Posted inmemcache nginx

Nginx Memcached Module, Caching Webiste Image Using Memcached

During my exploration of optimzing website using memcached, i’ve found this tutorial. It’s quite interesting using key value application (memcached) for serving website’s static content, Such as image, jss or js file. As we know, Reading/writing Hardrive is slower than accessing memory. although compared with SSD or 7,200 RPM hard drives. Even when an application is loaded, any files that are opened for use in that application are loaded into memory. As well as how web servers work.

First time following the tutorial, it isn’t work. image files not loaded into memcached, no warn, now error. after slightly modifying the script, image files can be stored into the memcached perfectly.

Here’s the php script after modification, i saved it as mem.php

<?php

function rscandir($base='', &$data=array()) {
        $array = array_diff(scandir($base), array('.', '..'));

        foreach($array as $value) {
                if (is_dir($base."/".$value)) {
                        $data = rscandir($base."/".$value,$data);

                }
                elseif (is_file($base."/".$value)) {
                $rest = substr($value, -4);
                        if ((!strcmp($rest,'.jpg')) || (!strcmp($rest,'.png')) || (!strcmp($rest,'.gif'))) {
                                $data[] = $base."/".$value;
                        }
                }

        }
return $data;

}

$mylist=rscandir("/path/to/public_html");

$srch = array('/path/to/public_html');
$newval = array('');

$memcache_obj = memcache_connect("127.0.0.1", 11211);

while (list($key, $val) = each($mylist)) {
        $url=str_replace($srch,$newval,$val);
        echo "$key => $val -> ".filesize($val)."\n";
        $value = file_get_contents($val);
        memcache_add($memcache_obj, $url, $value, false, 0);
}

?>
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Posted inmemcache nginx php

Nginx Memcached module And PHP

I’ve seen lots of tutorials on internet explaining how set nginx to use memcached module. But, i’ve rarely seen them explaining, even the easiest one on how to populate memcached with data generated by php. When i’m getting in touch with memcached for the first time, i thought default configuration like this will be working out of the box. without touching php script. 😀

server {

	listen 80;
	server_name  example.com www.example.com;

	# ...

	location ~ \.php$ {
		set $memcached_key "kutu:$request_uri";
		memcached_pass 127.0.0.1:11211;

		default_type       text/html;
		error_page 404 405 502 = @cache_miss;
	}

	location @cache_miss {
		fastcgi_pass 127.0.0.1:9000;
		fastcgi_index index.php;
		fastcgi_param SCRIPT_FILENAME /path/to/yoursite/htdocs$fastcgi_script_name;
		include /etc/nginx/fastcgi_params;
	}

	# ...
}

Well, i was totally confused :D. so, to prevent other people misinterpret on how nginx memcached module works, i wrote simple examples, and simple explainations on how to configure nginx and populate data generated from php.

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Posted inmemcache

Memcached In A shell Using nc And echo

Some example accessing memcached from a shell using nc and echo

Storage Commands

set
add
get
gets
replace
append
prepend
cas
delete
command [key] [flags] [exptime] [bytes] [noreply]\r\n[value]\r

Parameters :

[key]			: the key of the data stored
[flags]			: 32-bit unsigned integer that the server store with the data (provided by the user), and return along the data when the item is retrieved
[exptime]		: expiration time in seconds, 0 mean no delay, if exptime is superior to 30 day, Memcached will use it as a UNIX timestamps for expiration
[bytes]			: number of bytes in the data block
[cas unique]		: unique 64-bit value of an existing entry (retrieved with gets command) to use with cas command
[noreply]		: optional parameter that inform the server to not send the reply
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Posted inmemcache mysql php

Memcached And PHP, Caching Mysql Query Result

I’ve been messing around with memcached and php-pecl-memcache to cache sql query result. Many web sites & applications such as Facebook, LiveJournal, Flickr, Slashdot, WikiPedia/MediaWiki, SourceForge, Digg and Twitter use memcached to enhance their performance.

Memcached (Memory Cache Daemon) was developed by the team at LiveJournal to improve performance of their social blogging site by minimizing the impact of the bottleneck caused by reading data directly from the database. Memcached is a server that caches Name Value Pairs in memory. The “Name”, or key, is limited to 250 characters, and the “Value” is limited to 1MB in size. Values can consist of data, HTML  Fragments, or binary objects; almost any type of data that can be serialized and fits in memcached can be stored.

here is simple example/demonstration how to cache regular sql query

memcached flow
memcached flow

First of all, we need memcached daemon run on system

$ ps ax | grep memcached
 8955 ?        Ssl    0:00 memcached -d -p 11211 -u memcached -m 256 -c 1024 -P /var/run/memcached/memcached.pid -l 127.0.0.1

Setup simple mysql database/tables as shown bellow:

mysql-shell> CREATE DATABASE memcache;

Copy/Paste this tables schema to your mysql shell/console

CREATE TABLE memc
(
 personID int NOT NULL AUTO_INCREMENT,
 PRIMARY KEY(personID),
 FirstName varchar(15),
 LastName varchar(15),
 Age int
);
hit enter/return key

Insert some data

mysql-shell> INSERT INTO memc (FirstName, LastName, Age) VALUES('Memory', 'Cache', '100');
Tags: , , 7