io.netty.util.concurrent.RejectedExecutionHandlers Maven / Gradle / Ivy
/*
* Copyright 2016 The Netty Project
*
* The Netty Project 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 io.netty.util.concurrent;
import io.netty.util.internal.ObjectUtil;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;
/**
* Expose helper methods which create different {@link RejectedExecutionHandler}s.
*/
public final class RejectedExecutionHandlers {
private static final RejectedExecutionHandler REJECT = new RejectedExecutionHandler() {
@Override
public void rejected(Runnable task, SingleThreadEventExecutor executor) {
throw new RejectedExecutionException();
}
};
private RejectedExecutionHandlers() { }
/**
* Returns a {@link RejectedExecutionHandler} that will always just throw a {@link RejectedExecutionException}.
*/
public static RejectedExecutionHandler reject() {
return REJECT;
}
/**
* Tries to backoff when the task can not be added due restrictions for an configured amount of time. This
* is only done if the task was added from outside of the event loop which means
* {@link EventExecutor#inEventLoop()} returns {@code false}.
*/
public static RejectedExecutionHandler backoff(final int retries, long backoffAmount, TimeUnit unit) {
ObjectUtil.checkPositive(retries, "retries");
final long backOffNanos = unit.toNanos(backoffAmount);
return new RejectedExecutionHandler() {
@Override
public void rejected(Runnable task, SingleThreadEventExecutor executor) {
if (!executor.inEventLoop()) {
for (int i = 0; i < retries; i++) {
// Try to wake up the executor so it will empty its task queue.
executor.wakeup(false);
LockSupport.parkNanos(backOffNanos);
if (executor.offerTask(task)) {
return;
}
}
}
// Either we tried to add the task from within the EventLoop or we was not able to add it even with
// backoff.
throw new RejectedExecutionException();
}
};
}
}