feat: completed solutions

exercises/20_threads/threads1.rs

@@ -20,10 +20,12 @@ fn main() {
         handles.push(handle);
     }
 
-    let mut results = Vec::new();
+    let mut results: Vec<_> = Vec::<_>::new();
+
     for handle in handles {
         // TODO: Collect the results of all threads into the `results` vector.
         // Use the `JoinHandle` struct which is returned by `thread::spawn`.
+        results.push(handle.join().unwrap())
     }
 
     if results.len() != 10 {

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);
 }

exercises/20_threads/threads3.rs

@@ -17,18 +17,23 @@ impl Queue {
 fn send_tx(q: Queue, tx: mpsc::Sender<u32>) {
     // TODO: We want to send `tx` to both threads. But currently, it is moved
     // into the first thread. How could you solve this problem?
+
+    let transmission = tx.clone();
+
     thread::spawn(move || {
         for val in q.first_half {
             println!("Sending {val:?}");
-            tx.send(val).unwrap();
+            transmission.send(val).unwrap();
             thread::sleep(Duration::from_millis(250));
         }
     });
 
+    let transmission = tx.clone();
+
     thread::spawn(move || {
         for val in q.second_half {
             println!("Sending {val:?}");
-            tx.send(val).unwrap();
+            transmission.send(val).unwrap();
             thread::sleep(Duration::from_millis(250));
         }
     });