//! # Lock-free Bounded Non-Blocking Pub-Sub Queue //! //! This is a publish subscribe pattern queue, where the publisher is never blocked by //! slow subscribers. The side effect is that slow subscribers will miss messages. The intended //! use-case are high throughput streams where receiving the latest message is prioritized over //! receiving the entire stream. Market Data Feeds, Live Streams, etc.... //! //! The underlying data-structure is a vector of Arc(s) eliminating the use of copies. //! //! ## Features //! * Lock-Free Write/Read - Lock-Free for Publisher and Lock-Free for Subscribers. //! * Bounded - Constant size of memory used, max is `sizeof(MsgObject)*(queue_size + sub_cnt + 1)`. This is an //! edge-case where each subscriber is holding a ref to an object while the publisher has published a full length of //! queue in the mean time. //! * Non-Blocking - The queue never blocks the publisher, slow subscribers miss data proportinal to their speed. //! * Pub-Sub - Every Subscriber that can keep up with the Publisher will recieve all the data the Publisher publishes. //! * [`sync`]/[`async`] - both interfaces are provided, as well as a bare queue implementation without the thread //! synchronisation ,and futures logic. //! * std::sync::mpsc like interface - The API is modeled after the standard library mpsc queue, channel function are //! used to create a tuple of (Publisher, Subscriber), while the Clone trait on Subscriber creates additional //! subscribers to the same Publisher. //! //! [`sync::Publisher`], [`async::Publisher`], and [`BarePublisher`] are used to broadcast data to //! [`sync::Subscriber`], [`async::Subscriber`], and [`BareSubscriber`] pools. Subscribers are //! clone-able such that many threads, or futures, can receive data simultaneously. The only //! limitation is that Subscribers have to keep up with the frequency of the Publisher. If a //! Subscriber is slow it will drop data. //! //! ## Disconnection //! //! The broadcast and receive operations on channels will all return a [`Result`] //! indicating whether the operation succeeded or not. An unsuccessful operation //! is normally indicative of the other half of a channel having "hung up" by //! being dropped in its corresponding thread. //! //! Once half of a channel has been deallocated, most operations can no longer //! continue to make progress, so [`Err`] will be returned. Many applications //! will continue to [`unwrap`] the results returned from this module, //! instigating a propagation of failure among threads if one unexpectedly dies. //! //! //! # Examples //! ## Simple raw usage //! ```rust //! use tari_broadcast_channel::raw_bounded; //! //! let (tx, rx) = raw_bounded(10, 1); //! (1..15).for_each(|x| tx.broadcast(x).unwrap()); //! //! let received: Vec = rx.map(|x| *x).collect(); //! // Test that only the last 10 elements are in the received list. //! let expected: Vec = (5..15).collect(); //! //! assert_eq!(expected, received); //! ``` //! ## Simple asynchronous usage //! ```rust //! # use tari_broadcast_channel::bounded; //! # use futures::executor::block_on; //! # use futures::StreamExt; //! # use futures::stream; //! //! let (publisher, subscriber1) = bounded(10, 2); //! let subscriber2 = subscriber1.clone(); //! //! block_on(async move { //! stream::iter(1..15).map(|i| Ok(i)).forward(publisher).await.unwrap(); //! }); //! //! let received1: Vec = block_on(async { subscriber1.map(|x| *x).collect().await }); //! let received2: Vec = block_on(async { subscriber2.map(|x| *x).collect().await }); //! // Test that only the last 10 elements are in the received list. //! let expected = (5..15).collect::>(); //! assert_eq!(received1, expected); //! assert_eq!(received2, expected); //! ``` //! //! [`BarePublisher`]: struct.BarePublisher.html //! [`BareSubscriber`]: struct.BareSubscriber.html //! [`sync`]: sync/index.html //! [`async`]: async/index.html //! [`sync::Publisher`]: sync/struct.Publisher.html //! [`sync::Subscriber`]: sync/struct.Subscriber.html //! [`async::Publisher`]: async/struct.Publisher.html //! [`async::Subscriber`]: async/struct.Subscriber.html //! [`Result`]: ../../../std/result/enum.Result.html //! [`Err`]: ../../../std/result/enum.Result.html#variant.Err //! [`unwrap`]: ../../../std/result/enum.Result.html#method.unwrap mod async_channel; pub(crate) mod atomic_counter; mod channel; pub use async_channel::{bounded, Publisher, Subscriber}; pub use channel::{bounded as raw_bounded, SendError};