710963 - Improve delegate callback deferral

Status: RESOLVED INVALID

(Firefox for Android Graveyard :: Android Sync, defect, P4)

Description

[Richard Newman [:rnewman]]

The entire Sync implementation is structured around delegate callbacks. Sometimes it also uses locks. Mixing both synchronous and asynchronous invocation of callbacks with locks is a recipe for disaster -- either you'll get deadlocks, or you'll get recursive lock entry with mismatched notify/waits.

The "live" portion of the code now has a .deferredFooDelegate() method on each delegate interface, which returns a wrapper around the delegate implementation.

This should be switched to use either a common thread (pool) or an event loop. Additionally, the remaining less-used delegate interfaces should be extended in the same way.

If you don't understand one of the terms in the preceding three paragraphs, please don't attempt to fix this bug.

Comment 1

[Richard Newman [:rnewman]]

This now uses a thread pool, but I'd prefer to avoid even that.

Comment 2

[Richard Newman [:rnewman]]

We now use single-thread-pool ExecutorServices in most places. We might be able to do better than that, and we also need to use them in more places: Bug 713483.

Comment 3

[Nick Alexander :nalexander [he/him]]

The issues that we were worried about have largely not transpired; we have discovered patterns that work well in practice, and we're not going to retro-fit a lot of code for small benefit, so closing.