ScriptAlone is PHP class for limiting running only one instance of some script Project site: https://github.com/barbushin/scriptalone http://code.google.com/p/scriptalone GIT: https://github.com/barbushin/scriptalone.git SVN: http://scriptalone.googlecode.com/svn/trunk Example task: you have a live queue of emails(for example in DB) that must be sent as soon as possible. # You need to have some PHP-script that will check if there are any emails in queue, and if yes so send them. # This PHP-script must be runned all time, and check queue every second. # Only one instance of this PHP-script can be runned, to be sure that one email was not sent twice. # PHP-script can be interrupted in any moment by some error, so in this case it must be restarted as soon as possible. # PHP-script can have a bug on some iteration, mean: it will be lunched but not sending emails, so in this case it must be restarted as soon as possible. # PHP-script should be restarted every 5-10 hours to prevent memory leaks and do it in safe way (when all current tasks are complete). # Ability to stop script in any moment. What you do: # Use ScriptAlone in way like in http://code.google.com/p/scriptalone/source/browse/trunk/example.php # Configure CRON that will run this PHP-script every 5 minutes. What you have: # Script will be runned all time, and checked emails every second. # There will be only one instance of runned script. # Script will be restarted if there will be any errors or iteration time limit expire. # Script will be restarted in safe way every 5 hours. # You can any time check if script is runned by checking existing file with $stateFilepath path (./examples.php.works) # You can any time stop runned script by creating file with path $stateFilepath.'.stop' (./examples.php.works.stop). # All script restarts takes maximum 5 minutes (because of CRON try to run next script instance every 5 minute). Recommended: * Google Chrome extension PHP Console - http://goo.gl/b10YF * Google Chrome extension JavaScript Errors Notifier - http://goo.gl/kNix9