Deadlock due to race in FsEventWatcher

[michaelfairley]

Because the runloop thread signals that the runloop has started before CFRunLoopStart is called, it's possible for CFRunLoopStop to get called before CFRunLoopStart, causing the runloop to never stop and thus the done channel to be waited on forever.

In practice, if I have two watch commands back to back, I get a deadlock roughly 10% of the time on my Mac.

I have a somewhat cheesy workaround that I'm using right now, but an ideal solution probably involves CFRunLoopObserver or somesuch.

[cmyr]

I think this bug is serious enough that the proposed patch should be accepted. I'm not sure it's worth making major changes to FsEventWatcher when #117 will probably require another one. @passcod do you have any thoughts?

[passcod]

@michaelfairley are you okay with me using your workaround?

[michaelfairley]

Yes! Please do! It's been working well enough for me since I initially filed this issues.

[cmyr]

@michaelfairley are you in a position to PR your patch? If not I can, save @passcod the time.

[passcod]

Done with #134