Netty服务端的业务流程分析

privatestaticvoid doBind0(
finalChannelFuture regFuture,finalChannel channel,
finalSocketAddress localAddress,finalChannelPromise promise){
// This method is invoked before channelRegistered() is triggered.  Give user handlers a chance to set up
// the pipeline in its channelRegistered() implementation.
        channel.eventLoop().execute(newRunnable(){
@Override
publicvoid run(){
if(regFuture.isSuccess()){
                    channel.bind(localAddress, promise).addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
}else{
                    promise.setFailure(regFuture.cause());
}
}
});
}

@Override
protectedvoid run(){
for(;;){
boolean oldWakenUp = wakenUp.getAndSet(false);
try{
if(hasTasks()){
                    selectNow();
}else{
                    select(oldWakenUp);
// ‘wakenUp.compareAndSet(false, true)‘ is always evaluated
// before calling ‘selector.wakeup()‘ to reduce the wake-up
// overhead. (Selector.wakeup() is an expensive operation.)
//
// However, there is a race condition in this approach.
// The race condition is triggered when ‘wakenUp‘ is set to
// true too early.
//
// ‘wakenUp‘ is set to true too early if:
// 1) Selector is waken up between ‘wakenUp.set(false)‘ and
//    ‘selector.select(...)‘. (BAD)
// 2) Selector is waken up between ‘selector.select(...)‘ and
//    ‘if (wakenUp.get()) { ... }‘. (OK)
//
// In the first case, ‘wakenUp‘ is set to true and the
// following ‘selector.select(...)‘ will wake up immediately.
// Until ‘wakenUp‘ is set to false again in the next round,
// ‘wakenUp.compareAndSet(false, true)‘ will fail, and therefore
// any attempt to wake up the Selector will fail, too, causing
// the following ‘selector.select(...)‘ call to block
// unnecessarily.
//
// To fix this problem, we wake up the selector again if wakenUp
// is true immediately after selector.select(...).
// It is inefficient in that it wakes up the selector for both
// the first case (BAD - wake-up required) and the second case
// (OK - no wake-up required).
if(wakenUp.get()){
                        selector.wakeup();
}
}
                cancelledKeys =0;
                needsToSelectAgain =false;
finalint ioRatio =this.ioRatio;
if(ioRatio ==100){
                    processSelectedKeys();
                    runAllTasks();
}else{
finallong ioStartTime =System.nanoTime();
                    processSelectedKeys();
finallong ioTime =System.nanoTime()- ioStartTime;
                    runAllTasks(ioTime *(100- ioRatio)/ ioRatio);
}
if(isShuttingDown()){
                    closeAll();
if(confirmShutdown()){
break;
}
}
}catch(Throwable t){
                logger.warn("Unexpected exception in the selector loop.", t);
// Prevent possible consecutive immediate failures that lead to
// excessive CPU consumption.
try{
Thread.sleep(1000);
}catch(InterruptedException e){
// Ignore.
}
}
}
}