PHP: How to return information to a waiting script and continue processing

Question

Suppose there are two scripts Requester.php and Provider.php, and Requester requires processing from Provider and makes an http request to it (Provider.php?data="data"). In this situation, Provider quickly finds the answer, but to maintain the system must perform various updates throughout the database. Is there a way to immediately return the value to Requester, and then continue processing in Provider.

Psuedo Code

Provider.php 
{
   $answer = getAnswer($_GET['data']);
   echo $answer;
   //SIGNAL TO REQUESTER THAT WE ARE FINISHED
   processDBUpdates();
   return;
}

Answer 1

You can flush the output buffer with the flush() command.
Read the comments in the PHP manual for more info

Answer 2

I use this code for running a process in the background (works on Linux).

The process runs with its output redirected to a file.

That way, if I need to display status on the process, it's just a matter of writing a small amount of code to read and display the contents of the output file.

I like this approach because it means you can completely close the browser and easily come back later to check on the status.

Answer 3

You basically want to signal the end of 1 process (return to the original Requester.php) and spawn a new process (finish Provider.php). There is probably a more elegant way to pull this off, but I've managed this a couple different ways. All of them basically result in exec-ing a command in order to shell off the second process.

adding the following > /dev/null 2>&1 & to the end of your command will allow it to run in the background without inhibiting the actual execution of your current script

Something like the following may work for you:

exec("wget -O - \"$url\" > /dev/null 2>&1 &"); 

-- though you could do it as a command line PHP process as well.

You could also save the information that needs to be processed and handle the remaining processing on a cron job that re-creates the same sort of functionality without the need to exec.