/trunk/test/walcrash2.test |
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# 2010 May 25 |
# |
# 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. |
# |
#*********************************************************************** |
# |
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set testdir [file dirname $argv0] |
source $testdir/tester.tcl |
source $testdir/lock_common.tcl |
source $testdir/wal_common.tcl |
ifcapable !wal {finish_test ; return } |
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#------------------------------------------------------------------------- |
# This test case demonstrates a flaw in the wal-index manipulation that |
# existed at one point: If a process crashes mid-transaction, it may have |
# already added some entries to one of the hash-tables in the wal-index. |
# If the transaction were to be explicitly rolled back at this point, the |
# hash-table entries would be removed as part of the rollback. However, |
# if the process crashes, the transaction is implicitly rolled back and |
# the rogue entries remain in the hash table. |
# |
# Normally, this causes no problem - readers can tell the difference |
# between committed and uncommitted entries in the hash table. However, |
# if it happens often enough that all slots in the hash-table become |
# non-zero, the next process that attempts to read or write the hash |
# table falls into an infinite loop. |
# |
# Even if run with an SQLite version affected by the bug, this test case |
# only goes into an infinite loop if SQLite is compiled without SQLITE_DEBUG |
# defined. If SQLITE_DEBUG is defined, the program is halted by a failing |
# assert() before entering the infinite loop. |
# |
# walcrash2-1.1: Create a database. Commit a transaction that adds 8 frames |
# to the WAL (and 8 entry to the first hash-table in the |
# wal-index). |
# |
# walcrash2-1.2: Have an external process open a transaction, add 8 entries |
# to the wal-index hash-table, then crash. Repeat this 1023 |
# times (so that the wal-index contains 8192 entries - all |
# slots are non-zero). |
# |
# walcrash2-1.3: Using a new database connection, attempt to query the |
# database. This should cause the process to go into the |
# infinite loop. |
# |
do_test walcrash2-1.1 { |
execsql { |
PRAGMA page_size = 1024; |
PRAGMA auto_vacuum = off; |
PRAGMA journal_mode = WAL; |
PRAGMA synchronous = NORMAL; |
BEGIN; |
CREATE TABLE t1(x); |
CREATE TABLE t2(x); |
CREATE TABLE t3(x); |
CREATE TABLE t4(x); |
CREATE TABLE t5(x); |
CREATE TABLE t6(x); |
CREATE TABLE t7(x); |
COMMIT; |
} |
file size test.db-wal |
} [wal_file_size 8 1024] |
for {set nEntry 8} {$nEntry < 8192} {incr nEntry 8} { |
do_test walcrash2-1.2.[expr $nEntry/8] { |
set C [launch_testfixture] |
testfixture $C { |
sqlite3 db test.db |
db eval { |
PRAGMA cache_size = 15; |
BEGIN; |
INSERT INTO t1 VALUES(randomblob(900)); -- 1 row, 1 page |
INSERT INTO t1 SELECT * FROM t1; -- 2 rows, 3 pages |
INSERT INTO t1 SELECT * FROM t1; -- 4 rows, 5 pages |
INSERT INTO t1 SELECT * FROM t1; -- 8 rows, 9 pages |
INSERT INTO t1 SELECT * FROM t1; -- 16 rows, 17 pages |
INSERT INTO t1 SELECT * FROM t1 LIMIT 3; -- 20 rows, 20 pages |
} |
} |
close $C |
file size test.db-wal |
} [wal_file_size 16 1024] |
} |
do_test walcrash2-1.3 { |
sqlite3 db2 test.db |
execsql { SELECT count(*) FROM t1 } db2 |
} {0} |
catch { db2 close } |
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finish_test |
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