From 22e8d9be4582b78a500382e14046a653a14e3f43 Mon Sep 17 00:00:00 2001
From: Brett Profitt <brett.profitt@gmail.com>
Date: Sun, 16 Dec 2012 17:26:03 -0500
Subject: Refs #4643. Cleanup for the upgrade lock.

---
 engine/lib/upgrade.php                          | 20 ++++++++++++--------
 languages/en.php                                |  3 ++-
 upgrade.php                                     |  5 +++--
 views/default/widgets/control_panel/content.php | 10 ++--------
 4 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/engine/lib/upgrade.php b/engine/lib/upgrade.php
index 7f55c4cba..f4f4b16f5 100644
--- a/engine/lib/upgrade.php
+++ b/engine/lib/upgrade.php
@@ -313,7 +313,9 @@ function elgg_upgrade_bootstrap_17_to_18() {
 }
 
 /**
- * Locks a mutual execution of upgrade
+ * Creates a table {prefix}upgrade_lock that is used as a mutex for upgrades.
+ *
+ * @see _elgg_upgrade_lock()
  *
  * @return bool
  * @access private
@@ -323,24 +325,26 @@ function _elgg_upgrade_lock() {
 	
 	if (!_elgg_upgrade_is_locked()) {
 		// lock it
-		insert_data("create table {$CONFIG->dbprefix}locked (id INT)");
-		error_log('Upgrade continue running');
+		insert_data("create table {$CONFIG->dbprefix}upgrade_lock (id INT)");
+		elgg_log('Locked for upgrade.', 'NOTICE');
 		return true;
 	}
 	
-	error_log('Upgrade is locked');
+	elgg_log('Cannot lock for upgrade: already locked.', 'WARNING');
 	return false;
 }
 
 /**
- * Unlocks upgrade for new upgrade executions
+ * Unlocks upgrade.
+ *
+ * @see _elgg_upgrade_lock()
  *
  * @access private
  */
 function _elgg_upgrade_unlock() {
 	global $CONFIG;
-	delete_data("drop table {$CONFIG->dbprefix}locked");
-	error_log('Upgrade unlocks itself');
+	delete_data("drop table {$CONFIG->dbprefix}upgrade_lock");
+	elgg_log('Upgrade unlocked.', 'NOTICE');
 }
 
 /**
@@ -352,7 +356,7 @@ function _elgg_upgrade_unlock() {
 function _elgg_upgrade_is_locked() {
 	global $CONFIG, $DB_QUERY_CACHE;
 	
-	$is_locked = count(get_data("show tables like '{$CONFIG->dbprefix}locked'"));
+	$is_locked = count(get_data("show tables like '{$CONFIG->dbprefix}upgrade_lock'"));
 	
 	// Invalidate query cache
 	if ($DB_QUERY_CACHE) {
diff --git a/languages/en.php b/languages/en.php
index 159867e2f..f1a1d650b 100644
--- a/languages/en.php
+++ b/languages/en.php
@@ -1048,7 +1048,8 @@ Once you have logged in, we highly recommend that you change your password.
 	'upgrade:db' => 'Your database was upgraded.',
 	'upgrade:core' => 'Your Elgg installation was upgraded.',
 	'upgrade:unlock' => 'Unlock upgrade',
-	'upgrade:unlock:confirm' => "Somebody is performing an upgrade. You should cancel and wait until upgrade is done. Are you sure you want to continue?",
+	'upgrade:unlock:confirm' => "The database is locked for another upgrade. Running concurrent upgrades is dangerous. You should only continue if you know there is not another upgrade running. Unlock?",
+	'upgrade:locked' => "Cannot upgrade. Another upgrade is running. To clear the upgrade lock, visit the Admin section.",
 	'upgrade:unlock:success' => "Upgrade unlocked suscessfully.",
 	'upgrade:unable_to_upgrade' => 'Unable to upgrade.',
 	'upgrade:unable_to_upgrade_info' =>
diff --git a/upgrade.php b/upgrade.php
index a58fcdc96..c5f158c61 100644
--- a/upgrade.php
+++ b/upgrade.php
@@ -9,6 +9,8 @@
  * new version of the script. Deleting the script is not a requirement and
  * leaving it behind does not affect the security of the site.
  *
+ * Upgrades use a table {db_prefix}upgrade_lock as a mutex to prevent concurrent upgrades.
+ *
  * @package Elgg.Core
  * @subpackage Upgrade
  */
@@ -20,9 +22,9 @@ 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 (!_elgg_upgrade_lock()) {
+		register_error(elgg_echo('upgrade:locked'));
 		forward();
 	}
 	
@@ -40,7 +42,6 @@ if (get_input('upgrade') == 'upgrade') {
 	elgg_invalidate_simplecache();
 	elgg_reset_system_cache();
 	
-	// critical region has past
 	_elgg_upgrade_unlock();
 	
 } else {
diff --git a/views/default/widgets/control_panel/content.php b/views/default/widgets/control_panel/content.php
index e6763d851..a348d612f 100644
--- a/views/default/widgets/control_panel/content.php
+++ b/views/default/widgets/control_panel/content.php
@@ -12,13 +12,7 @@ elgg_register_menu_item('admin_control_panel', array(
 ));
 
 // @todo Move in this in ElggUpgradeManager::isLocked() when #4682 fixed
-global $CONFIG, $DB_QUERY_CACHE;
-$is_locked = count(get_data("show tables like '{$CONFIG->dbprefix}locked'"));
-// Invalidate query cache
-if ($DB_QUERY_CACHE) {
-	$DB_QUERY_CACHE->clear();
-	elgg_log("Query cache invalidated", 'NOTICE');
-}
+$is_locked = _elgg_upgrade_is_locked();
 
 if (!$is_locked) {
 	elgg_register_menu_item('admin_control_panel', array(
@@ -33,7 +27,7 @@ if (!$is_locked) {
 		'text' => elgg_echo('upgrade:unlock'),
 		'href' => 'action/admin/site/unlock_upgrade',
 		'is_action' => true,
-		'link_class' => 'elgg-button elgg-button-delete',
+		'link_class' => 'elgg-button elgg-button-action',
 		'confirm' => elgg_echo('upgrade:unlock:confirm'),
 	));
 }
-- 
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