Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.1214
diff -u -p -r1.1214 common.inc
--- includes/common.inc	5 Sep 2010 15:38:16 -0000	1.1214
+++ includes/common.inc	10 Sep 2010 03:39:24 -0000
@@ -3221,42 +3221,64 @@ function drupal_build_css_cache($css) {
     $uri = $map[$key];
   }
 
-  if (empty($uri) || !file_exists($uri)) {
-    // Build aggregate CSS file.
-    foreach ($css as $stylesheet) {
-      // Only 'file' stylesheets can be aggregated.
-      if ($stylesheet['type'] == 'file') {
-        $contents = drupal_load_stylesheet($stylesheet['data'], TRUE);
-        // Return the path to where this CSS file originated from.
-        $base = base_path() . dirname($stylesheet['data']) . '/';
-        _drupal_build_css_path(NULL, $base);
-        // Prefix all paths within this CSS file, ignoring external and absolute paths.
-        $data .= preg_replace_callback('/url\(\s*[\'"]?(?![a-z]+:|\/+)([^\'")]+)[\'"]?\s*\)/i', '_drupal_build_css_path', $contents);
-      }
-    }
+  $lock_acquire_attempts = 0;
+  $mtime = $uri ? filemtime($uri) : 0;
+  do {
+    if (empty($uri) || !$mtime || (isset($map['clear']) && $mtime < $map['clear'])) {
+      if ($lock_acquired = lock_acquire('css_cache')) {
+        // Build aggregate CSS file.
+        foreach ($css as $stylesheet) {
+          // Only 'file' stylesheets can be aggregated.
+          if ($stylesheet['type'] == 'file') {
+            $contents = drupal_load_stylesheet($stylesheet['data'], TRUE);
+            // Return the path to where this CSS file originated from.
+            $base = base_path() . dirname($stylesheet['data']) . '/';
+            _drupal_build_css_path(NULL, $base);
+            // Prefix all paths within this CSS file, ignoring external and absolute paths.
+            $data .= preg_replace_callback('/url\([\'"]?(?![a-z]+:|\/+)([^\'")]+)[\'"]?\)/i', '_drupal_build_css_path', $contents);
+          }
+        }
 
-    // Per the W3C specification at http://www.w3.org/TR/REC-CSS2/cascade.html#at-import,
-    // @import rules must proceed any other style, so we move those to the top.
-    $regexp = '/@import[^;]+;/i';
-    preg_match_all($regexp, $data, $matches);
-    $data = preg_replace($regexp, '', $data);
-    $data = implode('', $matches[0]) . $data;
-
-    // Prefix filename to prevent blocking by firewalls which reject files
-    // starting with "ad*".
-    $filename = 'css_' . drupal_hash_base64($data) . '.css';
-    // Create the css/ within the files folder.
-    $csspath = 'public://css';
-    $uri = $csspath . '/' . $filename;
-    // Create the CSS file.
-    file_prepare_directory($csspath, FILE_CREATE_DIRECTORY);
-    if (!file_exists($uri) && !file_unmanaged_save_data($data, $uri, FILE_EXISTS_REPLACE)) {
-      return FALSE;
+        // Per the W3C specification at http://www.w3.org/TR/REC-CSS2/cascade.html#at-import,
+        // @import rules must proceed any other style, so we move those to the top.
+        $regexp = '/@import[^;]+;/i';
+        preg_match_all($regexp, $data, $matches);
+        $data = preg_replace($regexp, '', $data);
+        $data = implode('', $matches[0]) . $data;
+
+        // Prefix filename to prevent blocking by firewalls which reject files
+        // starting with "ad*".
+        $filename = 'css_' . drupal_hash_base64($data) . '.css';
+        // Create the css/ within the files folder.
+        $csspath = 'public://css';
+        $uri = $csspath . '/' . $filename;
+        // Create the CSS file.
+        file_prepare_directory($csspath, FILE_CREATE_DIRECTORY);
+        if (!file_unmanaged_save_data($data, $uri, FILE_EXISTS_REPLACE)) {
+          lock_release('css_cache');
+          return FALSE;
+        }
+        // If this took more than one attempt, get the map again, because it has likely changed.
+        if ($lock_acquire_attempts) {
+          $vars = variable_initialize(array());
+          $map = $vars['drupal_css_cache_files'];
+        }
+        // Save the updated map.
+        $map = variable_get('drupal_css_cache_files', array());
+        $map[$key] = $uri;
+        variable_set('drupal_css_cache_files', $map);
+        lock_release('css_cache');
+      }
+      else {
+        if ($mtime) {
+          break;
+        }
+        lock_wait('css_cache');
+      }
+      $mtime = $uri ? filemtime($uri) : 0;
     }
-    // Save the updated map.
-    $map[$key] = $uri;
-    variable_set('drupal_css_cache_files', $map);
   }
+  while (!$mtime && $lock_acquired === FALSE && ++$lock_acquire_attempts < 5);
   return $uri;
 }
 
@@ -3394,8 +3416,7 @@ function _drupal_load_stylesheet($matche
  * Deletes old cached CSS files.
  */
 function drupal_clear_css_cache() {
-  variable_del('drupal_css_cache_files');
-  file_scan_directory('public://css', '/.*/', array('callback' => 'drupal_delete_file_if_stale'));
+  drupal_clear_js_css_cache('css');
 }
 
 /**
@@ -4432,28 +4453,50 @@ function drupal_build_js_cache($files) {
     $uri = $map[$key];
   }
 
-  if (empty($uri) || !file_exists($uri)) {
-    // Build aggregate JS file.
-    foreach ($files as $path => $info) {
-      if ($info['preprocess']) {
-        // Append a ';' and a newline after each JS file to prevent them from running together.
-        $contents .= file_get_contents($path) . ";\n";
-      }
-    }
-    // Prefix filename to prevent blocking by firewalls which reject files
-    // starting with "ad*".
-    $filename = 'js_' . drupal_hash_base64($contents) . '.js';
-    // Create the js/ within the files folder.
-    $jspath = 'public://js';
-    $uri = $jspath . '/' . $filename;
-    // Create the JS file.
-    file_prepare_directory($jspath, FILE_CREATE_DIRECTORY);
-    if (!file_unmanaged_save_data($contents, $uri, FILE_EXISTS_REPLACE)) {
-      return FALSE;
+  $lock_acquire_attempts = 0;
+  $mtime = $uri ? filemtime($uri) : 0;
+  do {
+    if (empty($uri) || !$mtime || (isset($map['clear']) && $mtime < $map['clear'])) {
+      if ($lock_acquired = lock_acquire('js_cache')) {
+        // Build aggregate JS file.
+        foreach ($files as $path => $info) {
+          if ($info['preprocess']) {
+            // Append a ';' and a newline after each JS file to prevent them from running together.
+            $contents .= file_get_contents($path) . ";\n";
+          }
+        }
+        // Prefix filename to prevent blocking by firewalls which reject files
+        // starting with "ad*".
+        $filename = 'js_' . drupal_hash_base64($contents) . '.js';
+        // Create the js/ within the files folder.
+        $jspath = 'public://js';
+        $uri = $jspath . '/' . $filename;
+        // Create the JS file.
+        file_prepare_directory($jspath, FILE_CREATE_DIRECTORY);
+        if (!file_unmanaged_save_data($contents, $uri, FILE_EXISTS_REPLACE)) {
+          lock_release('js_cache');
+          return FALSE;
+        }
+        // If this took more than one attempt, get the map again, because it has likely changed.
+        if ($lock_acquire_attempts) {
+          $vars = variable_initialize(array());
+          $map = $vars['drupal_js_cache_files'];
+        }
+        // Save the updated map.
+        $map[$key] = $uri;
+        variable_set('drupal_js_cache_files', $map);
+        lock_release('js_cache');
+      }
+      else {
+        if ($mtime) {
+          break;
+        }
+        lock_wait('js_cache');
+      }
+      $mtime = $uri ? filemtime($uri) : 0;
     }
-    $map[$key] = $uri;
-    variable_set('drupal_js_cache_files', $map);
   }
+  while (!$mtime && $lock_acquired === FALSE && ++$lock_acquire_attempts < 5);
   return $uri;
 }
 
@@ -4462,8 +4505,22 @@ function drupal_build_js_cache($files) {
  */
 function drupal_clear_js_cache() {
   variable_del('javascript_parsed');
-  variable_del('drupal_js_cache_files');
-  file_scan_directory('public://js', '/.*/', array('callback' => 'drupal_delete_file_if_stale'));
+  drupal_clear_js_css_cache('js');
+}
+
+/**
+ * Deletes old cached JavaScript or CSS files and variables.
+ */
+function drupal_clear_js_css_cache($type) {
+  // Set the cache clear timestamp.
+  $var = 'drupal_' . $type . '_cache_files';
+  if ($map = variable_get($var, array())) {
+    $map['clear'] = REQUEST_TIME;
+    variable_set($var, $map);
+  }
+
+  // Delete old stale files.
+  file_scan_directory('public://' . $type, '/.*/', array('callback' => 'drupal_delete_file_if_stale'));
 }
 
 /**
@@ -6154,7 +6211,7 @@ function drupal_write_record($table, &$r
     }
 
     if (!property_exists($object, $field)) {
-      // Skip fields that are not provided, default values are already known 
+      // Skip fields that are not provided, default values are already known
       // by the database.
       continue;
     }
Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.959
diff -u -p -r1.959 system.module
--- modules/system/system.module	5 Sep 2010 02:21:38 -0000	1.959
+++ modules/system/system.module	10 Sep 2010 03:39:25 -0000
@@ -2905,6 +2905,8 @@ function system_cron() {
   foreach ($cache_tables as $table) {
     cache_clear_all(NULL, $table);
   }
+  system_cleanup_cache_map('css');
+  system_cleanup_cache_map('js');
 
   // Cleanup the batch table and the queue for failed batches.
   db_delete('batch')
@@ -2936,6 +2938,34 @@ function system_flush_caches() {
 }
 
 /**
+ * Helper function to remove stale css and js from the cache maps.
+ *
+ * @param $type
+ *   'css' or 'js'
+ */
+function system_cleanup_cache_map($type) {
+  $var = 'drupal_' . $type . '_cache_files';
+  $map = variable_get($var, array());
+  if (!empty($map['clear'])) {
+    $clear = $map['clear'];
+    foreach ($map as $key => $uri) {
+      if ($key == 'clear') {
+        continue;
+      }
+      $mtime = filemtime($uri);
+      if ($mtime && $mtime < $clear && $mtime < REQUEST_TIME - variable_get('drupal_stale_map_threshold', 3600)) {
+        unset($map[$key]);
+        $changed = TRUE;
+      }
+    }
+    if (!isset($changed)) {
+      unset($map['clear']);
+    }
+    variable_set($var, $map);
+  }
+}
+
+/**
  * Implements hook_action_info().
  */
 function system_action_info() {