| 1 | //! Built-in executors and related tools. |
| 2 | //! |
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| 3 | //! All asynchronous computation occurs within an executor, which is |
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| 4 | //! capable of spawning futures as tasks. This module provides several |
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| 5 | //! built-in executors, as well as tools for building your own. |
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| 6 | //! |
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| 7 | //! All items are only available when the `std` feature of this |
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| 8 | //! library is activated, and it is activated by default. |
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| 9 | //! |
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| 10 | //! # Using a thread pool (M:N task scheduling) |
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| 11 | //! |
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| 12 | //! Most of the time tasks should be executed on a [thread pool](ThreadPool). |
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| 13 | //! A small set of worker threads can handle a very large set of spawned tasks |
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| 14 | //! (which are much lighter weight than threads). Tasks spawned onto the pool |
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| 15 | //! with the [`spawn_ok`](ThreadPool::spawn_ok) function will run ambiently on |
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| 16 | //! the created threads. |
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| 17 | //! |
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| 18 | //! # Spawning additional tasks |
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| 19 | //! |
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| 20 | //! Tasks can be spawned onto a spawner by calling its [`spawn_obj`] method |
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| 21 | //! directly. In the case of `!Send` futures, [`spawn_local_obj`] can be used |
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| 22 | //! instead. |
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| 23 | //! |
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| 24 | //! # Single-threaded execution |
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| 25 | //! |
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| 26 | //! In addition to thread pools, it's possible to run a task (and the tasks |
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| 27 | //! it spawns) entirely within a single thread via the [`LocalPool`] executor. |
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| 28 | //! Aside from cutting down on synchronization costs, this executor also makes |
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| 29 | //! it possible to spawn non-`Send` tasks, via [`spawn_local_obj`]. The |
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| 30 | //! [`LocalPool`] is best suited for running I/O-bound tasks that do relatively |
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| 31 | //! little work between I/O operations. |
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| 32 | //! |
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| 33 | //! There is also a convenience function [`block_on`] for simply running a |
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| 34 | //! future to completion on the current thread. |
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| 35 | //! |
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| 36 | //! [`spawn_obj`]: https://docs.rs/futures/0.3/futures/task/trait.Spawn.html#tymethod.spawn_obj |
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| 37 | //! [`spawn_local_obj`]: https://docs.rs/futures/0.3/futures/task/trait.LocalSpawn.html#tymethod.spawn_local_obj |
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| 38 | |
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| 39 | #![no_std ] |
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| 40 | #![doc (test( |
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| 41 | no_crate_inject, |
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| 42 | attr( |
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| 43 | deny(warnings, rust_2018_idioms, single_use_lifetimes), |
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| 44 | allow(dead_code, unused_assignments, unused_variables) |
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| 45 | ) |
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| 46 | ))] |
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| 47 | #![warn (missing_docs, unsafe_op_in_unsafe_fn)] |
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| 48 | #![cfg_attr (docsrs, feature(doc_cfg))] |
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| 49 | |
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| 50 | #[cfg (feature = "std" )] |
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| 51 | extern crate std; |
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| 52 | |
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| 53 | #[cfg (feature = "std" )] |
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| 54 | mod local_pool; |
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| 55 | #[cfg (feature = "std" )] |
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| 56 | pub use crate::local_pool::{block_on, block_on_stream, BlockingStream, LocalPool, LocalSpawner}; |
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| 57 | |
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| 58 | #[cfg (feature = "thread-pool" )] |
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| 59 | #[cfg_attr (docsrs, doc(cfg(feature = "thread-pool" )))] |
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| 60 | #[cfg (feature = "std" )] |
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| 61 | mod thread_pool; |
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| 62 | #[cfg (feature = "thread-pool" )] |
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| 63 | #[cfg (feature = "std" )] |
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| 64 | mod unpark_mutex; |
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| 65 | #[cfg (feature = "thread-pool" )] |
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| 66 | #[cfg_attr (docsrs, doc(cfg(feature = "thread-pool" )))] |
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| 67 | #[cfg (feature = "std" )] |
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| 68 | pub use crate::thread_pool::{ThreadPool, ThreadPoolBuilder}; |
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| 69 | |
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| 70 | #[cfg (feature = "std" )] |
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| 71 | mod enter; |
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| 72 | #[cfg (feature = "std" )] |
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| 73 | pub use crate::enter::{enter, Enter, EnterError}; |
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| 74 | |
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