mirror of https://github.com/rust-lang/async-book
Merge pull request #191 from Nereuxofficial/spawning
Added Spawning example
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commit
1ef20c71ba
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@ -9,6 +9,7 @@ AsyncRead
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AsyncWrite
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AwaitingFutOne
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AwaitingFutTwo
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cancelling
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combinator
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combinators
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compat
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@ -37,6 +38,7 @@ interprocess
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IoBlocker
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IOCP
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IoObject
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JoinHandle
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kqueue
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localhost
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LocalExecutor
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@ -0,0 +1,13 @@
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[package]
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name = "example_06_04_spawning"
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version = "0.1.0"
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edition = "2021"
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# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
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[dependencies]
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futures = "0.3"
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[dependencies.async-std]
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version = "1.12.0"
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features = ["attributes"]
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@ -0,0 +1,46 @@
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#![cfg(test)]
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#![allow(dead_code)]
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// ANCHOR: example
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use async_std::{task, net::TcpListener, net::TcpStream};
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use futures::AsyncWriteExt;
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async fn process_request(stream: &mut TcpStream) -> Result<(), std::io::Error>{
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stream.write_all(b"HTTP/1.1 200 OK\r\n\r\n").await?;
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stream.write_all(b"Hello World").await?;
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Ok(())
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}
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async fn main() {
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let listener = TcpListener::bind("127.0.0.1:8080").await.unwrap();
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loop {
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// Accept a new connection
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let (mut stream, _) = listener.accept().await.unwrap();
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// Now process this request without blocking the main loop
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task::spawn(async move {process_request(&mut stream).await});
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}
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}
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// ANCHOR_END: example
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use std::time::Duration;
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async fn my_task(time: Duration) {
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println!("Hello from my_task with time {:?}", time);
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task::sleep(time).await;
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println!("Goodbye from my_task with time {:?}", time);
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}
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// ANCHOR: join_all
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use futures::future::join_all;
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async fn task_spawner(){
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let tasks = vec![
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task::spawn(my_task(Duration::from_secs(1))),
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task::spawn(my_task(Duration::from_secs(2))),
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task::spawn(my_task(Duration::from_secs(3))),
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];
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// If we do not await these tasks and the function finishes, they will be dropped
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join_all(tasks).await;
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}
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// ANCHOR_END: join_all
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#[test]
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fn run_task_spawner() {
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futures::executor::block_on(task_spawner());
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}
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@ -10,6 +10,7 @@ members = [
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"05_02_iteration_and_concurrency",
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"06_02_join",
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"06_03_select",
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"06_04_spawning",
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"07_05_recursion",
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"09_01_sync_tcp_server",
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"09_02_async_tcp_server",
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@ -0,0 +1,24 @@
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# `Spawning`
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Spawning allows you to run a new asynchronous task in the background. This allows us to continue executing other code
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while it runs.
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Say we have a web server that wants to accept connections without blocking the main thread.
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To achieve this, we can use the `async_std::task::spawn` function to create and run a new task that handles the
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connections. This function takes a future and returns a `JoinHandle`, which can be used to wait for the result of the
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task once it's completed.
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```rust,edition2018
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{{#include ../../examples/06_04_spawning/src/lib.rs:example}}
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```
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The `JoinHandle` returned by `spawn` implements the `Future` trait, so we can `.await` it to get the result of the task.
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This will block the current task until the spawned task completes. If the task is not awaited, your program will
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continue executing without waiting for the task, cancelling it if the function is completed before the task is finished.
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```rust,edition2018
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{{#include ../../examples/06_04_spawning/src/lib.rs:join_all}}
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```
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To communicate between the main task and the spawned task, we can use channels
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provided by the async runtime used.
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@ -16,7 +16,7 @@
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- [Executing Multiple Futures at a Time](06_multiple_futures/01_chapter.md)
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- [`join!`](06_multiple_futures/02_join.md)
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- [`select!`](06_multiple_futures/03_select.md)
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- [TODO: Spawning]()
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- [Spawning](06_multiple_futures/04_spawning.md)
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- [TODO: Cancellation and Timeouts]()
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- [TODO: `FuturesUnordered`]()
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- [Workarounds to Know and Love](07_workarounds/01_chapter.md)
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