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Overview
Comment: | Remove the requirement to open the wal file before sqlite3_snapshot_recover() is called. Also add some comments to new functions. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | serializable-snapshot |
Files: | files | file ages | folders |
SHA1: |
28393c413cc4505b94411730e728583c |
User & Date: | dan 2016-11-19 18:31:37.017 |
Context
2016-11-22
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21:11 | Enclose the sqlite3WalSnapshotRecover() routine within (check-in: e7be3183eb user: drh tags: serializable-snapshot) | |
2016-11-19
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18:31 | Remove the requirement to open the wal file before sqlite3_snapshot_recover() is called. Also add some comments to new functions. (check-in: 28393c413c user: dan tags: serializable-snapshot) | |
17:30 | Test some extra error conditions in sqlite3_recover_snapshot(). (check-in: db314213c0 user: dan tags: serializable-snapshot) | |
Changes
Changes to src/main.c.
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4060 4061 4062 4063 4064 4065 4066 | #endif sqlite3_mutex_enter(db->mutex); iDb = sqlite3FindDbName(db, zDb); if( iDb==0 || iDb>1 ){ Btree *pBt = db->aDb[iDb].pBt; if( 0==sqlite3BtreeIsInReadTrans(pBt) ){ | > > | > > | 4060 4061 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072 4073 4074 4075 4076 4077 4078 | #endif sqlite3_mutex_enter(db->mutex); iDb = sqlite3FindDbName(db, zDb); if( iDb==0 || iDb>1 ){ Btree *pBt = db->aDb[iDb].pBt; if( 0==sqlite3BtreeIsInReadTrans(pBt) ){ rc = sqlite3BtreeBeginTrans(pBt, 0); if( rc==SQLITE_OK ){ rc = sqlite3PagerSnapshotRecover(sqlite3BtreePager(pBt)); sqlite3BtreeCommit(pBt); } } } sqlite3_mutex_leave(db->mutex); #endif /* SQLITE_OMIT_WAL */ return rc; } |
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Changes to src/sqlite.h.in.
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8413 8414 8415 8416 8417 8418 8419 8420 8421 8422 8423 8424 8425 8426 | sqlite3_snapshot *p1, sqlite3_snapshot *p2 ); /* ** CAPI3REF: Recover snapshots from a wal file ** EXPERIMENTAL */ SQLITE_EXPERIMENTAL int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb); /* ** Undo the hack that converts floating point types to integer for ** builds on processors without floating point support. */ | > > > > > > > > > > > > > > > > | 8413 8414 8415 8416 8417 8418 8419 8420 8421 8422 8423 8424 8425 8426 8427 8428 8429 8430 8431 8432 8433 8434 8435 8436 8437 8438 8439 8440 8441 8442 | sqlite3_snapshot *p1, sqlite3_snapshot *p2 ); /* ** CAPI3REF: Recover snapshots from a wal file ** EXPERIMENTAL ** ** If all connections disconnect from a database file but do not perform ** a checkpoint, the existing wal file is opened along with the database ** file the next time the database is opened. At this point it is only ** possible to successfully call sqlite3_snapshot_open() to open the most ** recent snapshot of the database (the one at the head of the wal file), ** even though the wal file may contain other valid snapshots for which ** clients have sqlite3_snapshot handles. ** ** This function attempts to scan the wal file associated with database zDb ** of database handle db and make all valid snapshots available to ** sqlite3_snapshot_open(). It is an error if there is already a read ** transaction open on the database, or if the database is not a wal mode ** database. ** ** SQLITE_OK is returned if successful, or an SQLite error code otherwise. */ SQLITE_EXPERIMENTAL int sqlite3_snapshot_recover(sqlite3 *db, const char *zDb); /* ** Undo the hack that converts floating point types to integer for ** builds on processors without floating point support. */ |
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Changes to src/wal.c.
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2376 2377 2378 2379 2380 2381 2382 | assert( mxReadMark<=pWal->hdr.mxFrame ); pWal->readLock = (i16)mxI; } return rc; } /* | > | > > > > > > > > > > > > > > > < | < | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | < < < < < < < < | 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 | assert( mxReadMark<=pWal->hdr.mxFrame ); pWal->readLock = (i16)mxI; } return rc; } /* ** Attempt to reduce the value of the WalCkptInfo.nBackfillAttempted ** variable so that older snapshots can be accessed. To do this, loop ** through all wal frames from nBackfillAttempted to (nBackfill+1), ** comparing their content to the corresponding page with the database ** file, if any. Set nBackfillAttempted to the frame number of the ** first frame for which the wal file content matches the db file. ** ** This is only really safe if the file-system is such that any page ** writes made by earlier checkpointers were atomic operations, which ** is not always true. It is also possible that nBackfillAttempted ** may be left set to a value larger than expected, if a wal frame ** contains content that duplicate of an earlier version of the same ** page. ** ** SQLITE_OK is returned if successful, or an SQLite error code if an ** error occurs. It is not an error if nBackfillAttempted cannot be ** decreased at all. */ int sqlite3WalSnapshotRecover(Wal *pWal){ int rc; assert( pWal->readLock>=0 ); rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1); if( rc==SQLITE_OK ){ volatile WalCkptInfo *pInfo = walCkptInfo(pWal); int szPage = (int)pWal->szPage; i64 szDb; /* Size of db file in bytes */ rc = sqlite3OsFileSize(pWal->pDbFd, &szDb); if( rc==SQLITE_OK ){ void *pBuf1 = sqlite3_malloc(szPage); void *pBuf2 = sqlite3_malloc(szPage); if( pBuf1==0 || pBuf2==0 ){ rc = SQLITE_NOMEM; }else{ u32 i = pInfo->nBackfillAttempted; for(i=pInfo->nBackfillAttempted; i>pInfo->nBackfill; i--){ volatile ht_slot *dummy; volatile u32 *aPgno; /* Array of page numbers */ u32 iZero; /* Frame corresponding to aPgno[0] */ u32 pgno; /* Page number in db file */ i64 iDbOff; /* Offset of db file entry */ i64 iWalOff; /* Offset of wal file entry */ rc = walHashGet(pWal, walFramePage(i), &dummy, &aPgno, &iZero); if( rc!=SQLITE_OK ) break; pgno = aPgno[i-iZero]; iDbOff = (i64)(pgno-1) * szPage; if( iDbOff+szPage<=szDb ){ iWalOff = walFrameOffset(i, szPage) + WAL_FRAME_HDRSIZE; rc = sqlite3OsRead(pWal->pWalFd, pBuf1, szPage, iWalOff); if( rc==SQLITE_OK ){ rc = sqlite3OsRead(pWal->pDbFd, pBuf2, szPage, iDbOff); } if( rc!=SQLITE_OK || 0==memcmp(pBuf1, pBuf2, szPage) ){ break; } } pInfo->nBackfillAttempted = i-1; } } sqlite3_free(pBuf1); sqlite3_free(pBuf2); } walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1); } return rc; } /* ** Begin a read transaction on the database. |
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Changes to test/snapshot2.test.
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127 128 129 130 131 132 133 | do_test 2.5 { execsql { PRAGMA wal_checkpoint } sqlite3_db_config db NO_CKPT_ON_CLOSE 1 db close sqlite3 db test.db | < | 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | do_test 2.5 { execsql { PRAGMA wal_checkpoint } sqlite3_db_config db NO_CKPT_ON_CLOSE 1 db close sqlite3 db test.db sqlite3_snapshot_recover db main execsql BEGIN list [catch { sqlite3_snapshot_open_blob db main $snap } msg] $msg } {1 SQLITE_BUSY_SNAPSHOT} #------------------------------------------------------------------------- # Check that calling sqlite3_snapshot_recover() does not confuse the |
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