| /** |
| * |
| * 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.hadoop.hbase; |
| |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.Delayed; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.RunnableScheduledFuture; |
| import java.util.concurrent.ScheduledThreadPoolExecutor; |
| import java.util.concurrent.ThreadFactory; |
| import java.util.concurrent.ThreadLocalRandom; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.TimeoutException; |
| |
| import org.apache.yetus.audience.InterfaceAudience; |
| |
| /** |
| * ScheduledThreadPoolExecutor that will add some jitter to the RunnableScheduledFuture.getDelay. |
| * |
| * This will spread out things on a distributed cluster. |
| */ |
| @InterfaceAudience.Private |
| public class JitterScheduledThreadPoolExecutorImpl extends ScheduledThreadPoolExecutor { |
| private final double spread; |
| |
| /** |
| * Main constructor. |
| * @param spread The percent up and down that RunnableScheduledFuture.getDelay should be jittered. |
| */ |
| public JitterScheduledThreadPoolExecutorImpl(int corePoolSize, |
| ThreadFactory threadFactory, |
| double spread) { |
| super(corePoolSize, threadFactory); |
| this.spread = spread; |
| } |
| |
| @Override |
| protected <V> java.util.concurrent.RunnableScheduledFuture<V> decorateTask( |
| Runnable runnable, java.util.concurrent.RunnableScheduledFuture<V> task) { |
| return new JitteredRunnableScheduledFuture<>(task); |
| } |
| |
| @Override |
| protected <V> java.util.concurrent.RunnableScheduledFuture<V> decorateTask( |
| Callable<V> callable, java.util.concurrent.RunnableScheduledFuture<V> task) { |
| return new JitteredRunnableScheduledFuture<>(task); |
| } |
| |
| /** |
| * Class that basically just defers to the wrapped future. |
| * The only exception is getDelay |
| */ |
| protected class JitteredRunnableScheduledFuture<V> implements RunnableScheduledFuture<V> { |
| private final RunnableScheduledFuture<V> wrapped; |
| JitteredRunnableScheduledFuture(RunnableScheduledFuture<V> wrapped) { |
| this.wrapped = wrapped; |
| } |
| |
| @Override |
| public boolean isPeriodic() { |
| return wrapped.isPeriodic(); |
| } |
| |
| @Override |
| public long getDelay(TimeUnit unit) { |
| long baseDelay = wrapped.getDelay(unit); |
| long spreadTime = (long) (baseDelay * spread); |
| long delay = spreadTime <= 0 ? baseDelay |
| : baseDelay + ThreadLocalRandom.current().nextLong(-spreadTime, spreadTime); |
| // Ensure that we don't roll over for nanoseconds. |
| return (delay < 0) ? baseDelay : delay; |
| } |
| |
| @Override |
| public int compareTo(Delayed o) { |
| return wrapped.compareTo(o); |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| return obj instanceof Delayed? compareTo((Delayed)obj) == 0: false; |
| } |
| |
| @Override |
| public int hashCode() { |
| return this.wrapped.hashCode(); |
| } |
| |
| @Override |
| public void run() { |
| wrapped.run(); |
| } |
| |
| @Override |
| public boolean cancel(boolean mayInterruptIfRunning) { |
| return wrapped.cancel(mayInterruptIfRunning); |
| } |
| |
| @Override |
| public boolean isCancelled() { |
| return wrapped.isCancelled(); |
| } |
| |
| @Override |
| public boolean isDone() { |
| return wrapped.isDone(); |
| } |
| |
| @Override |
| public V get() throws InterruptedException, ExecutionException { |
| return wrapped.get(); |
| } |
| |
| @Override |
| public V get(long timeout, |
| TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { |
| return wrapped.get(timeout, unit); |
| } |
| } |
| } |