From cc71a3e68a4da96b881f8e7a64ed201b40267b4a Mon Sep 17 00:00:00 2001
From: David Stoline <drupal@davidstoline.com>
Date: Mon, 11 Feb 2013 14:57:11 -0500
Subject: [PATCH 1/3] refactor menu_rebuild

---
 includes/menu.inc | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/includes/menu.inc b/includes/menu.inc
index 0d377d0d387..dcbe7440766 100644
--- a/includes/menu.inc
+++ b/includes/menu.inc
@@ -581,7 +581,7 @@ function _menu_translate(&$router_item, $map, $to_arg = FALSE) {
   $router_item['href'] = implode('/', $link_map);
   $router_item['options'] = array();
   _menu_check_access($router_item, $map);
-  
+
   // For performance, don't localize an item the user can't access.
   if ($router_item['access']) {
     _menu_item_localize($router_item, $map);
@@ -1695,31 +1695,31 @@ function menu_cache_clear_all() {
 function menu_rebuild() {
   if (!lock_acquire('menu_rebuild')) {
     // Wait for another request that is already doing this work.
-    // We choose to block here since otherwise the router item may not 
+    // We choose to block here since otherwise the router item may not
     // be avaiable in menu_execute_active_handler() resulting in a 404.
-    lock_wait('menu_rebuild');
     return FALSE;
   }
 
   // Encapsulate the rebuild in a transaction.
   db_query('BEGIN');
 
-  $menu = menu_router_build(TRUE);
-  _menu_navigation_links_rebuild($menu);
-  // Clear the menu, page and block caches.
-  menu_cache_clear_all();
-  _menu_clear_page_cache();
-  
   if (defined('MAINTENANCE_MODE')) {
     variable_set('menu_rebuild_needed', TRUE);
   }
   else {
     variable_del('menu_rebuild_needed');
   }
+
+  $menu = menu_router_build(TRUE);
+  _menu_navigation_links_rebuild($menu);
+  // Clear the menu, page and block caches.
+  menu_cache_clear_all();
+  _menu_clear_page_cache();
+
   lock_release('menu_rebuild');
-  
+
   db_query('COMMIT');
-  
+
   return TRUE;
 }
 
@@ -1904,7 +1904,7 @@ function _menu_delete_item($item, $force = FALSE) {
  *   - router_path: The path of the relevant router item.
  *
  * @return
- *   The mlid of the saved menu link, or FALSE if the menu link could not be 
+ *   The mlid of the saved menu link, or FALSE if the menu link could not be
  *   saved.
  */
 function menu_link_save(&$item) {

From 633d0220e0a7b76b4a00c4109f5aa54a77bf8cde Mon Sep 17 00:00:00 2001
From: David Stoline <drupal@davidstoline.com>
Date: Mon, 11 Feb 2013 15:55:16 -0500
Subject: [PATCH 2/3] adding back whitespace

---
 includes/menu.inc | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/includes/menu.inc b/includes/menu.inc
index dcbe7440766..42fcdec2ceb 100644
--- a/includes/menu.inc
+++ b/includes/menu.inc
@@ -581,7 +581,7 @@ function _menu_translate(&$router_item, $map, $to_arg = FALSE) {
   $router_item['href'] = implode('/', $link_map);
   $router_item['options'] = array();
   _menu_check_access($router_item, $map);
-
+  
   // For performance, don't localize an item the user can't access.
   if ($router_item['access']) {
     _menu_item_localize($router_item, $map);
@@ -1695,7 +1695,7 @@ function menu_cache_clear_all() {
 function menu_rebuild() {
   if (!lock_acquire('menu_rebuild')) {
     // Wait for another request that is already doing this work.
-    // We choose to block here since otherwise the router item may not
+    // We choose to block here since otherwise the router item may not 
     // be avaiable in menu_execute_active_handler() resulting in a 404.
     return FALSE;
   }
@@ -1717,9 +1717,9 @@ function menu_rebuild() {
   _menu_clear_page_cache();
 
   lock_release('menu_rebuild');
-
+  
   db_query('COMMIT');
-
+  
   return TRUE;
 }
 
@@ -1904,7 +1904,7 @@ function _menu_delete_item($item, $force = FALSE) {
  *   - router_path: The path of the relevant router item.
  *
  * @return
- *   The mlid of the saved menu link, or FALSE if the menu link could not be
+ *   The mlid of the saved menu link, or FALSE if the menu link could not be 
  *   saved.
  */
 function menu_link_save(&$item) {

From 951b98763ef6b8f80335bc70a0792b9ff788f11e Mon Sep 17 00:00:00 2001
From: David Stoline <drupal@davidstoline.com>
Date: Mon, 11 Feb 2013 16:29:41 -0500
Subject: [PATCH 3/3] Rework documentation for menu_rebuild lock
 implementation.

---
 includes/menu.inc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/includes/menu.inc b/includes/menu.inc
index 42fcdec2ceb..7269e5ed85a 100644
--- a/includes/menu.inc
+++ b/includes/menu.inc
@@ -1694,9 +1694,9 @@ function menu_cache_clear_all() {
  */
 function menu_rebuild() {
   if (!lock_acquire('menu_rebuild')) {
-    // Wait for another request that is already doing this work.
-    // We choose to block here since otherwise the router item may not 
-    // be avaiable in menu_execute_active_handler() resulting in a 404.
+    // In high traffic situations, calling lock_wait() here, as core does, can
+    // cause processes to stack up that could result in an outage. Since the
+    // work below is in a transaction the lock_wait() is unnecessary.
     return FALSE;
   }