Im writing a server that regularly needs to change the format of the send/received messages. when this happens the server should send a notification that all future messages have the new format and read all received in the old format until the client sends his ack.
i thought about keeping a reference to the decoder shared by all pipelines and reconfigure it from the outside as needed. I’m worried about concurrency in this case.
- how can i make sure that no writes are handled by the pipeline while
i’m working on the decoder? - and how to be sure that the notification
is the first message handled after reconfiguration?
the only other way i see is to send a “notification” object through the pipeline (by using channel.write), catch the object in the decoder and do the reconfig then while forwarding the notification message. In this case there shouldn’t be any concurrency in the pipeline.
- would this be the better/state of the art way to do this?
i decided to use the second way. A StateHandler catches ConfigurationEvents reconfigures the pipeline. Unfortunately this means that i can’t be sure that all channels use the same configuration because race conditions between the reconfiguration and extremely young channels can happen. but i’m pretty sure this won’t matter in my case.