README

This class is intended to avoid having multiple instances of a certain process (like an upgrade, such as with cs_webdbupgrade) from "tripping" over each other. Create a lock file somewhere on the system (which is readable + writable), and remove it when the operation completes. The file should stay if there's a problem that keeps the operation from completing (because trying again would probably fail, or would make things worse).

use crazedsanity\lockfile\LockFile;

$lock = new LockFile('/path/to/rw/dir', 'file.lock');

if(!$lock->is_lockfile_present()) {
	$lock->create_lockfile($upgradeWording);
	
	// ... do some stuff...
	// Only delete the lockfile if it all succeeded
	$lock->delete_lockfile();
}
else {
	throw new exception($lock->read_lockfile());
}

You may want to look at Web DB Upgrade for an implementation example.