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Annotation of embedaddon/sqlite3/test/walcrash2.test, revision 1.1.1.1

1.1       misho       1: # 2010 May 25
                      2: #
                      3: # The author disclaims copyright to this source code.  In place of
                      4: # a legal notice, here is a blessing:
                      5: #
                      6: #    May you do good and not evil.
                      7: #    May you find forgiveness for yourself and forgive others.
                      8: #    May you share freely, never taking more than you give.
                      9: #
                     10: #***********************************************************************
                     11: #
                     12: 
                     13: 
                     14: set testdir [file dirname $argv0]
                     15: source $testdir/tester.tcl
                     16: source $testdir/lock_common.tcl
                     17: source $testdir/wal_common.tcl
                     18: ifcapable !wal {finish_test ; return }
                     19: 
                     20: 
                     21: #-------------------------------------------------------------------------
                     22: # This test case demonstrates a flaw in the wal-index manipulation that
                     23: # existed at one point: If a process crashes mid-transaction, it may have
                     24: # already added some entries to one of the hash-tables in the wal-index.
                     25: # If the transaction were to be explicitly rolled back at this point, the
                     26: # hash-table entries would be removed as part of the rollback. However,
                     27: # if the process crashes, the transaction is implicitly rolled back and
                     28: # the rogue entries remain in the hash table.
                     29: #
                     30: # Normally, this causes no problem - readers can tell the difference 
                     31: # between committed and uncommitted entries in the hash table. However,
                     32: # if it happens often enough that all slots in the hash-table become 
                     33: # non-zero, the next process that attempts to read or write the hash
                     34: # table falls into an infinite loop.
                     35: #
                     36: # Even if run with an SQLite version affected by the bug, this test case
                     37: # only goes into an infinite loop if SQLite is compiled without SQLITE_DEBUG
                     38: # defined. If SQLITE_DEBUG is defined, the program is halted by a failing
                     39: # assert() before entering the infinite loop.
                     40: #
                     41: # walcrash2-1.1: Create a database. Commit a transaction that adds 8 frames
                     42: #                to the WAL (and 8 entry to the first hash-table in the 
                     43: #                wal-index).
                     44: #
                     45: # walcrash2-1.2: Have an external process open a transaction, add 8 entries
                     46: #                to the wal-index hash-table, then crash. Repeat this 1023
                     47: #                times (so that the wal-index contains 8192 entries - all
                     48: #                slots are non-zero).
                     49: #
                     50: # walcrash2-1.3: Using a new database connection, attempt to query the 
                     51: #                database. This should cause the process to go into the
                     52: #                infinite loop.
                     53: #
                     54: do_test walcrash2-1.1 {
                     55:   execsql {
                     56:     PRAGMA page_size = 1024;
                     57:     PRAGMA auto_vacuum = off;
                     58:     PRAGMA journal_mode = WAL;
                     59:     PRAGMA synchronous = NORMAL;
                     60:     BEGIN;
                     61:       CREATE TABLE t1(x);
                     62:       CREATE TABLE t2(x);
                     63:       CREATE TABLE t3(x);
                     64:       CREATE TABLE t4(x);
                     65:       CREATE TABLE t5(x);
                     66:       CREATE TABLE t6(x);
                     67:       CREATE TABLE t7(x);
                     68:     COMMIT;
                     69:   }
                     70:   file size test.db-wal
                     71: } [wal_file_size 8 1024] 
                     72: for {set nEntry 8} {$nEntry < 8192} {incr nEntry 8} {
                     73:   do_test walcrash2-1.2.[expr $nEntry/8] {
                     74:     set C [launch_testfixture]
                     75:     testfixture $C {
                     76:       sqlite3 db test.db
                     77:       db eval {
                     78:         PRAGMA cache_size = 15;
                     79:         BEGIN;
                     80:           INSERT INTO t1 VALUES(randomblob(900));         --  1 row,  1  page
                     81:           INSERT INTO t1 SELECT * FROM t1;                --  2 rows, 3  pages
                     82:           INSERT INTO t1 SELECT * FROM t1;                --  4 rows, 5  pages
                     83:           INSERT INTO t1 SELECT * FROM t1;                --  8 rows, 9  pages
                     84:           INSERT INTO t1 SELECT * FROM t1;                -- 16 rows, 17 pages
                     85:           INSERT INTO t1 SELECT * FROM t1 LIMIT 3;        -- 20 rows, 20 pages
                     86:       }
                     87:     } 
                     88:     close $C
                     89:     file size test.db-wal
                     90:   } [wal_file_size 16 1024]
                     91: }
                     92: do_test walcrash2-1.3 {
                     93:   sqlite3 db2 test.db
                     94:   execsql { SELECT count(*) FROM t1 } db2
                     95: } {0}
                     96: catch { db2 close }
                     97: 
                     98: finish_test
                     99: