<?php
// $Id: Cache.php,v 1.1.2.17 2010-08-20 21:36:19 andypost Exp $

/**
 * @file
 *   Defines the base class for cache engines
 */

class CacheRouterEngine {
  var $settings = array();
  var $content = array();
  var $prefix;
  var $name;
  var $lookup;
  var $lock;
  var $lock_dir;
  var $lock_fp;
  var $fast_cache = TRUE;
  var $static = FALSE;
  var $lifetime = 0;

  function __construct($bin, $options, $default_options) {

    $this->name = $bin;
    // Setup our prefixes so that we can prefix a particular bin, or if not set use the default prefix.
    if (isset($options['prefix'])) {
      $this->prefix = $options['prefix'] . '-';
    }
    elseif (!empty($default_options['prefix'])) {
      $this->prefix = $default_options['prefix'] . '-';
    }

    // This allows us to turn off fast_cache for cache_page so that we can get anonymous statistics.
    if (isset($options['fast_cache'])) {
      $this->fast_cache = $default_options['fast_cache'];
    }
    elseif (isset($default_options['fast_cache'])) {
      $this->fast_cache = $default_options['fast_cache'];
    }

    // This allows us to turn off static content caching for modules/bins that are already doing this.
    if (isset($options['static'])) {
      $this->static = $options['static'];
    }
    elseif (isset($default_options['static'])) {
      $this->static = $default_options['static'];
    }

    if (isset($options['lock_dir'])) {
      $this->lock_dir = $options['lock_dir'];
    }
    elseif (isset($default_options['lock_dir'])) {
      $this->lock_dir = $default_options['lock_dir'];
    }
    else {
      $tmp_dir = ini_get('upload_tmp_dir');
      $this->lock_dir =  (!empty($tmp_dir)) ? $tmp_dir : '/tmp';
    }

    // Setup our prefixed lookup and lock table names for shared storage.
    $this->lookup = $this->prefix . $this->name . '_lookup';
    $this->lock = $this->lock_dir . '/' . $this->prefix . $this->name . '_lock';
  }

  function get($key) {
    if (isset($this->content[$key]) && $this->static) {
      return $this->content[$key];
    }
  }

  function garbage_collection() {
    // Do nothing. Child classes may want to do something.
  }
  
  function set($key, $value) {
    if ($this->static) {
      $this->content[$key] = $value;
    }
  }

  function delete($key) {
    if ($this->static) {
      unset($this->content[$key]);
    }
  }

  function flush() {
    if ($this->static) {
      $this->content = array();
    }
  }

  /**
   * key()
   *   Get the full key of the item
   *
   * @param string $key
   *   The key to set.
   * @return string
   *   Returns the full key of the cache item.
   */
  function key($key) {
    return urlencode($this->prefix . $this->name . '-' . $key);
  }

  /**
   * lock()
   *   lock the cache from other writes.
   *
   * @param none
   * @return string
   *   Returns TRUE on success, FALSE on failure
   */
  function lock() {
    $this->lock_fp = fopen($this->lock, "w");
    flock($this->lock_fp, LOCK_EX);
    return TRUE;
  }

  /**
   * unlock()
   *   lock the cache from other writes.
   *
   * @param none
   * @return bool
   *   Returns TRUE on success, FALSE on failure
   */
  function unlock() {
    unlink($this->lock);
  }
}