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(PECL memcached >= 0.1.0)
Memcached::__construct — Create a Memcached instance
Creates a Memcached instance representing the connection to the memcache servers.
By default the Memcached instances are destroyed at the end of the request. To create an instance that persists between requests, use persistent_id to specify a unique ID for the instance. All instances created with the same persistent_id will share the same connection.
A Memcached object.
Beispiel #1 Creating a Memcached object
<?php
/* Create a regular instance */
$m1 = new Memcached();
echo get_class($m);
/* Create a persistent instance */
$m2 = new Memcached('story_pool');
$m3 = new Memcached('story_pool');
/* now $m2 and $m3 share the same connection */
?>
Using multiple memcached instances with options in combination with persistent connections might be confusing:
<?php
$a = new Memcached('memcached_pool');
$a->setOption(Memcached::OPT_COMPRESSION, false);
$b = new Memcached('memcached_pool');
$b->setOption(Memcached::OPT_COMPRESSION, true);
$a->add('key', 'some data');
?>
You might think that connection $a will store everything uncompressed, but this is not the case.
The persistent connection options are changed by the second object creation.
When using persistent connections, it is important to not re-add servers.
This is what you do not want to do:
<?php
$mc = new Memcached('mc');
$mc->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE, true);
$mc->addServers(array(
array('mc1.example.com',11211),
array('mc2.example.com',11211),
));
?>
Every time the page is loaded those servers will be appended to the list resulting in many simultaneous open connections to the same server. The addServer/addServers functions to not check for existing references to the specified servers.
A better approach is something like:
<?php
$mc = new Memcached('mc');
$mc->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE, true);
if (!count($mc->getServerList())) {
$mc->addServers(array(
array('mc1.example.com',11211),
array('mc2.example.com',11211),
));
}
?>
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