Question

I’ve got a download script which checks a couple of things and then streams a file across in chunks of 8kb.

The loop that does the transfer looks like:

$file = @fopen($file_path,"rb");
if ($file) {
  while(!feof($file)) {
    set_time_limit(60);
    print(fread($file, 1024*8));
    flush();
    if (connection_status()!=0) {
      @fclose($file);
      die();
    }
  }
  @fclose($file);
}

I wrote a small application which simulated a very slow download. It waits for 2 minutes before continuing the download. I expected that the script would time out given that I’ve set a 60 second time limit. This does not happen and the download continues until it has finished. It seems that the time spent in print / flush doesn’t count towards the script execution time. Is this correct? Is there a better way to send the file to the client / browser such that I can specify a time limit for the print / flush command?

Answer 1

From set_time_limit():

The set_time_limit() function and the configuration directive max_execution_time
only affect the execution time of the script itself. Any time spent on activity
that happens outside the execution of the script such as system calls using system(),
stream operations, database queries, etc. is not included when determining the
maximum time that the script has been running. This is not true on Windows where
the measured time is real.

So it looks like you can either measure the passage of real time with calls to the time() function, along the lines of:

$start = time();
while (something) {
    // do something
    if( time()-$start > 60) die();
}

Or you can use Windows. I prefer the first option :p