Add layer to select fast or slow cache for storing values

lib/cache.php

@@ -10,7 +10,17 @@ class OC_Cache {
 	static protected $cache;
 
 	static protected function init() {
+		$fast_cache = null;
+		if (!$fast_cache && function_exists('xcache_set')) {
+			$fast_cache = new OC_Cache_XCache();
+		}
+		if (!$fast_cache && function_exists('apc_store')) {
+			$fast_cache = new OC_Cache_APC();
+		}
 		self::$cache = new OC_Cache_File();
+		if ($fast_cache) {
+			self::$cache = new OC_Cache_Broker($fast_cache, self::$cache);
+		}
 	}
 
 	static public function get($key) {

lib/cache/broker.php

@@ -0,0 +1,55 @@
+<?php
+/**
+ * Copyright (c) 2012 Bart Visscher <bartv@thisnet.nl>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+class OC_Cache_Broker {
+	protected $fast_cache;
+	protected $slow_cache;
+
+	public function __construct($fast_cache, $slow_cache) {
+		$this->fast_cache = $fast_cache;
+		$this->slow_cache = $slow_cache;
+	}
+
+	public function get($key) {
+		if ($r = $this->fast_cache->get($key)) {
+			return $r;
+		}
+		return $this->slow_cache->get($key);
+	}
+
+	public function set($key, $value, $ttl=0) {
+		$set_slow = strlen($value) > 8192;
+		if ($set_slow) {
+			if ($this->fast_cache->hasKey($key)) {
+				$this->fast_cache->remove($key);
+			}
+			$this->slow_cache->set($key, $value, $ttl);
+		} else {
+			$this->fast_cache->set($key, $value, $ttl);
+		}
+	}
+
+	public function hasKey($key) {
+		if ($this->fast_cache->hasKey($key)) {
+			return true;
+		}
+		return $this->slow_cache->hasKey($key);
+	}
+
+	public function remove($key) {
+		if ($this->fast_cache->remove($key)) {
+			return true;
+		}
+		return $this->slow_cache->remove($key);
+	}
+
+	public function clear(){
+		$this->fast_cache->clear();
+		$this->slow_cache->clear();
+	}
+}