Step 1.8: Thread safety

1_concepts/1_8_thread_safety/src/main.rs

@@ -1,3 +1,58 @@
+#![allow(warnings)]
+
+use std::{
+    cell::Cell,
+    marker::PhantomData,
+    rc::Rc,
+    sync::{Arc, Mutex, MutexGuard},
+    thread,
+};
+
 fn main() {
-    println!("Implement me!");
+    let only_send = OnlySend(Cell::new(0));
+    let sync_and_send = SyncAndSend(0);
+    let not_sync_not_send = NotSyncNotSend(Rc::new(0));
+    let only_sync = Arc::new(Mutex::new(SyncAndSend(0)));
+
+    let mut handles = vec![];
+    for _ in 0..10 {
+        let counter = Arc::clone(&only_sync);
+        let handle = thread::spawn(move || {
+            let mut num = counter.lock().unwrap();
+
+            num.0 += 1;
+        });
+        handles.push(handle);
+    }
+    for handle in handles {
+        handle.join().unwrap();
+    }
+
+    println!("{:?}", only_sync);
+    println!("{:?}", only_send);
+    println!("{:?}", sync_and_send);
+
+    let only_sync_instance = OnlySync(SyncAndSend(0), PhantomData);
+    println!("{:?}", only_sync_instance);
+
+    let handle = thread::spawn(move || {
+        println!("{:?}", only_send);
+        println!("{:?}", sync_and_send);
+    });
+
+    handle.join().unwrap();
 }
+
+#[derive(Debug)]
+struct OnlySync<T: Sync>(T, PhantomData<Rc<()>>);
+
+#[derive(Debug)]
+struct OnlySend<T: Copy>(Cell<T>);
+
+#[derive(Debug)]
+struct SyncAndSend(i32);
+
+#[derive(Debug)]
+struct NotSyncNotSend<T>(Rc<T>);
+
+unsafe impl<T: Sync> Sync for OnlySync<T> {}

README.md

@@ -78,7 +78,7 @@ Each step must be performed as a separate [PR (pull request)][PR] with an approp
     - [ ] [1.5. Conversions, casting and dereferencing][Step 1.5] (1 day)
     - [ ] [1.6. Static and dynamic dispatch][Step 1.6] (1 day)
     - [ ] [1.7. `Sized` and `?Sized` types][Step 1.7] (1 day)
-    - [ ] [1.8. Thread safety][Step 1.8] (1 day)
+    - [x] [1.8. Thread safety][Step 1.8] (1 day)
     - [ ] [1.9. Phantom types][Step 1.9] (1 day)
 - [ ] [2. Idioms][Step 2] (2 days, after all sub-steps)
     - [ ] [2.1. Rich types ensure correctness][Step 2.1] (1 day)