Many hyperlinks are disabled.
Use anonymous login
to enable hyperlinks.
Overview
| Comment: | Add tests and fix bugs in WAL locking mechanism. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | wal |
| Files: | files | file ages | folders |
| SHA1: |
c18077f2465fc34830f11c9832e76be5 |
| User & Date: | dan 2010-04-14 18:50:08 |
Context
|
2010-04-15
| ||
| 02:37 | Bring over the recent query planner enhancements from the trunk. (check-in: 82969f27 user: drh tags: wal) | |
|
2010-04-14
| ||
| 18:50 | Add tests and fix bugs in WAL locking mechanism. (check-in: c18077f2 user: dan tags: wal) | |
| 18:06 | Add tests to check inter-process WAL locking. (check-in: 9435f313 user: dan tags: wal) | |
Changes
Changes to src/log.c.
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
....
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
|
/* Normal reader lock operations */
|| (op==LOG_RDLOCK && mRegion==(LOG_REGION_A|LOG_REGION_B))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_A))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_B))
/* Region D reader lock operations */
|| (op==LOG_RDLOCK && mRegion==(LOG_REGION_D))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_D))
/* Checkpointer lock operations */
|| (op==LOG_WRLOCK && mRegion==(LOG_REGION_B|LOG_REGION_C))
|| (op==LOG_WRLOCK && mRegion==(LOG_REGION_A))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_B|LOG_REGION_C))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_A|LOG_REGION_B|LOG_REGION_C))
................................................................................
*/
void sqlite3LogMaxpgno(Log *pLog, Pgno *pPgno){
assert( pLog->isLocked );
*pPgno = pLog->hdr.nPage;
}
/*
** The caller must hold at least a RESERVED lock on the database file
** when invoking this function.
**
** This function returns SQLITE_OK if the caller may write to the database.
** Otherwise, if the caller is operating on a snapshot that has already
** been overwritten by another writer, SQLITE_OBE is returned.
*/
int sqlite3LogWriteLock(Log *pLog, int op){
assert( pLog->isLocked );
if( op ){
/* Obtain the writer lock */
int rc = logLockRegion(pLog, LOG_REGION_C|LOG_REGION_D, LOG_WRLOCK);
if( rc!=SQLITE_OK ){
return rc;
}
/* TODO: What if this is a region D reader? And after writing this
** transaction it continues to hold a read-lock on the db? Maybe we
** need to switch it to a region A reader here so that unlocking C|D
** does not leave the connection with no lock at all.
*/
assert( pLog->isLocked!=LOG_REGION_D );
if( memcmp(&pLog->hdr, pLog->pSummary->aData, sizeof(pLog->hdr)) ){
return SQLITE_BUSY;
}
pLog->isWriteLocked = 1;
}else if( pLog->isWriteLocked ){
logLockRegion(pLog, LOG_REGION_C|LOG_REGION_D, LOG_UNLOCK);
memcpy(&pLog->hdr, pLog->pSummary->aData, sizeof(pLog->hdr));
|
>
<
<
<
|
|
|
|
|
>
>
>
>
>
>
>
>
|
>
>
|
>
>
|
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
....
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
|
/* Normal reader lock operations */
|| (op==LOG_RDLOCK && mRegion==(LOG_REGION_A|LOG_REGION_B))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_A))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_B))
/* Region D reader lock operations */
|| (op==LOG_RDLOCK && mRegion==(LOG_REGION_D))
|| (op==LOG_RDLOCK && mRegion==(LOG_REGION_A))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_D))
/* Checkpointer lock operations */
|| (op==LOG_WRLOCK && mRegion==(LOG_REGION_B|LOG_REGION_C))
|| (op==LOG_WRLOCK && mRegion==(LOG_REGION_A))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_B|LOG_REGION_C))
|| (op==LOG_UNLOCK && mRegion==(LOG_REGION_A|LOG_REGION_B|LOG_REGION_C))
................................................................................
*/
void sqlite3LogMaxpgno(Log *pLog, Pgno *pPgno){
assert( pLog->isLocked );
*pPgno = pLog->hdr.nPage;
}
/*
** This function returns SQLITE_OK if the caller may write to the database.
** Otherwise, if the caller is operating on a snapshot that has already
** been overwritten by another writer, SQLITE_BUSY is returned.
*/
int sqlite3LogWriteLock(Log *pLog, int op){
assert( pLog->isLocked );
if( op ){
/* Obtain the writer lock */
int rc = logLockRegion(pLog, LOG_REGION_C|LOG_REGION_D, LOG_WRLOCK);
if( rc!=SQLITE_OK ){
return rc;
}
/* If this is connection is a region D, then the SHARED lock on region
** D has just been upgraded to EXCLUSIVE. But no lock at all is held on
** region A. This means that if the write-transaction is committed
** and this connection downgrades to a reader, it will be left with no
** lock at all. And its snapshot could get clobbered by a checkpoint
** operation.
**
** To stop this from happening, grab a SHARED lock on region A now.
** This should always be successful, as the only time a client holds
** an EXCLUSIVE lock on region A, it must also be holding an EXCLUSIVE
** lock on region C (a checkpointer does this). This is not possible,
** as this connection currently has the EXCLUSIVE lock on region C.
*/
if( pLog->isLocked==LOG_REGION_D ){
logLockRegion(pLog, LOG_REGION_A, LOG_RDLOCK);
pLog->isLocked = LOG_REGION_A;
}
if( memcmp(&pLog->hdr, pLog->pSummary->aData, sizeof(pLog->hdr)) ){
logLockRegion(pLog, LOG_REGION_C|LOG_REGION_D, LOG_UNLOCK);
return SQLITE_BUSY;
}
pLog->isWriteLocked = 1;
}else if( pLog->isWriteLocked ){
logLockRegion(pLog, LOG_REGION_C|LOG_REGION_D, LOG_UNLOCK);
memcpy(&pLog->hdr, pLog->pSummary->aData, sizeof(pLog->hdr));
|
Changes to test/wal.test.
443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 |
proc busyhandler x {
if {$x==3} { sql3 { BEGIN; SELECT * FROM t1 } }
if {$x==4} { sql2 COMMIT }
if {$x<5} { return 0 }
return 1
}
db busy busyhandler
do_test wal-10.$tn.9 {
execsql { PRAGMA checkpoint }
} {}
do_test wal-10.$tn.10 {
sql3 { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12}
do_test wal-10.$tn.11 {
catchsql { INSERT INTO t1 VALUES(13, 14) }
} {1 {database is locked}}
do_test wal-10.$tn.12 {
execsql { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12}
do_test wal-10.$tn.13 {
sql3 COMMIT
} {}
do_test wal-10.$tn.14 {
execsql { INSERT INTO t1 VALUES(13, 14) }
execsql { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12 13 14}
catch { db close }
catch { code2 { db2 close } }
catch { code3 { db3 close } }
catch { close $::code2_chan }
catch { close $::code3_chan }
}
finish_test
|
| | | | | | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > |
443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 |
proc busyhandler x {
if {$x==3} { sql3 { BEGIN; SELECT * FROM t1 } }
if {$x==4} { sql2 COMMIT }
if {$x<5} { return 0 }
return 1
}
db busy busyhandler
do_test wal-10.$tn.17 {
execsql { PRAGMA checkpoint }
} {}
do_test wal-10.$tn.18 {
sql3 { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12}
do_test wal-10.$tn.19 {
catchsql { INSERT INTO t1 VALUES(13, 14) }
} {1 {database is locked}}
do_test wal-10.$tn.20 {
execsql { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12}
do_test wal-10.$tn.21 {
sql3 COMMIT
} {}
do_test wal-10.$tn.22 {
execsql { INSERT INTO t1 VALUES(13, 14) }
execsql { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12 13 14}
# Set [db3] up as a "region D" reader again. Then upgrade it to a writer
# and back down to a reader. Then, check that a checkpoint is not possible
# (as [db3] still has a snapshot locked).
#
do_test wal-10.$tn.23 {
execsql { PRAGMA checkpoint }
} {}
do_test wal-10.$tn.24 {
sql2 { BEGIN; SELECT * FROM t1; }
} {1 2 3 4 5 6 7 8 9 10 11 12 13 14}
do_test wal-10.$tn.25 {
execsql { PRAGMA checkpoint }
} {}
do_test wal-10.$tn.26 {
catchsql { INSERT INTO t1 VALUES(15, 16) }
} {1 {database is locked}}
do_test wal-10.$tn.27 {
sql3 { INSERT INTO t1 VALUES(15, 16) }
} {}
do_test wal-10.$tn.28 {
code3 {
set ::STMT [sqlite3_prepare db3 "SELECT * FROM t1" -1 TAIL]
sqlite3_step $::STMT
}
sql3 COMMIT
execsql { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16}
db busy {}
do_test wal-10.$tn.29 {
execsql { INSERT INTO t1 VALUES(17, 18) }
catchsql { PRAGMA checkpoint }
} {1 {database is locked}}
do_test wal-10.$tn.30 {
code3 { sqlite3_finalize $::STMT }
execsql { PRAGMA checkpoint }
} {}
# At one point, if a reader failed to upgrade to a writer because it
# was reading an old snapshot, the write-locks were not being released.
# Test that this bug has been fixed.
#
do_test wal-10.$tn.31 {
execsql { BEGIN ; SELECT * FROM t1 }
sql2 { INSERT INTO t1 VALUES(19, 20) }
catchsql { INSERT INTO t1 VALUES(21, 22) }
} {1 {database is locked}}
do_test wal-10.$tn.32 {
# This statement would fail when the bug was present.
sql2 { INSERT INTO t1 VALUES(21, 22) }
} {}
do_test wal-10.$tn.33 {
execsql { SELECT * FROM t1 ; COMMIT }
} {1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18}
do_test wal-10.$tn.34 {
execsql { SELECT * FROM t1 }
} {1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22}
catch { db close }
catch { code2 { db2 close } }
catch { code3 { db3 close } }
catch { close $::code2_chan }
catch { close $::code3_chan }
}
finish_test
|