Disk cache plugin

plugins/DiskCachePlugin.php

@@ -0,0 +1,155 @@
+<?php
+/**
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2009, StatusNet, Inc.
+ *
+ * Plugin to implement cache interface with disk files
+ *
+ * PHP version 5
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  Cache
+ * @package   StatusNet
+ * @author    Evan Prodromou <evan@status.net>
+ * @copyright 2009 StatusNet, Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://status.net/
+ */
+
+if (!defined('STATUSNET')) {
+    // This check helps protect against security problems;
+    // your code file can't be executed directly from the web.
+    exit(1);
+}
+
+/**
+ * A plugin to cache data on local disk
+ *
+ * @category  Cache
+ * @package   StatusNet
+ * @author    Evan Prodromou <evan@status.net>
+ * @copyright 2009 StatusNet, Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://status.net/
+ */
+
+class DiskCachePlugin extends Plugin
+{
+    var $root = '/tmp';
+
+    function keyToFilename($key)
+    {
+        return $this->root . '/' . str_replace(':', '/', $key);
+    }
+
+    /**
+     * Get a value associated with a key
+     *
+     * The value should have been set previously.
+     *
+     * @param string &$key   in; Lookup key
+     * @param mixed  &$value out; value associated with key
+     *
+     * @return boolean hook success
+     */
+
+    function onStartCacheGet(&$key, &$value)
+    {
+        $filename = $this->keyToFilename($key);
+        if (file_exists($filename)) {
+            $this->log(LOG_INFO, "Cache hit on key '$key'");
+            $data = file_get_contents($filename);
+            $value = unserialize($data);
+        } else {
+            $this->log(LOG_INFO, "Cache miss on key '$key'");
+        }
+
+        Event::handle('EndCacheGet', array($key, &$value));
+        return false;
+    }
+
+    /**
+     * Associate a value with a key
+     *
+     * @param string  &$key     in; Key to use for lookups
+     * @param mixed   &$value   in; Value to associate
+     * @param integer &$flag    in; Flag (passed through to Memcache)
+     * @param integer &$expiry  in; Expiry (passed through to Memcache)
+     * @param boolean &$success out; Whether the set was successful
+     *
+     * @return boolean hook success
+     */
+
+    function onStartCacheSet(&$key, &$value, &$flag, &$expiry, &$success)
+    {
+        $this->log(LOG_INFO, "Setting value for key '$key'");
+
+        $filename = $this->keyToFilename($key);
+        $parent = dirname($filename);
+
+        $sofar = '';
+
+        foreach (explode('/', $parent) as $part) {
+            if (empty($part)) {
+                continue;
+            }
+            $sofar .= '/' . $part;
+            if (!is_dir($sofar)) {
+                $this->debug("Creating new directory '$sofar'");
+                $success = mkdir($sofar, 0750);
+                if (!$success) {
+                    $this->log(LOG_ERR, "Can't create directory '$sofar'");
+                    return false;
+                }
+            }
+        }
+
+        if (is_dir($filename)) {
+            $success = false;
+            return false;
+        }
+
+        file_put_contents($filename, serialize($value));
+
+        Event::handle('EndCacheSet', array($key, $value, $flag,
+                                           $expiry));
+
+        return false;
+    }
+
+    /**
+     * Delete a value associated with a key
+     *
+     * @param string  &$key     in; Key to lookup
+     * @param boolean &$success out; whether it worked
+     *
+     * @return boolean hook success
+     */
+
+    function onStartCacheDelete(&$key, &$success)
+    {
+        $this->log(LOG_INFO, "Deleting value for key '$key'");
+
+        $filename = $this->keyToFilename($key);
+
+        if (file_exists($filename) && !is_dir($filename)) {
+            unlink($filename);
+        }
+
+        Event::handle('EndCacheDelete', array($key));
+        return false;
+    }
+}
+