Netty NIO 通道可以写但不连接吗？

Question

我有一个接收channelInterestChanged 回调的处理程序，然后在该回调中测试通道的isWritable() 方法，并在下游触发writeRequest 事件。

有时如果在打开通道时发生这种情况，通道会抛出异常事件，原因为java.nio.channels.NotYetConnectedException。

应该isWritable() == true 假设isConnected() == true 还是我搞砸了？

例子：

@Override
public void channelInterestChanged(ChannelHandlerContext ctx,
        ChannelStateEvent e) throws Exception {
    MyMessage msg;
    while(ctx.getChannel().isWritable()){
        msg = queue.poll();
        Channels.write(ctx, Channels.succeededFuture(ctx.getChannel()), msg);
    }
}

堆栈跟踪：

java.nio.channels.NotYetConnectedException
at org.jboss.netty.channel.socket.nio.AbstractNioWorker.cleanUpWriteBuffer(AbstractNioWorker.java:696)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.writeFromUserCode(AbstractNioWorker.java:421)
    at org.jboss.netty.channel.socket.nio.NioClientSocketPipelineSink.eventSunk(NioClientSocketPipelineSink.java:116)
    at org.jboss.netty.channel.Channels.write(Channels.java:733)
    at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:65)
    at org.jboss.netty.channel.Channels.write(Channels.java:733)
    at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:65)
    at org.jboss.netty.channel.Channels.write(Channels.java:733)
    at org.jboss.netty.channel.Channels.write(Channels.java:694) <--- this call is guarded by `isWritable()`
    at foo.bar.MyHandler.channelInterestChanged(MyHandler.java:44) <--- My handler
    at org.jboss.netty.handler.codec.oneone.OneToOneDecoder.handleUpstream(OneToOneDecoder.java:61)
    at org.jboss.netty.channel.Channels.fireChannelInterestChanged(Channels.java:361)
    at org.jboss.netty.channel.Channels$3.run(Channels.java:349)
    at org.jboss.netty.channel.socket.ChannelRunnableWrapper.run(ChannelRunnableWrapper.java:41)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.processEventQueue(AbstractNioWorker.java:373)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:254)
    at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:35)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)

Answer 1

可连接和可写在底层是相同的条件。确保首先测试可连接，当它触发时完成连接，如果成功则对可连接状态/事件失去所有兴趣。在连接完成之前，请勿以书面形式注册。