117 lines
2.8 KiB
Rust
117 lines
2.8 KiB
Rust
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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Async,
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AsyncSink,
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Sink,
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Stream,
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sync::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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};
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use odds::vec::VecExt;
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use crate::chunk::Chunk;
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pub enum Never {}
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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 for Transmitter {
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type SinkItem = Chunk;
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type SinkError = Never; // never errors, slow clients are simply dropped
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fn start_send(&mut self, chunk: Chunk) -> Result<AsyncSink<Chunk>, 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(AsyncSink::Ready)
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}
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fn poll_complete(&mut self) -> Result<Async<()>, Never> {
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let mut channel = self.channel.lock().expect("Locking channel");
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channel.listeners.retain_mut(|listener| listener.poll_complete().is_ok());
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Ok(Async::Ready(()))
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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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type Error = Never; // no transmitter errors are exposed to the listeners
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fn poll(&mut self) -> Result<Async<Option<Chunk>>, Never> {
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Ok(self.receiver.poll().expect("Channel receiving can't error"))
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}
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}
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