PHP queue multiple script calls
<p>I have a PHP script that opens an XML document, gets the DOM and modifies it, and then overwrites the original document.<br>
As I understand it, PHP calls are made asynchronously, so multiple users could be accessing the document at the same time and then saving to it with the second save overwriting the first.<br>
I need this not to be the case. I can't use <code>flock()</code> since that only applies to the current process, so how can I accomplish this?   </p>
