Руководство по PHP
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# LXXXIII. Memcache Functions

# Введение

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/.

# Требования

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.

# Установка

Это расширение PECL не поставляется вместе с PHP. Дополнительная информация, такая как новый версии, скачивание, исходные файлы, информация о разработчике и CHANGELOG, могут быть найдены здесь: 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. Вы можете скачать DLL этого расширения PECL со страницы PHP Downloads или http://snaps.php.net/.

# Настройка во время выполнения

Поведение этих функций зависит от установок в `php.ini`.

Таблица 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

Для подробного описания констант PHP_INI_*, обратитесь к документации функции ini_set().

Краткое разъяснение конфигурационных директив.

`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.

# Типы ресурсов

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

# Предопределенные константы

Таблица 2. MemCache Constants

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

# Примеры

Пример 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.

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