declare(ticks=1);

class DaemonRunner {
    public static function exec($className) {
        $argv = $_SERVER['argv'];
        $daemon = new $className($argv);
        $daemon->init();
        while (!$daemon->isDone()) {
            $daemon->run();
        }
        $daemon->shutdown();
    }
}

The first statement is a PHPism. This allows PHP to check for signals every 1 tick. A tick is simply a low-level PHP interpreter step. The way I’ve setup my daemon and signal handling by default, the PHP will finish its current iteration and then quit when receiving a signal. This ensures that the database, and whatever background stuff aren’t left in inconsistent states. As with anything, you’re free to modify, extend, or otherwise alter this behavior.

great for background/async processing of:

• photos
• movies
• reports
• imports of data

advantages:

• use the same codebase as your app
• use the same expertise on your team of programmers

challenges:

• signals
• one thread
• memory (this will have to be a whole separate article)
• starting and stopping

A typical Daemon class I use:

abstract class Daemon {
    protected $done = false;

    public function __construct($argv) {
    }
    public function init() {
        pnctl_signal(SIGTERM, array($this, "onSignal"));
        pnctl_signal(SIGINT, array($this, "onSignal"));

    }
    abstract public function run();
    public function shutdown() {}
    public function isDone() {
        return $this->done;
    }
    public onSignal($signal){
        switch ($signal) {
             case SIGTERM:
             case SIGINT:
                $this->done = true;
                 break;
             default:
                 // handle all other signals
        }
    }
}

As you can see, we’ve started to tackle some of the challenges here. The idea is to handle signals, specifically I usually care about SIGTERM (default when using ‘kill’ on *nix) and SIGINT (from pressing Ctrl-C). Both will cause the program to exit gracefully.

I’ll be posting the class I use to run Daemon’s tomorrow.

The whole talk and its supporting files can also be downloaded.

• web – Web Browse
• remote administration – Use a terminal
• services – Run servers
• video – Transcode, edit, convert, and Backup DVD’s
• music – Listen to music

A few things Linux hasn’t done well and why I’m considering adding a second OS to my desk here (alongside Linux):

• Money Management – GNUCash is the closest thing here, but doesn’t hold a candle to the financial institution integration MS Money and Quicken can offer
• audible.com – my audible.com content forces me to boot into Windows every few months to add new audio books to my iPod mini
• Music – I’ve made limited use and I’d like to make more use of services like Rhapsody.com, Napster.com, or Yahoo Music to have a wider variety of music to listen to.

There are a few ancillary things that don’t necessitate daily Windows usage, but I do need them occasionally:

• Harmony Remote – make my Harmony remote do new things
• Some multimedia stuff, CNN Video – most of this is going to Flash anyway

Wow, that’s a pretty short list. I had in my head that there were more things I wanted from Windows. Maybe I’ll suck it up and work with GNUCash!

On that note, recently solved things that used to suck about Linux on the desktop:

• Flash 9 – Like it or not, Linux is all about choice, now you have the option of running Flash 9 on Linux.
• DVD Backups: This has gotten easier and easier on Windows; I just tried an amazing piece of Linux software called Thoggen which backs up DVD’s to my hard-drive-based media server with a surprisingly few number of clicks.
• Music Management – Rhythmbox and the new player Banshee have made music management and playback much more manageable on Linux. Keep up the great work!
• Network Manager – the network manager makes wireless/wired connection management a cinch. I highly recommend it!

The name Iceweasel sounds like the odd name of an infant open-source project. Many people give up on Linux read names like Iceweasel and GIMP.