Netty 4.0-将数据发送到不同事件循环上的通道

Question

I'm not sure how to do this and I think my approach is wrong - Could someone please give me a hint?

I have made a proxy server very similar to the example HexDumpProxy . The purpose is not to dump traffic but to manipulate the data parsing through the proxy and this part works perfectly. Lets call this the proxy part.

In the same program I start up a second thread listening on another port using another ServerBootstrap and this has it's own eventloop etc. When I receive something on this listening port I would like to send this data to one of channels of the proxy part and I want to be to change this channel dynamically. When I send data to one of the proxy channels I get this error:

Apr 29, 2013 10:05:10 PM BackendListenHandler exceptionCaught WARNING: Unexpected exception from downstream. java.lang.IllegalStateException: nextOutboundByteBuffer() called from outside the eventLoop

@Sharable
public class BackendListenHandler extends ChannelInboundByteHandlerAdapter {

private Channel outboundChannel;

@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
    ctx.read();
    ctx.flush();
}

@Override
public void inboundBufferUpdated(final ChannelHandlerContext ctx, ByteBuf in) throws Exception {

    outboundChannel = Proxy.connectionTable.frontendListenChannel;

    if (!outboundChannel.isActive()) {
        System.out.println("channel id=" + outboundChannel.id() + " is NOT active...");
    } else if (outboundChannel.isActive()) {
        ByteBuf out = outboundChannel.outboundByteBuffer();
        out.writeBytes(in);
        outboundChannel.flush().addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                if (future.isSuccess()) {
                    // was able to flush out data, start to read the next chunk
                    ctx.channel().read();
                } else {
                    future.channel().close();
                }
            }
        });
    }
}

public void channelInactive(ChannelHandlerContext ctx) throws Exception {
    if (outboundChannel != null) {
        closeOnFlush(outboundChannel);
    }
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    logger.log(
        Level.WARNING,
        "Unexpected exception from downstream.", cause);
    ctx.close();
}

static void closeOnFlush(Channel ch) {
    if (ch.isActive()) {
        ch.flush().addListener(ChannelFutureListener.CLOSE);
    }
}
}

For testing I keep and change my proxy Channels in this static variable:

Proxy.connectionTable.frontendListenChannel;

Answer 1

Use the same EventLoop when create the Bootstrap for the "outbound" connection like shown in the HexDump example. This will ensure everything is handled from the same IO threads. See [1].

[1] https://github.com/netty/netty/blob/master/example/src/main/java/io/netty/example/proxy/HexDumpProxyFrontendHandler.java#L46

Answer 2

Instead of using "outboundChannel.outboundByteBuffer()" - I used "Unpooled.copiedBuffer()" to write bytes to channel from another EventLoop.

@Override
public void inboundBufferUpdated(final ChannelHandlerContext ctx, ByteBuf in) throws   Exception {
outboundChannel = null;
if (Proxy.connectionTable.channelId != 0) {
    outboundChannel = Proxy.allChannels.find(Proxy.connectionTable.channelId);
    if (outboundChannel.isActive()) {               
        System.out.println("NOTIFY channel id=" + outboundChannel.id() + " is active...");
        Rewrite rewrite = new Rewrite(byteBufConverter.byteBufToString(in), 2);
        in.clear();
        in = byteBufConverter.stringToByteBuf(rewrite.getFixedMessage());   
        outboundChannel.write(in);
        outboundChannel.flush().addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                if (future.isSuccess()) {
                    ctx.channel().read();
                } else {
                    future.channel().close();
                }
            }
        });
    }
}
}

Where "byteBufConverter.stringToByteBuf(rewrite.getFixedMessage())" returns "Unpooled.copiedBuffer(strFixed.getBytes())"