[Day3] Read Rust Atomics and Locks

by Mara Bos

At Topics: Chapter 1. Basics of Rust Concurrency

Recall

What is .join()? => make sure the threads are finished before we return from main

fn main() {
    let t1 = thread::spawn(f);

    // use JoinHandle to ahcieve it
    // The .join() method waits until the thread has finished executing 
    // and returns a std::thread::Result.
    // unwrap() is for panic
    t1.join().unwrap();
}

Notes

• The std::thread::spawn function is actually just a convenient shorthand for std::thread::Builder::new().spawn().unwrap()

  Eg:

  let numbers = Vec::from_iter(0..=1000);
  
  let t = thread::spawn(move || {
      let len = numbers.len();
      let sum = numbers.iter().sum::<usize>();
      sum / len
  });
  
  let average = t.join().unwrap();
  
  println!("average: {average}");

• A std::thread::Builder can: eg set size, give thread a name

• The std::thread::spawn function simply panics if it is unable to spawn a new thread => by std::io::Result

Not Understand Yet

• for loop in closure: &number vs number

  let numbers = vec![1, 2, 3];
  
  thread::spawn(move || {
      for n in &numbers { // <== here
          println!("{n}");
      }
  }).join().unwrap();
  
  // vs
  
  let numbers = vec![1, 2, 3];
  
  thread::spawn(move || {
      for n in numbers { // <== here
          println!("{n}");
      }
  }).join().unwrap();

References

• Rust Atomics and Locks by Mara Bos