Basic Caching Middleware

Middleware/Cache.php

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+<?php
+/**
+ * Cache
+ *
+ * Use this middleware with your Slim Framework application
+ * for basic caching abilities
+ *
+ * @author Timothy Boronczyk
+ * @version 1.0
+ *
+ * USAGE
+ *
+ * use \Slim\Slim;
+ * use \Slim\Extras\Middleware\Cache;
+ * use \Slim\Extras\Middleware\Cache\PDOCacheHandler;
+ *
+ * $db = ...
+ * $app = new Slim();
+ * $handler = new PDOCacheHandler($db);
+ * $app->add(new Cache($handler));
+ *
+ * MIT LICENSE
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+namespace Slim\Extras\Middleware;
+use \Slim\Extras\Middleware\Cache\ICacheHandler;
+
+class Cache extends \Slim\Middleware
+{
+    protected $handler;
+
+    public function __construct(ICacheHandler $handler)
+    {
+        $this->handler = $handler;
+    }
+
+    public function call()
+    {
+        $req     = $this->app->request();
+        $resp    = $this->app->response();
+        $handler = $this->handler;
+
+        $key = $req->getResourceUri();
+        $data = $handler->fetch($key);
+        if ($data) {
+            $resp['Content-Type'] = $data['content_type'];
+            $resp->body($data['body']);
+            return;
+        }
+
+        $this->next->call();
+
+        if ($resp->status() == 200) {
+            $handler->save($key, $resp['Content-Type'], $resp->body());
+        }
+    }
+}

Middleware/Cache/ICacheHandler.php

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+<?php
+/**
+ * Cache Handler Interface
+ *
+ * Implement this interface to create your own cache handler.
+ *
+ * @author Timothy Boronczyk
+ * @version 1.0
+ *
+ * MIT LICENSE
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+namespace Slim\Extras\Middleware\Cache;
+
+Interface ICacheHandler
+{
+    /**
+     * Retrieve content from cache.
+     * Looks up content in the cache for the given key and returns either
+     * an array with the content or false if the content is not found.
+     * 
+     * @param string $key the cache key
+     * @return array|false array with the elements content_type and body on
+     *  success, false if content not found
+     */
+    public function fetch($key);
+
+    /**
+     * Store content in the cache.
+     * Persists content in the cache storeage for later lookup.
+     *
+     * @param string $key the cache key
+     * @param string $contenType the content's Content-Type
+     * @param string $body the content
+     */
+    public function save($key, $contentType, $body);
+}

Middleware/Cache/PDOCacheHandler.php

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+<?php
+/**
+ * Example Cache Handler
+ *
+ * This example implementation uses a PDO connection to a MySQL database and
+ * the table structure included in cache.sql. You can write your own handler
+ * by implementing the ICacheHandler interface.
+ *
+ * @author Timothy Boronczyk
+ * @version 1.0
+ *
+ * MIT LICENSE
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+namespace Slim\Extras\Middleware\Cache;
+
+class PDOCacheHandler implements ICacheHandler
+{
+    protected $db;
+    protected $ttl;
+
+    public function __construct(\PDO $db, $ttl = 300)
+    {
+        $this->db = $db;
+        $this->ttl = $ttl;
+    }
+
+    public function fetch($key)
+    {
+        $query = sprintf(
+            'SELECT `content_type`, `body` FROM `cache` 
+            WHERE `key` = %s AND `tstamp` > %d',
+            $this->db->quote(md5($key)),
+            time() - $this->ttl
+        );
+        $result = $this->db->query($query);
+        $row = $result->fetch(\PDO::FETCH_ASSOC);
+        $result->closeCursor();
+        return $row;
+    }
+
+    public function save($key, $contentType, $body)
+    {
+        $query = sprintf(
+            'INSERT INTO `cache` (`key`, `content_type`, `body`, `tstamp`)
+            VALUES (%s, %s, %s, %d)
+            ON DUPLICATE KEY UPDATE
+            `content_type` = %2$s, `body` = %3$s, `tstamp` = %4$d',
+            $this->db->quote(md5($key)),
+            $this->db->quote($contentType),
+            $this->db->quote($body),
+            time()
+        );
+        $this->db->query($query);
+    }
+}

Middleware/Cache/cache.sql

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+CREATE TABLE `cache` (
+    `key` CHAR(40) NOT NULL PRIMARY KEY,
+    `content_type` VARCHAR(100) NOT NULL,
+    `body` TEXT NOT NULL,
+    `tstamp` INTEGER UNSIGNED NOT NULL
+);

Middleware/README.markdown

@@ -1,5 +1,24 @@
 # Slim Authentication and XSS Middlewares
 
+## Cache
+
+Provides basic Caching functionality.
+
+### How to use
+
+    use \Slim\Slim;
+    use \Slim\Extras\Middleware\Cache;
+    use \Slim\Extras\Middleware\Cache\PDOCacheHandler;
+
+    $db = ...
+    $app = new Slim();
+    $handler = new PDOCacheHandler($db);
+    $app->add(new Cache($handler));
+
+The example implementation `PDOCacheHandler` uses a PDO connection to a MySQL
+database and the table structure included in `Cache/cache.sql`. You can write
+your own handler by implementing the `ICacheHandler` interface.
+
 ## CsrfGuard
 
 This is used to protect your website from CSRF attacks.