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/.
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.
This PECL extension
is not bundled with PHP.
Information for installing this PECL extension may be
found in the manual chapter titled Installation
of PECL extensions. 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/.
The behaviour of these functions is affected by settings in php.ini.
Table 1. Memcache Configuration Options
| Name | Default | Changeable | Changelog |
|---|
| memcache.allow_failover | "1" | PHP_INI_ALL | Available since Memcache 2.0.2 |
| 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 |
For further details and definitions of the
PHP_INI_* constants, see the
Appendix G.
Here's a short explanation of
the configuration directives.
- memcache.allow_failover
boolean
Whether to transparently failover to other servers on
errors.
- 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.
There is only one resource type used in memcache module - it's
the link identifier for a cache server connection.
Table 2. MemCache Constants
| Name | Description |
|---|
|
MEMCACHE_COMPRESSED
(integer)
|
Used to turn on-the-fly data compression on with
Memcache::set(),
Memcache::add() and
Memcache::replace().
|
Example 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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