77 lines
2.6 KiB
Rust
77 lines
2.6 KiB
Rust
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//! A "hello world" echo server with Tokio
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//!
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//! This server will create a TCP listener, accept connections in a loop, and
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//! write back everything that's read off of each TCP connection.
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//!
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//! Because the Tokio runtime uses a thread pool, each TCP connection is
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//! processed concurrently with all other TCP connections across multiple
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//! threads.
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//!
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//! To see this server in action, you can run this in one terminal:
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//!
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//! cargo run --example echo
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//!
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//! and in another terminal you can run:
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//!
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//! cargo run --example connect 127.0.0.1:8080
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//!
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//! Each line you type in to the `connect` terminal should be echo'd back to
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//! you! If you open up multiple terminals running the `connect` example you
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//! should be able to see them all make progress simultaneously.
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#![warn(rust_2018_idioms)]
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use tokio::io::{AsyncReadExt};
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use tokio::net::TcpListener;
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use std::env;
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use std::error::Error;
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#[tokio::main]
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async fn main() -> Result<(), Box<dyn Error>> {
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// Allow passing an address to listen on as the first argument of this
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// program, but otherwise we'll just set up our TCP listener on
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// 127.0.0.1:8080 for connections.
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let addr = env::args()
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.nth(1)
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.unwrap_or_else(|| "127.0.0.1:8080".to_string());
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// Next up we create a TCP listener which will listen for incoming
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// connections. This TCP listener is bound to the address we determined
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// above and must be associated with an event loop.
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let listener = TcpListener::bind(&addr).await?;
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println!("Listening on: {addr}");
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loop {
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// Asynchronously wait for an inbound socket.
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let (mut socket, _) = listener.accept().await?;
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// And this is where much of the magic of this server happens. We
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// crucially want all clients to make progress concurrently, rather than
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// blocking one on completion of another. To achieve this we use the
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// `tokio::spawn` function to execute the work in the background.
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//
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// Essentially here we're executing a new task to run concurrently,
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// which will allow all of our clients to be processed concurrently.
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tokio::spawn(async move {
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let mut buf = vec![0; 1024];
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// In a loop, read data from the socket and write the data back.
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loop {
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let n = socket
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.read(&mut buf)
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.await
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.expect("failed to read data from socket");
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if n == 0 {
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return;
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}
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use std::str;
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println!("{}", str::from_utf8(&buf[0..n]).unwrap());
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}
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});
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}
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}
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