netty之NioEventLoop和NioEventLoopGroup

类结构图

NioEventLoopGroup

MultithreadEventLoopGroup NioEventLoopGroup MultithreadEventExecutorGroup AbstractEventExecutorGroup <<interface>> EventExecutorGroup <<interface>> EventLoopGroup

NioEventLoop

<<interface>> EventExecutor AbstractEventExecutor AbstractScheduledEventExecutor SingleThreadEventExecutor SingleThreadEventLoop NioEventLoop <<interface>> EventLoop

初始化

线程池创建是通过MultithreadEventExecutorGroup构造函数，创建线程是通过DefaultThreadFactory

首先创建EventExecutor的数组

cpp 复制代码

children = new EventExecutor[nThreads];

NioEventLoopGroup的newChild创建具体的eventloop即NioEventLoop

SingleThreadEventExecutor在重写了线程池的execute方法时，其会创建线程，执行SingleThreadEventExecutor.this.run()抽象方法

同时会初始化EventExecutorChooser, 有两种类型

PowerOfTwoEventExecutorChooser
GenericEventExecutorChooser

初始化SelectorProvider，默认使用sun.nio.ch.DefaultSelectorProvider.create()

java 复制代码

public static SelectorProvider provider() {
        synchronized (lock) {
            if (provider != null)
                return provider;
            return AccessController.doPrivileged(
                new PrivilegedAction<SelectorProvider>() {
                    public SelectorProvider run() {
                            if (loadProviderFromProperty())
                                return provider;
                            if (loadProviderAsService())
                                return provider;
                            provider = sun.nio.ch.DefaultSelectorProvider.create();
                            return provider;
                        }
                    });
        }
    }

初始化DefaultSelectStrategy，默认使用SelectStrategy.SELECT

创建NioEventLoop传递的executor参数为ThreadPerTaskExecutor