While Loop Speed

Special behavior with sockets?

[ChainsawXIV]

I have a while loop in a script that is listening to a socket, opened with fsockopen(), and I'm getting some inconsistent behavior in terms of the rate at which it's looping. When a message comes in over the socket, it seems to be processed immediately. When I introduce a change on my end though - in this case, updating a database entry with a message to be sent out over the socket, it seems not to be processed until a new incoming message is received.

So, my question is this. Is there some special behavior with while loops and sockets (or something else in my code) that's causing this? Is this just a weird coincidence of some kind? It seems like desirable behavior in terms of efficiency on the server, but I also need to be able to force it some how, so that changes are processed promptly. Your help would be appreciated. Code snippet follows:

// Establish the IRC server connection 
$server['SOCKET'] = @fsockopen($config['host'], $config['port'], $errno, $errstr, 2); 

// Confirm that connection was established 
if($server['SOCKET']){ 

// Set agent kill status to false 
$config['kill'] = FALSE;</span> 

// Send essential login commands 
SendCommand("PASS NOPASS"); 
SendCommand("NICK " . $config['nick']);  
SendCommand("USER " . $config['nick'] . " USING PHP IRC"); 

// MAIN LOOP - Process all messages recieved 
while(!feof($server['SOCKET']) &&!$config['kill']){ 

// Get a line of data from the server 
$server['read_buffer'] = fgets($server['SOCKET'], 1024); 

// Ouput the message to the viewer 
PublishLine($server['read_buffer'] . "\n\r"); 

// If a ping request is recieved, reply with pong 
if(substr($server['read_buffer'], 0, 6) == "PING :"){ 
SendCommand("PONG :" . substr($server['read_buffer'], 6)); 

}  

// When the end of the MOTD is recieved join a channel 
if(strpos($server['read_buffer'], "422") ¦¦ strpos($server['read_buffer'], "376")){  

// Enter the specified chanel 
SendCommand("JOIN " . $config['chan']); 

} 

// Check for user commands in database 
$query = "SELECT `user`,`send` FROM `sessions` WHERE `user` = " . $_GET['user']; 
$result = mysql_query($query); 
$updates = mysql_fetch_assoc($result); 

// If the user entry is gone then kill the loop 
if(mysql_num_rows($result) == 0){ 

// Set the kill flag in the config 
$config['kill'] = TRUE; 

// Send the quit command to the server 
SendCommand('QUIT :Agent disconnecting...'); 

// Close the socket 
fclose($server['SOCKET']); 

} 

// If there's a new message from the user 
if($updates['send']){ 

// Relay the message to the server 
SendCommand($updates['send']); 

// Clear the command buffer 
$query = "UPDATE `sessions` SET `send` = '' WHERE `user` = " . $_GET['user']; 
$result = mysql_query($query); 

} 

} 

// Agent is shutting down, clean up the database 
$query = "DELETE FROM `messages` WHERE `user` = " . $_GET['user']; 
$result = mysql_query($query); 

} 

[edited by: ChainsawXIV at 4:07 am (utc) on Jan. 28, 2008]

[vincevincevince]

$server['read_buffer'] = fgets($server['SOCKET'], 1024);

The code won't pass this line until it's managed to read 1024 bytes from the server. Sounds like you need a multi-threaded process to me - one thread doing the reading, one doing the writing.

[ChainsawXIV]

Thank you. That makes perfect sense now that you explain it.

How would you go about multi-threading this, given that I need to use the same socket for both sending and receiving? Is there a way I can accessing the same socket from a second script, or some way of running two loops simultaneously within a single script? I haven't worked with any deliberate multi-threading prior to this, and I'm not sure what my options are.