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Rust对多线程的支持

rust默认仅支持一对一线程，也就是说操作系统线程。

可以引入crate包来使用绿色线程。

std::thread::spawn创建线程

use std::thread;
use std::time::Duration;fn main() {let handle = thread::spawn(|| {for i in 1..10 {println!("hi number {} from the spawned thread!", i);thread::sleep(Duration::from_millis(1));}});for i in 1..5 {println!("hi number {} from the main thread!", i);thread::sleep(Duration::from_millis(1));}handle.join().unwrap();
}

编译

 cargo run
warning: unused `Result` that must be used--> src/main.rs:17:5|
17 |     handle.join();|     ^^^^^^^^^^^^^|= note: this `Result` may be an `Err` variant, which should be handled= note: `#[warn(unused_must_use)]` on by default
help: use `let _ = ...` to ignore the resulting value|
17 |     let _ = handle.join();|     +++++++warning: `smartPtr` (bin "smartPtr") generated 1 warningFinished `dev` profile [unoptimized + debuginfo] target(s) in 0.00sRunning `target/debug/smartPtr`
hi number 1 from the main thread!
hi number 1 from the spawned thread!
hi number 2 from the main thread!
hi number 2 from the spawned thread!
hi number 3 from the main thread!
hi number 3 from the spawned thread!
hi number 4 from the main thread!
hi number 4 from the spawned thread!
hi number 5 from the spawned thread!
hi number 6 from the spawned thread!
hi number 7 from the spawned thread!
hi number 8 from the spawned thread!
hi number 9 from the spawned thread!

线程与 move 闭包

use std::thread;fn main() {let v = vec![1, 2, 3];let handle = thread::spawn(move || {println!("Here's a vector: {:?}", v);});handle.join().unwrap();
}

编译

 cargo runBlocking waiting for file lock on build directoryCompiling smartPtr v0.1.0 (/home/wangji/installer/rust/bobo/smartPtr)Finished `dev` profile [unoptimized + debuginfo] target(s) in 19.07sRunning `target/debug/smartPtr`
Here's a vector: [1, 2, 3]

使用消息传递在线程间传送数据

std::sync::mpsc::channel()

只支持多个生产者和一个消费者

use std::sync::mpsc; //mpsc：multi-producer， single-consumer
use std::thread;fn main() {let (tx, rx) = mpsc::channel();thread::spawn(move || {let val = String::from("hi");tx.send(val).unwrap();});// recv()会阻塞// try_recv()是非阻塞,适合使用loop来尝试接收let received = rx.recv().unwrap();println!("Got: {}", received);
}

for received in rx接收

use std::sync::mpsc;
use std::thread;
use std::time::Duration;fn main() {let (tx, rx) = mpsc::channel();thread::spawn(move || {let vals = vec![String::from("hi"),String::from("from"),String::from("the"),String::from("thread"),];for val in vals {tx.send(val).unwrap();thread::sleep(Duration::from_secs(1));}});// 当发送方tx结束了，接收方rx就会结束（for循环也会结束）for received in rx {println!("Got: {}", received);}
}

两个producer

use std::sync::mpsc;
use std::thread;
use std::time::Duration;fn main() {// --snip--let (tx, rx) = mpsc::channel();let tx1 = tx.clone(); //tx和tx1都连接到mpsc::channel()thread::spawn(move || {let vals = vec![String::from("hi"),String::from("from"),String::from("the"),String::from("thread"),];for val in vals {tx1.send(val).unwrap();thread::sleep(Duration::from_secs(1));}});thread::spawn(move || {let vals = vec![String::from("more"),String::from("messages"),String::from("for"),String::from("you"),];for val in vals {tx.send(val).unwrap();thread::sleep(Duration::from_secs(1));}});for received in rx {println!("Got: {}", received);}// --snip--
}

共享状态并发

std::sync::Mutex

use std::sync::Mutex;fn main() {let m = Mutex::new(5);{// m.lock()会阻塞当前线程，获取锁位置let mut num = m.lock().unwrap();*num = 6;// 退出时会自动释放锁}println!("m = {:?}", m);
}

编译及运行

 cargo runCompiling smartPtr v0.1.0 (/home/wangji/installer/rust/bobo/smartPtr)Finished `dev` profile [unoptimized + debuginfo] target(s) in 6.57sRunning `target/debug/smartPtr`
m = Mutex { data: 6, poisoned: false, .. }

在多个线程间共享Mutex，使用std::sync::Arc

use std::sync::Arc;
use std::sync::Mutex;
use std::thread;fn main() {// Mutex于Arc经常一起使用// Rc::new可以让Mutex拥有多个所有者let counter = Arc::new(Mutex::new(0));let mut handles = vec![];for _ in 0..10 {let counter = Arc::clone(&counter); //Rc::clone不是真正的clone，只是增加引用计数let handle = thread::spawn(move || {let mut num = counter.lock().unwrap(); //counter.lock()可以获得可变的引用（类似于RefCell智能指针）*num += 1;});handles.push(handle);}for handle in handles {handle.join().unwrap();}println!("Result: {}", *counter.lock().unwrap());
}

编译

 cargo runCompiling smartPtr v0.1.0 (/home/wangji/installer/rust/bobo/smartPtr)Finished `dev` profile [unoptimized + debuginfo] target(s) in 5.85sRunning `target/debug/smartPtr`
Result: 10

参考

• 第16章~创建线程