alexarcherr/phacterl

The Actor Model in PHP

Phacterl

Implementation of The Actor Model in PHP.

Installation

Add "videlalvaro/phacterl": "dev-master" to your composer.json require section.

Usage

Your Actors need to extend the abstract class Actor for example, and implement two methods: Actor::init and Actor::receive. For example:

class Counter extends Actor {
    public function init($args) {
        return array(
            'count' => 0
        );
    }

    public function receive() {
        return array('incr', 'get_count');
    }
}

The method init should return an array that would be the State of the process. The runtime system will take care of managing the process state.

The method receive should return an array with strings specifying to which message tags this process responds to.

In our case, the process Counter should also provide a method called handle_incr and another one called handle_get_count.

Implementing the Handlers

A handler is a function that takes two parameters, a Message and the process State and returns a new state, like this:

class Counter extends Actor {
// snip

    public function handle_incr($msg, $state) {
        $state['counter'] += $msg['amount'];
        return $state;
    }

// snip
}

Sending messages

To send a message, your actor can call the function Actor::send, which expects a process id and a Message. When creating a Message instance, you need to provide a tag, like 'count' in this case, and the message data. The tag is used to dispatch to a message handler called handle_<tag>.

class Counter extends Actor {
// snip

    public function handle_get_count($msg, $state) {
        $pid = $msg['sender'];
        $this->send(
                $pid,
                new Message(
                    'count',
                    array('sender' => $this->self(), 'count' => $state['counter'])
                )
            );
        return $state;
    }

// snip
}

Then, once you to run your actors, first get an instance of the Scheduler, and spawn your actor, by passing in the class name and the initial parameters for the Actor's init function.

$scheduler = new Scheduler();
$pid = $scheduler->spawn('Counter', array());
$scheduler->run();

Stopping the System

From inside an actor you can simply call $this->stop(). Otherwise call $scheduler->stop().

Examples

On the demo folder you can find many examples which are implementations of the algorithms presented in the book Distributed Algorithms for Message-Passing Systems.

Why?

Because implementing these algorithms in Erlang would be too easy.

Also, why not:

Is this an April's Fool Joke

According to my Julian Calendar, it's April's First here.

LICENSE

The MIT License (MIT)

Copyright (c) 2014 - Alvaro Videla

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.