Netty源码分析NioEventLoop初始化线程选择器创建

protected MultithreadEventExecutorGroup(int nThreads, Executor executor, 
                                        EventExecutorChooserFactory chooserFactory, Object... args) {
    //代码省略
    if (executor == null) {
        //创建一个新的线程执行器(1)
        executor = new ThreadPerTaskExecutor(newDefaultThreadFactory());
    }
    //构造NioEventLoop(2)
    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) {
            throw new IllegalStateException("failed to create a child event loop", e);
        } finally {
           //代码省略
        }
    }
    //创建线程选择器(3)
    chooser = chooserFactory.newChooser(children);
    //代码省略
}

chooser = chooserFactory.newChooser(children);

public EventExecutorChooser newChooser(EventExecutor[] executors) { 
    if (isPowerOfTwo(executors.length)) { 
        return new PowerOfTowEventExecutorChooser(executors);
    } else {
        return new GenericEventExecutorChooser(executors);
    }
}

private static final class PowerOfTowEventExecutorChooser implements EventExecutorChooser {
    private final AtomicInteger idx = new AtomicInteger();
    private final EventExecutor[] executors;
    PowerOfTowEventExecutorChooser(EventExecutor[] executors) {
        this.executors = executors;
    }
    @Override
    public EventExecutor next() {
        return executors[idx.getAndIncrement() & executors.length - 1];
    }
}

private static final class GenericEventExecutorChooser implements EventExecutorChooser {
    private final AtomicInteger idx = new AtomicInteger();
    private final EventExecutor[] executors;
    GenericEventExecutorChooser(EventExecutor[] executors) {
        this.executors = executors;
    }
    @Override
    public EventExecutor next() {
        return executors[Math.abs(idx.getAndIncrement() % executors.length)];
    }
}