How to skip certain handlers and directly go to specific handler in netty

Question

Let's say I have these handler flow in netty pipeline:

UpHandler1 -> UpHandler2 -> UpHandler3 -> ... -> DownHandler1 -> DownHandler2 -> DownHandler3

Based on certain condition (ie already found response to request without doing further processing), is there anyway, in my UpHandler2, I can straight go to DownHandler2 (so skip certain upstream as well as downstream handlers in between)? Is this recommended?

Answer 1

You can use UpHandler2's ChannelHandlerContext to retrieve the ChannelPipeline. From here you can retrieve the channel handler context of any channel handler using one of the context(...) methods. Then sendDownstream for Netty 3, or write for Netty 4, will forward to the next downstream handler after the handler to which the context responds. In effect I think you'll need to get the ChannelHandlerContext for DownHandler1 and use that to write your message.

Alternatively you can build the netty pipeline such that DownHandler2 is the next down stream handler from UpHandler2. If I've understood your pipeline correctly then something like

pipeline.addLast("down3", downhandler3);
pipeline.addLast('up1", uphandler1);
pipeline.addLast("down2", downhandler2);
pipeline.addLast("up2", uphandler2);
pipeline.addLast("down1", downhandler1);
pipeline.addLast("up3", uphandler3);

might work. However this could be quite brittle and also depends on whether your processing logic allows it.