🛡️ Send & Sync

round_trip moves a value into a new thread and hands it straight back. Add the trait bounds T needs so it compiles.

`value`	`round_trip(value)`	exercises
`42i32`	`42`	a `Copy` scalar
`String::from("hi")`	`String::from("hi")`	an owned heap type
`vec![1, 2, 3]`	`vec![1, 2, 3]`	an owned collection

Send marks a type that is safe to move to another thread. thread::spawn additionally requires 'static: the spawned closure may outlive the caller, so it must not hold anything borrowed from it.

Rust

/// Spawn a thread that takes ownership of `value` and returns it.
/// Add the trait bounds T needs so it can be moved into a thread.
fn round_trip<T
    : Send + 'static
>(value: T) -> T {
    thread::spawn(move || value).join().unwrap()
}

Move It to a Thread

Why Rc Isn't Thread-Safe