[−][src]Module futures::executor
Task execution.
All asynchronous computation occurs within an executor, which is capable of spawning futures as tasks. This module provides several built-in executors, as well as tools for building your own.
Using a thread pool (M:N task scheduling)
Most of the time tasks should be executed on a thread pool. A small set of worker threads can handle a very large set of spawned tasks (which are much lighter weight than threads).
The simplest way to use a thread pool is to
run
an initial task on it, which
can then spawn further tasks back onto the pool to complete its work:
#![feature(pin, arbitrary_self_types, futures_api)] use futures::executor::ThreadPool; // assumping `my_app: Future` ThreadPool::new().expect("Failed to create threadpool").run(my_app);
The call to run
will block the
current thread until the future defined by my_app
completes, and will
return the result of that future.
Spawning additional tasks
Tasks can be spawned onto a spawner by calling its
spawn_obj
method directly.
In the case of !Send
futures,
spawn_local_obj
can be used instead.
Single-threaded execution
In addition to thread pools, it's possible to run a task (and the tasks
it spawns) entirely within a single thread via the
LocalPool
executor. Aside from cutting
down on synchronization costs, this executor also makes it possible to
spawn non-Send
tasks, via
spawn_local_obj
.
The LocalPool
is best suited for running I/O-bound tasks that do
relatively little work between I/O operations.
There is also a convenience function,
block_on
, for simply running a future to
completion on the current thread, while routing any spawned tasks
to a global thread pool.
Structs
BlockingStream |
An iterator which blocks on values from a stream until they become available. |
Enter |
Represents an executor context. |
EnterError |
An error returned by |
LocalPool |
A single-threaded task pool for polling futures to completion. |
LocalSpawner | |
ThreadPool |
A general-purpose thread pool for scheduling tasks that poll futures to completion. |
ThreadPoolBuilder |
Thread pool configuration object. |
Functions
block_on |
Run a future to completion on the current thread. |
block_on_stream |
Turn a stream into a blocking iterator. |
enter |
Marks the current thread as being within the dynamic extent of an executor. |