<?php
/*
**	Copyright (C) 1995-2008 by the ITools Authors.
**	This file is part of ITools - the Internet Tools Library
**
**	ITools 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.
**
**	ITools 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/>.
**
**	it_cache.class - Caching functions
*/

class it_cache
{
	static $_fetch_func;
	static $_store_func;

static function _defaults($p)
{
	$p += array(
		'ttl' => 2,
		'distributed' => $p['distributed_on_devel'],
		'hostsfile' => '/opt/ultra/etc/memcached.hosts',
		'safety' => 1,
	);

	if (!it::is_live() && !$p['distributed_on_devel'])
		$p['distributed'] = false;	# Always local cache on non-live systems

	return $p;
}

/**
 * Get value for specific key from cache. Can be mixed value but no objects. WARNING: only distributed works from shell
 * @param $key Key to get value for
 * @param $p['distributed'] Use distributed memcache (scalars may become strings) [false]
 * @return Value for given key or null
 */
static function get($key, $p = array())
{
	$p = it_cache::_defaults($p);

	if (isset($GLOBALS['it_cache_local'][$key]))
	{
		# Use local copy
		$result = $GLOBALS['it_cache_local'][$key];
		$success = true;
	}
	else if ($p['distributed'] && ($memcache = it_cache::_get_memcache($p)))
	{
		$result = @$memcache->get($key);
		$success = !$memcache->getResultCode();
	}
	else
		$result = ($func = self::$_fetch_func) ? $func($key, $success) : null;

	return $success === false ? null : $result;
}

/**
 * Put value for specific key into cache. Can be mixed value but no objects. WARNING: only distributed works from shell
 * @param $key Key to put value with
 * @param $value Value to put (mixed but no objects allowed)
 * @param $p['distributed'] Use distributed memcache on live machines (scalars may become strings) [false]
 * @param $p['distributed_on_devel'] Like $p['distributed'], but also use memcache on devel and twin
 * @param $p['ttl'] Time to live for this key/value-pair in seconds
 * @param $p['safety'] set to 0 to suppress an it::error in case of failure [1]
 * @return Returns $value
 */
static function put($key, $value, $p = array())
{
	$p = it_cache::_defaults($p);

	if ($p['distributed'] && ($memcache = it_cache::_get_memcache($p)))
		$success = @$memcache->set($key, $value, $p['ttl']);
	else
		$success = ($func = self::$_store_func) ? $func($key, $value, $p['ttl']) : null;

	if (!$success && $p['safety'] == 1)
		it::error(array('title' => ($p['distributed'] ? "memcache (" . ($memcache ? ($memcache->getResultMessage() . " on " . $memcache->getServerByKey($key)['host']) : "n/a") . ")" : self::$_store_func) . " in it_cache::put failed for key '$key'", 'id' => "it_cache_put", 'graceperiod' => 300, 'timewindow' => 10));

	$GLOBALS['it_cache_local'][$key] = $value;	# Also store local copy

	return $value;
}

static function _get_memcache($p)
{
	$memcache_id = "it_cache_memcache_" . $p['hostsfile'];

	if (!isset($GLOBALS[$memcache_id]) && class_exists("Memcached", false))
	{
		$memcache = new Memcached;

		foreach (array_filter(it::replace(array('[#\s].*' => ""), file($p['hostsfile']))) as $host)
			$reachable += intval(@$memcache->addServer($host, 11211));

		$GLOBALS[$memcache_id] = $reachable ? $memcache : false;
	}

	return $GLOBALS[$memcache_id];
}

}

it_cache::$_fetch_func = function_exists("apcu_fetch") ? "apcu_fetch" : (function_exists("apc_fetch") ? "apc_fetch" : null);
it_cache::$_store_func = function_exists("apcu_store") ? "apcu_store" : (function_exists("apc_store") ? "apc_store" : null);