When does php <5.3.0 script signal appear?

I have a PHP script in the works that works in the workplace; its main task is to check the database table for new jobs, and if any, act on them. But jobs will appear in queues with long gaps in between, so I designed a sleep cycle like:

while(true) {
  if ($jobs = get_new_jobs()) {
    // Act upon the jobs
  } else {
    // No new jobs now
    sleep(30);
  }
}

      

        
        
        
      

    

Okay, but in some cases this means that it may take a 30 second lag before a new job is executed. Since this is a script daemon, I figured I would try to pcntl_signal

intercept the SIGUSR1 signal to nudge the script to wake up, like this:

$_isAwake = true;
function user_sig($signo) {
  global $_isAwake;
  daemon_log("Caught SIGUSR1");
  $_isAwake = true;
}
pcntl_signal(SIGUSR1, 'user_sig');

while(true) {
  if ($jobs = get_new_jobs()) {
    // Act upon the jobs
  } else {
    // No new jobs now
    daemon_log("No new jobs, sleeping...");
    $_isAwake = false;
    $ts = time();
    while(time() < $ts+30) {
      sleep(1);
      if ($_isAwake) break; // Did a signal happen while we were sleeping? If so, stop sleeping
    }
    $_isAwake = true;
  }
}

      

        
        
        
      

    

I broke sleep(30)

into smaller sleep bits, in case the signal does not interrupt the command sleep()

, assuming that this would result in a maximum delay of one second, but in the log file that SIGUSR1 does not hit until the full 30 seconds have passed (and, perhaps the outer loop is while

reset).

I found a command pcntl_signal_dispatch

, but this is only for PHP 5.3 and up. If I were using this version, I could invoke this command before invoking if ($_isAwake)

, but since it currently stands, I'm in 5.2.13.

In what situations is a signal queue interpreted in PHP versions without means to explicitly call the queue parsing? Can I add some other useless command to this sleep loop that will run the signal queue syntax internally?