294 lines
11 KiB
Java
294 lines
11 KiB
Java
/*
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* Copyright 2012 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.util.concurrent;
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import io.netty.util.internal.EmptyArrays;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.Iterator;
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import java.util.List;
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import java.util.concurrent.Executor;
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import java.util.concurrent.ThreadFactory;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicInteger;
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import java.util.concurrent.atomic.AtomicLong;
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import static io.netty.util.internal.ObjectUtil.checkPositive;
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/**
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* {@link EventExecutorGroup} implementation that handles their tasks with multiple threads at
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* the same time.
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*/
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public class MultithreadEventExecutorGroup implements EventExecutorGroup {
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private final EventExecutor[] children;
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private final List<EventExecutor> readonlyChildren;
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private final AtomicInteger terminatedChildren = new AtomicInteger();
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private final Promise<?> terminationFuture = GlobalEventExecutor.INSTANCE.newPromise();
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private final boolean powerOfTwo;
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/**
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* Create a new instance.
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*
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* @param nThreads the number of threads that will be used by this instance.
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* @param threadFactory the ThreadFactory to use, or {@code null} if the default should be used.
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*/
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public MultithreadEventExecutorGroup(int nThreads, ThreadFactory threadFactory) {
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this(nThreads, threadFactory, SingleThreadEventExecutor.DEFAULT_MAX_PENDING_EXECUTOR_TASKS,
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RejectedExecutionHandlers.reject());
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}
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/**
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* Create a new instance.
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*
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* @param nThreads the number of threads that will be used by this instance.
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* @param executor the {@link Executor} to use, or {@code null} if the default should be used.
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*/
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public MultithreadEventExecutorGroup(int nThreads, Executor executor) {
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this(nThreads, executor, SingleThreadEventExecutor.DEFAULT_MAX_PENDING_EXECUTOR_TASKS,
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RejectedExecutionHandlers.reject());
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}
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/**
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* Create a new instance.
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*
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* @param nThreads the number of threads that will be used by this instance.
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* @param threadFactory the {@link ThreadFactory} to use, or {@code null} if the default should be used.
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* @param maxPendingTasks the maximum number of pending tasks before new tasks will be rejected.
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* @param rejectedHandler the {@link RejectedExecutionHandler} to use.
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*/
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public MultithreadEventExecutorGroup(int nThreads, ThreadFactory threadFactory,
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int maxPendingTasks, RejectedExecutionHandler rejectedHandler) {
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this(nThreads, threadFactory, maxPendingTasks, rejectedHandler, EmptyArrays.EMPTY_OBJECTS);
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}
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/**
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* Create a new instance.
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*
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* @param nThreads the number of threads that will be used by this instance.
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* @param executor the Executor to use, or {@code null} if the default should be used.
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* @param maxPendingTasks the maximum number of pending tasks before new tasks will be rejected.
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* @param rejectedHandler the {@link RejectedExecutionHandler} to use.
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*/
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public MultithreadEventExecutorGroup(int nThreads, Executor executor,
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int maxPendingTasks, RejectedExecutionHandler rejectedHandler) {
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this(nThreads, executor, maxPendingTasks, rejectedHandler, EmptyArrays.EMPTY_OBJECTS);
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}
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/**
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* Create a new instance.
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*
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* @param nThreads the number of threads that will be used by this instance.
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* @param threadFactory the ThreadFactory to use, or {@code null} if the default should be used.
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* @param maxPendingTasks the maximum number of pending tasks before new tasks will be rejected.
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* @param rejectedHandler the {@link RejectedExecutionHandler} to use.
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* @param args arguments which will passed to each {@link #newChild(Executor, int,
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* RejectedExecutionHandler, Object...)} call
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*/
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protected MultithreadEventExecutorGroup(int nThreads, ThreadFactory threadFactory, int maxPendingTasks,
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RejectedExecutionHandler rejectedHandler, Object... args) {
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this(nThreads, threadFactory == null ? null : new ThreadPerTaskExecutor(threadFactory),
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maxPendingTasks, rejectedHandler, args);
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}
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/**
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* Create a new instance.
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*
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* @param nThreads the number of threads that will be used by this instance.
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* @param executor the Executor to use, or {@code null} if the default should be used.
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* @param maxPendingTasks the maximum number of pending tasks before new tasks will be rejected.
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* @param rejectedHandler the {@link RejectedExecutionHandler} to use.
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* @param args arguments which will passed to each {@link #newChild(Executor, int,
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* RejectedExecutionHandler, Object...)} call
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*/
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protected MultithreadEventExecutorGroup(int nThreads, Executor executor, int maxPendingTasks,
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RejectedExecutionHandler rejectedHandler, Object... args) {
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checkPositive(nThreads, "nThreads");
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if (executor == null) {
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executor = new ThreadPerTaskExecutor(new DefaultThreadFactory(getClass()));
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}
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children = new EventExecutor[nThreads];
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powerOfTwo = isPowerOfTwo(children.length);
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for (int i = 0; i < nThreads; i ++) {
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boolean success = false;
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try {
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children[i] = newChild(executor, maxPendingTasks, rejectedHandler, args);
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success = true;
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} catch (Exception e) {
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// TODO: Think about if this is a good exception type
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throw new IllegalStateException("failed to create a child event executor", e);
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} finally {
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if (!success) {
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for (int j = 0; j < i; j ++) {
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children[j].shutdownGracefully();
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}
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for (int j = 0; j < i; j ++) {
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EventExecutor e = children[j];
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try {
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while (!e.isTerminated()) {
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e.awaitTermination(Integer.MAX_VALUE, TimeUnit.SECONDS);
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}
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} catch (InterruptedException interrupted) {
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// Let the caller handle the interruption.
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Thread.currentThread().interrupt();
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break;
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}
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}
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}
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}
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}
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final FutureListener<Object> terminationListener = future -> {
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if (terminatedChildren.incrementAndGet() == children.length) {
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terminationFuture.setSuccess(null);
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}
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};
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for (EventExecutor e: children) {
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e.terminationFuture().addListener(terminationListener);
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}
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readonlyChildren = Collections.unmodifiableList(Arrays.asList(children));
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}
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// Use a 'long' counter to avoid non-round-robin behaviour at the 32-bit overflow boundary.
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// The 64-bit long solves this by placing the overflow so far into the future, that no system
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// will encounter this in practice.
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private final AtomicLong idx = new AtomicLong();
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/**
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* The {@link EventExecutor}s that are used by this {@link MultithreadEventExecutorGroup}.
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*/
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protected final List<EventExecutor> executors() {
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return readonlyChildren;
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}
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/**
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* Returns the next {@link EventExecutor} to use. The default implementation will use round-robin, but you may
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* override this to change the selection algorithm.
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*/
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@Override
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public EventExecutor next() {
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if (powerOfTwo) {
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return children[(int) idx.getAndIncrement() & children.length - 1];
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}
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return children[(int) Math.abs(idx.getAndIncrement() % children.length)];
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}
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private static boolean isPowerOfTwo(int val) {
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return (val & -val) == val;
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}
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@Override
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public Iterator<EventExecutor> iterator() {
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return executors().iterator();
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}
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/**
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* Return the number of {@link EventExecutor} this implementation uses. This number is the maps
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* 1:1 to the threads it use.
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*/
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public final int executorCount() {
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return executors().size();
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}
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/**
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* Create a new EventExecutor which will later then accessible via the {@link #next()} method. This method will be
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* called for each thread that will serve this {@link MultithreadEventExecutorGroup}.
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*
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* As this method is called from within the constructor you can only use the parameters passed into the method when
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* overriding this method.
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*/
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protected EventExecutor newChild(Executor executor, int maxPendingTasks,
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RejectedExecutionHandler rejectedExecutionHandler,
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Object... args) {
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assert args.length == 0;
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return new SingleThreadEventExecutor(executor, maxPendingTasks, rejectedExecutionHandler);
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}
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@Override
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public final Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
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for (EventExecutor l: children) {
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l.shutdownGracefully(quietPeriod, timeout, unit);
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}
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return terminationFuture();
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}
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@Override
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public final Future<?> terminationFuture() {
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return terminationFuture.asFuture();
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}
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@Override
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@Deprecated
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public final void shutdown() {
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for (EventExecutor l: children) {
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l.shutdown();
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}
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}
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@Override
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public final boolean isShuttingDown() {
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for (EventExecutor l: children) {
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if (!l.isShuttingDown()) {
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return false;
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}
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}
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return true;
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}
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@Override
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public final boolean isShutdown() {
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for (EventExecutor l: children) {
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if (!l.isShutdown()) {
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return false;
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}
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}
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return true;
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}
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@Override
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public final boolean isTerminated() {
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for (EventExecutor l: children) {
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if (!l.isTerminated()) {
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return false;
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}
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}
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return true;
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}
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@Override
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public final boolean awaitTermination(long timeout, TimeUnit unit)
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throws InterruptedException {
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long deadline = System.nanoTime() + unit.toNanos(timeout);
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loop: for (EventExecutor l: children) {
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for (;;) {
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long timeLeft = deadline - System.nanoTime();
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if (timeLeft <= 0) {
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break loop;
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}
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if (l.awaitTermination(timeLeft, TimeUnit.NANOSECONDS)) {
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break;
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}
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}
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}
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return isTerminated();
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}
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}
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