moodle/lib/adodb/adodb-memcache.lib.inc.php

<?php

// security - hide paths
if (!defined('ADODB_DIR')) die();

global $ADODB_INCLUDED_MEMCACHE;
$ADODB_INCLUDED_MEMCACHE = 1;

global $ADODB_INCLUDED_CSV;
if (empty($ADODB_INCLUDED_CSV)) include_once(ADODB_DIR.'/adodb-csvlib.inc.php');

/*

  @version   v5.21.0  2021-02-27
  @copyright (c) 2000-2013 John Lim (jlim#natsoft.com). All rights reserved.
  @copyright (c) 2014      Damien Regad, Mark Newnham and the ADOdb community
  Released under both BSD license and Lesser GPL library license.
  Whenever there is any discrepancy between the two licenses,
  the BSD license will take precedence. See License.txt.
  Set tabs to 4 for best viewing.

  Latest version is available at https://adodb.org/

Usage:

$db = NewADOConnection($driver);
$db->memCache = true; /// should we use memCache instead of caching in files
$db->memCacheHost = array($ip1, $ip2, $ip3);
$db->memCachePort = 11211; /// this is default memCache port
$db->memCacheCompress = false; /// Use 'true' to store the item compressed (uses zlib)
                               /// Note; compression is not supported w/the memcached library

$db->Connect(...);
$db->CacheExecute($sql);

  Notes; The memcache class is shared by all connections, is created during the first call to Connect/PConnect.
         We'll look for both the memcache library (https://pecl.php.net/package/memcache) and the  memcached
         library (https://pecl.php.net/package/memcached). If both exist, the memcache library will be used.

  Class instance is stored in $ADODB_CACHE
*/

	class ADODB_Cache_MemCache {
		var $createdir = false; // create caching directory structure?

		// $library will be populated with the proper library on connect
		// and is used later when there are differences in specific calls
		// between memcache and memcached
		var $library = false;

		//-----------------------------
		// memcache specific variables

		var $hosts;	// array of hosts
		var $port = 11211;
		var $compress = false; // memcache compression with zlib

		var $_connected = false;
		var $_memcache = false;

		function __construct(&$obj)
		{
			$this->hosts = $obj->memCacheHost;
			$this->port = $obj->memCachePort;
			$this->compress = $obj->memCacheCompress;
		}

		// implement as lazy connection. The connection only occurs on CacheExecute call
		function connect(&$err)
		{
			// do we have memcache or memcached?
			if (class_exists('Memcache')) {
				$this->library='Memcache';
				$memcache = new MemCache;
			} elseif (class_exists('Memcached')) {
				$this->library='Memcached';
				$memcache = new MemCached;
			} else {
				$err = 'Neither the Memcache nor Memcached PECL extensions were found!';
				return false;
			}

			if (!is_array($this->hosts)) $this->hosts = array($this->hosts);

			$failcnt = 0;
			foreach($this->hosts as $host) {
				if (!@$memcache->addServer($host,$this->port)) {
					$failcnt += 1;
				}
			}
			if ($failcnt == sizeof($this->hosts)) {
				$err = 'Can\'t connect to any memcache server';
				return false;
			}
			$this->_connected = true;
			$this->_memcache = $memcache;
			return true;
		}

		// returns true or false. true if successful save
		function writecache($filename, $contents, $debug, $secs2cache)
		{
			if (!$this->_connected) {
				$err = '';
				if (!$this->connect($err) && $debug) ADOConnection::outp($err);
			}
			if (!$this->_memcache) return false;

			$failed=false;
			switch ($this->library) {
				case 'Memcache':
					if (!$this->_memcache->set($filename, $contents, $this->compress ? MEMCACHE_COMPRESSED : 0, $secs2cache)) {
						$failed=true;
					}
					break;
				case 'Memcached':
					if (!$this->_memcache->set($filename, $contents, $secs2cache)) {
						$failed=true;
					}
					break;
				default:
					$failed=true;
					break;
			}

			if($failed) {
				if ($debug) ADOConnection::outp(" Failed to save data at the memcache server!<br>\n");
				return false;
			}

			return true;
		}

		// returns a recordset
		function readcache($filename, &$err, $secs2cache, $rsClass)
		{
			$false = false;
			if (!$this->_connected) $this->connect($err);
			if (!$this->_memcache) return $false;

			$rs = $this->_memcache->get($filename);
			if (!$rs) {
				$err = 'Item with such key doesn\'t exist on the memcache server.';
				return $false;
			}

			// hack, should actually use _csv2rs
			$rs = explode("\n", $rs);
            unset($rs[0]);
            $rs = join("\n", $rs);
 			$rs = unserialize($rs);
			if (! is_object($rs)) {
				$err = 'Unable to unserialize $rs';
				return $false;
			}
			if ($rs->timeCreated == 0) return $rs; // apparently have been reports that timeCreated was set to 0 somewhere

			$tdiff = intval($rs->timeCreated+$secs2cache - time());
			if ($tdiff <= 2) {
				switch($tdiff) {
					case 2:
						if ((rand() & 15) == 0) {
							$err = "Timeout 2";
							return $false;
						}
						break;
					case 1:
						if ((rand() & 3) == 0) {
							$err = "Timeout 1";
							return $false;
						}
						break;
					default:
						$err = "Timeout 0";
						return $false;
				}
			}
			return $rs;
		}

		function flushall($debug=false)
		{
			if (!$this->_connected) {
				$err = '';
				if (!$this->connect($err) && $debug) ADOConnection::outp($err);
			}
			if (!$this->_memcache) return false;

			$del = $this->_memcache->flush();

			if ($debug)
				if (!$del) ADOConnection::outp("flushall: failed!<br>\n");
				else ADOConnection::outp("flushall: succeeded!<br>\n");

			return $del;
		}

		function flushcache($filename, $debug=false)
		{
			if (!$this->_connected) {
  				$err = '';
  				if (!$this->connect($err) && $debug) ADOConnection::outp($err);
			}
			if (!$this->_memcache) return false;

			$del = $this->_memcache->delete($filename);

			if ($debug)
				if (!$del) ADOConnection::outp("flushcache: $key entry doesn't exist on memcache server!<br>\n");
				else ADOConnection::outp("flushcache: $key entry flushed from memcache server!<br>\n");

			return $del;
		}

		// not used for memcache
		function createdir($dir, $hash)
		{
			return true;
		}
	}