1521566 - Support recording from the browser toolbox

Status: RESOLVED INCOMPLETE

(Core Graveyard :: Web Replay, enhancement, P2)

Description

[Brian Hackett [Laid off!]]

Attachment: WIP

Currently, we only record/replay content process behavior. If we extended this so that we could record/replay the behavior of the main firefox process itself, we would get a couple important benefits:

• It would give me an opportunity to use web replay for my own day-to-day development in the firefox devtools. While the debugger can run independently as a content tab and be recorded/replayed, this is not full featured (e.g. no worker support) and is not an option for other devtools. I'd like to be able to use web replay for my own development, to give me a first-hand way to think about how it can be improved and benefit the development workflow in general.

• It would allow anyone else working on chrome code (for devtools, or any other part of the browser) to use web replay, which would greatly increase the scope of potential internal users.

Recording/replaying a firefox process that is running with e10s would require some new methods to deal with the memory shared with other processes, but it is possible to run firefox without e10s so that all communication is within a single process. The workflow would be to run firefox with special command line options so that it records itself, save the recording from within firefox, then open up a new firefox instance (not recording) and replay the recording just saved.

This case is a little simpler architecturally than the content process case (no IPC), and getting it to work mainly just needs redirection support for the logic that can run in the firefox process but not content processes. The attached patch is a rough WIP that can record a minimal firefox session (start with a new profile, then immediately save the recording) and partially replay it.

Comment 2

[Brian Hackett [Laid off!]]

Attachment: WIP

WIP that I did some more work on a few weeks ago. This can record a single-process firefox instance but isn't yet able to reliably replay it. I'm tabling this for now because I have other higher priority things to work on and because I need to think some more about the approach here --- recording/replaying a single-process firefox instance lets us see everything that happens in the browser, but it also prevents us from being able to debug behavior that is dependent on the usual multi-process behavior (like the fission related work I've been doing lately).]