I am trying to build a basic plugin system like the kind you often find in a CMS like WordPress. You have a folder of plugins which tie into the main system's operation through event notifications using an Observer or Event design pattern.
The problem is it's impossible for the system to know which events the plugin wants to act upon - so the system has to load each plugin for every page request just to find out if that plugin is actually needed at some point. Needless to say, that's a lot of wasted resources right there-- in the case of WordPress, that adds up to several extra MB of memory for each request!
Are there alternative ways to do this?
For example, is there a way to load all this once and then cache the results so that your system knows how to lazy-load plugins? In other words, the system loads a configuration file that specifies all the events that plugin wishes to tie into and then saves it in APC or something for future requests?
If that also performs poorly, then perhaps there is a special file-structure that could be used to make educated guesses about when certain plugins are unneeded to fulfill the request.
Source: Tips4all
Wordpress and other CMS systems are very bad examples.
ReplyDeleteWhat we have to understand is that modular, almost always means heavier.
The best scheme that I ever worked with to solve this situation is a class based plugin, with a strict naming convention using an auto loader.
So, before using the plugin, you´ll need to create an instance, or use static functions.
You can even call the plugin like:
<?php $thePlugin::method(); ?>
eg:
<?php
spl_autoload_register('systemAutoload');
function systemAutoload($class)
{
$parts = explode('_',$class);
switch($parts[1])
{
case "Plugin":
include("/plugins/{$parts[2]}/{$parts[2]}.php");
break;
}
// ...
}
?>
Regarding Events:
You have to register this events statically to avoid bringing it in a dynamic manner.
The database would be the right place to do it. You can have an events table, and install() and uninstall() methods on the plugin class to add specific events or bind methods to other events. It´s one database query, and if you want more from it, add it to memcached, or to a flat ini file.
Works well for me. This way I was able to get a heavy system that was consuming 8mb per request to drop to 1mb, with the exactly same list of features, without advanced caching. Now we can add more features and mantain the system "clean"
Hope that helps
I would save the plugin class name along with it's subscribed events in a configuration file and then save the parsed config file in APC, for example. Then when an event is triggered the system can lazy load the appropriate plugin classes as needed.
ReplyDelete