How to cancel a PHP process, when ajax call is cancelled?

Question

i am currently working on a CRM system with a huge database. If the user wants to search a customer, he can use the ajax search. Everytime he changes something in the search field, while a call is pending, the old call is cancelled and a new one will be send to the server. My problem is, that the php processes on server side continue running. So if the user starts typing in an address, several requests are started and cancelled and the server needs more and more time to answer.

Is is possible to cancel the running php process, when the ajax call is cancelled? Or is there a possible solution on server side, to detect if a search request from the same user is running and cancel it before starting the new one?

Thanks in advance for your answers.

Answer 1

Your server side php has to output something to detect the request is canceled. But as you are likely performing a lengthy sql query, you can't output anything.

But still you can save your connection id into a session, and kill the connection if it's detected:

1. Open session
2. Open sql connection
3. If search_connection_id is set in session, kill the connection
4. Find your connection id, save in session as search_connection_id
5. Close the session - important, else the next request will be blocked in step 1
6. Query database
7. If connection is broken, it's another search killing you in step 3, exit
8. Open session, remove search_connection_id
9. Send response, close sql connection