netty源码分析-NioEventLoopGroup

/*
 * 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.channel.nio;

import io.netty.channel.Channel;
import io.netty.channel.EventLoop;
import io.netty.channel.DefaultSelectStrategyFactory;
import io.netty.channel.MultithreadEventLoopGroup;
import io.netty.channel.SelectStrategyFactory;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.EventExecutorChooserFactory;
import io.netty.util.concurrent.RejectedExecutionHandler;
import io.netty.util.concurrent.RejectedExecutionHandlers;

import java.nio.channels.Selector;
import java.nio.channels.spi.SelectorProvider;
import java.util.concurrent.Executor;
import java.util.concurrent.ThreadFactory;

/**
 * {@link MultithreadEventLoopGroup} implementations which is used for NIO {@link Selector} based {@link Channel}s.MultithreadEventLoopGroup 实现了channel接口
 */
public class NioEventLoopGroup extends MultithreadEventLoopGroup {

    /**
     * Create a new instance using the default number of threads, the default {@link ThreadFactory} and
     * the {@link SelectorProvider} which is returned by {@link SelectorProvider#provider()}.
     * 创建一个新的线程对象使用默认的线程数 默认情况ThreadFactory和SelectorProvider通过SelectorProvider#provider()                 *        返回
     */
    public NioEventLoopGroup() {
        this(0);
    }

    /**
     * Create a new instance using the specified number of threads, {@link ThreadFactory} and the
     * {@link SelectorProvider} which is returned by {@link SelectorProvider#provider()}.
     */
    public NioEventLoopGroup(int nThreads) {
        this(nThreads, (Executor) null);
    }

    /**
     * Create a new instance using the specified number of threads, the given {@link ThreadFactory} and the
     * {@link SelectorProvider} which is returned by {@link SelectorProvider#provider()}.
     */
    public NioEventLoopGroup(int nThreads, ThreadFactory threadFactory) {
        this(nThreads, threadFactory, SelectorProvider.provider());
    }

    public NioEventLoopGroup(int nThreads, Executor executor) {
        this(nThreads, executor, SelectorProvider.provider());
    }

    /**
     * Create a new instance using the specified number of threads, the given {@link ThreadFactory} and the given
     * {@link SelectorProvider}.
     */
    public NioEventLoopGroup(
            int nThreads, ThreadFactory threadFactory, final SelectorProvider selectorProvider) {
        this(nThreads, threadFactory, selectorProvider, DefaultSelectStrategyFactory.INSTANCE);
    }

//默认的构造方法最后执行的方法
    public NioEventLoopGroup(int nThreads, ThreadFactory threadFactory,
        final SelectorProvider selectorProvider, final SelectStrategyFactory selectStrategyFactory) {
        super(nThreads, threadFactory, selectorProvider, selectStrategyFactory, RejectedExecutionHandlers.reject());
    }
以下为父类的构造方法      

/**
 * @see MultithreadEventExecutorGroup#MultithreadEventExecutorGroup(int, ThreadFactory, Object...)
 * 根据传过来的线程数进行判断是否为0如果不是的话根据系统核心数*2的值将他设置为默认的线程数之后创建线程池，线程数数为    nthread
 */
protected MultithreadEventLoopGroup(int nThreads, ThreadFactory threadFactory, Object... args) {
    super(nThreads == 0 ? DEFAULT_EVENT_LOOP_THREADS : nThreads, threadFactory, args);
}      

public NioEventLoopGroup(
            int nThreads, Executor executor, final SelectorProvider selectorProvider) {
        this(nThreads, executor, selectorProvider, DefaultSelectStrategyFactory.INSTANCE);
    }

    public NioEventLoopGroup(int nThreads, Executor executor, final SelectorProvider selectorProvider,
                             final SelectStrategyFactory selectStrategyFactory) {
        super(nThreads, executor, selectorProvider, selectStrategyFactory, RejectedExecutionHandlers.reject());
    }

    public NioEventLoopGroup(int nThreads, Executor executor, EventExecutorChooserFactory chooserFactory,
                             final SelectorProvider selectorProvider,
                             final SelectStrategyFactory selectStrategyFactory) {
         (nThreads, executor, chooserFactory, selectorProvider, selectStrategyFactory,
                RejectedExecutionHandlers.reject());
    }

    public NioEventLoopGroup(int nThreads, Executor executor, EventExecutorChooserFactory chooserFactory,
                             final SelectorProvider selectorProvider,
                             final SelectStrategyFactory selectStrategyFactory,
                             final RejectedExecutionHandler rejectedExecutionHandler) {
        super(nThreads, executor, chooserFactory, selectorProvider, selectStrategyFactory, rejectedExecutionHandler);
    }

    /**
     * Sets the percentage of the desired amount of time spent for I/O in the child event loops.  The default value is
     * {@code 50}, which means the event loop will try to spend the same amount of time for I/O as for non-I/O tasks.
     */
    public void setIoRatio(int ioRatio) {
        for (EventExecutor e: this) {
            ((NioEventLoop) e).setIoRatio(ioRatio);
        }
    }

    /**
     * Replaces the current {@link Selector}s of the child event loops with newly created {@link Selector}s to work
     * around the  infamous epoll 100% CPU bug.
     */
    public void rebuildSelectors() {
        for (EventExecutor e: this) {
            ((NioEventLoop) e).rebuildSelector();
        }
    }

    @Override
    protected EventLoop newChild(Executor executor, Object... args) throws Exception {
        return new NioEventLoop(this, executor, (SelectorProvider) args[0],
            ((SelectStrategyFactory) args[1]).newSelectStrategy(), (RejectedExecutionHandler) args[2]);
    }
}      

对于NioEventLoopGroup来说他其实主要做的工作有创建线程池和nio的selector  channel对于这个类涉及到的东西不多就不多讲了