Import SQLite 3.7.6.3.

third_party/sqlite/src/test/walcrash2.test

+# 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.
+#
+#***********************************************************************
+#
+
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/wal_common.tcl
+ifcapable !wal {finish_test ; return }
+
+
+#-------------------------------------------------------------------------
+# 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 }
+
+finish_test
+