First draft memcache object. No testing yet carried out, submitted 'cos I'm moving computers.

git-svn-id: https://code.elgg.org/elgg/trunk@2392 36083f99-b078-4883-b0ff-0f9b5a30f544

1 files changed, 147 insertions, 0 deletions

diff --git a/engine/lib/memcache.php b/engine/lib/memcache.php
new file mode 100644
index 000000000..2df93cbaf
--- /dev/null
+++ b/engine/lib/memcache.php
@@ -0,0 +1,147 @@
+<?php
+	/**
+	 * Elgg memcache support.
+	 * 
+	 * Requires php5-memcache to work.
+	 * 
+	 * @package Elgg
+	 * @subpackage API
+	 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
+	 * @author Curverider Ltd <info@elgg.com>
+	 * @copyright Curverider Ltd 2008
+	 * @link http://elgg.org/
+	 */
+
+
+	class ElggMemcache extends ElggCache
+	{
+		/**
+		 * Namespace variable used for key
+		 *
+		 * @var string
+		 */
+		private $namespace;
+		
+		/**
+		 * Memcache object
+		 */
+		private $memcache;
+		
+		/**
+		 * Expiry of saved items (defaults forever)
+		 */
+		private $expires = 0;
+		
+		/**
+		 * The version of memcache running
+		 */
+		private $version = 0;
+		
+		/**
+		 * Keys so far.
+		 * This variable holds a list of keys we have seen so that when we call ->clear() we invalidate only those keys.
+		 * TODO: Could this be done better?
+		 */
+		private $keys_so_far = array();
+		
+		/**
+		 * Connect to memcache.
+		 * 
+		 * @param string $cache_id The namespace for this cache to write to - note, namespaces of the same name are shared!
+		 */
+		function __construct($namespace = 'default')
+		{	
+			global $CONFIG;
+			
+			$this->namespace = $namespace;
+			
+			// Do we have memcache?
+			if (!class_exists('Memcache'))
+				throw new ConfigurationException(elgg_echo('memcache:notinstalled'));
+
+			// Create memcache object
+			$this->memcache	= new Memcache;
+			
+			// Now add servers
+			if (!$CONFIG->memcache_servers)
+				throw new ConfigurationException(elgg_echo('memcache:noservers'));
+				
+			foreach ($CONFIG->memcache_servers as $server)
+			{
+				if (is_array($server))
+				{
+					$this->memcache->addServer(
+						$server[0], 
+						isset($server[1]) ? $server[1] : 11211,
+						isset($server[2]) ? $server[2] : true,
+						isset($server[3]) ? $server[3] : null,
+						isset($server[4]) ? $server[4] : 1,
+						isset($server[5]) ? $server[5] : 15,
+						isset($server[6]) ? $server[6] : true
+					);
+					
+				}
+				else
+					$this->memcache->addServer($server, 11211);
+			}
+			
+			// Get version
+			$this->version = $this->memcache->getversion();
+			if (version_compare($this->version, '2.0.0', '<'))
+				throw new ConfigurationException(sprintf(elgg_echo('memcache:versiontoolow'), $this->version));
+			
+			// Set some defaults
+			if (isset($CONFIG->memcache_expires))
+				$this->expires = $CONFIG->memcache_expires;
+			
+		}
+		
+		/**
+		 * Combine a key with the namespace.
+		 * Memcache can only accept <250 char key. If the given key is too long it is shortened.
+		 * 
+		 * @param string $key The key
+		 * @return string The new key. 
+		 */
+		private function make_memcache_key($key)
+		{
+			$prefix = $this->namespace . ":";
+			
+			if (strlen($prefix.$key)> 250)
+				$key = md5($key);
+				
+			return $prefix.$key;
+		}
+		
+		public function save($key, $data) 
+		{
+			$key = $this->make_memcache_key($key);
+			
+			return $this->memcache->add($key, $data, null, $this->expires);	
+		}
+		
+		public function load($key, $offset = 0, $limit = null)
+		{
+			$key = $this->make_memcache_key($key);
+			
+			return $this->memcache->get($key);
+		}
+		
+		public function delete($key) 
+		{
+			$key = $this->make_memcache_key($key);
+			
+			return $this->memcache->delete($key, 0);
+		}
+		
+		public function clear()
+		{
+			foreach ($this->keys_so_far as $key)
+				$this->memcache->delete($key, 0);
+				
+			$this->keys_so_far = array();
+			
+			return true;
+		}
+	}
+?>
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