From 9f33a091958d60f47ffd3ee3d9ca1691f547da19 Mon Sep 17 00:00:00 2001
From: Gordon Heydon <gordon@heydon.com.au>
Date: Fri, 7 Aug 2009 23:20:14 +1000
Subject: [PATCH] Restrict caching of Nodes to reduce memory #375494

- Increase limit to 30 to be inline with max number of nodes on a standard node page
- Remove use of array_chunk() and array_slice()
- Write tests to check the node cashe is acting as expected.
- Fix up issue with single node_load() not moving the node to the head of the cache
- Remove the defined variable NODE_LOAD_MAX_CACHE to a variable_get()
---
 modules/node/node.module |   21 +++++++++++---
 modules/node/node.test   |   66 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+), 5 deletions(-)

diff --git modules/node/node.module modules/node/node.module
index c1f6ee0..a941b6e 100644
--- modules/node/node.module
+++ modules/node/node.module
@@ -809,11 +809,11 @@ function node_load_multiple($nids = array(), $conditions = array(), $reset = FAL
       $function = $module . '_node_load';
       $function($queried_nodes, array_keys($typed_nodes));
     }
+
+    // Add the current nodes that came from the cache to the end of the
+    // nodes so they will get purged after the newly loaded nodes.
+    // This will give a sort of least recently used method for purging nodes.
     $nodes += $queried_nodes;
-    // Add nodes to the cache if we're not loading a revision.
-    if (!$vid) {
-      $node_cache += $queried_nodes;
-    }
   }
 
   // Ensure that the returned array is ordered the same as the original $nids
@@ -826,7 +826,18 @@ function node_load_multiple($nids = array(), $conditions = array(), $reset = FAL
     }
     $nodes = $passed_nids;
   }
-
+  
+  // Add nodes to the cache if we're not loading a revision.
+  if (!$vid) {
+    $node_cache = $nodes + $node_cache;
+    
+    // check if the cache is greater than the max cache size and purge
+    // the nodes at the bottom of the array as they are the least used.
+    if (count($node_cache) > variable_get('node_load_max_cache', 30)) {
+      $node_cache = array_slice($node_cache, 0, variable_get('node_load_max_cache', 30), TRUE);
+    }
+  }
+  
   return $nodes;
 }
 
diff --git modules/node/node.test modules/node/node.test
index 315d7c1..6c72b8e 100644
--- modules/node/node.test
+++ modules/node/node.test
@@ -840,3 +840,69 @@ class NodeAccessRebuildTestCase extends DrupalWebTestCase {
     $this->assertText(t('Content permissions have been rebuilt.'));
   }
 }
+
+/**
+ * Test restriction of the number of nodes to be held in the static cache.
+ */
+class NodeLoadRestrictionTestCase extends DrupalWebTestCase {
+  public static function getInfo() {
+    return array(
+      'name' => 'Node restriction',
+      'description' => 'Check cache size restriction of node_load() to only retain only NODE_LOAD_MAX_CACHE.',
+      'group' => 'Node',
+    );
+  }
+  
+  function testNodeRestrictions() {
+    for ($i = 0; $i < variable_get('node_load_max_cache', 30) + 10; $i ++) {
+      $node = $this->drupalCreateNode(array('type' => 'article'));
+      $node_keys[] = $node->nid;
+    }
+    
+    $node_cache = &drupal_static('node_load_multiple', array(), TRUE);
+    
+    // Over fill the node cache.
+    foreach ($node_keys as $nid) {
+      node_load($nid);
+    }
+    
+    // Check if the cache has too many nodes in it.
+    $this->assertTrue(count($node_cache) <= variable_get('node_load_max_cache', 30), t('The static node cache is less than or equal to the Maximum cache size'));
+  }
+}
+
+/**
+ * Test restriction of the number of nodes to make sure the most used is at
+ * the beginning of the node cache and less likey to be removed.
+ */
+class NodeLoadPurgeOrderTestCase extends DrupalWebTestCase {
+  public static function getInfo() {
+    return array(
+      'name' => 'Node restriction purge order',
+      'description' => 'Check cashe size restriction of node_load() is moving the most recently loaded nodes to the beginning.',
+      'group' => 'Node',
+    );
+  }
+  
+  function testNodeRestrictionsPurgeOrder() {
+    for ($i = 0; $i < variable_get('node_load_max_cache', 30) + 10; $i ++) {
+      $node = $this->drupalCreateNode(array('type' => 'article'));
+      $node_keys[] = $node->nid;
+    }
+    
+    $popular_nid = array_shift($node_keys);
+    
+    drupal_static('node_load_multiple', array(), TRUE);
+    $node_cache = &drupal_static('node_load_multiple', array());
+    
+    // Over fill the node cache.
+    foreach ($node_keys as $nid) {
+      node_load($nid);
+      node_load($popular_nid);
+    }
+    
+    $popular_node = reset($node_cache);
+    // Check if the cache has too many nodes in it.
+    $this->assertEqual($popular_node->nid, $popular_nid, t('The node at the top of the cache is the popular node'));
+  }
+}
-- 
1.6.4.rc0.17.gd9eb0