1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279
#![doc(html_root_url = "https://docs.rs/tokio/0.2.6")] #![allow(clippy::cognitive_complexity)] #![warn( missing_debug_implementations, missing_docs, rust_2018_idioms, unreachable_pub )] #![deny(intra_doc_link_resolution_failure)] #![doc(test( no_crate_inject, attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables)) ))] #![cfg_attr(docsrs, feature(doc_cfg))] //! A runtime for writing reliable, asynchronous, and slim applications. //! //! Tokio is an event-driven, non-blocking I/O platform for writing asynchronous //! applications with the Rust programming language. At a high level, it //! provides a few major components: //! //! * Tools for [working with asynchronous tasks][tasks], including //! [synchronization primitives and channels][sync] and [timeouts, delays, and //! intervals][time]. //! * APIs for [performing asynchronous I/O][io], including [TCP and UDP][net] sockets, //! [filesystem][fs] operations, and [process] and [signal] management. //! * A [runtime] for executing asynchronous code, including a task scheduler, //! an I/O driver backed by the operating system's event queue (epoll, kqueue, //! IOCP, etc...), and a high performance timer. //! //! Guide level documentation is found on the [website]. //! //! [tasks]: #working-with-tasks //! [sync]: crate::sync //! [time]: crate::time //! [io]: #asynchronous-io //! [net]: crate::net //! [fs]: crate::fs //! [process]: crate::process //! [signal]: crate::signal //! [fs]: crate::fs //! [runtime]: crate::runtime //! [website]: https://tokio.rs/docs/ //! //! # A Tour of Tokio //! //! Tokio consists of a number of modules that provide a range of functionality //! essential for implementing asynchronous applications in Rust. In this //! section, we will take a brief tour of Tokio, summarizing the major APIs and //! their uses. //! //! Note that Tokio uses [Cargo feature flags][features] to allow users to //! control what features are present, so that unused code can be eliminated. //! This documentation also lists what feature flags are necessary to enable each API. //! //! The easiest way to get started is to enable all features. Do this by //! enabling the `full` feature flag: //! //! ```toml //! tokio = { version = "0.2", features = ["full"] } //! ``` //! //! [features]: https://doc.rust-lang.org/cargo/reference/manifest.html#the-features-section //! //! ## Working With Tasks //! //! Asynchronous programs in Rust are based around lightweight, non-blocking //! units of execution called [_tasks_][tasks]. The [`tokio::task`] module provides //! important tools for working with tasks: //! //! * The [`spawn`] function and [`JoinHandle`] type, for scheduling a new task //! on the Tokio runtime and awaiting the output of a spawned task, respectively, //! * Functions for [running blocking operations][blocking] in an asynchronous //! task context. //! //! The [`tokio::task`] module is present only when the "rt-core" feature flag //! is enabled. //! //! [tasks]: task/index.html#what-are-tasks //! [`tokio::task`]: crate::task //! [`spawn`]: crate::task::spawn() //! [`JoinHandle`]: crate::task::JoinHandle //! [blocking]: task/index.html#blocking-and-yielding //! //! The [`tokio::sync`] module contains synchronization primitives to use when //! needing to communicate or share data. These include: //! //! * channels ([`oneshot`], [`mpsc`], and [`watch`]), for sending values //! between tasks, //! * a non-blocking [`Mutex`], for controlling access to a shared, mutable //! value, //! * an asynchronous [`Barrier`] type, for multiple tasks to synchronize before //! beginning a computation. //! //! The `tokio::sync` module is present only when the "sync" feature flag is //! enabled. //! //! [`tokio::sync`]: crate::sync //! [`Mutex`]: crate::sync::Mutex //! [`Barrier`]: crate::sync::Barrier //! [`oneshot`]: crate::sync::oneshot //! [`mpsc`]: crate::sync::mpsc //! [`watch`]: crate::sync::watch //! //! The [`tokio::time`] module provides utilities for tracking time and //! scheduling work. This includes functions for setting [timeouts][timeout] for //! tasks, [delaying][delay] work to run in the future, or [repeating an operation at an //! interval][interval]. //! //! In order to use `tokio::time`, the "time" feature flag must be enabled. //! //! [`tokio::time`]: crate::time //! [delay]: crate::time::delay_for() //! [interval]: crate::time::interval() //! [timeout]: crate::time::timeout() //! //! Finally, Tokio provides a _runtime_ for executing asynchronous tasks. Most //! applications can use the [`#[tokio::main]`][main] macro to run their code on the //! Tokio runtime. In use-cases where manual control over the runtime is //! required, the [`tokio::runtime`] module provides APIs for configuring and //! managing runtimes. //! //! Using the runtime requires the "rt-core" or "rt-threaded" feature flags, to //! enable the basic [single-threaded scheduler][rt-core] and the [thread-pool //! scheduler][rt-threaded], respectively. See the [`runtime` module //! documentation][rt-features] for details. In addition, the "macros" feature //! flag enables the `#[tokio::main]` and `#[tokio::test]` attributes. //! //! [main]: attr.main.html //! [`tokio::runtime`]: crate::runtime //! [`Builder`]: crate::runtime::Builder //! [`Runtime`]: crate::runtime::Runtime //! [rt-core]: runtime/index.html#basic-scheduler //! [rt-threaded]: runtime/index.html#threaded-scheduler //! [rt-features]: runtime/index.html#runtime-scheduler //! //! ## Asynchronous IO //! //! As well as scheduling and running tasks, Tokio provides everything you need //! to perform input and output asynchronously. //! //! The [`tokio::io`] module provides Tokio's asynchronous core I/O primitives, //! the [`AsyncRead`], [`AsyncWrite`], and [`AsyncBufRead`] traits. In addition, //! when the "io-util" feature flag is enabled, it also provides combinators and //! functions for working with these traits, forming as an asynchronous //! counterpart to [`std::io`]. When the "io-driver" feature flag is enabled, it //! also provides utilities for library authors implementing I/O resources. //! //! Tokio also includes APIs for performing various kinds of I/O and interacting //! with the operating system asynchronously. These include: //! //! * [`tokio::net`], which contains non-blocking versions of [TCP], [UDP], and //! [Unix Domain Sockets][UDS] (enabled by the "net" feature flag), //! * [`tokio::fs`], similar to [`std::fs`] but for performing filesystem I/O //! asynchronously (enabled by the "fs" feature flag), //! * [`tokio::signal`], for asynchronously handling Unix and Windows OS signals //! (enabled by the "signal" feature flag), //! * [`tokio::process`], for spawning and managing child processes (enabled by //! the "process" feature flag). //! //! [`tokio::io`]: crate::io //! [`AsyncRead`]: crate::io::AsyncRead //! [`AsyncWrite`]: crate::io::AsyncWrite //! [`AsyncBufRead`]: crate::io::AsyncBufRead //! [`std::io`]: std::io //! [`tokio::net`]: crate::net //! [TCP]: crate::net::tcp //! [UDP]: crate::net::udp //! [UDS]: crate::net::unix //! [`tokio::fs`]: crate::fs //! [`std::fs`]: std::fs //! [`tokio::signal`]: crate::signal //! [`tokio::process`]: crate::process //! //! # Examples //! //! A simple TCP echo server: //! //! ```no_run //! use tokio::net::TcpListener; //! use tokio::prelude::*; //! //! #[tokio::main] //! async fn main() -> Result<(), Box<dyn std::error::Error>> { //! let mut listener = TcpListener::bind("127.0.0.1:8080").await?; //! //! loop { //! let (mut socket, _) = listener.accept().await?; //! //! tokio::spawn(async move { //! let mut buf = [0; 1024]; //! //! // In a loop, read data from the socket and write the data back. //! loop { //! let n = match socket.read(&mut buf).await { //! // socket closed //! Ok(n) if n == 0 => return, //! Ok(n) => n, //! Err(e) => { //! eprintln!("failed to read from socket; err = {:?}", e); //! return; //! } //! }; //! //! // Write the data back //! if let Err(e) = socket.write_all(&buf[0..n]).await { //! eprintln!("failed to write to socket; err = {:?}", e); //! return; //! } //! } //! }); //! } //! } //! ``` // macros used internally #[macro_use] mod macros; cfg_fs! { pub mod fs; } mod future; pub mod io; pub mod net; mod loom; mod park; pub mod prelude; cfg_process! { pub mod process; } pub mod runtime; cfg_signal! { pub mod signal; } cfg_stream! { pub mod stream; } cfg_sync! { pub mod sync; } cfg_not_sync! { mod sync; } cfg_rt_core! { pub mod task; pub use task::spawn; } cfg_time! { pub mod time; } mod util; cfg_macros! { #[cfg(not(test))] // Work around for rust-lang/rust#62127 pub use tokio_macros::main; pub use tokio_macros::test; } // Tests #[cfg(test)] mod tests; // TODO: rm #[cfg(feature = "io-util")] #[cfg(test)] fn is_unpin<T: Unpin>() {}