Enum Output 

pub enum Output {
    Event(Event),
    Watermark(i64),
    LateEvent(Event),
    SideOutput(Box<SideOutputData>),
    Changelog(ChangelogRecord),
    CheckpointComplete(Box<CheckpointCompleteData>),
    Barrier(CheckpointBarrier),
}

Output from an operator

Infrequent variants (SideOutput, CheckpointComplete) are boxed to keep the enum size small for the common hot-path variants (Event, Watermark).

Variants

Event(Event)

Regular event output

Watermark(i64)

Watermark update

LateEvent(Event)

Late event that arrived after watermark (no side output configured)

SideOutput(Box<SideOutputData>)

Late event routed to a named side output (boxed — infrequent path).

Changelog(ChangelogRecord)

Changelog record with Z-set weight.

Used by EmitStrategy::Changelog to emit structured change records for CDC pipelines and cascading materialized views.

CheckpointComplete(Box<CheckpointCompleteData>)

Checkpoint completion with snapshotted operator states (boxed — infrequent path).

Emitted when a CheckpointRequest is processed by a core thread. Carries the checkpoint ID and all operator states for persistence by Ring 1.

Barrier(CheckpointBarrier)

Checkpoint barrier forwarded from a core thread.

When a core receives a CoreMessage::Barrier, it flushes the reactor and forwards the barrier as an output so the coordinator can track barrier alignment across sources.

CheckpointBarrier is 24 bytes (#[repr(C)], Copy), small enough to store inline without boxing.

Trait Implementations

impl Debug for Output

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

Formats the value using the given formatter.