Struct SubscriberGroup

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pub struct SubscriberGroup<T: Copy, const N: usize> { /* private fields */ }

Expand description

A group of N logical subscribers backed by a single ring read.

All N logical subscribers share one cursor — try_recv performs one seqlock read and a single cursor increment, eliminating the N-element sweep loop.

let (mut p, subs) = photon_ring::channel::<u64>(64);
let mut group = subs.subscribe_group::<4>();
p.publish(42);
assert_eq!(group.try_recv(), Ok(42));

Implementations§

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impl<T: Copy, const N: usize> SubscriberGroup<T, N>

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pub fn try_recv(&mut self) -> Result<T, TryRecvError>

Try to receive the next message for the group.

Performs a single seqlock read and one cursor increment — no N-element sweep needed since all logical subscribers share one cursor.

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pub fn recv(&mut self) -> T

Spin until the next message is available.

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pub fn recv_with(&mut self, strategy: WaitStrategy) -> T

Block until the next message using the given WaitStrategy.

Like Subscriber::recv_with, but for the grouped fast path.

§Example

use photon_ring::{channel, WaitStrategy};

let (mut p, s) = channel::<u64>(64);
let mut group = s.subscribe_group::<2>();
p.publish(42);
assert_eq!(group.recv_with(WaitStrategy::BusySpin), 42);

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pub fn aligned_count(&self) -> usize

How many of the N logical subscribers are aligned.

With the single-cursor design all subscribers are always aligned, so this trivially returns N.

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pub fn pending(&self) -> u64

Number of messages available to read (capped at ring capacity).

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pub fn total_received(&self) -> u64

Total messages successfully received by this group.

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pub fn total_lagged(&self) -> u64

Total messages lost due to lag (group fell behind the ring).

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pub fn receive_ratio(&self) -> f64

Ratio of received to total (received + lagged). Returns 0.0 if no messages have been processed.

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pub fn recv_batch(&mut self, buf: &mut [T]) -> usize

Receive up to buf.len() messages in a single call.

Messages are written into the provided slice starting at index 0. Returns the number of messages received. On lag, the cursor is advanced and filling continues from the oldest available message.