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UdpBind

hclient_rt

Trait UdpBind 

Source 
pub trait UdpBind {
    type Socket: UdpDatagrams;

    // Required method
    fn bind(&self, local: SocketAddr) -> Result<Self::Socket>;
}
Expand description

Bind a UDP socket.

§Why bind is sync where TcpConnect::connect is async

Not for symmetry’s sake in either direction. Binding performs no network round trip on any runtime this workspace targets — std::net::UdpSocket:: bind is a syscall, tokio::net::UdpSocket::from_std and async_io::Async::new are registrations, and embassy_net::udp:: UdpSocket::bind returns immediately. connect, by contrast, is a real handshake and has to be async.

There is also a consumer-side reason, and it is the decisive one: a QUIC stack asks its runtime to wrap a socket from a synchronous call (quinn::Runtime::wrap_udp_socket, quinn-0.11.11/src/runtime.rs:24). An async bind could not serve it, and inventing a second synchronous method beside an async one would be two ways to say the same thing.

Required Associated Types§

Source

type Socket: UdpDatagrams

No Send, Sync, 'static or Debug bound here, deliberately.

A QUIC stack needs all four (quinn::AsyncUdpSocket: Send + Sync + Debug + 'static), and the research this crate is built on proposed putting them on this associated type. They are not here, because a bound in the trait is paid by every implementer for the benefit of one consumer, and this seam has an implementer — an embassy-net backend — for which Send is not free. The bounds live in hclient_h3::H3’s where clause instead, so the compile error lands on whoever asked for QUIC rather than on whoever implemented UDP.

TcpConnect::Stream keeps the same property and pays nothing for it: hclient-native’s FakeStream holds an Rc<()> precisely to prove that no path in that vertical requires Send. This trait preserves that proof rather than spending it.

Required Methods§

Source

fn bind(&self, local: SocketAddr) -> Result<Self::Socket>

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§