有界通道

With bounded (synchronous) channels, send can block the current thread:

  1. use std::sync::mpsc;
  2. use std::thread;
  3. use std::time::Duration;
  5. fn main() {
  6.     let (tx, rx) = mpsc::sync_channel(3);
  8.     thread::spawn(move || {
  9.         let thread_id = thread::current().id();
  10.         for i in 1..10 {
  11.             tx.send(format!("Message {i}")).unwrap();
  12.             println!("{thread_id:?}: sent Message {i}");
  13.         }
  14.         println!("{thread_id:?}: done");
  15.     });
  16.     thread::sleep(Duration::from_millis(100));
  18.     for msg in rx.iter() {
  19.         println!("Main: got {msg}");
  20.     }
  21. }
  • 调用 send 将阻塞当前线程，直到通道中有足够的空间放置新消息。如果无人从通道读取数据，线程会被无限期地阻塞。
  • 如果通道关闭，调用 send 将中止并返回错误（这就是它会返回 Result 的原因）。当接收器被丢弃时，通道将关闭。
  • A bounded channel with a size of zero is called a “rendezvous channel”. Every send will block the current thread until another thread calls recv.