Consider renaming task park / unpark

[carllerche]

Placeholder issue for an 0.2 discussion.

Originally, the names were picked for symmetry with thread park / unpark. However, the behavior is sufficiently difficult that I believe the naming is leading to unnecessary confusion (this is also based off of observing questions in Gitter).

[leoyvens]

To unpark a thread means immediately wake it, to unpark a task usually means to schedule it to be polled. I'd suggest park -> suspend/delay/pause and unpark -> schedule. Since future is a time metaphor it seems helpful to use other time metaphors.

[carllerche]

To unpark a thread means immediately wake it

That's not strictly true. unparking a thread has no guarantees in terms of when the thread gets scheduled to execute. Just like w/ futures, the OS scheduler is free to schedule the thread as appropriate.

[carllerche]

I propose either:

• task::current() & Task::notify()
• Leave it as is.

Now is the time to make the change (#436). It should either happen or we leave the naming as is.

[ipetkov]

+1 on current/notify. It always bothered me that park implied side effects when it had none

[alexcrichton]

Done! (#436)