Rust中多线程并发编程
1.Arc和Mutex
使用Arc和Mutex来创建并发安全的共享数据结构。这里通过Arc（原子引用计数指针）将Mutex包装成可跨线程共享的数据结构，并展示了如何在多个线程间进行安全的数据写入和读取操作。
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fn mutex_test() {
println!("---mutex_test---");
//当使用 Rust 的 Mutex 智能指针时，一般情况下会将内部数据封装在 Arc 和 Mutex 中，以确保多线程下的安全性
let shared_data = Arc::new(Mutex::new(0));
let threads: Vec<_> = (0..6).map(|i| {
let thread_data = Arc::clone(&shared_data);
thread::spawn(move || {
for j in 0..10 {
let mut data = thread_data.lock().unwrap();
*data += i * j;
}
})
}).collect();
for t in threads {
t.join().unwrap();
}
println!("Final value: {}", *shared_data.lock().unwrap());
}
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2.Arc和RwLock
使用Arc和RwLock实现读写锁，允许多个线程同时读取数据，但只有一个线程能写入数据。该函数还演示了如何使用Mutex作为条件变量来实现线程间的同步通信。
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fn rwlock_test() {
// Rust 中的 RwLock（读写锁），可以使用 Arc 和 RwLock 结合起来，以实现多线程下的读写安全。
println!("---rwlock_test---");
let shared_data = Arc::new(RwLock::new(0));
let exit_flag = Arc::new(Mutex::new(false));
let read_threads:Vec<_> = (0..5).map(|_x| {
let thread_data = Arc::clone(&shared_data);
//let thread_flag = Arc::clone(&exit_flag);
let thread_flag = Arc::clone(&exit_flag);
thread::spawn(move || {
loop {
let data = thread_data.read().unwrap();
println!("read thread {:?}: data = {}", thread::current().id(), *data);
let flag = thread_flag.lock().unwrap();
if *flag {
println!("read thread {:?}: flag = {}", thread::current().id(), *flag);
break;
}
}
println!("read thread end!");
})
}).collect();
let write_threads: Vec<_> = (0..3).map(|_x| {
let thread_data = Arc::clone(&shared_data);
let thread_flag = Arc::clone(&exit_flag);
thread::spawn(move || {
for i in 0..3 {
let mut data = thread_data.write().unwrap();
*data = i;
println!("write thread {:?}: data = {}", thread::current().id(), *data);
thread::sleep(Duration::from_secs(2));
}
let mut flag_data = thread_flag.lock().unwrap();
*flag_data = true;
println!("write thread end!");
})
}).collect();
//wait for write
for write_t in write_threads {
write_t.join().unwrap();
}
//read
for read_thread in read_threads {
read_thread.join().unwrap();
}
let final_value = shared_data.read().unwrap();
println!("rwlock_test Final value: {}", *final_value);
}
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3.Pin类型
它用于固定数据在堆上的内存位置，以防止数据被移动。这对于处理涉及异步操作或存在自引用数据结构的情况特别有用。
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struct XData {
value: i64,
}
impl XData {
fn new(value: i64) -> Self {
XData{value}
}
}
fn pin_test() {
//使用 as_ref 方法获取指向固定数据的引用。值得注意的是，一旦数据被固定，就无法再次移动它。
println!("---pin_test---");
let data = XData::new(100);
let pin_data: Pin<Box<XData>> = Box::pin(data);
let pin_data_ref = pin_data.as_ref();
println!("pin data: {}", pin_data_ref.value);
}
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4 Mutex和Condvar
Mutex和Condvar来实现条件变量，主线程使用条件变量通知子线程结束，并等待子线程执行完毕。
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fn cond_var_test() {
println!("---cond_var_test---");
let pair = Arc::new((Mutex::new(false), Condvar::new()));
let pair_clone_data = Arc::clone(&pair);
thread::spawn(move || {
let (lock, cvar) = &*pair_clone_data;
let mut exit_flag = lock.lock().unwrap();
while !*exit_flag {
println!("exit_flag = {}", *exit_flag);
exit_flag = cvar.wait(exit_flag).unwrap();
}
println!("Thread end, exit_flag = {:?}", *exit_flag);
thread::sleep(Duration::from_secs(1))
});
thread::sleep(Duration::from_micros(500));
let (lock, cvar) = &*pair;
let mut exit_flag = lock.lock().unwrap();
*exit_flag = true;
cvar.notify_one();
println!("main thread exit_flag = {}", *exit_flag);
// 等待子线程执行完毕，并添加一些延迟等待的时间
//handle.join().unwrap();
thread::sleep(Duration::from_secs(1));
println!("cond_var_test end");
}
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5.效果
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---mutex_test---
Final value: 675
---rwlock_test---
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(16): data = 0
read thread ThreadId(17): data = 0
read thread ThreadId(18): data = 0
read thread ThreadId(19): data = 0
write thread ThreadId(20): data = 0
write thread ThreadId(21): data = 0
write thread ThreadId(22): data = 0
read thread ThreadId(15): data = 0
read thread ThreadId(19): data = 0
read thread ThreadId(16): data = 0
read thread ThreadId(17): data = 0
read thread ThreadId(18): data = 0
write thread ThreadId(20): data = 1
write thread ThreadId(21): data = 1
write thread ThreadId(22): data = 1
read thread ThreadId(15): data = 1
read thread ThreadId(19): data = 1
read thread ThreadId(16): data = 1
read thread ThreadId(17): data = 1
read thread ThreadId(18): data = 1
write thread ThreadId(20): data = 2
write thread end!
write thread ThreadId(21): data = 2
write thread end!
write thread ThreadId(22): data = 2
write thread end!
read thread ThreadId(15): data = 2
read thread ThreadId(15): flag = true
read thread end!
read thread ThreadId(19): data = 2
read thread ThreadId(19): flag = true
read thread end!
read thread ThreadId(16): data = 2
read thread ThreadId(16): flag = true
read thread end!
read thread ThreadId(17): data = 2
read thread ThreadId(17): flag = true
read thread end!
read thread ThreadId(18): data = 2
read thread ThreadId(18): flag = true
read thread end!
rwlock_test Final value: 2
---pin_test---
pin data: 100
---cond_var_test---
exit_flag = false
main thread exit_flag = true
cond_var_test end
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文章作者
梵梵爸
上次更新
2024-02-06
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