X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/0223210576f27d0743c2d12b890d30f5c2ef6b2d..ab7f9b241429bd675b437d2437799de75d2f409b:/workspace/src/part14.rs?ds=sidebyside diff --git a/workspace/src/part14.rs b/workspace/src/part14.rs deleted file mode 100644 index d939265..0000000 --- a/workspace/src/part14.rs +++ /dev/null @@ -1,72 +0,0 @@ -// 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>); - -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`. - -