feat: completed solutions

exercises/20_threads/threads2.rs

@@ -2,24 +2,31 @@
 // work. But this time, the spawned threads need to be in charge of updating a
 // shared value: `JobStatus.jobs_done`
 
-use std::{sync::Arc, thread, time::Duration};
+use std::{
+    sync::{Arc, Mutex},
+    thread,
+    time::Duration,
+};
 
+#[derive(Debug)]
 struct JobStatus {
     jobs_done: u32,
 }
 
 fn main() {
     // TODO: `Arc` isn't enough if you want a **mutable** shared state.
-    let status = Arc::new(JobStatus { jobs_done: 0 });
+    let status = Arc::new(Mutex::new(JobStatus { jobs_done: 0 }));
 
     let mut handles = Vec::new();
     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_done += 1;
+            let mut acquired_status = status_shared.lock().unwrap();
+            acquired_status.jobs_done += 1;
         });
         handles.push(handle);
     }
@@ -30,5 +37,7 @@ fn main() {
     }
 
     // TODO: Print the value of `JobStatus.jobs_done`.
-    println!("Jobs done: {}", todo!());
+    let mutex = Arc::try_unwrap(status).unwrap();
+    let job_status = mutex.into_inner().unwrap();
+    println!("Jobs done: {}", job_status.jobs_done);
 }