Use dynamic ports in zmq tests

[pancak3]

resolve #164

[irar2]

Looking at https://libzmq.readthedocs.io/en/zeromq4-1/zmq_tcp.html, it looks like the address to start should be tcp://*:* (please make it a constant)

[pancak3]

Looking at https://libzmq.readthedocs.io/en/zeromq4-1/zmq_tcp.html, it looks like the address to start should be tcp://*:* (please make it a constant)

How about tcp://127.0.0.1:*? Listening on all interface sounds too open for test purpose
Using wildcard as port will panic zmq.NewSocket (https://libzmq.readthedocs.io/en/zeromq4-1/zmq_socket.html#toc3)
Which fails case run add/remove requests in parallel, use partial cache at
https://github.com/pancak3/llm-d-inference-sim/blob/fab7019849fdcdfba989d4f66b3ecd230b53e9d6/pkg/kv-cache/kv_cache_test.go#L421

Among the combinations of host [*, 127.0.0.1, localhost] with port [*, 0], only tcp://127.0.0.1:0 works.
Can we use tcp://127.0.0.1:0?

[irar2]

The tests fail in https://github.com/pancak3/llm-d-inference-sim/blob/fab7019849fdcdfba989d4f66b3ecd230b53e9d6/pkg/kv-cache/kv_cache_test.go#L421
because there is no sub there, the solution for this is to prevent publishing events by not updating ZMQEndpoint in the configuration, and in this case there is no need to create a publisher (in newBlockCache) and then in KVEventSender.Run we should continue if there is no publisher.

[pancak3]

@irar2 Not sure whether the change matches the above comment. I think I am not very familiar with the business logic of the KVEvent

[irar2]

This check should be in Run() in two cases:
case eventData, ok := <-s.eventChan:
after if !ok{} please add in line 90
if s.publisher == nil { continue }
and
case <-timer.C:
please add the same check first thing in this case.

I don't think we need a log message here, there can be too many.

[irar2]

@pancak3 Thanks!

/lgtm
/approve