Solved threads exercises; Join handle, Arc and Mutex, and MPSC.

exercises/threads/threads1.rs

@@ -2,20 +2,17 @@
 // Execute `rustlings hint threads1` or use the `hint` watch subcommand for a hint.
 // This program should wait until all the spawned threads have finished before exiting.
 
-// I AM NOT DONE
-
 use std::thread;
 use std::time::Duration;
 
 
 fn main() {
-
     let mut handles = vec![];
     for i in 0..10 {
-        thread::spawn(move || {
+        handles.push(thread::spawn(move || {
             thread::sleep(Duration::from_millis(250));
             println!("thread {} is complete", i);
-        });
+        }));
     }
 
     let mut completed_threads = 0;
@@ -27,5 +24,4 @@ fn main() {
     if completed_threads != 10 {
         panic!("Oh no! All the spawned threads did not finish!");
     }
-
 }

exercises/threads/threads2.rs

@@ -3,9 +3,7 @@
 // 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
 
-// I AM NOT DONE
-
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::Duration;
 
@@ -14,21 +12,26 @@ struct JobStatus {
 }
 
 fn main() {
-    let status = Arc::new(JobStatus { jobs_completed: 0 });
+    // let status = Arc::new(JobStatus { jobs_completed: 0 });
+    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;
+            // status_shared.jobs_completed += 1;
+            // [aziz]: BTW, this is an example of Rust's `Interior Mutability`.
+            status_shared.lock().unwrap().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 {}", ???);
+        // println!("jobs completed {}", ???);
     }
+    let completed_jobs_cnt = status.lock().unwrap().jobs_completed;
+    println!("jobs completed= {}", completed_jobs_cnt);
 }

exercises/threads/threads3.rs

@@ -1,8 +1,6 @@
 // threads3.rs
 // Execute `rustlings hint threads3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
-
 use std::sync::mpsc;
 use std::sync::Arc;
 use std::thread;
@@ -29,6 +27,8 @@ fn send_tx(q: Queue, tx: mpsc::Sender<u32>) -> () {
     let qc1 = Arc::clone(&qc);
     let qc2 = Arc::clone(&qc);
 
+    // [aziz]: Let's clone the sending end(tx= transmitter) to have more than one transmitter.
+    let tx1 = tx.clone();
     thread::spawn(move || {
         for val in &qc1.first_half {
             println!("sending {:?}", val);
@@ -40,7 +40,7 @@ fn send_tx(q: Queue, tx: mpsc::Sender<u32>) -> () {
     thread::spawn(move || {
         for val in &qc2.second_half {
             println!("sending {:?}", val);
-            tx.send(*val).unwrap();
+            tx1.send(*val).unwrap();
             thread::sleep(Duration::from_secs(1));
         }
     });