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-rw-r--r--upgrade.php41
1 files changed, 40 insertions, 1 deletions
diff --git a/upgrade.php b/upgrade.php
index 60764ba93..38be476a4 100644
--- a/upgrade.php
+++ b/upgrade.php
@@ -13,6 +13,35 @@
* @subpackage Upgrade
*/
+function upgrade_lock() {
+ global $CONFIG, $DB_QUERY_CACHE;
+
+ $is_locked = count(get_data("show tables like '{$CONFIG->dbprefix}locked'"));
+
+ // Invalidate query cache
+ if ($DB_QUERY_CACHE) {
+ $DB_QUERY_CACHE->clear();
+ elgg_log("Query cache invalidated", 'NOTICE');
+ }
+
+ if (!$is_locked) {
+ // lock it
+ insert_data("create table {$CONFIG->dbprefix}locked (id INT)");
+ error_log('Upgrade continue running');
+ return true;
+ }
+
+ error_log('Upgrade is locked');
+ return false;
+}
+
+function upgrade_unlock() {
+ global $CONFIG;
+ delete_data("drop table {$CONFIG->dbprefix}locked");
+ error_log('Upgrade unlocks itself');
+}
+
+
// we want to know if an error occurs
ini_set('display_errors', 1);
@@ -20,6 +49,12 @@ define('UPGRADING', 'upgrading');
require_once(dirname(__FILE__) . "/engine/start.php");
if (get_input('upgrade') == 'upgrade') {
+
+ // prevent someone from running the upgrade script in parallel (see #4643)
+ if (!upgrade_lock()) {
+ forward();
+ }
+
// disable the system log for upgrades to avoid exceptions when the schema changes.
elgg_unregister_event_handler('log', 'systemlog', 'system_log_default_logger');
elgg_unregister_event_handler('all', 'all', 'system_log_listener');
@@ -33,6 +68,10 @@ if (get_input('upgrade') == 'upgrade') {
elgg_trigger_event('upgrade', 'system', null);
elgg_invalidate_simplecache();
elgg_reset_system_cache();
+
+ // critical region has past
+ upgrade_unlock();
+
} else {
// if upgrading from < 1.8.0, check for the core view 'welcome' and bail if it's found.
// see http://trac.elgg.org/ticket/3064
@@ -53,4 +92,4 @@ if (get_input('upgrade') == 'upgrade') {
exit;
}
-forward(); \ No newline at end of file
+forward();