From 53b226d0e3d81c0cf45b2b39b506275a7a149ebe Mon Sep 17 00:00:00 2001
From: cash <cash.costello@gmail.com>
Date: Sat, 13 Apr 2013 14:28:01 -0400
Subject: adds LRU cache

---
 engine/classes/ElggLRUCache.php | 132 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 engine/classes/ElggLRUCache.php

(limited to 'engine/classes/ElggLRUCache.php')

diff --git a/engine/classes/ElggLRUCache.php b/engine/classes/ElggLRUCache.php
new file mode 100644
index 000000000..add78ecb4
--- /dev/null
+++ b/engine/classes/ElggLRUCache.php
@@ -0,0 +1,132 @@
+<?php
+
+/**
+ * Least Recently Used Cache
+ *
+ * A fixed sized cache that removes the element used last when it reaches its
+ * size limit.
+ * 
+ * Based on https://github.com/cash/LRUCache
+ * 
+ * @access private
+ * 
+ * @package    Elgg.Core
+ * @subpackage Cache
+ */
+class ElggLRUCache {
+	/** @var int */
+	protected $maximumSize;
+
+	/**
+	 * The front of the array contains the LRU element
+	 *
+	 * @var array
+	 */
+	protected $data = array();
+
+	/**
+	 * Create a LRU Cache
+	 *
+	 * @param int $size The size of the cache
+	 * @throws InvalidArgumentException
+	 */
+	public function __construct($size) {
+		if (!is_int($size) || $size <= 0) {
+			throw new InvalidArgumentException();
+		}
+		$this->maximumSize = $size;
+	}
+
+	/**
+	 * Get the value cached with this key
+	 *
+	 * @param int|string $key     The key. Strings that are ints are cast to ints.
+	 * @param mixed      $default The value to be returned if key not found. (Optional)
+	 * @return mixed
+	 */
+	public function get($key, $default = null) {
+		if (isset($this->data[$key])) {
+			$this->recordAccess($key);
+			return $this->data[$key];
+		} else {
+			return $default;
+		}
+	}
+
+	/**
+	 * Put something in the cache
+	 *
+	 * @param int|string $key   The key. Strings that are ints are cast to ints.
+	 * @param mixed      $value The value to cache
+	 * @return void
+	 */
+	public function put($key, $value) {
+		if (isset($this->data[$key])) {
+			$this->data[$key] = $value;
+			$this->recordAccess($key);
+		} else {
+			$this->data[$key] = $value;
+			if ($this->size() > $this->maximumSize) {
+				// remove least recently used element (front of array)
+				reset($this->data);
+				unset($this->data[key($this->data)]);
+			}
+		}
+	}
+
+	/**
+	 * Get the number of elements in the cache
+	 *
+	 * @return int
+	 */
+	public function size() {
+		return count($this->data);
+	}
+
+	/**
+	 * Does the cache contain an element with this key
+	 *
+	 * @param int|string $key The key
+	 * @return boolean
+	 */
+	public function containsKey($key) {
+		return isset($this->data[$key]);
+	}
+
+	/**
+	 * Remove the element with this key.
+	 *
+	 * @param int|string $key The key
+	 * @return mixed Value or null if not set
+	 */
+	public function remove($key) {
+		if (isset($this->data[$key])) {
+			$value = $this->data[$key];
+			unset($this->data[$key]);
+			return $value;
+		} else {
+			return null;
+		}
+	}
+
+	/**
+	 * Clear the cache
+	 * 
+	 * @return void
+	 */
+	public function clear() {
+		$this->data = array();
+	}
+
+	/**
+	 * Moves the element from current position to end of array
+	 * 
+	 * @param int|string $key The key
+	 * @return void
+	 */
+	protected function recordAccess($key) {
+		$value = $this->data[$key];
+		unset($this->data[$key]);
+		$this->data[$key] = $value;
+	}
+}
-- 
cgit v1.2.3


From fc9a1e985b0b20c74a913f22ec9ea7e0c16848a7 Mon Sep 17 00:00:00 2001
From: cash <cash.costello@gmail.com>
Date: Sat, 13 Apr 2013 14:35:24 -0400
Subject: updated lru cache so easier to integrate

---
 engine/classes/ElggLRUCache.php | 55 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 52 insertions(+), 3 deletions(-)

(limited to 'engine/classes/ElggLRUCache.php')

diff --git a/engine/classes/ElggLRUCache.php b/engine/classes/ElggLRUCache.php
index add78ecb4..90e63bb61 100644
--- a/engine/classes/ElggLRUCache.php
+++ b/engine/classes/ElggLRUCache.php
@@ -13,7 +13,7 @@
  * @package    Elgg.Core
  * @subpackage Cache
  */
-class ElggLRUCache {
+class ElggLRUCache implements ArrayAccess {
 	/** @var int */
 	protected $maximumSize;
 
@@ -54,13 +54,13 @@ class ElggLRUCache {
 	}
 
 	/**
-	 * Put something in the cache
+	 * Add something to the cache
 	 *
 	 * @param int|string $key   The key. Strings that are ints are cast to ints.
 	 * @param mixed      $value The value to cache
 	 * @return void
 	 */
-	public function put($key, $value) {
+	public function set($key, $value) {
 		if (isset($this->data[$key])) {
 			$this->data[$key] = $value;
 			$this->recordAccess($key);
@@ -129,4 +129,53 @@ class ElggLRUCache {
 		unset($this->data[$key]);
 		$this->data[$key] = $value;
 	}
+
+	/**
+	 * Assigns a value for the specified key
+	 *
+	 * @see ArrayAccess::offsetSet()
+	 *
+	 * @param int|string $key   The key to assign the value to.
+	 * @param mixed      $value The value to set.
+	 * @return void
+	 */
+	function offsetSet($key, $value) {
+		$this->set($key, $value);
+	}
+
+	/**
+	 * Get the value for specified key
+	 *
+	 * @see ArrayAccess::offsetGet()
+	 *
+	 * @param int|string $key The key to retrieve.
+	 * @return mixed
+	 */
+	function offsetGet($key) {
+		return $this->get($key);
+	}
+
+	/**
+	 * Unsets a key.
+	 *
+	 * @see ArrayAccess::offsetUnset()
+	 *
+	 * @param int|string $key The key to unset.
+	 * @return void
+	 */
+	function offsetUnset($key) {
+		$this->remove($key);
+	}
+
+	/**
+	 * Does key exist?
+	 *
+	 * @see ArrayAccess::offsetExists()
+	 *
+	 * @param int|string $key A key to check for.
+	 * @return boolean
+	 */
+	function offsetExists($key) {
+		return $this->containsKey($key);
+	}
 }
-- 
cgit v1.2.3


From 21c92cf39d719a913cd9e29474c04781e9cd72ef Mon Sep 17 00:00:00 2001
From: cash <cash.costello@gmail.com>
Date: Sat, 13 Apr 2013 15:05:40 -0400
Subject: Fixes #4978 integrates LRU cache for db query cache

---
 engine/classes/ElggLRUCache.php |  8 ++++----
 engine/lib/database.php         | 29 +++++++++++++++--------------
 2 files changed, 19 insertions(+), 18 deletions(-)

(limited to 'engine/classes/ElggLRUCache.php')

diff --git a/engine/classes/ElggLRUCache.php b/engine/classes/ElggLRUCache.php
index 90e63bb61..f51af2ed7 100644
--- a/engine/classes/ElggLRUCache.php
+++ b/engine/classes/ElggLRUCache.php
@@ -139,7 +139,7 @@ class ElggLRUCache implements ArrayAccess {
 	 * @param mixed      $value The value to set.
 	 * @return void
 	 */
-	function offsetSet($key, $value) {
+	public function offsetSet($key, $value) {
 		$this->set($key, $value);
 	}
 
@@ -151,7 +151,7 @@ class ElggLRUCache implements ArrayAccess {
 	 * @param int|string $key The key to retrieve.
 	 * @return mixed
 	 */
-	function offsetGet($key) {
+	public function offsetGet($key) {
 		return $this->get($key);
 	}
 
@@ -163,7 +163,7 @@ class ElggLRUCache implements ArrayAccess {
 	 * @param int|string $key The key to unset.
 	 * @return void
 	 */
-	function offsetUnset($key) {
+	public function offsetUnset($key) {
 		$this->remove($key);
 	}
 
@@ -175,7 +175,7 @@ class ElggLRUCache implements ArrayAccess {
 	 * @param int|string $key A key to check for.
 	 * @return boolean
 	 */
-	function offsetExists($key) {
+	public function offsetExists($key) {
 		return $this->containsKey($key);
 	}
 }
diff --git a/engine/lib/database.php b/engine/lib/database.php
index b41eb4cda..3553d787d 100644
--- a/engine/lib/database.php
+++ b/engine/lib/database.php
@@ -12,18 +12,19 @@
 /**
  * Query cache for all queries.
  *
- * Each query and its results are stored in this array as:
+ * Each query and its results are stored in this cache as:
  * <code>
- * $DB_QUERY_CACHE[$query] => array(result1, result2, ... resultN)
+ * $DB_QUERY_CACHE[query hash] => array(result1, result2, ... resultN)
  * </code>
+ * @see elgg_query_runner() for details on the hash.
  *
- * @warning be array this var may be an array or ElggStaticVariableCache depending on when called :(
+ * @warning Elgg used to set this as an empty array to turn off the cache
  *
- * @global ElggStaticVariableCache|array $DB_QUERY_CACHE
+ * @global ElggLRUCache|null $DB_QUERY_CACHE
  * @access private
  */
 global $DB_QUERY_CACHE;
-$DB_QUERY_CACHE = array();
+$DB_QUERY_CACHE = null;
 
 /**
  * Queries to be executed upon shutdown.
@@ -127,9 +128,8 @@ function establish_db_link($dblinkname = "readwrite") {
 
 	// Set up cache if global not initialized and query cache not turned off
 	if ((!$DB_QUERY_CACHE) && (!$db_cache_off)) {
-		// @todo everywhere else this is assigned to array(), making it dangerous to call
-		// object methods on this. We should consider making this an plain array
-		$DB_QUERY_CACHE = new ElggStaticVariableCache('db_query_cache');
+		// @todo if we keep this cache in 1.9, expose the size as a config parameter
+		$DB_QUERY_CACHE = new ElggLRUCache(200);		
 	}
 }
 
@@ -404,11 +404,9 @@ function elgg_query_runner($query, $callback = null, $single = false) {
 
 	// Is cached?
 	if ($DB_QUERY_CACHE) {
-		$cached_query = $DB_QUERY_CACHE[$hash];
-
-		if ($cached_query !== FALSE) {
+		if (isset($DB_QUERY_CACHE[$hash])) {
 			elgg_log("DB query $query results returned from cache (hash: $hash)", 'NOTICE');
-			return $cached_query;
+			return $DB_QUERY_CACHE[$hash];			
 		}
 	}
 
@@ -531,10 +529,13 @@ function delete_data($query) {
  */
 function _elgg_invalidate_query_cache() {
 	global $DB_QUERY_CACHE;
-	if ($DB_QUERY_CACHE) {
-		/* @var ElggStaticVariableCache $DB_QUERY_CACHE */
+	if ($DB_QUERY_CACHE instanceof ElggLRUCache) {
 		$DB_QUERY_CACHE->clear();
 		elgg_log("Query cache invalidated", 'NOTICE');
+	} elseif ($DB_QUERY_CACHE) {
+		// In case someone sets the cache to an array and primes it with data 
+		$DB_QUERY_CACHE = array();
+		elgg_log("Query cache invalidated", 'NOTICE');
 	}
 }
 
-- 
cgit v1.2.3