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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.action.bulk;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.support.PlainActionFuture;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.threadpool.Scheduler;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.RemoteTransportException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.function.BiConsumer;
import java.util.function.Predicate;
/**
* Encapsulates synchronous and asynchronous retry logic.
*/
public class Retry {
private final BackoffPolicy backoffPolicy;
private final Scheduler scheduler;
public Retry(BackoffPolicy backoffPolicy, Scheduler scheduler) {
this.backoffPolicy = backoffPolicy;
this.scheduler = scheduler;
}
/**
* Invokes #accept(BulkRequest, ActionListener). Backs off on the provided exception and delegates results to the
* provided listener. Retries will be scheduled using the class's thread pool.
* @param consumer The consumer to which apply the request and listener
* @param bulkRequest The bulk request that should be executed.
* @param listener A listener that is invoked when the bulk request finishes or completes with an exception. The listener is not
*/
public void withBackoff(BiConsumer> consumer, BulkRequest bulkRequest,
ActionListener listener) {
RetryHandler r = new RetryHandler(backoffPolicy, consumer, listener, scheduler);
r.execute(bulkRequest);
}
/**
* Invokes #accept(BulkRequest, ActionListener). Backs off on the provided exception. Retries will be scheduled using
* the class's thread pool.
*
* @param consumer The consumer to which apply the request and listener
* @param bulkRequest The bulk request that should be executed.
* @return a future representing the bulk response returned by the client.
*/
public PlainActionFuture withBackoff(BiConsumer> consumer,
BulkRequest bulkRequest) {
PlainActionFuture future = PlainActionFuture.newFuture();
withBackoff(consumer, bulkRequest, future);
return future;
}
static class RetryHandler implements ActionListener {
private static final RestStatus RETRY_STATUS = RestStatus.TOO_MANY_REQUESTS;
private static final Logger logger = LogManager.getLogger(RetryHandler.class);
private final Scheduler scheduler;
private final BiConsumer> consumer;
private final ActionListener listener;
private final Iterator backoff;
// Access only when holding a client-side lock, see also #addResponses()
private final List responses = new ArrayList<>();
private final long startTimestampNanos;
// needed to construct the next bulk request based on the response to the previous one
// volatile as we're called from a scheduled thread
private volatile BulkRequest currentBulkRequest;
private volatile Scheduler.Cancellable retryCancellable;
RetryHandler(BackoffPolicy backoffPolicy, BiConsumer> consumer,
ActionListener listener, Scheduler scheduler) {
this.backoff = backoffPolicy.iterator();
this.consumer = consumer;
this.listener = listener;
this.scheduler = scheduler;
// in contrast to System.currentTimeMillis(), nanoTime() uses a monotonic clock under the hood
this.startTimestampNanos = System.nanoTime();
}
@Override
public void onResponse(BulkResponse bulkItemResponses) {
if (!bulkItemResponses.hasFailures()) {
// we're done here, include all responses
addResponses(bulkItemResponses, (r -> true));
finishHim();
} else {
if (canRetry(bulkItemResponses)) {
addResponses(bulkItemResponses, (r -> !r.isFailed()));
retry(createBulkRequestForRetry(bulkItemResponses));
} else {
addResponses(bulkItemResponses, (r -> true));
finishHim();
}
}
}
@Override
public void onFailure(Exception e) {
if (e instanceof RemoteTransportException && ((RemoteTransportException) e).status() == RETRY_STATUS && backoff.hasNext()) {
retry(currentBulkRequest);
} else {
try {
listener.onFailure(e);
} finally {
if (retryCancellable != null) {
retryCancellable.cancel();
}
}
}
}
private void retry(BulkRequest bulkRequestForRetry) {
assert backoff.hasNext();
TimeValue next = backoff.next();
logger.trace("Retry of bulk request scheduled in {} ms.", next.millis());
Runnable command = scheduler.preserveContext(() -> this.execute(bulkRequestForRetry));
retryCancellable = scheduler.schedule(command, next, ThreadPool.Names.SAME);
}
private BulkRequest createBulkRequestForRetry(BulkResponse bulkItemResponses) {
BulkRequest requestToReissue = new BulkRequest();
int index = 0;
for (BulkItemResponse bulkItemResponse : bulkItemResponses.getItems()) {
if (bulkItemResponse.isFailed()) {
requestToReissue.add(currentBulkRequest.requests().get(index));
}
index++;
}
return requestToReissue;
}
private boolean canRetry(BulkResponse bulkItemResponses) {
if (!backoff.hasNext()) {
return false;
}
for (BulkItemResponse bulkItemResponse : bulkItemResponses) {
if (bulkItemResponse.isFailed()) {
final RestStatus status = bulkItemResponse.status();
if (status != RETRY_STATUS) {
return false;
}
}
}
return true;
}
private void finishHim() {
try {
listener.onResponse(getAccumulatedResponse());
} finally {
if (retryCancellable != null) {
retryCancellable.cancel();
}
}
}
private void addResponses(BulkResponse response, Predicate filter) {
for (BulkItemResponse bulkItemResponse : response) {
if (filter.test(bulkItemResponse)) {
// Use client-side lock here to avoid visibility issues. This method may be called multiple times
// (based on how many retries we have to issue) and relying that the response handling code will be
// scheduled on the same thread is fragile.
synchronized (responses) {
responses.add(bulkItemResponse);
}
}
}
}
private BulkResponse getAccumulatedResponse() {
BulkItemResponse[] itemResponses;
synchronized (responses) {
itemResponses = responses.toArray(new BulkItemResponse[1]);
}
long stopTimestamp = System.nanoTime();
long totalLatencyMs = TimeValue.timeValueNanos(stopTimestamp - startTimestampNanos).millis();
return new BulkResponse(itemResponses, totalLatencyMs);
}
public void execute(BulkRequest bulkRequest) {
this.currentBulkRequest = bulkRequest;
consumer.accept(bulkRequest, this);
}
}
}