zBuf[50]; int rc; int isBlocking = !(clientData==0); if( objc!=5 && objc!=4 ){ Tcl_AppendResult(interp, "wrong # args: should be \"", Tcl_GetString(objv[0]), " DB sql bytes tailvar", 0); return TCL_ERROR; } if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR; zSql = Tcl_GetString(objv[2]); if( Tcl_GetIntFromObj(interp, objv[3], &bytes) ) return TCL_ERROR; if( isBlocking ){ rc = sqlite3_blocking_prepare_v2(db, zSql, bytes, &pStmt, &zTail); }else{ rc = sqlite3_prepare_v2(db, zSql, bytes, &pStmt, &zTail); } assert(rc==SQLITE_OK || pStmt==0); if( zTail && objc>=5 ){ if( bytes>=0 ){ bytes = bytes - (zTail-zSql); } Tcl_ObjSetVar2(interp, objv[4], 0, Tcl_NewStringObj(zTail, bytes), 0); } |
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599 600 601 602 603 604 605 | ** Register commands with the TCL interpreter. */ int SqlitetestThread_Init(Tcl_Interp *interp){ Tcl_CreateObjCommand(interp, "sqlthread", sqlthread_proc, 0, 0); Tcl_CreateObjCommand(interp, "clock_seconds", clock_seconds_proc, 0, 0); #if defined(OS_UNIX) && defined(SQLITE_ENABLE_UNLOCK_NOTIFY) Tcl_CreateObjCommand(interp, "sqlite3_blocking_step", blocking_step_proc,0,0); | | | > > | 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 | ** Register commands with the TCL interpreter. */ int SqlitetestThread_Init(Tcl_Interp *interp){ Tcl_CreateObjCommand(interp, "sqlthread", sqlthread_proc, 0, 0); Tcl_CreateObjCommand(interp, "clock_seconds", clock_seconds_proc, 0, 0); #if defined(OS_UNIX) && defined(SQLITE_ENABLE_UNLOCK_NOTIFY) Tcl_CreateObjCommand(interp, "sqlite3_blocking_step", blocking_step_proc,0,0); Tcl_CreateObjCommand(interp, "sqlite3_blocking_prepare_v2", blocking_prepare_v2_proc, (void *)1, 0); Tcl_CreateObjCommand(interp, "sqlite3_nonblocking_prepare_v2", blocking_prepare_v2_proc, 0, 0); #endif return TCL_OK; } #else int SqlitetestThread_Init(Tcl_Interp *interp){ return TCL_OK; } #endif |
Changes to src/vdbe.c.
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39 40 41 42 43 44 45 | ** ** Various scripts scan this source file in order to generate HTML ** documentation, headers files, or other derived files. The formatting ** of the code in this file is, therefore, important. See other comments ** in this file for details. If in doubt, do not deviate from existing ** commenting and indentation practices when changing or adding code. ** | | | 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | ** ** Various scripts scan this source file in order to generate HTML ** documentation, headers files, or other derived files. The formatting ** of the code in this file is, therefore, important. See other comments ** in this file for details. If in doubt, do not deviate from existing ** commenting and indentation practices when changing or adding code. ** ** $Id: vdbe.c,v 1.828 2009/03/23 17:11:27 danielk1977 Exp $ */ #include "sqliteInt.h" #include "vdbeInt.h" /* ** The following global variable is incremented every time a cursor ** moves, either by the OP_SeekXX, OP_Next, or OP_Prev opcodes. The test |
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4367 4368 4369 4370 4371 4372 4373 | ** is false, the SQLITE_MASTER table is only parsed if the rest of the ** schema is already loaded into the symbol table. ** ** This opcode invokes the parser to create a new virtual machine, ** then runs the new virtual machine. It is thus a re-entrant opcode. */ case OP_ParseSchema: { | < < < < < < | > > > > > > > > > > > > > > > > > > > > > > > > | > > | | | | | | | > > | | | | | | | | | | > > > | 4367 4368 4369 4370 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389 4390 4391 4392 4393 4394 4395 4396 4397 4398 4399 4400 4401 4402 4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415 4416 4417 4418 4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 | ** is false, the SQLITE_MASTER table is only parsed if the rest of the ** schema is already loaded into the symbol table. ** ** This opcode invokes the parser to create a new virtual machine, ** then runs the new virtual machine. It is thus a re-entrant opcode. */ case OP_ParseSchema: { int iDb = pOp->p1; assert( iDb>=0 && iDb<db->nDb ); /* If pOp->p2 is 0, then this opcode is being executed to read a ** single row, for example the row corresponding to a new index ** created by this VDBE, from the sqlite_master table. It only ** does this if the corresponding in-memory schema is currently ** loaded. Otherwise, the new index definition can be loaded along ** with the rest of the schema when it is required. ** ** Although the mutex on the BtShared object that corresponds to ** database iDb (the database containing the sqlite_master table ** read by this instruction) is currently held, it is necessary to ** obtain the mutexes on all attached databases before checking if ** the schema of iDb is loaded. This is because, at the start of ** the sqlite3_exec() call below, SQLite will invoke ** sqlite3BtreeEnterAll(). If all mutexes are not already held, the ** iDb mutex may be temporarily released to avoid deadlock. If ** this happens, then some other thread may delete the in-memory ** schema of database iDb before the SQL statement runs. The schema ** will not be reloaded becuase the db->init.busy flag is set. This ** can result in a "no such table: sqlite_master" or "malformed ** database schema" error being returned to the user. */ assert( sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) ); sqlite3BtreeEnterAll(db); if( pOp->p2 || DbHasProperty(db, iDb, DB_SchemaLoaded) ){ const char *zMaster = SCHEMA_TABLE(iDb); char *zSql; InitData initData; initData.db = db; initData.iDb = pOp->p1; initData.pzErrMsg = &p->zErrMsg; zSql = sqlite3MPrintf(db, "SELECT name, rootpage, sql FROM '%q'.%s WHERE %s", db->aDb[iDb].zName, zMaster, pOp->p4.z); if( zSql==0 ){ rc = SQLITE_NOMEM; }else{ (void)sqlite3SafetyOff(db); assert( db->init.busy==0 ); db->init.busy = 1; initData.rc = SQLITE_OK; assert( !db->mallocFailed ); rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0); if( rc==SQLITE_OK ) rc = initData.rc; sqlite3DbFree(db, zSql); db->init.busy = 0; (void)sqlite3SafetyOn(db); } } sqlite3BtreeLeaveAll(db); if( rc==SQLITE_NOMEM ){ goto no_mem; } break; } #if !defined(SQLITE_OMIT_ANALYZE) && !defined(SQLITE_OMIT_PARSER) |
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Changes to test/notify2.test.
1 2 3 4 5 6 7 8 9 10 11 | # 2009 March 04 # # The author disclaims copyright to this source code. In place of # a legal notice, here is a blessing: # # May you do good and not evil. # May you find forgiveness for yourself and forgive others. # May you share freely, never taking more than you give. # #*********************************************************************** # | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | # 2009 March 04 # # The author disclaims copyright to this source code. In place of # a legal notice, here is a blessing: # # May you do good and not evil. # May you find forgiveness for yourself and forgive others. # May you share freely, never taking more than you give. # #*********************************************************************** # # $Id: notify2.test,v 1.3 2009/03/23 17:11:27 danielk1977 Exp $ set testdir [file dirname $argv0] source $testdir/tester.tcl # The tests in this file test the sqlite3_blocking_step() function in # test_thread.c. sqlite3_blocking_step() is not an SQLite API function, # it is just a demonstration of how the sqlite3_unlock_notify() function |
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57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 | set ThreadProgram { # Proc used by threads to execute SQL. # proc execsql_blocking {db zSql} { set lRes [list] set rc SQLITE_OK while {$rc=="SQLITE_OK" && $zSql ne ""} { set STMT [$::xPrepare $db $zSql -1 zSql] while {[set rc [$::xStep $STMT]] eq "SQLITE_ROW"} { for {set i 0} {$i < [sqlite3_column_count $STMT]} {incr i} { lappend lRes [sqlite3_column_text $STMT 0] } } set rc [sqlite3_finalize $STMT] } | > > | > > > > > > > > | | < | | > > > > | < | | | < > | > > | > > > > | | 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 | set ThreadProgram { # Proc used by threads to execute SQL. # proc execsql_blocking {db zSql} { set lRes [list] set rc SQLITE_OK set sql $zSql while {$rc=="SQLITE_OK" && $zSql ne ""} { set STMT [$::xPrepare $db $zSql -1 zSql] while {[set rc [$::xStep $STMT]] eq "SQLITE_ROW"} { for {set i 0} {$i < [sqlite3_column_count $STMT]} {incr i} { lappend lRes [sqlite3_column_text $STMT 0] } } set rc [sqlite3_finalize $STMT] } if {$rc != "SQLITE_OK"} { error "$rc $sql [sqlite3_errmsg $db]" } return $lRes } proc execsql_retry {db sql} { set msg "SQLITE_LOCKED blah..." while { [string match SQLITE_LOCKED* $msg] } { catch { execsql_blocking $db $sql } msg } } proc select_one {args} { set n [llength $args] lindex $args [expr int($n*rand())] } proc opendb {} { # Open a database connection. Attach the two auxillary databases. set ::DB [sqlite3_open test.db] execsql_retry $::DB { ATTACH 'test2.db' AS aux2; } execsql_retry $::DB { ATTACH 'test3.db' AS aux3; } } opendb #after 2000 # This loop runs for ~20 seconds. # set iStart [clock_seconds] while { ([clock_seconds]-$iStart) < $nSecond } { # Each transaction does 3 operations. Each operation is either a read # or write of a randomly selected table (t1, t2 or t3). Set the variables # $SQL(1), $SQL(2) and $SQL(3) to the SQL commands used to implement # each operation. # for {set ii 1} {$ii <= 3} {incr ii} { foreach {tbl database} [select_one {t1 main} {t2 aux2} {t3 aux3}] {} set SQL($ii) [string map [list xxx $tbl yyy $database] [select_one { SELECT (SELECT b FROM xxx WHERE a=(SELECT max(a) FROM xxx))==total(a) FROM xxx WHERE a!=(SELECT max(a) FROM xxx); } { DELETE FROM xxx WHERE a<(SELECT max(a)-100 FROM xxx); INSERT INTO xxx SELECT NULL, total(a) FROM xxx; } { CREATE INDEX IF NOT EXISTS yyy.xxx_i ON xxx(b); } { DROP INDEX IF EXISTS yyy.xxx_i; } ]] } # Execute the SQL transaction. # set rc [catch { execsql_blocking $::DB " BEGIN; $SQL(1); $SQL(2); $SQL(3); COMMIT; " } msg] if {$rc && [string match "SQLITE_LOCKED*" $msg] || [string match "SQLITE_SCHEMA*" $msg] } { # Hit an SQLITE_LOCKED error. Rollback the current transaction. set rc [catch { execsql_blocking $::DB ROLLBACK } msg] if {$rc && [string match "SQLITE_LOCKED*" $msg]} { sqlite3_close $::DB opendb } } elseif {$rc} { # Hit some other kind of error. This is a malfunction. error $msg } else { # No error occured. Check that any SELECT statements in the transaction # returned "1". Otherwise, the invariant was false, indicating that # some malfunction has occured. foreach r $msg { if {$r != 1} { puts "Invariant check failed: $msg" } } } } # Close the database connection and return 0. # sqlite3_close $::DB expr 0 } foreach {iTest xStep xPrepare} { 1 sqlite3_blocking_step sqlite3_blocking_prepare_v2 2 sqlite3_step sqlite3_nonblocking_prepare_v2 } { file delete -force test.db test2.db test3.db set ThreadSetup "set xStep $xStep;set xPrepare $xPrepare;set nSecond $nSecond" # Set up the database schema used by this test. Each thread opens file # test.db as the main database, then attaches files test2.db and test3.db |
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