Struct RoundRobin 

pub struct RoundRobin { /* private fields */ }

A PublishTransform distributing replies round-robin across the first count partitions.

Each reply gets the PARTITION_HEADER of an incrementing counter modulo count, so the publisher targets partitions 0..count in a cycle, one message each - the evenest possible spread for long, near-constant-cost messages. A reply that already carries an explicit partition or a record key is left alone: keys exist for ordering, and overriding either would silently break the caller’s placement.

The count is explicit on purpose (cheap and predictable); it must match the destination topic’s partition count, or the tail partitions simply receive nothing (a smaller count) or publishes fail (a larger one).

Examples

use ruststream::runtime::TypedPublisher;
use ruststream_rdkafka::{KafkaBroker, RoundRobin};

let replies = TypedPublisher::new(broker.publisher()).transform(RoundRobin::partitions(8));

Implementations

impl RoundRobin

pub fn partitions(count: i32) -> Self

A round-robin cycle over partitions 0..count.

Panics

Panics when count is zero: a cycle over no partitions cannot place anything.

Trait Implementations

impl Debug for RoundRobin

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

Formats the value using the given formatter.

impl<C> PublishTransform<C> for RoundRobin

fn apply(&self, out: &mut Outgoing<'_>, _cx: &PublishContext<'_, C>)

Transforms out in place before it is sent, reading the delivery through cx.