قنوات Crossbeam

ما بعد std mpsc

إضافة الاعتمادية

// Cargo.toml
// [dependencies]
// crossbeam-channel = "0.5"

use crossbeam_channel::unbounded;

fn main() {
    let (s, r) = unbounded();
    s.send("hello").unwrap();
    println!("{}", r.recv().unwrap());
}

unbounded و bounded

use crossbeam_channel::bounded;
use std::thread;

fn main() {
    let (s, r) = bounded(2);
    thread::spawn(move || {
        for i in 1..=3 {
            s.send(i).unwrap();
        }
    });
    while let Ok(v) = r.recv() {
        println!("got {}", v);
    }
}

مستهلكون متعددون

use crossbeam_channel::unbounded;
use std::thread;

fn main() {
    let (s, r) = unbounded();
    let mut workers = vec![];
    for id in 0..3 {
        let rx = r.clone();
        workers.push(thread::spawn(move || {
            while let Ok(job) = rx.recv() {
                println!("worker {} got job {}", id, job);
            }
        }));
    }
    for job in 0..6 { s.send(job).unwrap(); }
    drop(s);
    for w in workers { w.join().unwrap(); }
}

ماكرو select!

use crossbeam_channel::{unbounded, select};
use std::thread;

fn main() {
    let (s1, r1) = unbounded();
    let (s2, r2) = unbounded();
    thread::spawn(move || { s1.send("from one").unwrap(); });
    thread::spawn(move || { s2.send("from two").unwrap(); });
    for _ in 0..2 {
        select! {
            recv(r1) -> msg => println!("r1: {}", msg.unwrap()),
            recv(r2) -> msg => println!("r2: {}", msg.unwrap()),
        }
    }
}

المهلات الزمنية مع select!

use crossbeam_channel::{unbounded, select, after};
use std::time::Duration;

fn main() {
    let (_s, r) = unbounded::<i32>();
    select! {
        recv(r) -> msg => println!("received {:?}", msg),
        recv(after(Duration::from_millis(100))) -> _ => {
            println!("timed out waiting for a message");
        }
    }
}

try_send و try_recv

use crossbeam_channel::{bounded, TrySendError};

fn main() {
    let (s, _r) = bounded(1);
    s.send(1).unwrap();
    match s.try_send(2) {
        Ok(()) => println!("sent"),
        Err(TrySendError::Full(v)) => println!("full, kept {}", v),
        Err(TrySendError::Disconnected(v)) => println!("closed, kept {}", v),
    }
}

tick والعمل الدوري

use crossbeam_channel::{tick, select};
use std::time::Duration;

fn main() {
    let ticker = tick(Duration::from_millis(50));
    let mut count = 0;
    while count < 3 {
        select! {
            recv(ticker) -> _ => {
                count += 1;
                println!("tick {}", count);
            }
        }
    }
}

خط أنابيب من المراحل

use crossbeam_channel::unbounded;
use std::thread;

fn main() {
    let (in_s, in_r) = unbounded();
    let (out_s, out_r) = unbounded();
    thread::spawn(move || {
        for n in in_r { out_s.send(n * n).unwrap(); }
    });
    for n in 1..=4 { in_s.send(n).unwrap(); }
    drop(in_s);
    for sq in out_r { println!("square: {}", sq); }
}

متى تتفوق Crossbeam على std

تُغلق القنوات بحذفها

use crossbeam_channel::unbounded;
use std::thread;

fn main() {
    let (s, r) = unbounded();
    let h = thread::spawn(move || {
        let total: i32 = r.iter().sum();
        println!("total: {}", total);
    });
    for i in 1..=5 { s.send(i).unwrap(); }
    drop(s); // closes channel so the loop ends
    h.join().unwrap();
}

اختبار سريع

مراجعة