Add waitForAllTaskTermination

[norio-nomura]

Fix segmentation fault on Carthage termination.
Carthage/Carthage#474 (comment)

[jspahrsummers]

I think this should be created within launchTask, since TaskDescriptions can be reused across multiple task invocations.

[jspahrsummers]

Thanks for the pull request! ✨

I think I've misunderstood the purpose, so my comments above may not be valuable. If we need to wait for all tasks to complete before exiting on the main thread, I'd prefer to incorporate that into our SignalProducers somehow (instead of calling a special function before termination—which is easy to forget).

[norio-nomura]

I did want to prove what happened and how can be fixed. 😄
I couldn't fix it with RAC way by using SignalProducer, so I wrote this instead.
Yes, it should be fixed on the way you prefer. 👍

[jspahrsummers]

Ah, okay. I'm happy to give it a shot!

Thank you so much for finding the issue. 🙇⭐

[norio-nomura]

I hope that all reported segmentation fault on termination are on this scenario and will be fixed. 🙏

[jspahrsummers]

Should be fixed by #23. 🎉

Thanks again for finding that!

[norio-nomura]

I'm sorry I couldn't write proper code for fix this by my self.

[robrix]

@norio-nomura No apologies necessary, you contributed a great deal by diagnosing the issue 🙇

[norio-nomura]

@robrix Thanks 😃