Calling consumer.close() multiple times should not raise an Exception

[mkmoisen]

Currently, calling consumer.close more than once will raise a RuntimeError: Consumer already closed.

The proposed changes will just return NULL if the user calls close on a consumer that has already been closed.

This will make it rerunnable and allow the developer to not have to trap this exception.

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[mkmoisen]

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[edenhill]

What's the use-case for calling close multiple times?

[mkmoisen]

Hi @edenhill please check the new PR here which is passing. I've copied and pasted the following over there.

The use case is to make close rerunnable, for example if you wanted to make a context manager, or if you had a large function wrapped in a try/except/finally. Another programmer who calls your context manager can close inside if he wants; otherwise the context manager will close for him.

import contextlib
from confluent_kafka import Consumer

@contextlib.contextmanager
def kafka():
    consumer = Consumer({...})
    try:
        yield consumer
    finally:
        # currently, would need to wrap this in a try/except
        consumer.close()

# ...
# Some programmers may want to call close explicitly
with kafka() as consumer:
        # do something
        consumer.close()

# Other programmers would prefer the context manager to take care
with kafka() as consumer:
    # do something

I'm also under the impression that the majority of the other python libraries that close resources also make close rerunnable. I think it would be a good idea to have confluent_kafka follow this pattern.

from requests import Session
s = Session()
s.close()
s.close()  # does not raise an exception

import sqlite3
conn = sqlite3.connect(':memory:')
conn.close()
conn.close()  # does not raise an exception

[edenhill]

@rnpridgeon What are your thoughts on this?