Add JoinSet::spawn_blocking

[shepmaster]

Motivation

I recently wrote some code that boiled down to spawning a blocking task inside of an async task, which has undesired indentation and unwrapping:

joinset.spawn(async move {
    tokio::task::spawn_blocking(move || {
        // blocking work
    })
        .await
        .unwrap(/* Panic occurred; re-raising */)
});

Solution

This is better expressed as spawning the blocking task directly on the JoinSet. The above code can now be written as:

joinset.spawn_blocking(move || {
    // blocking work
});

[Darksonn]

Thank you. This looks reasonable.

[Darksonn]

Can you add a spawn_blocking_on that takes a tokio::runtime::Handle too?

[shepmaster]

Added!

[Darksonn]

Thanks.