Get `gn gen` to succeed on Windows

third_party/sqlite/src/test/thread005.test

+# 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...
+#
+
+file delete -force 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