c-async-await—concurrent futures

Okay, so we’ll build on the last example and do just the same thing. Create a new project called c-async-await and copy Cargo.toml and everything in the src folder over.

The first thing we’ll do is go to future.rs and add a join_all function below our existing code:

ch07/c-async-await/src/future.rs

pub fn join_all<F: Future>(futures: Vec<F>) -> JoinAll<F> {
    let futures = futures.into_iter().map(|f| (false, f)).collect();
    JoinAll {
        futures,
        finished_count: 0,
    }
}

This function takes a collection of futures as an argument and returns a JoinAll<F> future.

The function simply creates a new collection. In this collection, we will have tuples consisting of the original futures we received and a bool value indicating whether the future...