How can I create a progress bar attached to a server-side process?

We just ran into a problem with our cloud host - they've changed their apache settings to force a much shorter page timeout, and now during certain processes (report creation, etc.) that take more than 15 seconds (which the client is fine with; we're processing huge amounts of data) we get an error:

The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request POST /administrator/index.php.

Reason: Error reading from remote server

I have confirmed that our code is still running correctly in the background, and double-checked with the host that this is reall开发者_如何学Goy just a timeout. Their suggestion was to create a progress bar that is associated with the backend code; that way apache knows something is still going on and won't time out.

I've done progress bars associated the page load events (i.e. when all images are loaded, etc.) but have no idea how to go about creating a progress bar associated with backend code. This is a Joomla site, coded in mvc php, and the code that's causing the issue is part of the model - the various pieces that could be involved are all doing humongous queries. The tables are indexed correctly and the queries are optimized; the issue is not how to make the processes take less time - because we're on a cloud server the timeout limit could be changed to 5 seconds tomorrow without any kind of warning. What I need is someone to point me in the right direction of how to create the progress bar so it's actually associated with the function being run in the model.

Any ideas? I'm a complete beginner as far as this goes.

The easiest way I can think of is to use a two-step process:

1. Have the model write out events to a textfile or something when it gets to a critical point.
2. Use some ajax method to have the page regularly check that file for updates, and update the progress bar as such.

Whatever the background process does should update something like a file or database entry with a percentage completed every X seconds or at set places in its flow. Then you can call another script from Javascript every X seconds and it returns the percentage completed via the database record.

updateRecord(0);
readLargeFile();

updateRecord(25);
encodeLargeFile();

updateRecord(50);
writeLargeFile();

updateRecord(75);
celebrate();

updateRecord(100);