Encapsulate cache pool instantiation in CacheFactory

src/mibew/configs/default_config.yml

@@ -39,6 +39,19 @@ mailer:
     # "tls".
     encryption: false
 
+# Cache subsystem
+cache:
+    # This value determines where the cached data will be stored. Possible
+    # values are "none" and "file_system".
+    #
+    # If "none" is used the caching will be disabled. This option should be used
+    # only if none of the other options works.
+    #
+    # If "file_system" is used the cached data will be stored in files within
+    # the "cache/" directory. Notice, that the file system storage does not work
+    # on NFS systems bucause exclusive file locks are not supported where.
+    storage: file_system
+
 # Locales
 ## Native name will be used in this locale
 home_locale: en

src/mibew/index.php

@@ -22,6 +22,7 @@ require_once(dirname(__FILE__) . '/libs/init.php');
 
 use Mibew\Application;
 use Mibew\Authentication\AuthenticationManager;
+use Mibew\Cache\CacheFactory;
 use Mibew\Mail\MailerFactory;
 use Mibew\Routing\Router;
 use Mibew\Routing\Loader\CacheLoader;
@@ -31,14 +32,17 @@ use Symfony\Component\Config\Loader\LoaderResolver;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\Routing\Loader\YamlFileLoader;
 
-// Use custom cache
-$cache_driver = new \Stash\Driver\FileSystem();
-$cache_driver->setOptions(array('path' => MIBEW_FS_ROOT . '/cache/stash'));
-$cache = new \Stash\Pool($cache_driver);
+$configs = load_system_configs();
+
+// Prepare the cache
+$cache_factory = new CacheFactory($configs['cache']);
+// For now directory for cache files cannot be changed via the configs file.
+// TODO: Evaluate possibility of using custom cache directory.
+$cache_factory->setOption('path', MIBEW_FS_ROOT . '/cache/stash');
 
 // The main route loader which loads nothig but works as a cache proxy for other
 // loaders.
-$route_loader = new CacheLoader($cache);
+$route_loader = new CacheLoader($cache_factory->getCache());
 // Real loaders are attached via the resolver.
 $loader_resolver = new LoaderResolver(array(
     $route_loader,
@@ -49,10 +53,9 @@ $loader_resolver = new LoaderResolver(array(
 $router = new Router($route_loader, 'configs/routing.yml');
 
 $application = new Application($router, new AuthenticationManager());
-$application->setCache($cache);
+$application->setCache($cache_factory->getCache());
 
 // Use custom config-dependent mailer factory
-$configs = load_system_configs();
 $application->setMailerFactory(new MailerFactory($configs['mailer']));
 
 // Process request

src/mibew/libs/classes/Mibew/Cache/CacheFactory.php

@@ -0,0 +1,152 @@
+<?php
+/*
+ * This file is a part of Mibew Messenger.
+ *
+ * Copyright 2005-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Mibew\Cache;
+
+use Stash\Interfaces\PoolInterface;
+use Stash\Driver\Ephemeral as EphemeralDriver;
+use Stash\Driver\FileSystem as FileSystemDriver;
+use Stash\Pool as CachePool;
+
+/**
+ * Creates and configures appropriate instance of Cache pool.
+ */
+class CacheFactory
+{
+    /**
+     * @var PoolInterface|null
+     */
+    private $cache = null;
+
+    /**
+     * List of factory's options.
+     *
+     * @var array
+     */
+    private $options;
+
+    /**
+     * Class constructor.
+     *
+     * @param Array $options Associative array of options that should be used.
+     */
+    public function __construct($options = array())
+    {
+        $this->setOptions($options);
+    }
+
+    /**
+     * Gets factory's option.
+     *
+     * @param string $name Name of the option to retrieve.
+     * @throws \InvalidArgumentException If the option is unknown.
+     */
+    public function getOption($name)
+    {
+        if (!isset($this->options[$name])) {
+            throw new \InvalidArgumentException(sprintf('Unknown option "%s"', $name));
+        }
+
+        return $this->options[$name];
+    }
+
+    /**
+     * Sets factory's option.
+     *
+     * @param string $name Name of the option to set.
+     * @param string $value New value.
+     * @throws \InvalidArgumentException If the option is unknown.
+     */
+    public function setOption($name, $value)
+    {
+        if (!isset($this->options[$name])) {
+            throw new \InvalidArgumentException(sprintf('Unknown option "%s"', $name));
+        }
+
+        $this->options[$name] = $value;
+
+        // Cached instance of cache is not valid any more. New one should be
+        // created.
+        $this->cache = null;
+    }
+
+    /**
+     * Sets factory's options.
+     *
+     * @param array $options Associative array of options.
+     * @throws \InvalidArgumentException If specified array has unknow options.
+     */
+    public function setOptions($options)
+    {
+        $defaults = array(
+            'storage' => 'file_system',
+            'path' => '/tmp',
+        );
+
+        // Make sure all passed options are known
+        $unknown_options = array_diff(array_keys($options), array_keys($defaults));
+        if (count($unknown_options) != 0) {
+            throw new \InvalidArgumentException(sprintf(
+                'These options are unknown: %s',
+                implode(', ', $unknown_options)
+            ));
+        }
+
+        if (empty($this->options)) {
+            // The options are set for the first time.
+            $this->options = $options + $defaults;
+        } else {
+            // Update only specified options.
+            $this->options = $options + $this->options;
+        }
+
+        // Cached instance of cache is not valid any more. New one should be
+        // created.
+        $this->cache = null;
+    }
+
+    /**
+     * Builds cache pool instance.
+     *
+     * @return PoolInterface An instance of cache pool.
+     * @throws \RuntimeException If at least one of factory's options is
+     * invalid.
+     */
+    public function getCache()
+    {
+        if (is_null($this->cache)) {
+            $storage = $this->getOption('storage');
+            if ($storage === 'none') {
+                $driver = new EphemeralDriver();
+            } elseif ($storage === 'file_system') {
+                $driver = new FileSystemDriver();
+                $driver->setOptions(array('path' => $this->getOption('path')));
+            } else {
+                throw new \RuntimeException(sprintf(
+                    'Wrong value of "storage" option: "%s"',
+                    $storage
+                ));
+            }
+
+            $this->cache = new CachePool($driver);
+        }
+
+        return $this->cache;
+    }
+}

src/mibew/libs/common/configurations.php

@@ -33,9 +33,13 @@ function load_system_configs()
     if (is_null($configs)) {
         $parser = new YamlParser();
         $configs = $parser->parse(file_get_contents(MIBEW_FS_ROOT . '/configs/config.yml'));
-        // Mailer configs are not necessary and can be omited but the section
-        // must exist anyway.
-        $configs += array('mailer' => array());
+        $configs += array(
+            // Mailer configs are not necessary and can be omited but the
+            // section must exist anyway.
+            'mailer' => array(),
+            // Cache section must extst too.
+            'cache' => array(),
+        );
     }
 
     return $configs;