Merge pull request #1562 from kamisama/feature/2.5-memcached-cache-engine

2.5: Add Memcached storage engine for cache 

Fixes #3511

.travis.yml

@@ -11,6 +11,9 @@ env:
   - DB=pgsql
   - DB=sqlite
 
+services:
+  - memcached
+
 matrix:
   include:
     - php: 5.4
@@ -29,6 +32,7 @@ before_script:
   - sudo apt-get install lighttpd
   - sh -c "if [ '$PHPCS' = '1' ]; then pear channel-discover pear.cakephp.org; fi"
   - sh -c "if [ '$PHPCS' = '1' ]; then pear install --alldeps cakephp/CakePHP_CodeSniffer; fi"
+  - echo "extension = memcached.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
   - phpenv rehash
   - set +H
   - echo "<?php

lib/Cake/Cache/Engine/MemcachedEngine.php

@@ -0,0 +1,293 @@
+<?php
+/**
+ * Memcached storage engine for cache
+ *
+ *
+ * PHP 5
+ *
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @package       Cake.Cache.Engine
+ * @since         CakePHP(tm) v 2.5.0
+ * @license       http://www.opensource.org/licenses/mit-license.php MIT License
+ */
+
+/**
+ * Memcached storage engine for cache.  Memcached has some limitations in the amount of
+ * control you have over expire times far in the future.  See MemcacheEngine::write() for
+ * more information.
+ *
+ * Main advantage of this Memcached engine over the memcached engine is
+ * support of binary protocol, and igbibnary serialization
+ * (if memcached extension compiled with --enable-igbinary)
+ * Compressed keys can also be incremented/decremented
+ *
+ * @package       Cake.Cache.Engine
+ */
+class MemcachedEngine extends CacheEngine {
+
+/**
+ * memcached wrapper.
+ *
+ * @var Memcache
+ */
+	protected $_Memcached = null;
+
+/**
+ * Settings
+ *
+ *  - servers = string or array of memcached servers, default => 127.0.0.1. If an
+ *    array MemcacheEngine will use them as a pool.
+ *  - compress = boolean, default => false
+ *
+ * @var array
+ */
+	public $settings = array();
+
+/**
+ * Initialize the Cache Engine
+ *
+ * Called automatically by the cache frontend
+ * To reinitialize the settings call Cache::engine('EngineName', [optional] settings = array());
+ *
+ * @param array $settings array of setting for the engine
+ * @return boolean True if the engine has been successfully initialized, false if not
+ * @throws CacheException when you try use authentication without Memcached compiled with SASL support
+ */
+	public function init($settings = array()) {
+		if (!class_exists('Memcached')) {
+			return false;
+		}
+		if (!isset($settings['prefix'])) {
+			$settings['prefix'] = Inflector::slug(APP_DIR) . '_';
+		}
+		$settings += array(
+			'engine' => 'Memcached',
+			'servers' => array('127.0.0.1'),
+			'compress' => false,
+			'persistent' => true,
+			'persistent_id' => 'mc',
+			'login' => null,
+			'password' => null,
+		);
+		parent::init($settings);
+
+		if (!is_array($this->settings['servers'])) {
+			$this->settings['servers'] = array($this->settings['servers']);
+		}
+
+		if (isset($this->_Memcached)) {
+			return true;
+		}
+
+		$this->_Memcached = new Memcached($this->settings['persistent'] ? $this->settings['persistent_id'] : null);
+		$this->_setOptions();
+
+		if (count($this->_Memcached->getServerList())) {
+			return true;
+		}
+
+		$servers = array();
+		foreach ($this->settings['servers'] as $server) {
+			$servers[] = $this->_parseServerString($server);
+		}
+
+		if (!$this->_Memcached->addServers($servers)) {
+			return false;
+		}
+
+		if ($this->settings['login'] !== null && $this->settings['password'] !== null) {
+			if (!method_exists($this->_Memcached, 'setSaslAuthData')) {
+				throw new CacheException(
+					__d('cake_dev', 'Memcached extension is not build with SASL support')
+				);
+			}
+			$this->_Memcached->setSaslAuthData($this->settings['login'], $this->settings['password']);
+		}
+
+		return true;
+	}
+
+/**
+ * Settings the memcached instance
+ *
+ */
+	protected function _setOptions() {
+		$this->_Memcached->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE, true);
+
+		if (Memcached::HAVE_IGBINARY) {
+			$this->_Memcached->setOption(Memcached::OPT_SERIALIZER, Memcached::SERIALIZER_IGBINARY);
+		}
+
+		// Check for Amazon ElastiCache instance
+		if (defined('Memcached::OPT_CLIENT_MODE') && defined('Memcached::DYNAMIC_CLIENT_MODE')) {
+			$this->_Memcached->setOption(Memcached::OPT_CLIENT_MODE, Memcached::DYNAMIC_CLIENT_MODE);
+		}
+
+		$this->_Memcached->setOption(Memcached::OPT_COMPRESSION, (bool)$this->settings['compress']);
+	}
+
+/**
+ * Parses the server address into the host/port. Handles both IPv6 and IPv4
+ * addresses and Unix sockets
+ *
+ * @param string $server The server address string.
+ * @return array Array containing host, port
+ */
+	protected function _parseServerString($server) {
+		if ($server[0] === 'u') {
+			return array($server, 0);
+		}
+		if (substr($server, 0, 1) === '[') {
+			$position = strpos($server, ']:');
+			if ($position !== false) {
+				$position++;
+			}
+		} else {
+			$position = strpos($server, ':');
+		}
+		$port = 11211;
+		$host = $server;
+		if ($position !== false) {
+			$host = substr($server, 0, $position);
+			$port = substr($server, $position + 1);
+		}
+		return array($host, (int)$port);
+	}
+
+/**
+ * Write data for key into cache. When using memcached as your cache engine
+ * remember that the Memcached pecl extension does not support cache expiry times greater
+ * than 30 days in the future. Any duration greater than 30 days will be treated as never expiring.
+ *
+ * @param string $key Identifier for the data
+ * @param mixed $value Data to be cached
+ * @param integer $duration How long to cache the data, in seconds
+ * @return boolean True if the data was successfully cached, false on failure
+ * @see http://php.net/manual/en/memcache.set.php
+ */
+	public function write($key, $value, $duration) {
+		if ($duration > 30 * DAY) {
+			$duration = 0;
+		}
+
+		return $this->_Memcached->set($key, $value, $duration);
+	}
+
+/**
+ * Read a key from the cache
+ *
+ * @param string $key Identifier for the data
+ * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
+ */
+	public function read($key) {
+		return $this->_Memcached->get($key);
+	}
+
+/**
+ * Increments the value of an integer cached key
+ *
+ * @param string $key Identifier for the data
+ * @param integer $offset How much to increment
+ * @return New incremented value, false otherwise
+ * @throws CacheException when you try to increment with compress = true
+ */
+	public function increment($key, $offset = 1) {
+		return $this->_Memcached->increment($key, $offset);
+	}
+
+/**
+ * Decrements the value of an integer cached key
+ *
+ * @param string $key Identifier for the data
+ * @param integer $offset How much to subtract
+ * @return New decremented value, false otherwise
+ * @throws CacheException when you try to decrement with compress = true
+ */
+	public function decrement($key, $offset = 1) {
+		return $this->_Memcached->decrement($key, $offset);
+	}
+
+/**
+ * Delete a key from the cache
+ *
+ * @param string $key Identifier for the data
+ * @return boolean True if the value was successfully deleted, false if it didn't exist or couldn't be removed
+ */
+	public function delete($key) {
+		return $this->_Memcached->delete($key);
+	}
+
+/**
+ * Delete all keys from the cache
+ *
+ * @param boolean $check
+ * @return boolean True if the cache was successfully cleared, false otherwise
+ */
+	public function clear($check) {
+		if ($check) {
+			return true;
+		}
+
+		$keys = $this->_Memcached->getAllKeys();
+
+		foreach ($keys as $key) {
+			if (strpos($key, $this->settings['prefix']) === 0) {
+				$this->_Memcached->delete($key);
+			}
+		}
+
+		return true;
+	}
+
+/**
+ * Returns the `group value` for each of the configured groups
+ * If the group initial value was not found, then it initializes
+ * the group accordingly.
+ *
+ * @return array
+ */
+	public function groups() {
+		if (empty($this->_compiledGroupNames)) {
+			foreach ($this->settings['groups'] as $group) {
+				$this->_compiledGroupNames[] = $this->settings['prefix'] . $group;
+			}
+		}
+
+		$groups = $this->_Memcached->getMulti($this->_compiledGroupNames);
+		if (count($groups) !== count($this->settings['groups'])) {
+			foreach ($this->_compiledGroupNames as $group) {
+				if (!isset($groups[$group])) {
+					$this->_Memcached->set($group, 1, 0);
+					$groups[$group] = 1;
+				}
+			}
+			ksort($groups);
+		}
+
+		$result = array();
+		$groups = array_values($groups);
+		foreach ($this->settings['groups'] as $i => $group) {
+			$result[] = $group . $groups[$i];
+		}
+
+		return $result;
+	}
+
+/**
+ * Increments the group value to simulate deletion of all keys under a group
+ * old values will remain in storage until they expire.
+ *
+ * @return boolean success
+ */
+	public function clearGroup($group) {
+		return (bool)$this->_Memcached->increment($this->settings['prefix'] . $group);
+	}
+}

lib/Cake/Test/Case/Cache/Engine/MemcachedEngineTest.php

@@ -0,0 +1,594 @@
+<?php
+/**
+ * MemcachedEngineTest file
+ *
+ * PHP 5
+ *
+ * CakePHP(tm) Tests <http://book.cakephp.org/2.0/en/development/testing.html>
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://book.cakephp.org/2.0/en/development/testing.html CakePHP(tm) Tests
+ * @package       Cake.Test.Case.Cache.Engine
+ * @since         CakePHP(tm) v 2.5.0
+ * @license       http://www.opensource.org/licenses/mit-license.php MIT License
+ */
+
+App::uses('Cache', 'Cache');
+App::uses('MemcachedEngine', 'Cache/Engine');
+
+/**
+ * Class TestMemcachedEngine
+ *
+ * @package       Cake.Test.Case.Cache.Engine
+ */
+class TestMemcachedEngine extends MemcachedEngine {
+
+/**
+ * public accessor to _parseServerString
+ *
+ * @param string $server
+ * @return array
+ */
+	public function parseServerString($server) {
+		return $this->_parseServerString($server);
+	}
+
+	public function setMemcached($memcached) {
+		$this->_Memcached = $memcached;
+	}
+
+	public function getMemcached() {
+		return $this->_Memcached;
+	}
+
+}
+
+/**
+ * MemcachedEngineTest class
+ *
+ * @package       Cake.Test.Case.Cache.Engine
+ */
+class MemcachedEngineTest extends CakeTestCase {
+
+/**
+ * setUp method
+ *
+ * @return void
+ */
+	public function setUp() {
+		parent::setUp();
+		$this->skipIf(!class_exists('Memcached'), 'Memcached is not installed or configured properly.');
+
+		Cache::config('memcached', array(
+			'engine' => 'Memcached',
+			'prefix' => 'cake_',
+			'duration' => 3600
+		));
+	}
+
+/**
+ * tearDown method
+ *
+ * @return void
+ */
+	public function tearDown() {
+		parent::tearDown();
+		Cache::drop('memcached');
+		Cache::drop('memcached_groups');
+		Cache::drop('memcached_helper');
+		Cache::config('default');
+	}
+
+/**
+ * testSettings method
+ *
+ * @return void
+ */
+	public function testSettings() {
+		$settings = Cache::settings('memcached');
+		unset($settings['serialize'], $settings['path']);
+		$expecting = array(
+			'prefix' => 'cake_',
+			'duration' => 3600,
+			'probability' => 100,
+			'servers' => array('127.0.0.1'),
+			'persistent' => true,
+			'persistent_id' => 'mc',
+			'compress' => false,
+			'engine' => 'Memcached',
+			'login' => null,
+			'password' => null,
+			'groups' => array()
+		);
+		$this->assertEquals($expecting, $settings);
+	}
+
+/**
+ * testCompressionSetting method
+ *
+ * @return void
+ */
+	public function testCompressionSetting() {
+		$Memcached = new TestMemcachedEngine();
+		$Memcached->init(array(
+			'engine' => 'Memcached',
+			'servers' => array('127.0.0.1:11211'),
+			'compress' => false
+		));
+
+		$this->assertFalse($Memcached->getMemcached()->getOption(Memcached::OPT_COMPRESSION));
+
+		$MemcachedCompressed = new TestMemcachedEngine();
+		$MemcachedCompressed->init(array(
+			'engine' => 'Memcached',
+			'servers' => array('127.0.0.1:11211'),
+			'compress' => true
+		));
+
+		$this->assertTrue($MemcachedCompressed->getMemcached()->getOption(Memcached::OPT_COMPRESSION));
+	}
+
+/**
+ * test using authentication without memcached installed with SASL support
+ * throw an exception
+ *
+ * @return void
+ */
+	public function testSaslAuthException() {
+		$Memcached = new TestMemcachedEngine();
+		$settings = array(
+			'engine' => 'Memcached',
+			'servers' => array('127.0.0.1:11211'),
+			'persistent' => false,
+			'login' => 'test',
+			'password' => 'password'
+		);
+
+		$this->skipIf(
+			method_exists($Memcached->getMemcached(), 'setSaslAuthData'),
+			'Memcached extension is installed with SASL support'
+		);
+
+		$this->setExpectedException(
+			'CacheException', 'Memcached extension is not build with SASL support'
+		);
+		$Memcached->init($settings);
+	}
+
+/**
+ * testSettings method
+ *
+ * @return void
+ */
+	public function testMultipleServers() {
+		$servers = array('127.0.0.1:11211', '127.0.0.1:11222');
+		$available = true;
+		$Memcached = new Memcached();
+
+		foreach ($servers as $server) {
+			list($host, $port) = explode(':', $server);
+			//@codingStandardsIgnoreStart
+			if (!$Memcached->addServer($host, $port)) {
+				$available = false;
+			}
+			//@codingStandardsIgnoreEnd
+		}
+
+		$this->skipIf(!$available, 'Need memcached servers at ' . implode(', ', $servers) . ' to run this test.');
+
+		$Memcached = new MemcachedEngine();
+		$Memcached->init(array('engine' => 'Memcached', 'servers' => $servers));
+
+		$settings = $Memcached->settings();
+		$this->assertEquals($settings['servers'], $servers);
+		Cache::drop('dual_server');
+	}
+
+/**
+ * test connecting to an ipv6 server.
+ *
+ * @return void
+ */
+	public function testConnectIpv6() {
+		$Memcached = new MemcachedEngine();
+		$result = $Memcached->init(array(
+			'prefix' => 'cake_',
+			'duration' => 200,
+			'engine' => 'Memcached',
+			'servers' => array(
+				'[::1]:11211'
+			)
+		));
+		$this->assertTrue($result);
+	}
+
+/**
+ * test non latin domains.
+ *
+ * @return void
+ */
+	public function testParseServerStringNonLatin() {
+		$Memcached = new TestMemcachedEngine();
+		$result = $Memcached->parseServerString('schülervz.net:13211');
+		$this->assertEquals(array('schülervz.net', '13211'), $result);
+
+		$result = $Memcached->parseServerString('sülül:1111');
+		$this->assertEquals(array('sülül', '1111'), $result);
+	}
+
+/**
+ * test unix sockets.
+ *
+ * @return void
+ */
+	public function testParseServerStringUnix() {
+		$Memcached = new TestMemcachedEngine();
+		$result = $Memcached->parseServerString('unix:///path/to/memcachedd.sock');
+		$this->assertEquals(array('unix:///path/to/memcachedd.sock', 0), $result);
+	}
+
+/**
+ * testReadAndWriteCache method
+ *
+ * @return void
+ */
+	public function testReadAndWriteCache() {
+		Cache::set(array('duration' => 1), null, 'memcached');
+
+		$result = Cache::read('test', 'memcached');
+		$expecting = '';
+		$this->assertEquals($expecting, $result);
+
+		$data = 'this is a test of the emergency broadcasting system';
+		$result = Cache::write('test', $data, 'memcached');
+		$this->assertTrue($result);
+
+		$result = Cache::read('test', 'memcached');
+		$expecting = $data;
+		$this->assertEquals($expecting, $result);
+
+		Cache::delete('test', 'memcached');
+	}
+
+/**
+ * testExpiry method
+ *
+ * @return void
+ */
+	public function testExpiry() {
+		Cache::set(array('duration' => 1), 'memcached');
+
+		$result = Cache::read('test', 'memcached');
+		$this->assertFalse($result);
+
+		$data = 'this is a test of the emergency broadcasting system';
+		$result = Cache::write('other_test', $data, 'memcached');
+		$this->assertTrue($result);
+
+		sleep(2);
+		$result = Cache::read('other_test', 'memcached');
+		$this->assertFalse($result);
+
+		Cache::set(array('duration' => "+1 second"), 'memcached');
+
+		$data = 'this is a test of the emergency broadcasting system';
+		$result = Cache::write('other_test', $data, 'memcached');
+		$this->assertTrue($result);
+
+		sleep(3);
+		$result = Cache::read('other_test', 'memcached');
+		$this->assertFalse($result);
+
+		Cache::config('memcached', array('duration' => '+1 second'));
+
+		$result = Cache::read('other_test', 'memcached');
+		$this->assertFalse($result);
+
+		Cache::config('memcached', array('duration' => '+29 days'));
+		$data = 'this is a test of the emergency broadcasting system';
+		$result = Cache::write('long_expiry_test', $data, 'memcached');
+		$this->assertTrue($result);
+
+		sleep(2);
+		$result = Cache::read('long_expiry_test', 'memcached');
+		$expecting = $data;
+		$this->assertEquals($expecting, $result);
+
+		Cache::config('memcached', array('duration' => 3600));
+	}
+
+/**
+ * testDeleteCache method
+ *
+ * @return void
+ */
+	public function testDeleteCache() {
+		$data = 'this is a test of the emergency broadcasting system';
+		$result = Cache::write('delete_test', $data, 'memcached');
+		$this->assertTrue($result);
+
+		$result = Cache::delete('delete_test', 'memcached');
+		$this->assertTrue($result);
+	}
+
+/**
+ * testDecrement method
+ *
+ * @return void
+ */
+	public function testDecrement() {
+		$result = Cache::write('test_decrement', 5, 'memcached');
+		$this->assertTrue($result);
+
+		$result = Cache::decrement('test_decrement', 1, 'memcached');
+		$this->assertEquals(4, $result);
+
+		$result = Cache::read('test_decrement', 'memcached');
+		$this->assertEquals(4, $result);
+
+		$result = Cache::decrement('test_decrement', 2, 'memcached');
+		$this->assertEquals(2, $result);
+
+		$result = Cache::read('test_decrement', 'memcached');
+		$this->assertEquals(2, $result);
+
+		Cache::delete('test_decrement', 'memcached');
+	}
+
+/**
+ * test decrementing compressed keys
+ *
+ * @return void
+ */
+	public function testDecrementCompressedKeys() {
+		Cache::config('compressed_memcached', array(
+			'engine' => 'Memcached',
+			'duration' => '+2 seconds',
+			'servers' => array('127.0.0.1:11211'),
+			'compress' => true
+		));
+
+		$result = Cache::write('test_decrement', 5, 'compressed_memcached');
+		$this->assertTrue($result);
+
+		$result = Cache::decrement('test_decrement', 1, 'compressed_memcached');
+		$this->assertEquals(4, $result);
+
+		$result = Cache::read('test_decrement', 'compressed_memcached');
+		$this->assertEquals(4, $result);
+
+		$result = Cache::decrement('test_decrement', 2, 'compressed_memcached');
+		$this->assertEquals(2, $result);
+
+		$result = Cache::read('test_decrement', 'compressed_memcached');
+		$this->assertEquals(2, $result);
+
+		Cache::delete('test_decrement', 'compressed_memcached');
+	}
+
+/**
+ * testIncrement method
+ *
+ * @return void
+ */
+	public function testIncrement() {
+		$result = Cache::write('test_increment', 5, 'memcached');
+		$this->assertTrue($result);
+
+		$result = Cache::increment('test_increment', 1, 'memcached');
+		$this->assertEquals(6, $result);
+
+		$result = Cache::read('test_increment', 'memcached');
+		$this->assertEquals(6, $result);
+
+		$result = Cache::increment('test_increment', 2, 'memcached');
+		$this->assertEquals(8, $result);
+
+		$result = Cache::read('test_increment', 'memcached');
+		$this->assertEquals(8, $result);
+
+		Cache::delete('test_increment', 'memcached');
+	}
+
+/**
+ * test incrementing compressed keys
+ *
+ * @return void
+ */
+	public function testIncrementCompressedKeys() {
+		Cache::config('compressed_memcached', array(
+			'engine' => 'Memcached',
+			'duration' => '+2 seconds',
+			'servers' => array('127.0.0.1:11211'),
+			'compress' => true
+		));
+
+		$result = Cache::write('test_increment', 5, 'compressed_memcached');
+		$this->assertTrue($result);
+
+		$result = Cache::increment('test_increment', 1, 'compressed_memcached');
+		$this->assertEquals(6, $result);
+
+		$result = Cache::read('test_increment', 'compressed_memcached');
+		$this->assertEquals(6, $result);
+
+		$result = Cache::increment('test_increment', 2, 'compressed_memcached');
+		$this->assertEquals(8, $result);
+
+		$result = Cache::read('test_increment', 'compressed_memcached');
+		$this->assertEquals(8, $result);
+
+		Cache::delete('test_increment', 'compressed_memcached');
+	}
+
+/**
+ * test that configurations don't conflict, when a file engine is declared after a memcached one.
+ *
+ * @return void
+ */
+	public function testConfigurationConflict() {
+		Cache::config('long_memcached', array(
+			'engine' => 'Memcached',
+			'duration' => '+2 seconds',
+			'servers' => array('127.0.0.1:11211'),
+		));
+		Cache::config('short_memcached', array(
+			'engine' => 'Memcached',
+			'duration' => '+1 seconds',
+			'servers' => array('127.0.0.1:11211'),
+		));
+		Cache::config('some_file', array('engine' => 'File'));
+
+		$this->assertTrue(Cache::write('duration_test', 'yay', 'long_memcached'));
+		$this->assertTrue(Cache::write('short_duration_test', 'boo', 'short_memcached'));
+
+		$this->assertEquals('yay', Cache::read('duration_test', 'long_memcached'), 'Value was not read %s');
+		$this->assertEquals('boo', Cache::read('short_duration_test', 'short_memcached'), 'Value was not read %s');
+
+		sleep(1);
+		$this->assertEquals('yay', Cache::read('duration_test', 'long_memcached'), 'Value was not read %s');
+
+		sleep(2);
+		$this->assertFalse(Cache::read('short_duration_test', 'short_memcached'), 'Cache was not invalidated %s');
+		$this->assertFalse(Cache::read('duration_test', 'long_memcached'), 'Value did not expire %s');
+
+		Cache::delete('duration_test', 'long_memcached');
+		Cache::delete('short_duration_test', 'short_memcached');
+	}
+
+/**
+ * test clearing memcached.
+ *
+ * @return void
+ */
+	public function testClear() {
+		Cache::config('memcached2', array(
+			'engine' => 'Memcached',
+			'prefix' => 'cake2_',
+			'duration' => 3600
+		));
+
+		Cache::write('some_value', 'cache1', 'memcached');
+		$result = Cache::clear(true, 'memcached');
+		$this->assertTrue($result);
+		$this->assertEquals('cache1', Cache::read('some_value', 'memcached'));
+
+		Cache::write('some_value', 'cache2', 'memcached2');
+		$result = Cache::clear(false, 'memcached');
+		$this->assertTrue($result);
+		$this->assertFalse(Cache::read('some_value', 'memcached'));
+		$this->assertEquals('cache2', Cache::read('some_value', 'memcached2'));
+
+		Cache::clear(false, 'memcached2');
+	}
+
+/**
+ * test that a 0 duration can successfully write.
+ *
+ * @return void
+ */
+	public function testZeroDuration() {
+		Cache::config('memcached', array('duration' => 0));
+		$result = Cache::write('test_key', 'written!', 'memcached');
+
+		$this->assertTrue($result);
+		$result = Cache::read('test_key', 'memcached');
+		$this->assertEquals('written!', $result);
+	}
+
+/**
+ * test that durations greater than 30 days never expire
+ *
+ * @return void
+ */
+	public function testLongDurationEqualToZero() {
+		$memcached = new TestMemcachedEngine();
+		$memcached->settings['compress'] = false;
+
+		$mock = $this->getMock('Memcached');
+		$memcached->setMemcached($mock);
+		$mock->expects($this->once())
+			->method('set')
+			->with('key', 'value', 0);
+
+		$value = 'value';
+		$memcached->write('key', $value, 50 * DAY);
+	}
+
+/**
+ * Tests that configuring groups for stored keys return the correct values when read/written
+ * Shows that altering the group value is equivalent to deleting all keys under the same
+ * group
+ *
+ * @return void
+ */
+	public function testGroupReadWrite() {
+		Cache::config('memcached_groups', array(
+			'engine' => 'Memcached',
+			'duration' => 3600,
+			'groups' => array('group_a', 'group_b'),
+			'prefix' => 'test_'
+		));
+		Cache::config('memcached_helper', array(
+			'engine' => 'Memcached',
+			'duration' => 3600,
+			'prefix' => 'test_'
+		));
+		$this->assertTrue(Cache::write('test_groups', 'value', 'memcached_groups'));
+		$this->assertEquals('value', Cache::read('test_groups', 'memcached_groups'));
+
+		Cache::increment('group_a', 1, 'memcached_helper');
+		$this->assertFalse(Cache::read('test_groups', 'memcached_groups'));
+		$this->assertTrue(Cache::write('test_groups', 'value2', 'memcached_groups'));
+		$this->assertEquals('value2', Cache::read('test_groups', 'memcached_groups'));
+
+		Cache::increment('group_b', 1, 'memcached_helper');
+		$this->assertFalse(Cache::read('test_groups', 'memcached_groups'));
+		$this->assertTrue(Cache::write('test_groups', 'value3', 'memcached_groups'));
+		$this->assertEquals('value3', Cache::read('test_groups', 'memcached_groups'));
+	}
+
+/**
+ * Tests that deleteing from a groups-enabled config is possible
+ *
+ * @return void
+ */
+	public function testGroupDelete() {
+		Cache::config('memcached_groups', array(
+			'engine' => 'Memcached',
+			'duration' => 3600,
+			'groups' => array('group_a', 'group_b')
+		));
+		$this->assertTrue(Cache::write('test_groups', 'value', 'memcached_groups'));
+		$this->assertEquals('value', Cache::read('test_groups', 'memcached_groups'));
+		$this->assertTrue(Cache::delete('test_groups', 'memcached_groups'));
+
+		$this->assertFalse(Cache::read('test_groups', 'memcached_groups'));
+	}
+
+/**
+ * Test clearing a cache group
+ *
+ * @return void
+ */
+	public function testGroupClear() {
+		Cache::config('memcached_groups', array(
+			'engine' => 'Memcached',
+			'duration' => 3600,
+			'groups' => array('group_a', 'group_b')
+		));
+
+		$this->assertTrue(Cache::write('test_groups', 'value', 'memcached_groups'));
+		$this->assertTrue(Cache::clearGroup('group_a', 'memcached_groups'));
+		$this->assertFalse(Cache::read('test_groups', 'memcached_groups'));
+
+		$this->assertTrue(Cache::write('test_groups', 'value2', 'memcached_groups'));
+		$this->assertTrue(Cache::clearGroup('group_b', 'memcached_groups'));
+		$this->assertFalse(Cache::read('test_groups', 'memcached_groups'));
+	}
+}