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Overview
| Comment: | Handle the race condition that may occur if another process connects and then checkpoints and truncates the wal file while a readonly-shm client is building its heap-memory wal-index. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | readonly-wal-recovery |
| Files: | files | file ages | folders |
| SHA3-256: |
5a6703fc3f2174b3e9a624c7272ae013 |
| User & Date: | dan 2017-11-07 21:15:07 |
Context
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2017-11-07
| ||
| 21:25 | Update an assert in wal.c. (check-in: 94527b89 user: dan tags: readonly-wal-recovery) | |
| 21:15 | Handle the race condition that may occur if another process connects and then checkpoints and truncates the wal file while a readonly-shm client is building its heap-memory wal-index. (check-in: 5a6703fc user: dan tags: readonly-wal-recovery) | |
| 15:43 | On unix, if the *-shm file cannot be opened for read/write access, open it read-only and proceed as if the readonly_shm=1 URI option were specified. (check-in: ba718754 user: dan tags: readonly-wal-recovery) | |
Changes
Changes to src/wal.c.
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testcase( pWal->szPage>=65536 );
}
/* The header was successfully read. Return zero. */
return 0;
}
/*
** Read the wal-index header from the wal-index and into pWal->hdr.
** If the wal-header appears to be corrupt, try to reconstruct the
** wal-index from the WAL before returning.
**
** Set *pChanged to 1 if the wal-index header value in pWal->hdr is
** changed by this operation. If pWal->hdr is unchanged, set *pChanged
................................................................................
*/
if( badHdr==0 && pWal->hdr.iVersion!=WALINDEX_MAX_VERSION ){
rc = SQLITE_CANTOPEN_BKPT;
}
if( pWal->bUnlocked ){
if( rc!=SQLITE_OK ){
walIndexClose(pWal, 0);
}
pWal->exclusiveMode = WAL_NORMAL_MODE;
}
return rc;
}
/*
** This is the value that walTryBeginRead returns when it needs to
** be retried.
*/
#define WAL_RETRY (-1)
/*
** Open an "unlocked" transaction. An unlocked transaction is a read
** transaction used by a read-only client in cases where the *-shm
** file cannot be mapped and its contents cannot be trusted. It is
** assumed that the *-wal file has been read and that a wal-index
** constructed in heap memory is currently available in Wal.apWiData[].
**
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testcase( pWal->szPage>=65536 );
}
/* The header was successfully read. Return zero. */
return 0;
}
/*
** This is the value that walTryBeginRead returns when it needs to
** be retried.
*/
#define WAL_RETRY (-1)
/*
** Read the wal-index header from the wal-index and into pWal->hdr.
** If the wal-header appears to be corrupt, try to reconstruct the
** wal-index from the WAL before returning.
**
** Set *pChanged to 1 if the wal-index header value in pWal->hdr is
** changed by this operation. If pWal->hdr is unchanged, set *pChanged
................................................................................
*/
if( badHdr==0 && pWal->hdr.iVersion!=WALINDEX_MAX_VERSION ){
rc = SQLITE_CANTOPEN_BKPT;
}
if( pWal->bUnlocked ){
if( rc!=SQLITE_OK ){
walIndexClose(pWal, 0);
pWal->bUnlocked = 0;
assert( pWal->nWiData>0 && pWal->apWiData[0]==0 );
if( rc==SQLITE_IOERR_SHORT_READ ) rc = WAL_RETRY;
}
pWal->exclusiveMode = WAL_NORMAL_MODE;
}
return rc;
}
/*
** Open an "unlocked" transaction. An unlocked transaction is a read
** transaction used by a read-only client in cases where the *-shm
** file cannot be mapped and its contents cannot be trusted. It is
** assumed that the *-wal file has been read and that a wal-index
** constructed in heap memory is currently available in Wal.apWiData[].
**
|
Changes to test/walro2.test.
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} {hello world ! world hello}
do_test 5.3 {
code1 { db close }
code1 { tvfs delete }
} {}
}
finish_test
|
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} {hello world ! world hello}
do_test 5.3 {
code1 { db close }
code1 { tvfs delete }
} {}
#-----------------------------------------------------------------------
#
#
catch { code1 { db close } }
catch { code2 { db2 close } }
catch { code3 { db3 close } }
do_test 6.1 {
code1 { forcedelete test.db }
code1 { sqlite3 db test.db }
sql1 {
PRAGMA journal_mode = wal;
CREATE TABLE t1(x);
INSERT INTO t1 VALUES('hello');
INSERT INTO t1 VALUES('world');
INSERT INTO t1 VALUES('!');
INSERT INTO t1 VALUES('world');
INSERT INTO t1 VALUES('hello');
}
forcecopy test.db test.db2
forcecopy test.db-wal test.db2-wal
forcecopy test.db-shm test.db2-shm
code1 { db close }
} {}
do_test 6.2 {
code1 {
set ::nRem 5
proc handle_read {op args} {
if {$op=="xRead" && [file tail [lindex $args 0]]=="test.db2-wal"} {
incr ::nRem -1
if {$::nRem==0} {
code2 { sqlite3 db2 test.db2 }
sql2 { PRAGMA wal_checkpoint = truncate }
}
}
return "SQLITE_OK"
}
testvfs tvfs -fullshm 1
tvfs filter xRead
tvfs script handle_read
sqlite3 db file:test.db2?readonly_shm=1&vfs=tvfs
db eval { SELECT * FROM t1 }
}
} {hello world ! world hello}
do_test 6.3 {
code1 { db close }
code1 { tvfs delete }
} {}
}
finish_test
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