netty5.0之EventLoop

1、EventExecutorGroup使用它的next()方法负责提供EventExecutor，除此之外,负责生命周期的任务处理，允许以全局方式关闭所有任务(The EventExecutorGroup is responsible to provide EventExecutor's to use via its next() method. Beside this it also is responsible to handle their live-cycle and allows to shut them down in a global fashion.)

public interface EventExecutorGroup extends ScheduledExecutorService {}

2、

EventLoopGroup 继承自EventExecutorGroup, 并提供EventLoop的生成方法next()（Special EventExecutorGroup which allows to register Channel's that get processed for later selection during the event loop.）

public interface EventLoopGroup extends EventExecutorGroup {
    @Override
    EventLoop next();
}

3、 EventLoop的英文解释是:Will handle all the I/O-Operations for a Channel once it was registered,即处理channel的io操作（ Will handle all the I/O-Operations for a  Channel  once it was registered. One  EventLoop  instance will usually handle more then one  Channel  but this may depend on implementation details and internals. ）

public interface EventLoop extends EventExecutor, EventLoopGroup {
    @Override
    EventLoopGroup parent();

    @Override
    EventLoop next();

    /**
     * Creates a new default {@link ChannelHandlerInvoker} implementation that uses this {@link EventLoop} to
     * invoke event handler methods.
     */
    ChannelHandlerInvoker asInvoker();
}

EventLoop 首先是一个Executor，任务执行器。  再者它本身是一个环，能够负载均衡执行压力。可以说EventLoop是Netty的一个核心，整个Netty的运转都是围绕着它。( http://www.cxyclub.cn/n/36389/)

EventLoop还继承了EventExecutor，下面看看吧

4、EventExecutor 是一个特殊的EventExecutorGroup,提供了检测一个线程是否在eventLoop中被执行之类的方法.
（The EventExecutor is a special EventExecutorGroup which comes with some handy methods to see if a Thread is executed in a event loop. Beside this it also extends the EventExecutorGroup to allow a generic way to access methods.）

public interface EventExecutor extends EventExecutorGroup{}

从这些方法，我们可以清晰的认识到EventLoop可以实现以下功能： 
1. 执行任务（IO/非IO任务） 
2. 将Channel绑定到EventLoop上 
3. 执行定时任务 
4. 关闭任务