How can I get two threads to read from one inputStream?

Question

I have on input stream coming in that is periodically receiving data. One of my threads (let's call it threadA) reads every message from the stream and makes sure the data is ok, but will through an error otherwise. My other thread (let's call it threadB) needs to read a few specific messages and then process it. As of now I have threadA just store the important messages in a global variable, and threadB read the messages from the global variable.

Is there any way to allow for two threads to read from the same source to avoid this?

edit: the data coming in are responses to commands threadB issued. My issue is that threadB needs the replies from certain commands, which are issued in no particular pattern, but it does not need all the replies.

Answer 1

You probably could create a threadsafe inputstream or a wrapper and if the stream supports mark/reset you could also have two streams read the data in parallel. However, you'd have to handle situations where one thread reads faster than the other thus making mark/reset unusable or having to skip data - there's so much involved, I doubt you'll want to bother with all this.

I'd suggest you keep your basic setup but try to get rid of global variables, eg by using the obverser pattern, passing references to the shared store to the threads etc.