// threads2.rs

//
// Building on the last exercise, we want all of the threads to complete their
// work but this time the spawned threads need to be in charge of updating a
// shared value: JobStatus.jobs_completed
//
// Execute `rustlings hint threads2` or use the `hint` watch subcommand for a
// hint.

// I AM NOT DONE

use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;

struct JobStatus {
    jobs_completed: u32,
}

fn main() {
    // 使用 Arc 实现共享所有权，Mutex 保证互斥访问
    let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));
    let mut handles = vec![];

    for _ in 0..10 {
        let status_shared = Arc::clone(&status);
        let handle = thread::spawn(move || {
            thread::sleep(Duration::from_millis(250));
            // 锁定 Mutex 以获取对内部数据的访问权
            let mut status = status_shared.lock().unwrap();
            status.jobs_completed += 1;
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
        // 锁定 Mutex 以读取当前完成的任务数
        let status = status.lock().unwrap();
        println!("jobs completed {}", status.jobs_completed);
    }
}

Author: unix-dot

exercises/threads/threads2.rs

@@ -9,7 +9,7 @@
 
 // I AM NOT DONE
 
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
 
@@ -18,22 +18,25 @@ struct JobStatus {
 }
 
 fn main() {
-    let status = Arc::new(JobStatus { jobs_completed: 0 });
+    // 使用 Arc 实现共享所有权，Mutex 保证互斥访问
+    let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));
     let mut handles = vec![];
+
     for _ in 0..10 {
         let status_shared = Arc::clone(&status);
         let handle = thread::spawn(move || {
             thread::sleep(Duration::from_millis(250));
-            // TODO: You must take an action before you update a shared value
-            status_shared.jobs_completed += 1;
+            // 锁定 Mutex 以获取对内部数据的访问权
+            let mut status = status_shared.lock().unwrap();
+            status.jobs_completed += 1;
         });
         handles.push(handle);
     }
+
     for handle in handles {
         handle.join().unwrap();
-        // TODO: Print the value of the JobStatus.jobs_completed. Did you notice
-        // anything interesting in the output? Do you have to 'join' on all the
-        // handles?
-        println!("jobs completed {}", ???);
+        // 锁定 Mutex 以读取当前完成的任务数
+        let status = status.lock().unwrap();
+        println!("jobs completed {}", status.jobs_completed);
     }
 }