LXXXIII. Memcache Functions

Introduzione

Memcache module provides handy procedural and object oriented interface to memcached, highly effective caching daemon, which was especially designed to decrease database load in dynamic web applications.

More information about memcached can be found at http://www.danga.com/memcached/.

Requisiti

This module uses functions of zlib to support on-the-fly data compression. Zlib is required to install this module.

PHP 4.3.3 or newer is required to use the memcache extension.

Installazione

This PECL extension is not bundled with PHP. Additional information such as new releases, downloads, source files, maintainer information, and a CHANGELOG, can be located here: http://pecl.php.net/package/memcache.

In order to use these functions you must compile PHP with Memcache support by using the --enable-memcache[=DIR] option.

Windows users will enable php_memcache.dll inside of php.ini in order to use these functions. You may download this PECL extension DLL from the PHP Downloads page or at http://snaps.php.net/.

Configurazione di Runtime

Il comportamento di queste funzioni è influenzato dalle impostazioni di php.ini.

Tabella 1. Memcache Configuration Options

Name	Default	Changeable	Changelog
memcache.allow_failover	"1"	PHP_INI_ALL	Available since Memcache 2.0.2
memcache.max_failover_attempts	"20"	PHP_INI_ALL	Available since Memcache 2.1.0
memcache.chunk_size	"8192"	PHP_INI_ALL	Available since Memcache 2.0.2
memcache.default_port	"11211"	PHP_INI_ALL	Available since Memcache 2.0.2

Per maggiori dettagli sulle costanti PHP_INI_* vedere Appendice G.

Breve descrizione dei parametri di configurazione.

memcache.allow_failover boolean: Whether to transparently failover to other servers on errors.
memcache.max_failover_attempts integer: Defines how many servers to try when setting and getting data. Used only in conjunction with memcache.allow_failover.
memcache.chunk_size integer: Data will be transferred in chunks of this size, setting the value lower requires more network writes. Try increasing this value to 32768 if noticing otherwise inexplicable slowdowns.
memcache.default_port string: The default TCP port number to use when connecting to the memcached server if no other port is specified.

Tipi di risorse

There is only one resource type used in memcache module - it's the link identifier for a cache server connection.

Costanti predefinite

Tabella 2. MemCache Constants

Name	Description
`MEMCACHE_COMPRESSED` (integer)	Used to turn on-the-fly data compression on with Memcache::set(), Memcache::add() e Memcache::replace().

Esempi

Esempio 1. memcache extension overview example
<?php $memcache = new Memcache; $memcache->connect('localhost', 11211) or die ("Could not connect"); $version = $memcache->getVersion(); echo "Server's version: ".$version."<br/>\n"; $tmp_object = new stdClass; $tmp_object->str_attr = 'test'; $tmp_object->int_attr = 123; $memcache->set('key', $tmp_object, false, 10) or die ("Failed to save data at the server"); echo "Store data in the cache (data will expire in 10 seconds)<br/>\n"; $get_result = $memcache->get('key'); echo "Data from the cache:<br/>\n"; var_dump($get_result); ?>

In the above example, an object is being saved in the cache and then retrieved back. Object and other non-scalar types are serialized before saving, so it's impossible to store resources (i.e. connection identifiers and others) in the cache.

Sommario
Memcache::add -- Add an item to the server
Memcache::addServer -- Add a memcached server to connection pool
Memcache::close -- Close memcached server connection
Memcache::connect -- Open memcached server connection
memcache_debug -- Turn debug output on/off
Memcache::decrement -- Decrement item's value
Memcache::delete -- Delete item from the server
Memcache::flush -- Flush all existing items at the server
Memcache::get -- Retrieve item from the server
Memcache::getExtendedStats -- Get statistics from all servers in pool
Memcache::getServerStatus -- Returns server status
Memcache::getStats -- Get statistics of the server
Memcache::getVersion -- Return version of the server
Memcache::increment -- Increment item's value
Memcache::pconnect -- Open memcached server persistent connection
Memcache::replace -- Replace value of the existing item
Memcache::set -- Store data at the server
Memcache::setCompressThreshold -- Enable automatic compression of large values
Memcache::setServerParams -- Changes server parameters and status at runtime