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a0557840eb
This refactors I/O registration in a few ways: - Cleans up the cached readiness in `PollEvented`. This cache used to be helpful when readiness was a linked list of `*mut Node`s in `Registration`. Previous refactors have turned `Registration` into just an `AtomicUsize` holding the current readiness, so the cache is just extra work and complexity. Gone. - Polling the `Registration` for readiness now gives a `ReadyEvent`, which includes the driver tick. This event must be passed back into `clear_readiness`, so that the readiness is only cleared from `Registration` if the tick hasn't changed. Previously, it was possible to clear the readiness even though another thread had *just* polled the driver and found the socket ready again. - Registration now also contains an `async fn readiness`, which stores wakers in an instrusive linked list. This allows an unbounded number of tasks to register for readiness (previously, only 1 per direction (read and write)). By using the intrusive linked list, there is no concern of leaking the storage of the wakers, since they are stored inside the `async fn` and released when the future is dropped. - Registration retains a `poll_readiness(Direction)` method, to support `AsyncRead` and `AsyncWrite`. They aren't able to use `async fn`s, and so there are 2 reserved slots for those methods. - IO types where it makes sense to have multiple tasks waiting on them now take advantage of this new `async fn readiness`, such as `UdpSocket` and `UnixDatagram`. Additionally, this makes the `io-driver` "feature" internal-only (no longer documented, not part of public API), and adds a second internal-only feature, `io-readiness`, to group together linked list part of registration that is only used by some of the IO types. After a bit of discussion, changing stream-based transports (like `TcpStream`) to have `async fn read(&self)` is punted, since that is likely too easy of a footgun to activate. Refs: #2779, #2728
87 lines
2.6 KiB
Rust
87 lines
2.6 KiB
Rust
fn main() {}
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// Disabled while future of UdpFramed is decided on.
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// See https://github.com/tokio-rs/tokio/issues/2830
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/*
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//! This example leverages `BytesCodec` to create a UDP client and server which
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//! speak a custom protocol.
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//!
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//! Here we're using the codec from `tokio-codec` to convert a UDP socket to a stream of
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//! client messages. These messages are then processed and returned back as a
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//! new message with a new destination. Overall, we then use this to construct a
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//! "ping pong" pair where two sockets are sending messages back and forth.
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#![warn(rust_2018_idioms)]
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use tokio::net::UdpSocket;
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use tokio::stream::StreamExt;
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use tokio::{io, time};
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use tokio_util::codec::BytesCodec;
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use tokio_util::udp::UdpFramed;
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use bytes::Bytes;
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use futures::{FutureExt, SinkExt};
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use std::env;
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use std::error::Error;
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use std::net::SocketAddr;
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use std::time::Duration;
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#[tokio::main]
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async fn main() -> Result<(), Box<dyn Error>> {
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let addr = env::args()
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.nth(1)
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.unwrap_or_else(|| "127.0.0.1:0".to_string());
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// Bind both our sockets and then figure out what ports we got.
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let a = UdpSocket::bind(&addr).await?;
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let b = UdpSocket::bind(&addr).await?;
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let b_addr = b.local_addr()?;
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let mut a = UdpFramed::new(a, BytesCodec::new());
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let mut b = UdpFramed::new(b, BytesCodec::new());
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// Start off by sending a ping from a to b, afterwards we just print out
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// what they send us and continually send pings
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let a = ping(&mut a, b_addr);
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// The second client we have will receive the pings from `a` and then send
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// back pongs.
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let b = pong(&mut b);
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// Run both futures simultaneously of `a` and `b` sending messages back and forth.
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match futures::future::try_join(a, b).await {
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Err(e) => println!("an error occurred; error = {:?}", e),
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_ => println!("done!"),
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}
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Ok(())
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}
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async fn ping(socket: &mut UdpFramed<BytesCodec>, b_addr: SocketAddr) -> Result<(), io::Error> {
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socket.send((Bytes::from(&b"PING"[..]), b_addr)).await?;
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for _ in 0..4usize {
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let (bytes, addr) = socket.next().map(|e| e.unwrap()).await?;
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println!("[a] recv: {}", String::from_utf8_lossy(&bytes));
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socket.send((Bytes::from(&b"PING"[..]), addr)).await?;
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}
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Ok(())
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}
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async fn pong(socket: &mut UdpFramed<BytesCodec>) -> Result<(), io::Error> {
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let timeout = Duration::from_millis(200);
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while let Ok(Some(Ok((bytes, addr)))) = time::timeout(timeout, socket.next()).await {
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println!("[b] recv: {}", String::from_utf8_lossy(&bytes));
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socket.send((Bytes::from(&b"PONG"[..]), addr)).await?;
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}
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Ok(())
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}
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*/
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