Memcache Functions
簡介
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.
The Memcache module also provides a session handler (memcache).
More information about memcached can be found at » https://www.danga.com/memcached/.
需求
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.
安裝
本 » PECL 擴充功能未包含於 PHP 中。 安裝此 PECL 擴充功能的訊息可在手冊中標題為 PECL 擴充功能安裝的一章中找到。 更多訊息如新版本，下載，原始文件，維護者訊息以及更新日誌等可以在這裡找到： » https://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. You may optionally disable memcache session handler support by specifying --disable-memcache-session.
Windows users will enable php_memcache.dll inside of php.ini in order to use these functions. 可以從 » PHP 下載頁面或者 » https://snaps.php.net/ 下載此 PECL 擴充功能的 DLL 文件。
執行時期設定
這些函式的行為受 php.ini 的影響。
| 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. |
| memcache.hash_strategy | "standard" | PHP_INI_ALL | Available since memcache 2.2.0. |
| memcache.hash_function | "crc32" | PHP_INI_ALL | Available since memcache 2.2.0. |
| session.save_handler | "files" | PHP_INI_ALL | Supported since memcache 2.1.2 |
| session.save_path | "" | PHP_INI_ALL | Supported since memcache 2.1.2 |
以下是設定選項的簡要解釋。
- 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.
- memcache.hash_strategy string
-
Controls which strategy to use when mapping keys to servers. Set this value to consistent to enable consistent hashing which allows servers to be added or removed from the pool without causing keys to be remapped. Setting this value to standard results in the old strategy being used.
- memcache.hash_function string
-
Controls which hash function to apply when mapping keys to servers, crc32 uses the standard CRC32 hash while fnv uses FNV-1a.
- session.save_handler string
-
Use memcache as a session handler by setting this value to memcache.
- session.save_path string
-
Defines a comma separated of server urls to use for session storage, for example "tcp://host1:11211, tcp://host2:11211".
Each url may contain parameters which are applied to that server, they are the same as for the Memcache::addServer() method. For example "tcp://host1:11211?persistent=1&weight=1&timeout=1&retry_interval=15"
資源類型
There is only one resource type used in memcache module - it's the link identifier for a cache server connection.
預設常數
| Name | Description |
|---|---|
| MEMCACHE_COMPRESSED (integer) | Used to turn on-the-fly data compression on with Memcache::set(), Memcache::add() 和 Memcache::replace(). |
| MEMCACHE_HAVE_SESSION (integer) | 1 if this Memcache session handler is available, 0 otherwise. |
範例
Example#1 memcache extension overview example
In this 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.
<?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);
?>
Example#2 Using memcache session handler
<?php
$session_save_path = "tcp://$host:$port?persistent=1&weight=2&timeout=2&retry_interval=10, ,tcp://$host:$port ";
ini_set('session.save_handler', 'memcache');
ini_set('session.save_path', $session_save_path);
?>
Table of Contents
- 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