148 lines
4.2 KiB
Rust
148 lines
4.2 KiB
Rust
use failure::*;
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use std::sync::{Mutex, Arc};
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use futures::*;
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use tokio::sync::oneshot;
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/// Broadcast results to registered listeners using asnyc oneshot channels
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pub struct BroadcastData<T> {
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result: Option<Result<T, String>>,
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listeners: Vec<oneshot::Sender<Result<T, Error>>>,
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}
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impl <T: Clone> BroadcastData<T> {
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pub fn new() -> Self {
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Self {
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result: None,
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listeners: vec![],
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}
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}
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pub fn notify_listeners(&mut self, result: Result<T, String>) {
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self.result = Some(result.clone());
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loop {
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match self.listeners.pop() {
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None => { break; },
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Some(ch) => {
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match &result {
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Ok(result) => { let _ = ch.send(Ok(result.clone())); },
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Err(err) => { let _ = ch.send(Err(format_err!("{}", err))); },
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}
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},
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}
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}
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}
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pub fn listen(&mut self) -> impl Future<Item=T, Error=Error> {
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match &self.result {
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None => {},
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Some(Ok(result)) => return futures::future::Either::A(futures::future::ok(result.clone())),
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Some(Err(err)) => return futures::future::Either::A(futures::future::err(format_err!("{}", err))),
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}
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let (tx, rx) = oneshot::channel::<Result<T, Error>>();
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self.listeners.push(tx);
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futures::future::Either::B(rx.flatten())
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}
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}
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/// Broadcast future results to registered listeners
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pub struct BroadcastFuture<T> {
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inner: Arc<Mutex<(BroadcastData<T>, Option<Box<Future<Item=T, Error=Error> + Send>>)>>,
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}
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impl <T: Clone + Send + 'static> BroadcastFuture<T> {
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/// Create instance for specified source future.
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///
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/// The result of the future is sent to all registered listeners.
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pub fn new(source: Box<Future<Item=T, Error=Error> + Send>) -> Self {
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Self { inner: Arc::new(Mutex::new((BroadcastData::new(), Some(source)))) }
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}
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/// Creates a new instance with a oneshot channel as trigger
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pub fn new_oneshot() -> (Self, oneshot::Sender<Result<T, Error>>) {
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let (tx, rx) = oneshot::channel::<Result<T, Error>>();
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let rx = rx.map_err(Error::from).flatten();
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let test = Box::new(rx);
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(Self::new(test), tx)
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}
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fn notify_listeners(inner: Arc<Mutex<(BroadcastData<T>, Option<Box<Future<Item=T, Error=Error> + Send>>)>>, result: Result<T, String>) {
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let mut data = inner.lock().unwrap();
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data.0.notify_listeners(result);
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}
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fn spawn(inner: Arc<Mutex<(BroadcastData<T>, Option<Box<Future<Item=T, Error=Error> + Send>>)>>) -> impl Future<Item=T, Error=Error> {
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let mut data = inner.lock().unwrap();
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if let Some(source) = data.1.take() {
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let inner1 = inner.clone();
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let task = source.then(move |value| {
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match value {
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Ok(value) => Self::notify_listeners(inner1, Ok(value.clone())),
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Err(err) => Self::notify_listeners(inner1, Err(err.to_string())),
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}
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Ok(())
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});
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tokio::spawn(task);
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}
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data.0.listen()
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}
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/// Register a listener
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pub fn listen(&self) -> impl Future<Item=T, Error=Error> {
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let inner2 = self.inner.clone();
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futures::future::lazy(move || { Self::spawn(inner2) })
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}
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}
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#[test]
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fn test_broadcast_future() {
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use std::sync::atomic::{AtomicUsize, Ordering};
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static CHECKSUM: AtomicUsize = AtomicUsize::new(0);
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let (sender, trigger) = BroadcastFuture::new_oneshot();
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let receiver1 = sender.listen()
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.and_then(|res| {
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CHECKSUM.fetch_add(res, Ordering::SeqCst);
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Ok(())
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})
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.map_err(|err| { panic!("got errror {}", err); });
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let receiver2 = sender.listen()
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.and_then(|res| {
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CHECKSUM.fetch_add(res*2, Ordering::SeqCst);
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Ok(())
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})
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.map_err(|err| { panic!("got errror {}", err); });
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tokio::run(futures::future::lazy(move || {
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tokio::spawn(receiver1);
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tokio::spawn(receiver2);
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trigger.send(Ok(1)).unwrap();
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Ok(())
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}));
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let result = CHECKSUM.load(Ordering::SeqCst);
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assert!(result == 3);
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}
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