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") 54 .field("sink1", &self.sink1) 55 .field("sink2", &self.sink2) 56 .finish() 57 } 58 } 59 60 impl<Si1, Si2, Item> Sink<Item> for Fanout<Si1, Si2> 61 where Si1: Sink<Item>, 62 Item: Clone, 63 Si2: Sink<Item, Error=Si1::Error> 64 { 65 type Error = Si1::Error; 66 poll_ready( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>67 fn poll_ready( 68 self: Pin<&mut Self>, 69 cx: &mut Context<'_>, 70 ) -> Poll<Result<(), Self::Error>> { 71 let this = self.project(); 72 73 let sink1_ready = this.sink1.poll_ready(cx)?.is_ready(); 74 let sink2_ready = this.sink2.poll_ready(cx)?.is_ready(); 75 let ready = sink1_ready && sink2_ready; 76 if ready { Poll::Ready(Ok(())) } else { Poll::Pending } 77 } 78 start_send( self: Pin<&mut Self>, item: Item, ) -> Result<(), Self::Error>79 fn start_send( 80 self: Pin<&mut Self>, 81 item: Item, 82 ) -> Result<(), Self::Error> { 83 let this = self.project(); 84 85 this.sink1.start_send(item.clone())?; 86 this.sink2.start_send(item)?; 87 Ok(()) 88 } 89 poll_flush( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>90 fn poll_flush( 91 self: Pin<&mut Self>, 92 cx: &mut Context<'_>, 93 ) -> Poll<Result<(), Self::Error>> { 94 let this = self.project(); 95 96 let sink1_ready = this.sink1.poll_flush(cx)?.is_ready(); 97 let sink2_ready = this.sink2.poll_flush(cx)?.is_ready(); 98 let ready = sink1_ready && sink2_ready; 99 if ready { Poll::Ready(Ok(())) } else { Poll::Pending } 100 } 101 poll_close( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Result<(), Self::Error>>102 fn poll_close( 103 self: Pin<&mut Self>, 104 cx: &mut Context<'_>, 105 ) -> Poll<Result<(), Self::Error>> { 106 let this = self.project(); 107 108 let sink1_ready = this.sink1.poll_close(cx)?.is_ready(); 109 let sink2_ready = this.sink2.poll_close(cx)?.is_ready(); 110 let ready = sink1_ready && sink2_ready; 111 if ready { Poll::Ready(Ok(())) } else { Poll::Pending } 112 } 113 } 114