<?php

global $globals;
$globals = array();

/**
 * Checks to see if another instance of this process is already running through
 * the use of file locks
 * @param void
 * @return boolean $result - true if the process is already running, false if not
 */
function isAlreadyRunning()
{
    global $globals;
    $LOCK_FILE = dirname(__FILE__) . \'/lock.txt\';
    print \'got file handle \' . PHP_EOL;

    # This creates the file if it doesnt exist.
    $globals[\'lock_file\'] = fopen($LOCK_FILE, \'w\');

    $result = flock($globals[\'lock_file\'], LOCK_NB | LOCK_EX); # LOCK_EX
    var_Dump($result);
    return !$result;
}


// The following code is just for demo purposes so that this script can be called twice
// simultaneously with the first running, and the second shutting down early.
function main()
{
    print \'running check\' . PHP_EOL;
    if (isAlreadyRunning())
    {
        print "already running, shutting down" . PHP_EOL;
    }
    else
    {
        print \'sleeping\' . PHP_EOL;
        sleep(10);
        print \'done\' . PHP_EOL;
        die();
    }
}

main();