Provides a Rust Stream combinator, to limit the rate at which items are produced.

• Throttling is implemented via poll(), and not via any sort of buffering.
• The throttling behaviour can be applied to both Stream's and Future's.
• Multiple streams/futures can be throttled together as a group.
• Feature flags to use various timer implementations.

• timer-tokio: Uses the tokio::time::delay_for() timer.
• timer-futures-timer: Uses the futures_timer::Delay timer.

If you don't use the default timer (tokio), make sure to set default-features = false in your Cargo.toml, when you add stream_throttle as a dependency.

// allow no more than 5 items every 1 second
let rate = ThrottleRate::new(5, Duration::new(1, 0));
let pool = ThrottlePool::new(rate);

let work = stream::repeat(())
  .throttle(pool)
  .then(|_| futures::future::ready("do something else"))
  .for_each(|_| futures::future::ready(()));
  
work.await;

let rate = ThrottleRate::new(5, Duration::new(1, 0));
let pool = ThrottlePool::new(rate);

let work = pool.queue()
  .then(|_| futures::future::ready("do something else"));
  
work.await;