/*
* Copyright 2015 Netflix, Inc.
*
* Licensed 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.reactivex.netty.threads;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelPromise;
import io.netty.channel.EventLoop;
import io.netty.channel.EventLoopGroup;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.FastThreadLocal;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.ScheduledFuture;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* This {@link EventLoopGroup} can be used for clients that favors use of the "current" {@link EventLoop} for the
* outbound connection. A current {@link EventLoop} is determined by checking if the thread calling {@link #next()} is
* an eventloop instance belonging to this group. If so, the same instance is returned from {@link #next()} otherwise,
* the call to {@link #next()} is delegated to the actual {@link EventLoopGroup} passed to this instance.
*
* This is generally useful for applications that process a received request by calling some other downstream
* applications. If, during processing of these requests, there is no new thread introduced, then the {@link EventLoop}
* processing the received request will also execute the outbound request to another application.
*
* The above, although being subtle has benefits around removing queuing while writing data to any channel in the entire
* request processing.
*/
public class PreferCurrentEventLoopGroup implements EventLoopGroup {
private final FastThreadLocal<EventLoop> self = new FastThreadLocal<>();
private final EventLoopGroup delegate;
public PreferCurrentEventLoopGroup(EventLoopGroup delegate) {
this.delegate = delegate;
for (final EventExecutor child : delegate) {
child.submit(new Runnable() {
@Override
public void run() {
if (child instanceof EventLoop) {
self.set((EventLoop) child);
}
}
}); // Since this is an optimization, there is no need for us to wait for this task to finish.
}
}
@Override
public EventLoop next() {
final EventLoop thisEventLoop = self.get();
return null != thisEventLoop ? thisEventLoop : delegate.next();
}
@Override
public ChannelFuture register(Channel channel) {
return next().register(channel);
}
@Override
public ChannelFuture register(ChannelPromise promise) {
return next().register(promise);
}
@Deprecated
@Override
public ChannelFuture register(Channel channel,
ChannelPromise promise) {
return next().register(channel, promise);
}
@Override
public boolean isShuttingDown() {
return delegate.isShuttingDown();
}
@Override
public Future<?> shutdownGracefully() {
return delegate.shutdownGracefully();
}
@Override
public Future<?> shutdownGracefully(long quietPeriod, long timeout,
TimeUnit unit) {
return delegate.shutdownGracefully(quietPeriod, timeout, unit);
}
@Override
public Future<?> terminationFuture() {
return delegate.terminationFuture();
}
@Override
@Deprecated
public void shutdown() {
delegate.shutdown();
}
@Override
@Deprecated
public List<Runnable> shutdownNow() {
return delegate.shutdownNow();
}
@Override
@Deprecated
public Iterator<EventExecutor> iterator() {
return delegate.iterator();
}
@Override
public Future<?> submit(Runnable task) {
return next().submit(task);
}
@Override
public <T> Future<T> submit(Runnable task, T result) {
return next().submit(task, result);
}
@Override
public <T> Future<T> submit(Callable<T> task) {
return next().submit(task);
}
@Override
public ScheduledFuture<?> schedule(Runnable command, long delay,
TimeUnit unit) {
return next().schedule(command, delay, unit);
}
@Override
public <V> ScheduledFuture<V> schedule(Callable<V> callable,
long delay, TimeUnit unit) {
return next().schedule(callable, delay, unit);
}
@Override
public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay,
long period,
TimeUnit unit) {
return next().scheduleAtFixedRate(command, initialDelay, period, unit);
}
@Override
public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay,
long delay,
TimeUnit unit) {
return next().scheduleWithFixedDelay(command, initialDelay, delay, unit);
}
@Override
public boolean isShutdown() {
return delegate.isShutdown();
}
@Override
public boolean isTerminated() {
return delegate.isTerminated();
}
@Override
public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
return delegate.awaitTermination(timeout, unit);
}
@Override
public <T> List<java.util.concurrent.Future<T>> invokeAll(
Collection<? extends Callable<T>> tasks) throws InterruptedException {
return next().invokeAll(tasks);
}
@Override
public <T> List<java.util.concurrent.Future<T>> invokeAll(
Collection<? extends Callable<T>> tasks, long timeout,
TimeUnit unit) throws InterruptedException {
return next().invokeAll(tasks, timeout, unit);
}
@Override
public <T> T invokeAny(Collection<? extends Callable<T>> tasks) throws InterruptedException, ExecutionException {
return next().invokeAny(tasks);
}
@Override
public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout,
TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
return next().invokeAny(tasks, timeout, unit);
}
@Override
public void execute(Runnable command) {
next().execute(command);
}
}