135 lines
3.4 KiB
Rust
135 lines
3.4 KiB
Rust
use std::pin::Pin;
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use std::task::{
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Context,
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Poll
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};
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use std::sync::{
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Arc,
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Mutex
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};
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use futures::{
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channel::mpsc::{
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channel as mpsc_channel,
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Sender,
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Receiver
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},
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Sink,
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Stream,
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never::Never,
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};
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use odds::vec::VecExt;
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use crate::chunk::Chunk;
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/// A collection of listeners to a stream of WebM chunks.
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/// Sending a chunk may fail due to a client being disconnected,
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/// or simply failing to keep up with the stream buffer. In either
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/// case, there's nothing practical the server can do to recover,
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/// so the failing client is just dropped from the listener list.
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pub struct Channel {
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pub name: String,
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header_chunk: Option<Chunk>,
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listeners: Vec<Sender<Chunk>>
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}
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pub type Handle = Arc<Mutex<Channel>>;
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impl Channel {
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pub fn new(name: String) -> Handle {
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Arc::new(Mutex::new(Channel {
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name,
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header_chunk: None,
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listeners: Vec::new()
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}))
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}
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}
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pub struct Transmitter {
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channel: Handle
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}
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impl Transmitter {
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pub fn new(channel_arc: Handle) -> Self {
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Transmitter {
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channel: channel_arc
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}
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}
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}
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impl Sink<Chunk> for Transmitter {
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type Error = Never; // never errors, slow clients are simply dropped
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fn poll_ready(self: Pin<&mut Self>, _cx: &mut Context) -> Poll<Result<(), Never>> {
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Poll::Ready(Ok(()))
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}
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fn start_send(self: Pin<&mut Self>, chunk: Chunk) -> Result<(), Never> {
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let mut channel = self.channel.lock().expect("Locking channel");
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if let Chunk::Headers { .. } = chunk {
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channel.header_chunk = Some(chunk.clone());
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}
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channel.listeners.retain_mut(|listener| listener.start_send(chunk.clone()).is_ok());
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Ok(())
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}
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fn poll_flush(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Never>> {
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let mut channel = self.channel.lock().expect("Locking channel");
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let mut result = Poll::Ready(Ok(()));
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// just disconnect any erroring listeners
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channel.listeners.retain_mut(|listener| match Pin::new(listener).poll_flush(cx) {
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Poll::Pending => {result = Poll::Pending; true},
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Poll::Ready(Ok(())) => true,
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Poll::Ready(Err(_)) => false,
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});
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result
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}
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fn poll_close(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Never>> {
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// don't actually disconnect listeners, since other sources may want to transmit to this channel;
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// just ensure we've sent everything we can out
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self.poll_flush(cx)
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}
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}
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pub struct Listener {
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/// not used in operation, but its refcount keeps the channel alive when there's no Transmitter
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_channel: Handle,
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receiver: Receiver<Chunk>
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}
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impl Listener {
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pub fn new(channel_arc: Handle) -> Self {
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let (mut sender, receiver) = mpsc_channel(5);
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{
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let mut channel = channel_arc.lock().expect("Locking channel");
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if let Some(ref chunk) = channel.header_chunk {
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sender.start_send(chunk.clone()).expect("Queuing existing header chunk");
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}
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channel.listeners.push(sender);
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}
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Listener {
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_channel: channel_arc,
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receiver: receiver
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}
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}
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}
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impl Stream for Listener {
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type Item = Chunk;
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fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Chunk>> {
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let receiver = &mut self.get_mut().receiver;
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Pin::new(receiver).poll_next(cx)
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}
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}
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