I am writing PHP code to be a game client. It uses socket; socket_create followed by socket_connect and then socket_read. It works fine, but the issue is that the server can send a packet at any time which means socket_read needs to be happening constantly in a "game loop". So something like this:
<?php
$reply = "";
do {
$recv = "";
$recv = socket_read($socket, '1400');
if($recv != "") {
$reply .= $recv;
}
} while($recv != "");
echo($reply);
?>
Doesn't work because it's stuck in the loop (server doesn't terminate connection until game is quit by client) and the PHP code needs to handle the packet stuff as it comes in.
So PHP doesn't really have threading. What's the best way of handling this?
Basically any software platform is going to butt up against this problem. Most, as you've figured out, solve it with threading. While threading IS possible in PHP. It requires MAJORHAXXX. Such as launching a commandline php thread from within php.
It really doesn't end up being ideal.
However, there are other ways to get around this.
But you need to check ALL the marks on this list first:
[] - My game doesn't need to constantly keep checking the server, such as for player locations or complex movements. Anything beyond a chat-room level of data transfer and update rates should leave this box un-checked.
[] - My game doesn't need to be told BY THE SERVER anything. It is perfectly acceptable for the client to ask for anything it needs, perhaps once a second or better off once a minute.
[] - My game doesn't need to keep a constant simulation of a complex world running on the server for longer than it takes to complete a request. Tracking chat is one thing, doing physics and graphics modifications is another.
If you checked all of these boxes, then PHP is STILL IN THE GAME! Otherwise. Don't bother.
Basically, what I am saying here is that PHP is great for games that aren't really multiplayer, and that are turn-based or at least not very interactive. But once you have to keep things going without the player, PHP falls on its face.
VOODOO LEVEL
But if you simply MUST do this. There ARE ways to get around it.
A - Create a PHP Daemon that runs your world, pipe all other traffic to either a getter or setter request file that interacts with the database. So, you might request a getting of the game world state, or set a value that the player performed. All other game-world related things can be handled by the daemon and the game itself takes place in the database.
B - Use cron, not a Daemon. (dangerous, but we already established you as a risk taker, right?)
C - TRY only a Daemon and listening to sockets, then sending out threads (via exec()) to respond. Kind of like AndreKR's idea above, only you don't need to sleep. Problem here is you will almost always end up missing stuff or otherwise getting cut off. And the whole thing might explode if the Daemon get's run twice somehow..