Crate futures

Abstractions for asynchronous programming.

This crate provides a number of core abstractions for writing asynchronous code:

• Futures are single eventual values produced by asynchronous computations. Some programming languages (e.g. JavaScript) call this concept "promise".
• Streams represent a series of values produced asynchronously.
• Sinks provide support for asynchronous writing of data.
• Executors are responsible for running asynchronous tasks.

The crate also contains abstractions for asynchronous I/O and cross-task communication.

Underlying all of this is the task system, which is a form of lightweight threading. Large asynchronous computations are built up using futures, streams and sinks, and then spawned as independent tasks that are run to completion, but do not block the thread running them.

Modules

channel	Cross-task communication.
compat	Interop between futures 0.1 and 0.3.
executor	Task execution.
future	Asynchronous values.
io	Asynchronous I/O.
lock	Futures-powered synchronization primitives.
never	This module contains the Never type.
prelude	A "prelude" for crates using the futures crate.
sink	Asynchronous sinks.
stream	Asynchronous streams.
task	Tools for working with tasks.

Macros

join	Polls multiple futures simultaneously, returning a tuple of all results once complete.
pending	A macro which yields to the event loop once.
pin_mut	Pins a value on the stack.
poll	A macro which returns the result of polling a future once within the current async context.
ready	Extracts the successful type of a Poll<T>.
select	Polls multiple futures and streams simultaneously, executing the branch for the future that finishes first. If multiple futures are ready, one will be pseudo-randomly selected at runtime. Futures passed to select! must be Unpin and implement FusedFuture. Futures and streams which are not already fused can be fused using the .fuse() method. Note, though, that fusing a future or stream directly in the call to select! will not be enough to prevent it from being polled after completion if the select! call is in a loop, so when select!ing in a loop, users should take care to fuse() outside of the loop.
try_join	Polls multiple futures simultaneously, resolving to a Result containing either a tuple of the successful outputs or an error.