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//! This crate provides multiple mechanisms for interrupting a `Stream`. //! //! # Stream combinator //! //! The extension trait [`StreamExt`] provides a single new `Stream` combinator: `take_until`. //! [`StreamExt::take_until`] continues yielding elements from the underlying `Stream` until a //! `Future` resolves, and at that moment immediately yields `None` and stops producing further //! elements. //! //! For convenience, the crate also includes the [`Tripwire`] type, which produces a cloneable //! `Future` that can then be passed to `take_until`. When a new `Tripwire` is created, an //! associated [`Trigger`] is also returned, which interrupts the `Stream` when it is dropped. //! //! //! ``` //! # extern crate stream_cancel; //! extern crate tokio; //! //! use stream_cancel::{StreamExt, Tripwire}; //! use tokio::prelude::*; //! //! let listener = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); //! let (trigger, tripwire) = Tripwire::new(); //! //! let mut rt = tokio::runtime::Runtime::new().unwrap(); //! rt.spawn( //! listener //! .incoming() //! .take_until(tripwire) //! .map_err(|e| eprintln!("accept failed = {:?}", e)) //! .for_each(|sock| { //! let (reader, writer) = sock.split(); //! tokio::spawn( //! tokio::io::copy(reader, writer) //! .map(|amt| println!("wrote {:?} bytes", amt)) //! .map_err(|err| eprintln!("IO error {:?}", err)), //! ) //! }), //! ); //! //! // tell the listener to stop accepting new connections //! drop(trigger); //! rt.shutdown_on_idle().wait().unwrap(); //! ``` //! //! # Stream wrapper //! //! Any stream can be wrapped in a [`Valved`], which enables it to be remotely terminated through //! an associated [`Trigger`]. This can be useful to implement graceful shutdown on "infinite" //! streams like a `TcpListener`. Once [`Trigger::close`] is called on the handle for a given //! stream's [`Valved`], the stream will yield `None` to indicate that it has terminated. //! //! ``` //! # extern crate stream_cancel; //! extern crate tokio; //! //! use stream_cancel::Valved; //! use tokio::prelude::*; //! use std::thread; //! //! let listener = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); //! let (exit, incoming) = Valved::new(listener.incoming()); //! //! let server = thread::spawn(move || { //! // start a tokio echo server //! tokio::run( //! incoming //! .map_err(|e| eprintln!("accept failed = {:?}", e)) //! .for_each(|sock| { //! let (reader, writer) = sock.split(); //! tokio::spawn( //! tokio::io::copy(reader, writer) //! .map(|amt| println!("wrote {:?} bytes", amt)) //! .map_err(|err| eprintln!("IO error {:?}", err)), //! ) //! }), //! ) //! }); //! //! // the server thread will normally never exit, since more connections //! // can always arrive. however, with a Valved, we can turn off the //! // stream of incoming connections to initiate a graceful shutdown //! drop(exit); //! server.join().unwrap(); //! ``` //! //! You can share the same [`Trigger`] between multiple streams by first creating a [`Valve`], //! and then wrapping multiple streams using [`Valve::Wrap`]: //! //! ``` //! # extern crate stream_cancel; //! extern crate tokio; //! //! use stream_cancel::Valve; //! use tokio::prelude::*; //! //! let (exit, valve) = Valve::new(); //! let listener1 = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); //! let listener2 = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); //! let incoming1 = valve.wrap(listener1.incoming()); //! let incoming2 = valve.wrap(listener2.incoming()); //! //! let mut rt = tokio::runtime::Runtime::new().unwrap(); //! rt.spawn( //! incoming1 //! .select(incoming2) //! .map_err(|e| eprintln!("accept failed = {:?}", e)) //! .for_each(|sock| { //! let (reader, writer) = sock.split(); //! tokio::spawn( //! tokio::io::copy(reader, writer) //! .map(|amt| println!("wrote {:?} bytes", amt)) //! .map_err(|err| eprintln!("IO error {:?}", err)), //! ) //! }), //! ); //! //! // the runtime will not become idle until both incoming1 and incoming2 have stopped //! // (due to the select). this checks that they are indeed both interrupted when the //! // valve is closed. //! drop(exit); //! rt.shutdown_on_idle().wait().unwrap(); //! ``` #![deny(missing_docs)] extern crate futures; #[cfg(test)] extern crate tokio; use futures::sync::oneshot; mod combinator; mod wrapper; pub use combinator::{StreamExt, TakeUntil, Tripwire}; pub use wrapper::{Valve, Valved}; /// A handle to a set of cancellable streams. /// /// If the `Trigger` is dropped, any streams associated with it are interrupted (this is equivalent /// to calling [`Trigger::close`]. To override this behavior, call [`Trigger::disable`]. #[derive(Debug)] pub struct Trigger(Option<oneshot::Sender<()>>); impl Trigger { /// Cancel all associated streams, and make them immediately yield `None`. pub fn cancel(self) { drop(self); } /// Disable the `Trigger`, and leave all associated streams running to completion. pub fn disable(mut self) { let _ = self.0.take(); drop(self); } } impl Drop for Trigger { fn drop(&mut self) { if let Some(tx) = self.0.take() { tx.send(()).unwrap(); } } } #[cfg(test)] mod tests { use super::*; use tokio::prelude::*; #[test] fn tokio_run() { use std::thread; let listener = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); let (exit, incoming) = Valved::new(listener.incoming()); let server = thread::spawn(move || { // start a tokio echo server tokio::run( incoming .map_err(|e| eprintln!("accept failed = {:?}", e)) .for_each(|sock| { let (reader, writer) = sock.split(); tokio::spawn( tokio::io::copy(reader, writer) .map(|amt| println!("wrote {:?} bytes", amt)) .map_err(|err| eprintln!("IO error {:?}", err)), ) }), ) }); // the server thread will normally never exit, since more connections // can always arrive. however, with a Valved, we can turn off the // stream of incoming connections to initiate a graceful shutdown drop(exit); server.join().unwrap(); } #[test] fn tokio_rt_on_idle() { let listener = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); let (exit, incoming) = Valved::new(listener.incoming()); let mut rt = tokio::runtime::Runtime::new().unwrap(); rt.spawn( incoming .map_err(|e| eprintln!("accept failed = {:?}", e)) .for_each(|sock| { let (reader, writer) = sock.split(); tokio::spawn( tokio::io::copy(reader, writer) .map(|amt| println!("wrote {:?} bytes", amt)) .map_err(|err| eprintln!("IO error {:?}", err)), ) }), ); drop(exit); rt.shutdown_on_idle().wait().unwrap(); } #[test] fn multi_interrupt() { let (exit, valve) = Valve::new(); let listener1 = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); let listener2 = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); let incoming1 = valve.wrap(listener1.incoming()); let incoming2 = valve.wrap(listener2.incoming()); let mut rt = tokio::runtime::Runtime::new().unwrap(); rt.spawn( incoming1 .select(incoming2) .map_err(|e| eprintln!("accept failed = {:?}", e)) .for_each(|sock| { let (reader, writer) = sock.split(); tokio::spawn( tokio::io::copy(reader, writer) .map(|amt| println!("wrote {:?} bytes", amt)) .map_err(|err| eprintln!("IO error {:?}", err)), ) }), ); // the runtime will not become idle until both incoming1 and incoming2 have stopped (due to // the select). this checks that they are indeed both interrupted when the valve is closed. drop(exit); rt.shutdown_on_idle().wait().unwrap(); } }