Accessing resources in parallel with RwLocks

When we shared resources with an Arc, we only did so immutably. The moment we want our threads to mutate our resources, we need to use some kind of locking mechanism to secure the golden rule of parallelism: multiple readers or one writer. RwLock enforces just that rule across threads and blocks them if they violate the rule.

How to do it...

1. In the folder bin, create a file called rw_lock.rs.

2. Add the following code and run it with cargo run --bin rwlock:

1 use std::sync::{Arc, RwLock};
2 use std::thread;
3 
4 fn main() {
5 // An RwLock works like the RefCell, but blocks the current
6 // thread if the resource is unavailable
7 let resource = Arc::new(RwLock::new("Hello 
      World!".to_string()));
8 
9 // The reader_a thread will print the current content of
10 // our resource fourty times
11 let reader_a = {
12 let resource = resource.clone();
13 thread::spawn(move || {
14 for _ in 0..40 {
15 // Lock resource for reading access
16 let resource =...