1 use core::fmt::{Debug, Formatter, Result as FmtResult}; 2 use core::pin::Pin; 3 use futures_core::task::{Context, Poll}; 4 use futures_sink::Sink; 5 use pin_project_lite::pin_project; 6 7 pin_project! { 8 /// Sink that clones incoming items and forwards them to two sinks at the same time. 9 /// 10 /// Backpressure from any downstream sink propagates up, which means that this sink 11 /// can only process items as fast as its _slowest_ downstream sink. 12 #[must_use = "sinks do nothing unless polled"] 13 pub struct Fanout<Si1, Si2> { 14 #[pin] 15 sink1: Si1, 16 #[pin] 17 sink2: Si2 18 } 19 } 20 21 impl<Si1, Si2> Fanout<Si1, Si2> { new(sink1: Si1, sink2: Si2) -> Self22 pub(super) fn new(sink1: Si1, sink2: Si2) -> Self { 23 Self { sink1, sink2 } 24 } 25 26 /// Get a shared reference to the inner sinks. get_ref(&self) -> (&Si1, &Si2)27 pub fn get_ref(&self) -> (&Si1, &Si2) { 28 (&self.sink1, &self.sink2) 29 } 30 31 /// Get a mutable reference to the inner sinks. get_mut(&mut self) -> (&mut Si1, &mut Si2)32 pub fn get_mut(&mut self) -> (&mut Si1, &mut Si2) { 33 (&mut self.sink1, &mut self.sink2) 34 } 35 36 /// Get a pinned mutable reference to the inner sinks. get_pin_mut(self: Pin<&mut Self>) -> (Pin<&mut Si1>, Pin<&mut Si2>)37 pub fn get_pin_mut(self: Pin<&mut Self>) -> (Pin<&mut Si1>, Pin<&mut Si2>) { 38 let this = self.project(); 39 (this.sink1, this.sink2) 40 } 41 42 /// Consumes this combinator, returning the underlying sinks. 43 /// 44 /// Note that this may discard intermediate state of this combinator, 45 /// so care should be taken to avoid losing resources when this is called. into_inner(self) -> (Si1, Si2)46 pub fn into_inner(self) -> (Si1, Si2) { 47 (self.sink1, self.sink2) 48 } 49 } 50 51 impl<Si1: Debug, Si2: Debug> Debug for Fanout<Si1, Si2> { fmt(&self, f: &mut Formatter<'_>) -> FmtResult52 fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult { 53 f.debug_struct("Fanout").field("sink1", &self.sink1).field("sink2", &self.sink2).finish() 54 } 55 } 56 57 impl<Si1, Si2, Item> Sink<Item> for Fanout<Si1, Si2> 58 where 59 Si1: Sink<Item>, 60 Item: Clone, 61 Si2: Sink<Item, Error = Si1::Error>, 62 { 63 type Error = Si1::Error; 64 poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>>65 fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { 66 let this = self.project(); 67 68 let sink1_ready = this.sink1.poll_ready(cx)?.is_ready(); 69 let sink2_ready = this.sink2.poll_ready(cx)?.is_ready(); 70 let ready = sink1_ready && sink2_ready; 71 if ready { 72 Poll::Ready(Ok(())) 73 } else { 74 Poll::Pending 75 } 76 } 77 start_send(self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error>78 fn start_send(self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error> { 79 let this = self.project(); 80 81 this.sink1.start_send(item.clone())?; 82 this.sink2.start_send(item)?; 83 Ok(()) 84 } 85 poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>>86 fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { 87 let this = self.project(); 88 89 let sink1_ready = this.sink1.poll_flush(cx)?.is_ready(); 90 let sink2_ready = this.sink2.poll_flush(cx)?.is_ready(); 91 let ready = sink1_ready && sink2_ready; 92 if ready { 93 Poll::Ready(Ok(())) 94 } else { 95 Poll::Pending 96 } 97 } 98 poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>>99 fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { 100 let this = self.project(); 101 102 let sink1_ready = this.sink1.poll_close(cx)?.is_ready(); 103 let sink2_ready = this.sink2.poll_close(cx)?.is_ready(); 104 let ready = sink1_ready && sink2_ready; 105 if ready { 106 Poll::Ready(Ok(())) 107 } else { 108 Poll::Pending 109 } 110 } 111 } 112