timeout for fread - php

Question

I am calling TCL script from PHP. I am sending a unique string from TCL process to PHP to make sure that script has ended .
If I don't send that string then my fread in PHP is blocked forever .
// PHP code
<?php
$id = 'done'; //Unique string
$app = 'c:/wamp/www/tcl/bin/tclsh84.exe';
$descriptorspec = array(
0 => array("pipe","r"),
1 => array("pipe","w"),
2 => array("pipe","w")
) ;
$process = proc_open($app, $descriptorspec, $pipes);
if (is_resource($process))
{
for($i=0;$i<2;$i++)
{
$output = '';
$continue = true;
$cTimeout = 0;
echo 'loop ', $i, "\n";
fwrite($pipes[0], "source c:/wamp/www/tcl/bin/helloworld.tcl\n");
echo "waiting for idle\n";
$timeout = time();
do {
$read=array($pipes[1]);
$write=array();
$except=array($pipes[1]);
$ready = stream_select($read, $write, $except, 1, 0);
$dif = time()- $timeout;
if ( $ready && $read )
{
$output .= fread($pipes[1], 2048); // is blocked indefinitely
// if the delimiter id shows up in $output
if ( false!==strpos($output, $id) ) {
// the script is done
$continue = false;
}
}
if($dif > 5) //timeout value not working
{
$continue = false;
}
} while($continue);
echo 'loop ', $i, "$output finished\n";
}
proc_close($process);
}
?>
//TCL code
puts "hello"
If i sends "done" from TCL, then my PHP script ends .
But I don't want to send just done, instead I need to do with the help of a timeout .
i.e I want to wait for a certain period of time for the unique string , else I should exit . But I can't seem to implement the timeout in this case.
Please can anyone guide me .

Answer 1

You'll have to rethink the logic of your program but you can:
Register a function for shutdown (as PHP is about to quit runs that function)
Set the max execution-time-limit
And your script would go like this
// sets the maximum execution time (seconds)
set_time_limit(3);
function shutdown () {
// if the script fails some logic goes here
}
// registers the function to run on shutdown
register_shutdown_function('shutdown');
This should set you on the right direction.
Hope it helps!