There are basically two memcached clients for PHP right now (memcache, and memcached), note the d at the latter. The memcache extension is older, lightweight, and most commonly used, and easier to install. The memcached module is feature-rich but still not widely adopted.
For the sake of simplicity, we will be using the memcache PHP extension in this recipe.
PHP is one of the most popular languages used for Web development today, it's very likely that you are actually using many pieces of software written in PHP on a daily basis without knowing.
I'm assuming you are using Ubuntu; you will need to have the simple setup of apache2 and php5. It's simple to get this stack working using this command:
sudo apt-get install apache2 php5
First, we need to install the PHP memcache extension using apt-get:
sudo apt-get install php5-memcache
This automatically installs the extension and gets everything wired and configured for you, if you want to use the memcached extension instead, all you need to do is to replace php5-memcache with php5-memcached and voila, everything just works!
If you are using Mac OS X, it's a slightly different story, and you will need to install apache2 and php5.
One of the quickest ways to do so is to install a nice package called MAMP (http://www.mamp.info/en/index.html); it will make life a lot easier for you. But, if you are an advanced user and want to go with the more manual route, you get really detailed instructions to get your OS X setup ready with Apache, MySQL, and PHP ready at (http://jason.pureconcepts.net/2012/10/install-apache-php-mysql-mac-os-x/).
First, we are going to start with a connection test to the memcached daemon:
<?php $memcache = new Memcache; $memcache->connect('localhost', 11211) or die ("Could not connect"); $version = $memcache->getVersion(); echo "Server's version: ".$version."<br/>\n"; ?>The output of this script actually depends on the current version of the memcached server running, in my case the output is:
Server's version: 1.4.13
Next, let's set and get some keys from the connected memcached server:
<?php $memcache = new Memcache; $memcache->connect('localhost', 11211) or die ("Could not connect"); $sample_obj = new stdClass; $sample_obj->str_attr = 'Memcache in PHP is cool'; $sample_obj->int_attr = 2468; $memcache->set('sample_user', $sample_obj, false, 15) or die ("Failed to store data in memcached"); echo "Data stored in Memcached (will expire in 15 seconds)<br/>\n"; $get_result = $memcache->get('sample_user'); echo "Object from the cache:<br/>\n"; var_dump($get_result); ?>
First, we are creating the Memcache object, that's the object we will be using to communicate with our memcached server in an object-oriented manner.
Then, we initialize the connection to the memcached server using the connect method that has the following signature which takes the host, port, and connection timeout:
bool Memcache::connect ( string $host [, int $port [, int $timeout ]] )
The connect method closes the connection to the memcached server automatically at the end of the execution of the script.
Then, we used the getVersion method to retrieve the version of the memcached server we are connected to. We are using this method only to test our connection to the memcached server.
We then moved to the real work, we created an instance of the stdClass of PHP and added two attributes to the object to serialize and store in memcached under the key "sample_user"; We set the timeout to 15 seconds, this means that the memcached server will delete the key after 15 seconds. We also used false for flags, since we don't need compression or any other setting at the moment.
Then, we retrieved the value back from memcached using the get method of the Memcache object, and then we printed it on the screen. The output of the script would be as follows:
Data stored in cached (will expire in 15 seconds)Object from the cache:object(stdClass)#3 (2) { ["str_attr"]=> string(23) "Memcache in PHP is cool" ["int_attr"]=> int(2468) }If you are planning to connect to a cluster of memcached servers you will need to add all the servers using the addServer method:
<?php
/* OO API */
$memcache = new Memcache;
$memcache->addServer('memcached_host1', 11211);
$memcache->addServer('memcached_host2', 11211);
?>Then, start using your memcache instance as usual and the magic will happen.