org.apache.bookkeeper.common.util.Retries Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.apache.bookkeeper.common.util;
import java.util.Iterator;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.apache.bookkeeper.common.concurrent.FutureUtils;
/**
* A util class for supporting retries with customized backoff.
*/
public final class Retries {
private Retries() {
}
public static final Predicate NonFatalPredicate =
cause -> !(cause instanceof RuntimeException);
/**
* Retry a given {@code task} on failures.
*
* It is a shortcut of {@link #run(Stream, Predicate, Supplier, OrderedScheduler, Object)}
* that runs retries on any threads in the provided {@code scheduler}.
*
* @param backoffs a stream of backoff delays, in milliseconds.
* @param retryPredicate a predicate to test if failures are retryable.
* @param task a task to execute.
* @param scheduler scheduler to schedule the task and complete the futures.
* @param the return type
* @return future represents the result of the task with retries.
*/
public static CompletableFuture run(
Stream backoffs,
Predicate retryPredicate,
Supplier> task,
OrderedScheduler scheduler) {
return run(backoffs, retryPredicate, task, scheduler, null);
}
/**
* Retry a given {@code task} on failures.
*
* It will only retry the tasks when the predicate {@code retryPredicate} tests
* it as a retryable failure and it doesn't exhaust the retry budget. The retry delays
* are defined in a stream of delay values (in milliseconds).
*
*
If a schedule {@code key} is provided, the {@code task} will be submitted to the
* scheduler using the provided schedule {@code key} and also the returned future
* will be completed in the same thread. Otherwise, the task and the returned future will
* be executed and scheduled on any threads in the scheduler.
*
* @param backoffs a stream of backoff delays, in milliseconds.
* @param retryPredicate a predicate to test if failures are retryable.
* @param task a task to execute.
* @param scheduler scheduler to schedule the task and complete the futures.
* @param key the submit key for the scheduler.
* @param the return tye.
* @return future represents the result of the task with retries.
*/
public static CompletableFuture run(
Stream backoffs,
Predicate retryPredicate,
Supplier> task,
OrderedScheduler scheduler,
Object key) {
CompletableFuture future = FutureUtils.createFuture();
if (null == key) {
execute(
future,
backoffs.iterator(),
retryPredicate,
task,
scheduler,
null);
} else {
scheduler.executeOrdered(key, () -> {
execute(
future,
backoffs.iterator(),
retryPredicate,
task,
scheduler,
key);
});
}
return future;
}
private static void execute(
CompletableFuture finalResult,
Iterator backoffIter,
Predicate retryPredicate,
Supplier> task,
OrderedScheduler scheduler,
Object key) {
FutureUtils.whenCompleteAsync(task.get(), (result, cause) -> {
if (null == cause) {
finalResult.complete(result);
return;
}
if (retryPredicate.test(cause)) {
if (!backoffIter.hasNext()) {
// exhausts all the retry budgets, fail the task now
finalResult.completeExceptionally(cause);
return;
}
long nextRetryDelayMs = backoffIter.next();
scheduler.scheduleOrdered(key, () -> execute(
finalResult,
backoffIter,
retryPredicate,
task,
scheduler,
key), nextRetryDelayMs, TimeUnit.MILLISECONDS);
} else {
// the exception can not be retried
finalResult.completeExceptionally(cause);
}
}, scheduler, key);
}
}