mirror of
https://github.com/notohh/rustlings.git
synced 2024-11-22 14:02:22 -05:00
95 lines
2.7 KiB
Rust
95 lines
2.7 KiB
Rust
// threads1.rs
|
|
// Make this compile! Scroll down for hints :) The idea is the thread
|
|
// spawned on line 19 is completing jobs while the main thread is
|
|
// monitoring progress until 10 jobs are completed. If you see 6 lines
|
|
// of "waiting..." and the program ends without timing out the playground,
|
|
// you've got it :)
|
|
|
|
use std::sync::Arc;
|
|
use std::thread;
|
|
use std::time::Duration;
|
|
|
|
struct JobStatus {
|
|
jobs_completed: u32,
|
|
}
|
|
|
|
fn main() {
|
|
let status = Arc::new(JobStatus { jobs_completed: 0 });
|
|
let status_shared = status.clone();
|
|
thread::spawn(move || {
|
|
for _ in 0..10 {
|
|
thread::sleep(Duration::from_millis(250));
|
|
status_shared.jobs_completed += 1;
|
|
}
|
|
});
|
|
while status.jobs_completed < 10 {
|
|
println!("waiting... ");
|
|
thread::sleep(Duration::from_millis(500));
|
|
}
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// `Arc` is an Atomic Reference Counted pointer that allows safe, shared access
|
|
// to **immutable** data. But we want to *change* the number of `jobs_completed`
|
|
// so we'll need to also use another type that will only allow one thread to
|
|
// mutate the data at a time. Take a look at this section of the book:
|
|
// https://doc.rust-lang.org/stable/book/concurrency.html#safe-shared-mutable-state
|
|
// and keep scrolling if you'd like more hints :)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// Do you now have an `Arc` `Mutex` `JobStatus` at the beginning of main? Like:
|
|
// `let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));`
|
|
// Similar to the code in the example in the book that happens after the text
|
|
// that says "We can use Arc<T> to fix this.". If not, give that a try! If you
|
|
// do and would like more hints, keep scrolling!!
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// Make sure neither of your threads are holding onto the lock of the mutex
|
|
// while they are sleeping, since this will prevent the other thread from
|
|
// being allowed to get the lock. Locks are automatically released when
|
|
// they go out of scope.
|
|
|
|
// Ok, so, real talk, this was actually tricky for *me* to do too. And
|
|
// I could see a lot of different problems you might run into, so at this
|
|
// point I'm not sure which one you've hit :) Please see a few possible
|
|
// answers on https://github.com/carols10cents/rustlings/issues/3 --
|
|
// mine is a little more complicated because I decided I wanted to see
|
|
// the number of jobs currently done when I was checking the status.
|
|
|
|
// Please open an issue if you're still running into a problem that
|
|
// these hints are not helping you with, or if you've looked at the sample
|
|
// answers and don't understand why they work and yours doesn't.
|
|
|
|
// If you've learned from the sample solutions, I encourage you to come
|
|
// back to this exercise and try it again in a few days to reinforce
|
|
// what you've learned :)
|