Struct StreamProtocolConfig 

pub struct StreamProtocolConfig {
    pub per_peer_channel_capacity: usize,
    pub stream_open_timeout: Duration,
    pub frame_writer_backpressure_bytes: usize,
    pub egress_backpressure_timeout: Duration,
}

Configuration of the per-peer egress stream layer.

Fields

per_peer_channel_capacity: usize

Capacity of the per-peer egress channel (in packets).

The egress drain enqueues each outgoing packet via try_send. When the channel is full the behaviour depends on the stream state: while the stream is still opening it drops the newest packet (a slow open for one peer must not head-of-line-block others); once the stream is open and its write pump is draining, it instead applies bounded backpressure — waiting up to EGRESS_BACKPRESSURE_TIMEOUT for space so wire-rate backpressure propagates upstream — and only drops the newest packet if the peer stays full past that timeout. The channel absorbs bursts while a stream is being opened; once open the write pump continuously drains it, so it stays near-empty under normal load.

Sized to absorb a typical SURB pre-fill burst (default SurbBalancer: target 7 000 / max 5 000/s).

Defaults to 5 000.

stream_open_timeout: Duration

Timeout for the NetworkStreamControl::open call when opening a new outgoing stream to a peer.

A timeout is mandatory: without it a permanently-unreachable peer would park the opener task indefinitely. When the open attempt fails or times out the buffered packets for that peer are dropped and a debug-level log entry is emitted. The cache entry is then invalidated so the next send triggers a fresh open attempt.

Must be at least 1 ms. Defaults to 2 seconds.

frame_writer_backpressure_bytes: usize

Pending-write-buffer byte threshold on the framed writer before a flush is forced.

A value of 1 flushes on every encoded frame (one syscall per message). Larger values coalesce adjacent small frames into a single quinn write call, reducing connection-mutex acquisitions and driver wake-ups on the hot path. A HOPR packet is ~1 440 bytes; at the default 128 KiB threshold roughly 91 packets are coalesced per write, cutting driver wake frequency ~30×.

Defaults to 131 072 bytes (128 KiB).

egress_backpressure_timeout: Duration

Maximum time the egress drain waits on a full — but open and draining — per-peer channel before falling back to drop-newest.

While the stream is open, a full channel means the wire is slower than the producer, so waiting here propagates wire-rate backpressure up through the mixer and session socket to the application writer (no packet loss). The bound ensures a single permanently-stalled peer cannot head-of-line-block delivery to other peers indefinitely: after this timeout the packet is dropped and the drain moves on. Healthy peers drain far faster than this, so the timeout is not hit in normal operation.

It doubles as the per-peer write-pump stall timeout: if the pump makes no progress writing to a peer’s stream for this long (a remote that stopped reading parks quinn’s poll_write forever), the pump fails and its cache entry is evicted so the next send reopens the stream, rather than the pump parking indefinitely and the drain serialising on it.

Defaults to 2 seconds. Must be at least 1 ms — a zero value would defeat the feature.

Trait Implementations

impl Clone for StreamProtocolConfig

fn clone(&self) -> StreamProtocolConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for StreamProtocolConfig

impl Debug for StreamProtocolConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for StreamProtocolConfig

fn default() -> Self

Return StreamProtocolConfig { per_peer_channel_capacity: default_per_peer_channel_capacity(), stream_open_timeout: default_stream_open_timeout(), frame_writer_backpressure_bytes: default_frame_writer_backpressure_bytes(), egress_backpressure_timeout: default_egress_backpressure_timeout() }

impl Eq for StreamProtocolConfig

impl PartialEq for StreamProtocolConfig

fn eq(&self, other: &StreamProtocolConfig) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for StreamProtocolConfig

impl Validate for StreamProtocolConfig

fn validate(&self) -> Result<(), ValidationErrors>

impl<'v_a> ValidateArgs<'v_a> for StreamProtocolConfig

type Args = ()

fn validate_with_args(&self, args: Self::Args) -> Result<(), ValidationErrors>