-// Rust-101, Part 14: Mutex, Interior Mutability, Sync
-// ===================================================
-
-use std::sync::{Arc, Mutex};
-use std::thread;
-
-
-// The derived `Clone` implementation will clone the `Arc`, so all clones will actually talk about the same counter.
-#[derive(Clone)]
-struct ConcurrentCounter(Arc<Mutex<usize>>);
-
-impl ConcurrentCounter {
- // The constructor just wraps the constructors of `Arc` and `Mutex`.
- pub fn new(val: usize) -> Self {
- unimplemented!()
- }
-
- pub fn increment(&self, by: usize) {
- // `lock` on a mutex returns a *guard*, giving access to the data contained in the mutex.
- let mut counter = self.0.lock().unwrap();
- *counter = *counter + by;
- }
-
- // The function `get` returns the current value of the counter.
- pub fn get(&self) -> usize {
- unimplemented!()
- }
-}
-
-// Now our counter is ready for action.
-pub fn main() {
- let counter = ConcurrentCounter::new(0);
-
- // We clone the counter for the first thread, which increments it by 2 every 15ms.
- let counter1 = counter.clone();
- let handle1 = thread::spawn(move || {
- for _ in 0..10 {
- thread::sleep_ms(15);
- counter1.increment(2);
- }
- });
-
- // The second thread increments the counter by 3 every 20ms.
- let counter2 = counter.clone();
- let handle2 = thread::spawn(move || {
- for _ in 0..10 {
- thread::sleep_ms(20);
- counter2.increment(3);
- }
- });
-
- // Now we watch the threads working on the counter.
- for _ in 0..50 {
- thread::sleep_ms(5);
- println!("Current value: {}", counter.get());
- }
-
- // Finally, we wait for all the threads to finish to be sure we can catch the counter's final value.
- handle1.join().unwrap();
- handle2.join().unwrap();
- println!("Final value: {}", counter.get());
-}
-
-// **Exercise 14.1**: Besides `Mutex`, there's also [`RwLock`](http://doc.rust-lang.org/stable/std/sync/struct.RwLock.html), which
-// provides two ways of locking: One that grants only read-only access, to any number of concurrent readers, and another one
-// for exclusive write access. (Notice that this is the same pattern we already saw with shared vs. mutable borrows.) Change
-// the code above to use `RwLock`, such that multiple calls to `get` can be executed at the same time.
-//
-// **Exercise 14.2**: Add an operation `compare_and_inc(&self, test: usize, by: usize)` that increments the counter by
-// `by` *only if* the current value is `test`.
-
-