oops adding filecache, a=chris

diff --git a/lib/file_cache.php b/lib/file_cache.php
new file mode 100644
index 000000000..e4f7b8c86
--- /dev/null
+++ b/lib/file_cache.php
@@ -0,0 +1,152 @@
+<?php
+/**
+ *  SeekQuarry/Yioop --
+ *  Open Source Pure PHP Search Engine, Crawler, and Indexer
+ *
+ *  Copyright (C) 2009, 2010, 2011  Chris Pollett chris@pollett.org
+ *
+ *  LICENSE:
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  END LICENSE
+ *
+ * @author Chris Pollett chris@pollett.org
+ * @package seek_quarry
+ * @subpackage library
+ * @license http://www.gnu.org/licenses/ GPL3
+ * @link http://www.seekquarry.com/
+ * @copyright 2009, 2010, 2011
+ * @filesource
+ */
+
+if(!defined('BASE_DIR')) {echo "BAD REQUEST"; exit();}
+
+/** Loads common constants for web crawling*/
+require_once BASE_DIR."/lib/crawl_constants.php";
+/** Used to manage for file i/o functions */
+require_once BASE_DIR."/models/datasources/".DBMS."_manager.php";
+
+/**
+ * Library of functions used to implement a simple file cache
+ * This might be used on systems that don't have memcache
+ *
+ * @author Chris Pollett
+ *
+ * @package seek_quarry
+ * @subpackage library
+ */
+class FileCache
+{
+    /**
+     * Folder name to use for this FileCache
+     * @var string
+     */
+    var $dir_name;
+
+    /**
+     * How many seconds a bin is vulnerable to be deleted as expired
+     */
+    const SECONDS_IN_A_BIN = 3600;
+
+    /**
+     * Total number of bins to cycle between
+     */
+    const NUMBER_OF_BINS = 24;
+
+    /**
+     * Creates the directory for the file cache, sets how frequently
+     * all items in the cache expire
+     *
+     * @param string $dir_name folder name of where to put the file cache
+     */
+    function __construct($dir_name)
+    {
+        $this->dir_name = $dir_name;
+
+        if(!is_dir($this->dir_name)) {
+            mkdir($this->dir_name);
+            $db_class = ucfirst(DBMS)."Manager";
+            $db = new $db_class();
+            $db->setWorldPermissionsRecursive($this->dir_name, true);
+        }
+    }
+
+    /**
+     * Retrieve data associated with a key that has been put in the cache
+     *
+     * @param string $key the key to look up
+     * @return mixed the data associated with the key if it exists, false
+     *      otherwise
+     */
+    function get($key)
+    {
+        $checksum_block = $this->checksum($key);
+        $cache_file = $this->dir_name."/$checksum_block/".webencode($key);
+        if(file_exists($cache_file)) {
+            return unserialize(file_get_contents($cache_file));
+        }
+        return false;
+    }
+
+    /**
+     * Stores in the cache a key-value pair
+     *
+     * @param string $key to associate with value
+     * @param mixed $value to store
+     */
+    function set($key, $value)
+    {
+        $expire_block = floor(time() / self::SECONDS_IN_A_BIN)
+            % self::NUMBER_OF_BINS;
+        $checksum_block = $this->checksum($key);
+        $checksum_dir = $this->dir_name."/$checksum_block";
+        if($expire_block == $checksum_block ) {
+            $last_expired =
+                unserialize(
+                    file_get_contents("$checksum_dir/last_expired.txt"));
+            if(time() - $last_expired > self::SECONDS_IN_A_BIN) {
+                $db_class = ucfirst(DBMS)."Manager";
+                $db = new $db_class();
+                $db->unlinkRecursive($checksum_dir);
+            }
+        }
+        if(!file_exists($checksum_dir)) {
+            mkdir($checksum_dir);
+            $last_expired = time();
+            file_put_contents("$checksum_dir/last_expired.txt",
+                serialize($last_expired));
+        }
+        $cache_file = "$checksum_dir/".webencode($key);
+        file_put_contents($cache_file, serialize($value));
+    }
+
+    /**
+     * Makes a 0 - self::NUMBER_OF_BINS value out of the provided key
+     *
+     * @param string $key to convert to a random value between
+     *      0 - self::NUMBER_OF_BINS
+     * @return int value between 0 and self::NUMBER_OF_BINS
+     */
+    function checksum($key)
+    {
+        $len = strlen($key);
+        $value = 0;
+        for($i = 0; $i < $len; $i++) {
+            $value += ord($key[$i]);
+        }
+        return ($value % self::NUMBER_OF_BINS);
+    }
+}
+?>