Question

I’m debugging some zeromq code and I would like to log socket instance send/recv. In other words, I have

context = zmq.Context()
socket = context.socket(zmq.REQ)
socket.connect("tcp://127.0.0.1:5000")

and I would like to somehow log the socket instance’s send/recv elsewhere in the code.

Any ideas here? I’m not sure where to get started.

Answer 1

Here’s an example of a Socket object that logs every message:

import logging
import time
import zmq

class LogSocket(object):
    socket = None
    log = None
    name = None

    def __init__(self, socket, log=None, name=None):
        """wrap a socket so send/recv_multipart log their messages"""
        self.socket = socket
        if log is None:
            logging.basicConfig(level=logging.INFO)
            log = logging.getLogger().info
        self.log = log

        if name is None:
            name = s.identity or repr(s)
        self.name = name

    def send_multipart(self, msg, *args, **kwargs):
        self.log("%s sending: %r" % (self.name, msg))
        return self.socket.send_multipart(msg, *args, **kwargs)

    def recv_multipart(self, *args, **kwargs):
        msg = self.socket.recv_multipart(*args, **kwargs)
        self.log("%s received: %r" % (self.name, msg))
        return msg

    def __getattr__(self, key):
        return getattr(self.socket, key)


ctx = zmq.Context.instance()

s = ctx.socket(zmq.REQ)
s.connect("tcp://127.0.0.1:5556")

# wrap the zmq socket in the Logging object:
# this object has exactly the same interface as 
s = LogSocket(s, name="REQ")

for i in range(5):
    time.sleep(1)
    s.send_multipart(['hello', 'world'])
    reply = s.recv_multipart()
    # in this case, only _multipart methods are logged, so straight send/recv are not:
    s.send("quiet")
    s.recv()

An example of the secondary object for handling serialization/logging/authentication, etc. all in one place is the Session object in IPython, which is a good deal more complicated than this simple case, but allows you to centralize all of the messaging abstractions in your code.