Drupal 7.59 reroll of Path Cache modifications

D7-pathcache-pathinc_reroll.patch

diff --git a/includes/path.inc b/includes/path.inc
index 6bd48d3..d3b8d9f 100644
--- a/includes/path.inc
+++ b/includes/path.inc
@@ -77,8 +77,7 @@ function drupal_lookup_path($action, $path = '', $path_language = NULL) {
   $path_language = $path_language ? $path_language : $language_url->language;
 
   if ($action == 'wipe') {
-    $cache = array();
-    $cache['whitelist'] = drupal_path_alias_whitelist_rebuild();
+    $cache = NULL;
   }
   elseif ($cache['whitelist'] && $path != '') {
     if ($action == 'alias') {
@@ -90,8 +89,47 @@ function drupal_lookup_path($action, $path = '', $path_language = NULL) {
         $cache['map'][$path_language] = array();
         // Load system paths from cache.
         $cid = current_path();
-        if ($cached = cache_get($cid, 'cache_path')) {
-          $cache['system_paths'] = $cached->data;
+
+        // Small hack to allow pre-filling of system paths cache via
+        // drupal_static(), you can set $cache['system_paths'] and
+        // $cache['first_call'] then get multiple lookups for any
+        // arbitrary set of system paths..
+        $cached = FALSE;
+        if (!empty($cache['system_paths']) || ($cached = cache_get($cid, 'cache_path'))) {
+          if ($cached) {
+            $cache['system_paths'] = $cached->data;
+          }
+          // End hack.
+
+          // Now fetch the aliases corresponding to these system paths.
+          // We order by ASC and overwrite array keys to ensure the correct
+          // alias is used when there are multiple aliases per path.
+
+          // First try to fetch the path aliaes from cache. By using
+          // cache_get_multiple() we allow caching backends which support it to
+          // fetch all cached paths in a single request. $cid needs to be built
+          // from both path language and path.
+          foreach ($cache['system_paths'] as $system_path) {
+            $system_cids[] = $path_language . ':' .  $system_path;
+            $system_paths[$system_path] = $system_path;
+          }
+          if ($cached_paths = cache_get_multiple($system_cids, 'cache_path_alias')) {
+            foreach ($cached_paths as $cached) {
+              $system_path = str_replace($path_language . ':', '', $cached->cid);
+              // Remove this path from the aliases to query against the
+              // database.
+              unset($system_paths[$system_path]);
+              if ($cached->data) {
+                $cache['map'][$path_language][$system_path] = $cached->data;
+              }
+              else {
+                $cache['no_aliases'][$path_language][$system_path] = $system_path;
+              }
+            }
+          }
+        }
+        // Fetch remaining paths from the database.
+        if (!empty($system_paths)) {
           // Now fetch the aliases corresponding to these system paths.
           $args = array(
             ':system' => $cache['system_paths'],
@@ -116,9 +154,20 @@ function drupal_lookup_path($action, $path = '', $path_language = NULL) {
           else {
             $result = db_query('SELECT source, alias FROM {url_alias} WHERE source IN (:system) AND language IN (:language, :language_none) ORDER BY language DESC, pid ASC', $args);
           }
-          $cache['map'][$path_language] = $result->fetchAllKeyed();
+          $new_paths = $result->fetchAllKeyed();
+          $cache['map'][$path_language] += $new_paths;
           // Keep a record of paths with no alias to avoid querying twice.
-          $cache['no_aliases'][$path_language] = array_flip(array_diff_key($cache['system_paths'], array_keys($cache['map'][$path_language])));
+          $new_misses = array_diff_key($cache['system_paths'], array_keys($cache['map'][$path_language]));
+          foreach ($new_misses as $new_miss) {
+            $path_cid = $path_language . ':' . $new_miss;
+            cache_set($path_cid, '', 'cache_path_alias');
+            $cache['no_aliases'][$path_language][$new_miss] = $new_miss;
+          }
+          // Cache the individual paths.
+          foreach ($new_paths as $new_path => $new_alias) {
+            $path_cid = $path_language . ':' . $new_path;
+            cache_set($path_cid, $new_alias, 'cache_path_alias');
+          }
         }
       }
       // If the alias has already been loaded, return it.
@@ -133,6 +182,12 @@ function drupal_lookup_path($action, $path = '', $path_language = NULL) {
       }
       // For system paths which were not cached, query aliases individually.
       elseif (!isset($cache['no_aliases'][$path_language][$path])) {
+        $path_cid = $path_language . ':' . $path;
+        $cached = cache_get($path_cid, 'cache_path_alias');
+        if ($cached) {
+          $cache['map'][$path_language][$path] = $alias = $cached->data;
+          return $alias;
+        }
         $args = array(
           ':source' => $path,
           ':language' => $path_language,
@@ -150,6 +205,15 @@ function drupal_lookup_path($action, $path = '', $path_language = NULL) {
           $alias = db_query("SELECT alias FROM {url_alias} WHERE source = :source AND language IN (:language, :language_none) ORDER BY language ASC, pid DESC", $args)->fetchField();
         }
         $cache['map'][$path_language][$path] = $alias;
+        if ($alias) {
+          cache_set($path_cid, $alias, 'cache_path_alias');
+        }
+        else {
+          // When there is no alias, cache this fact as well, but only when
+          // the user is anonymous to avoid bloating the cache with paths
+          // like node/n/edit.
+          cache_set($path_cid, '', 'cache_path_alias');
+        }
         return $alias;
       }
     }
@@ -159,6 +223,17 @@ function drupal_lookup_path($action, $path = '', $path_language = NULL) {
       // Look for the value $path within the cached $map
       $source = FALSE;
       if (!isset($cache['map'][$path_language]) || !($source = array_search($path, $cache['map'][$path_language]))) {
+        $path_cid = $path_language . ':' . $path;
+
+        if ($cached = cache_get($path_cid, 'cache_path_source')) {
+          if (!empty($cached->data)) {
+            $cache['map'][$path_language][$source] = $source =  $cached->data;
+          }
+          else {
+            $cache['no_source'][$path_language][$path] = TRUE;
+          }
+          return $source;
+        }
         $args = array(
           ':alias' => $path,
           ':language' => $path_language,
@@ -177,12 +252,22 @@ function drupal_lookup_path($action, $path = '', $path_language = NULL) {
         }
         if ($source = $result->fetchField()) {
           $cache['map'][$path_language][$source] = $path;
+          cache_set($path_cid, $source, 'cache_path_source');
         }
         else {
           // We can't record anything into $map because we do not have a valid
           // index and there is no need because we have not learned anything
           // about any Drupal path. Thus cache to $no_source.
           $cache['no_source'][$path_language][$path] = TRUE;
+          // Add a cache entry with an empty string - this saves hitting the
+          // db for zero results. We can afford to do this because the
+          // whitelist will prevent attempts to cache paths like comment/$cid.
+          // And because memcache operates an LRU cache. However, only do this
+          // for anonymous users to avoid bloating the cache with paths like
+          // node/n/edit.
+          if (empty($GLOBALS['user']->uid)) {
+            cache_set($path_cid, '', 'cache_path_source');
+          }
         }
       }
       return $source;
@@ -432,27 +517,21 @@ function path_load($conditions) {
  *   - language: (optional) The language of the alias.
  */
 function path_save(&$path) {
-  $path += array('language' => LANGUAGE_NONE);
+  $path += array('pid' => NULL, 'language' => LANGUAGE_NONE);
 
-  // Load the stored alias, if any.
-  if (!empty($path['pid']) && !isset($path['original'])) {
-    $path['original'] = path_load($path['pid']);
-  }
+  // Insert or update the alias.
+  $status = drupal_write_record('url_alias', $path, (!empty($path['pid']) ? 'pid' : array()));
 
-  if (empty($path['pid'])) {
-    drupal_write_record('url_alias', $path);
-    module_invoke_all('path_insert', $path);
-  }
-  else {
-    drupal_write_record('url_alias', $path, array('pid'));
-    module_invoke_all('path_update', $path);
+  // Verify that a record was written.
+  if ($status) {
+    if ($status === SAVED_NEW) {
+      module_invoke_all('path_insert', $path);
+    }
+    else {
+      module_invoke_all('path_update', $path);
+    }
+    drupal_clear_path_cache($path['source']);
   }
-
-  // Clear internal properties.
-  unset($path['original']);
-
-  // Clear the static alias cache.
-  drupal_clear_path_cache($path['source']);
 }
 
 /**