New caching provider using APC's shared memory cache.

Used now by default, if function apc_fetch() exists and no
other caching provide is explicitly set in header.inc.php or egw_cache
class. 
It's probably quicker on virtual machines, as it uses memory and not the
filesystem.

phpgwapi/inc/class.egw_cache.inc.php

@@ -7,7 +7,7 @@
  * @package api
  * @subpackage cache
  * @author Ralf Becker <RalfBecker-AT-outdoor-training.de>
- * @copyright (c) 2009 by Ralf Becker <RalfBecker-AT-outdoor-training.de>
+ * @copyright (c) 2009/10 by Ralf Becker <RalfBecker-AT-outdoor-training.de>
  * @version $Id$
  */
 
@@ -66,9 +66,12 @@ class egw_cache
 	 * $GLOBALS['egw_info']['server']['cache_provider_instance'] and optional
 	 * $GLOBALS['egw_info']['server']['cache_provider_tree'] (defaults to instance)
 	 *
+	 * Default is set (if not set here) after class definition to egw_cache_apc or egw_cache_files,
+	 * depending on function 'apc_fetch' exists or not
+	 *
 	 * @var array
 	 */
-	static $default_provider = array('egw_cache_files');// array('egw_cache_memcache','localhost');
+	static $default_provider;	// = array('egw_cache_files');// array('egw_cache_memcache','localhost');
 
 	/**
 	 * Set some data in the cache
@@ -510,6 +513,12 @@ class egw_cache
 	}
 }
 
+// setting apc as default provide, if apc_fetch function exists
+if (is_null(egw_cache::$default_provider))
+{
+	egw_cache::$default_provider = function_exists('apc_fetch') ? 'egw_cache_apc' : 'egw_cache_files';
+}
+
 /**
  * Interface for a caching provider for tree and instance level
  *

phpgwapi/inc/class.egw_cache_apc.inc.php

@@ -0,0 +1,92 @@
+<?php
+/**
+ * eGroupWare API: Caching provider storing data in PHP's APC
+ *
+ * @link http://www.egroupware.org
+ * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
+ * @package api
+ * @subpackage cache
+ * @author Ralf Becker <RalfBecker-AT-outdoor-training.de>
+ * @copyright (c) 2010 by Ralf Becker <RalfBecker-AT-outdoor-training.de>
+ * @version $Id$
+ */
+
+/**
+ * Caching provider storing data in PHP's APC
+ *
+ * The provider concats all $keys with '::' to get a single string.
+ *
+ * To use this provider set in your header.inc.php:
+ * $GLOBALS['egw_info']['server']['cache_provider_instance'] = array('egw_cache_apc');
+ * and optional also $GLOBALS['egw_info']['server']['cache_provider_tree'] (defaults to instance)
+ */
+class egw_cache_apc implements egw_cache_provider
+{
+	/**
+	 * Constructor, eg. opens the connection to the backend
+	 *
+	 * @throws Exception if connection to backend could not be established
+	 * @param array $params eg. array('localhost'[,'localhost:11211',...])
+	 */
+	function __construct(array $params)
+	{
+		if (!function_exists('apc_fetch'))	// apc >= 3.0
+		{
+			throw new Exception (__METHOD__.'('.array2string($params).") No function apc_fetch()!");
+		}
+	}
+
+	/**
+	 * Stores some data in the cache
+	 *
+	 * @param array $keys eg. array($level,$app,$location)
+	 * @param mixed $data
+	 * @param int $expiration=0
+	 * @return boolean true on success, false on error
+	 */
+	function set(array $keys,$data,$expiration=0)
+	{
+		return apc_store(self::key($keys),$data,$expiration);
+	}
+
+	/**
+	 * Get some data from the cache
+	 *
+	 * @param array $keys eg. array($level,$app,$location)
+	 * @return mixed data stored or NULL if not found in cache
+	 */
+	function get(array $keys)
+	{
+		$data = apc_fetch($key=self::key($keys),$success);
+
+		if (!$success)
+		{
+			//error_log(__METHOD__."(".array2string($keys).") key='$key' NOT found!");
+			return null;
+		}
+		//error_log(__METHOD__."(".array2string($keys).") key='$key' found ".bytes(serialize($data))." bytes).");
+		return $data;
+	}
+
+	/**
+	 * Delete some data from the cache
+	 *
+	 * @param array $keys eg. array($level,$app,$location)
+	 * @return boolean true on success, false on error (eg. $key not set)
+	 */
+	function delete(array $keys)
+	{
+		return apc_delete(self::key($keys));
+	}
+
+	/**
+	 * Create a single key from $keys
+	 *
+	 * @param array $keys
+	 * @return string
+	 */
+	private function key(array $keys)
+	{
+		return implode('::',$keys);
+	}
+}