Bounded Channels
With bounded (synchronous) channels, send()
can block the current thread:
use std::sync::mpsc; use std::thread; use std::time::Duration; fn main() { let (tx, rx) = mpsc::sync_channel(3); thread::spawn(move || { let thread_id = thread::current().id(); for i in 0..10 { tx.send(format!("Message {i}")).unwrap(); println!("{thread_id:?}: sent Message {i}"); } println!("{thread_id:?}: done"); }); thread::sleep(Duration::from_millis(100)); for msg in rx.iter() { println!("Main: got {msg}"); } }
This slide should take about 8 minutes.
- Calling
send()
will block the current thread until there is space in the channel for the new message. The thread can be blocked indefinitely if there is nobody who reads from the channel. - Like unbounded channels, a call to
send()
will abort with an error if the channel is closed. - 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()
.