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// SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: Apache-2.0
use std::sync::Arc;
use std::time::Duration;
use tokio::sync::mpsc;
use tokio_util::sync::CancellationToken;
use dynamo_kv_router::indexer::LocalKvIndexer;
use dynamo_kv_router::protocols::*;
use crate::kv_router::metrics::kv_publisher_metrics;
use super::DEFAULT_MAX_BATCH_BLOCKS;
use super::batching::BatchingState;
use super::dedup::{EventDedupFilter, EventDedupPolicy};
use super::sinks::{RouterEventBatchSink, emit};
pub(super) async fn run_event_processor_loop<P: RouterEventBatchSink + 'static>(
publisher: P,
worker_id: u64,
cancellation_token: CancellationToken,
mut rx: mpsc::UnboundedReceiver<Vec<PlacementEvent>>,
local_indexer: Option<Arc<LocalKvIndexer>>,
timeout_ms: Option<u64>,
max_batch_blocks: usize,
) {
let mut batching_state = BatchingState::new(max_batch_blocks);
let mut dedup = EventDedupFilter::new();
let mut last_raw_input_id: Option<u64> = None;
loop {
tokio::select! {
_ = cancellation_token.cancelled() => {
tracing::info!("KV Event source received cancellation signal");
let mut output = Vec::new();
batching_state.flush(&local_indexer, worker_id, &mut dedup, &mut output).await;
publish_output(&publisher, worker_id, &output).await;
break;
}
event_batch = rx.recv() => {
let Some(event_batch) = event_batch else {
tracing::debug!("Event processor channel closed.");
let mut output = Vec::new();
batching_state.flush(&local_indexer, worker_id, &mut dedup, &mut output).await;
publish_output(&publisher, worker_id, &output).await;
break;
};
let mut output = Vec::new();
// Process the complete source list before returning to `select!` so
// another channel item, the timeout, or cancellation cannot split it.
'event_batch: for placement_event in event_batch {
let raw_event_id = placement_event.event.event_id;
if let Some(last_id) = last_raw_input_id
&& raw_event_id > last_id + 1
{
let gap = raw_event_id - last_id - 1;
tracing::warn!(
worker_id,
last_raw_input_id = last_id,
raw_event_id,
gap,
"Input event gap detected: raw events dropped before batching"
);
if let Some(metrics) = kv_publisher_metrics() {
metrics.increment_engines_dropped_events(gap);
} else {
tracing::warn!(
worker_id,
gap,
"Failed to record dropped events metric: metrics not initialized"
);
}
}
last_raw_input_id = Some(raw_event_id);
let storage_tier = placement_event.placement.tier;
let residency_domain = placement_event.placement.residency_domain;
tracing::trace!(
"Event processor for worker_id {} processing event: {:?}",
worker_id,
placement_event.event.data
);
match &placement_event.event.data {
KvCacheEventData::Removed(_) | KvCacheEventData::Stored(_) => {
batching_state
.push(
placement_event,
&local_indexer,
worker_id,
&mut dedup,
&mut output,
)
.await;
}
KvCacheEventData::Cleared => {
batching_state.flush(&local_indexer, worker_id, &mut dedup, &mut output).await;
let event = placement_event.event;
dedup.clear_rank_domain(
event.dp_rank,
residency_domain,
EventDedupPolicy::RefCounted,
);
let applied = emit(
&local_indexer,
worker_id,
storage_tier,
residency_domain,
KvCacheEvent {
event_id: batching_state.next_publish_id,
data: KvCacheEventData::Cleared,
dp_rank: event.dp_rank,
},
&mut output,
)
.await;
if !applied {
output.pop();
tracing::error!(
worker_id,
dp_rank = event.dp_rank,
?residency_domain,
"Fencing KV event publisher after local reset failure"
);
// NOTE: This token owns the publisher's discovery and recovery
// advertisement too. Once the local reset barrier fails, withdrawing
// the complete source is the only safe way to avoid advertising a
// cursor whose local snapshot has diverged.
cancellation_token.cancel();
break 'event_batch;
}
batching_state.next_publish_id = batching_state
.next_publish_id
.checked_add(1)
.expect("KV event publisher outbound cursor exhausted");
}
}
}
// Without a timeout, flush the compatible tail at the native-list
// boundary. With a timeout, retain it for possible cross-list batching.
if batching_state.has_pending()
&& match timeout_ms {
None => true,
Some(ms) => batching_state.is_timeout_elapsed(ms),
}
{
batching_state.flush(&local_indexer, worker_id, &mut dedup, &mut output).await;
}
publish_output(&publisher, worker_id, &output).await;
}
_ = tokio::time::sleep(
timeout_ms
.map(|ms| batching_state.remaining_timeout(ms))
.unwrap_or(Duration::from_secs(3600))
), if timeout_ms.is_some() && batching_state.has_pending() => {
let mut output = Vec::new();
batching_state.flush(&local_indexer, worker_id, &mut dedup, &mut output).await;
publish_output(&publisher, worker_id, &output).await;
}
}
}
}
async fn publish_output<P: RouterEventBatchSink>(
publisher: &P,
worker_id: u64,
output: &[RouterEvent],
) {
if output.is_empty() {
return;
}
if let Err(e) = publisher.publish_events(output).await {
tracing::error!(
worker_id,
attempted_event_count = output.len(),
error = %e,
"One or more KV event publishes failed"
);
}
}
pub(super) async fn start_event_processor<P: RouterEventBatchSink + 'static>(
publisher: P,
worker_id: u64,
cancellation_token: CancellationToken,
rx: mpsc::UnboundedReceiver<Vec<PlacementEvent>>,
local_indexer: Option<Arc<LocalKvIndexer>>,
batching_timeout_ms: Option<u64>,
) {
run_event_processor_loop(
publisher,
worker_id,
cancellation_token,
rx,
local_indexer,
batching_timeout_ms,
DEFAULT_MAX_BATCH_BLOCKS,
)
.await
}