mirror of
https://gitlab.com/cznic/sqlite.git
synced 2024-11-24 02:26:14 +00:00
239 lines
7.4 KiB
Plaintext
239 lines
7.4 KiB
Plaintext
# 2009 March 11
|
|
#
|
|
# 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.
|
|
#
|
|
#***********************************************************************
|
|
#
|
|
# Test a race-condition that shows up in shared-cache mode.
|
|
#
|
|
# $Id: thread005.test,v 1.5 2009/03/26 14:48:07 danielk1977 Exp $
|
|
|
|
set testdir [file dirname $argv0]
|
|
|
|
source $testdir/tester.tcl
|
|
if {[run_thread_tests]==0} { finish_test ; return }
|
|
ifcapable !shared_cache {
|
|
finish_test
|
|
return
|
|
}
|
|
|
|
db close
|
|
|
|
# Use shared-cache mode for these tests.
|
|
#
|
|
set ::enable_shared_cache [sqlite3_enable_shared_cache]
|
|
sqlite3_enable_shared_cache 1
|
|
|
|
#-------------------------------------------------------------------------
|
|
# This test attempts to hit the race condition fixed by commit [6363].
|
|
#
|
|
proc runsql {zSql {db {}}} {
|
|
set rc SQLITE_OK
|
|
while {$rc=="SQLITE_OK" && $zSql ne ""} {
|
|
set STMT [sqlite3_prepare_v2 $db $zSql -1 zSql]
|
|
while {[set rc [sqlite3_step $STMT]] eq "SQLITE_ROW"} { }
|
|
set rc [sqlite3_finalize $STMT]
|
|
}
|
|
return $rc
|
|
}
|
|
do_test thread005-1.1 {
|
|
sqlite3 db test.db
|
|
db eval { CREATE TABLE t1(a, b) }
|
|
db close
|
|
} {}
|
|
for {set ii 2} {$ii < 500} {incr ii} {
|
|
unset -nocomplain finished
|
|
thread_spawn finished(0) {sqlite3_open test.db}
|
|
thread_spawn finished(1) {sqlite3_open test.db}
|
|
if {![info exists finished(0)]} { vwait finished(0) }
|
|
if {![info exists finished(1)]} { vwait finished(1) }
|
|
|
|
do_test thread005-1.$ii {
|
|
runsql { BEGIN } $finished(0)
|
|
runsql { INSERT INTO t1 VALUES(1, 2) } $finished(0)
|
|
|
|
# If the race-condition was hit, then $finished(0 and $finished(1)
|
|
# will not use the same pager cache. In this case the next statement
|
|
# can be executed succesfully. However, if the race-condition is not
|
|
# hit, then $finished(1) will be blocked by the write-lock held by
|
|
# $finished(0) on the shared-cache table t1 and the statement will
|
|
# return SQLITE_LOCKED.
|
|
#
|
|
runsql { SELECT * FROM t1 } $finished(1)
|
|
} {SQLITE_LOCKED}
|
|
|
|
sqlite3_close $finished(0)
|
|
sqlite3_close $finished(1)
|
|
}
|
|
|
|
|
|
#-------------------------------------------------------------------------
|
|
# This test tries to exercise a race-condition that existed in shared-cache
|
|
# mode at one point. The test uses two threads; each has a database connection
|
|
# open on the same shared cache. The schema of the database is:
|
|
#
|
|
# CREATE TABLE t1(a INTEGER PRIMARY KEY, b UNIQUE);
|
|
#
|
|
# One thread is a reader and the other thread a reader and a writer. The
|
|
# writer thread repeats the following transaction as fast as possible:
|
|
#
|
|
# BEGIN;
|
|
# DELETE FROM t1 WHERE a = (SELECT max(a) FROM t1);
|
|
# INSERT INTO t1 VALUES(NULL, NULL);
|
|
# UPDATE t1 SET b = a WHERE a = (SELECT max(a) FROM t1);
|
|
# SELECT count(*) FROM t1 WHERE b IS NULL;
|
|
# COMMIT;
|
|
#
|
|
# The reader thread does the following over and over as fast as possible:
|
|
#
|
|
# BEGIN;
|
|
# SELECT count(*) FROM t1 WHERE b IS NULL;
|
|
# COMMIT;
|
|
#
|
|
# The test runs for 20 seconds or until one of the "SELECT count(*)"
|
|
# statements returns a non-zero value. If an SQLITE_LOCKED error occurs,
|
|
# the connection issues a ROLLBACK immediately to abandon the current
|
|
# transaction.
|
|
#
|
|
# If everything is working correctly, the "SELECT count(*)" statements
|
|
# should never return a value other than 0. The "INSERT" statement
|
|
# executed by the writer adds a row with "b IS NULL" to the table, but
|
|
# the subsequent UPDATE statement sets its "b" value to an integer
|
|
# immediately afterwards.
|
|
#
|
|
# However, before the race-condition was fixed, if the reader's SELECT
|
|
# statement hit an error (say an SQLITE_LOCKED) at the same time as the
|
|
# writer was executing the UPDATE statement, then it could incorrectly
|
|
# rollback the statement-transaction belonging to the UPDATE statement.
|
|
# The UPDATE statement would still be reported as successful to the user,
|
|
# but it would have no effect on the database contents.
|
|
#
|
|
# Note that it has so far only proved possible to hit this race-condition
|
|
# when using an ATTACHed database. There doesn't seem to be any reason
|
|
# for this, other than that operating on an ATTACHed database means there
|
|
# are a few more mutex grabs and releases during the window of time open
|
|
# for the race-condition. Maybe this encourages the scheduler to context
|
|
# switch or something...
|
|
#
|
|
|
|
forcedelete test.db test2.db
|
|
unset -nocomplain finished
|
|
|
|
do_test thread005-2.1 {
|
|
sqlite3 db test.db
|
|
execsql { ATTACH 'test2.db' AS aux }
|
|
execsql {
|
|
CREATE TABLE aux.t1(a INTEGER PRIMARY KEY, b UNIQUE);
|
|
INSERT INTO t1 VALUES(1, 1);
|
|
INSERT INTO t1 VALUES(2, 2);
|
|
}
|
|
db close
|
|
} {}
|
|
|
|
|
|
set ThreadProgram {
|
|
proc execsql {zSql {db {}}} {
|
|
if {$db eq ""} {set db $::DB}
|
|
|
|
set lRes [list]
|
|
set rc SQLITE_OK
|
|
|
|
while {$rc=="SQLITE_OK" && $zSql ne ""} {
|
|
set STMT [sqlite3_prepare_v2 $db $zSql -1 zSql]
|
|
while {[set rc [sqlite3_step $STMT]] eq "SQLITE_ROW"} {
|
|
for {set i 0} {$i < [sqlite3_column_count $STMT]} {incr i} {
|
|
lappend lRes [sqlite3_column_text $STMT 0]
|
|
}
|
|
}
|
|
set rc [sqlite3_finalize $STMT]
|
|
}
|
|
|
|
if {$rc != "SQLITE_OK"} { error "$rc [sqlite3_errmsg $db]" }
|
|
return $lRes
|
|
}
|
|
|
|
if {$isWriter} {
|
|
set Sql {
|
|
BEGIN;
|
|
DELETE FROM t1 WHERE a = (SELECT max(a) FROM t1);
|
|
INSERT INTO t1 VALUES(NULL, NULL);
|
|
UPDATE t1 SET b = a WHERE a = (SELECT max(a) FROM t1);
|
|
SELECT count(*) FROM t1 WHERE b IS NULL;
|
|
COMMIT;
|
|
}
|
|
} else {
|
|
set Sql {
|
|
BEGIN;
|
|
SELECT count(*) FROM t1 WHERE b IS NULL;
|
|
COMMIT;
|
|
}
|
|
}
|
|
|
|
set ::DB [sqlite3_open test.db]
|
|
|
|
execsql { ATTACH 'test2.db' AS aux }
|
|
|
|
set result "ok"
|
|
set finish [expr [clock_seconds]+5]
|
|
while {$result eq "ok" && [clock_seconds] < $finish} {
|
|
set rc [catch {execsql $Sql} msg]
|
|
if {$rc} {
|
|
if {[string match "SQLITE_LOCKED*" $msg]} {
|
|
catch { execsql ROLLBACK }
|
|
} else {
|
|
sqlite3_close $::DB
|
|
error $msg
|
|
}
|
|
} elseif {$msg ne "0"} {
|
|
set result "failed"
|
|
}
|
|
}
|
|
|
|
sqlite3_close $::DB
|
|
set result
|
|
}
|
|
|
|
# There is a race-condition in btree.c that means that if two threads
|
|
# attempt to open the same database at roughly the same time, and there
|
|
# does not already exist a shared-cache corresponding to that database,
|
|
# then two shared-caches can be created instead of one. Things still more
|
|
# or less work, but the two database connections do not use the same
|
|
# shared-cache.
|
|
#
|
|
# If the threads run by this test hit this race-condition, the tests
|
|
# fail (because SQLITE_BUSY may be unexpectedly returned instead of
|
|
# SQLITE_LOCKED). To prevent this from happening, open a couple of
|
|
# connections to test.db and test2.db now to make sure that there are
|
|
# already shared-caches in memory for all databases opened by the
|
|
# test threads.
|
|
#
|
|
sqlite3 db test.db
|
|
sqlite3 db test2.db
|
|
|
|
puts "Running thread-tests for ~20 seconds"
|
|
thread_spawn finished(0) {set isWriter 0} $ThreadProgram
|
|
thread_spawn finished(1) {set isWriter 1} $ThreadProgram
|
|
if {![info exists finished(0)]} { vwait finished(0) }
|
|
if {![info exists finished(1)]} { vwait finished(1) }
|
|
|
|
catch { db close }
|
|
catch { db2 close }
|
|
|
|
do_test thread005-2.2 {
|
|
list $finished(0) $finished(1)
|
|
} {ok ok}
|
|
|
|
do_test thread005-2.3 {
|
|
sqlite3 db test.db
|
|
execsql { ATTACH 'test2.db' AS aux }
|
|
execsql { SELECT count(*) FROM t1 WHERE b IS NULL }
|
|
} {0}
|
|
|
|
sqlite3_enable_shared_cache $::enable_shared_cache
|
|
finish_test
|