/*
 * Copyright 2012 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 java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.concurrent.Executor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

Abstract base class for EventExecutorGroup implementations that handles their tasks with multiple threads at the same time.
/** * Abstract base class for {@link EventExecutorGroup} implementations that handles their tasks with multiple threads at * the same time. */
public abstract class MultithreadEventExecutorGroup extends AbstractEventExecutorGroup { private final EventExecutor[] children; private final Set<EventExecutor> readonlyChildren; private final AtomicInteger terminatedChildren = new AtomicInteger(); private final Promise<?> terminationFuture = new DefaultPromise(GlobalEventExecutor.INSTANCE); private final EventExecutorChooserFactory.EventExecutorChooser chooser;
Create a new instance.
Params:
  • nThreads – the number of threads that will be used by this instance.
  • threadFactory – the ThreadFactory to use, or null if the default should be used.
  • args – arguments which will passed to each newChild(Executor, Object...) call
/** * Create a new instance. * * @param nThreads the number of threads that will be used by this instance. * @param threadFactory the ThreadFactory to use, or {@code null} if the default should be used. * @param args arguments which will passed to each {@link #newChild(Executor, Object...)} call */
protected MultithreadEventExecutorGroup(int nThreads, ThreadFactory threadFactory, Object... args) { this(nThreads, threadFactory == null ? null : new ThreadPerTaskExecutor(threadFactory), args); }
Create a new instance.
Params:
  • nThreads – the number of threads that will be used by this instance.
  • executor – the Executor to use, or null if the default should be used.
  • args – arguments which will passed to each newChild(Executor, Object...) call
/** * Create a new instance. * * @param nThreads the number of threads that will be used by this instance. * @param executor the Executor to use, or {@code null} if the default should be used. * @param args arguments which will passed to each {@link #newChild(Executor, Object...)} call */
protected MultithreadEventExecutorGroup(int nThreads, Executor executor, Object... args) { this(nThreads, executor, DefaultEventExecutorChooserFactory.INSTANCE, args); }
Create a new instance.
Params:
/** * Create a new instance. * * @param nThreads the number of threads that will be used by this instance. * @param executor the Executor to use, or {@code null} if the default should be used. * @param chooserFactory the {@link EventExecutorChooserFactory} to use. * @param args arguments which will passed to each {@link #newChild(Executor, Object...)} call */
protected MultithreadEventExecutorGroup(int nThreads, Executor executor, EventExecutorChooserFactory chooserFactory, Object... args) { if (nThreads <= 0) { throw new IllegalArgumentException(String.format("nThreads: %d (expected: > 0)", nThreads)); } if (executor == null) { executor = new ThreadPerTaskExecutor(newDefaultThreadFactory()); } children = new EventExecutor[nThreads]; for (int i = 0; i < nThreads; i ++) { boolean success = false; try { children[i] = newChild(executor, args); success = true; } catch (Exception e) { // TODO: Think about if this is a good exception type throw new IllegalStateException("failed to create a child event loop", e); } finally { if (!success) { for (int j = 0; j < i; j ++) { children[j].shutdownGracefully(); } for (int j = 0; j < i; j ++) { EventExecutor e = children[j]; try { while (!e.isTerminated()) { e.awaitTermination(Integer.MAX_VALUE, TimeUnit.SECONDS); } } catch (InterruptedException interrupted) { // Let the caller handle the interruption. Thread.currentThread().interrupt(); break; } } } } } chooser = chooserFactory.newChooser(children); final FutureListener<Object> terminationListener = new FutureListener<Object>() { @Override public void operationComplete(Future<Object> future) throws Exception { if (terminatedChildren.incrementAndGet() == children.length) { terminationFuture.setSuccess(null); } } }; for (EventExecutor e: children) { e.terminationFuture().addListener(terminationListener); } Set<EventExecutor> childrenSet = new LinkedHashSet<EventExecutor>(children.length); Collections.addAll(childrenSet, children); readonlyChildren = Collections.unmodifiableSet(childrenSet); } protected ThreadFactory newDefaultThreadFactory() { return new DefaultThreadFactory(getClass()); } @Override public EventExecutor next() { return chooser.next(); } @Override public Iterator<EventExecutor> iterator() { return readonlyChildren.iterator(); }
Return the number of EventExecutor this implementation uses. This number is the maps 1:1 to the threads it use.
/** * Return the number of {@link EventExecutor} this implementation uses. This number is the maps * 1:1 to the threads it use. */
public final int executorCount() { return children.length; }
Create a new EventExecutor which will later then accessible via the next() method. This method will be called for each thread that will serve this MultithreadEventExecutorGroup.
/** * Create a new EventExecutor which will later then accessible via the {@link #next()} method. This method will be * called for each thread that will serve this {@link MultithreadEventExecutorGroup}. * */
protected abstract EventExecutor newChild(Executor executor, Object... args) throws Exception; @Override public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) { for (EventExecutor l: children) { l.shutdownGracefully(quietPeriod, timeout, unit); } return terminationFuture(); } @Override public Future<?> terminationFuture() { return terminationFuture; } @Override @Deprecated public void shutdown() { for (EventExecutor l: children) { l.shutdown(); } } @Override public boolean isShuttingDown() { for (EventExecutor l: children) { if (!l.isShuttingDown()) { return false; } } return true; } @Override public boolean isShutdown() { for (EventExecutor l: children) { if (!l.isShutdown()) { return false; } } return true; } @Override public boolean isTerminated() { for (EventExecutor l: children) { if (!l.isTerminated()) { return false; } } return true; } @Override public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException { long deadline = System.nanoTime() + unit.toNanos(timeout); loop: for (EventExecutor l: children) { for (;;) { long timeLeft = deadline - System.nanoTime(); if (timeLeft <= 0) { break loop; } if (l.awaitTermination(timeLeft, TimeUnit.NANOSECONDS)) { break; } } } return isTerminated(); } }