Duplicate message delivery for multiple subscriptions on nested topics

[psorowka]

I stumbled over the following issue.

When subscribing with a single client to a mosca instance to two nested topics, e.g.

mosquitto_sub -t some/thing/# -t some/thing/specific

And subsequently publishing to

mosquitto_pub -t some/thing/specific -m value

The client will receive the message twice (with different message ids).

I am not absolutely sure whether this is expected or not; I haven't found anything clear about it in the mqtt spec. however, at least cross-checking against test.mosquitto.org did not show this behavior.

@mcollina is that a mosca or ascoltatori topic? I think in either case the fix shouldn't be too tough and I could create a PR in a few days..

[mcollina]

on which backend?

There is a whole dedupe logic, so it is a bug
Il giorno mar 1 mar 2016 alle 09:47 Peter Sorowka notifications@github.com
ha scritto:

I stumbled over the following issue.

When subscribing with a single client to a mosca instance to two nested
topics, e.g.

mosquitto_sub -t some/thing/# -t some/thing/specific

And subsequently publishing to

mosquitto_pub -t some/thing/specific -m value

The client will receive the message twice (with different message ids).

I am not absolutely sure whether this is expected or not; I haven't found
anything clear about it in the mqtt spec. however, at least cross-checking
against test.mosquitto.org did not show this behavior.

@mcollina https://github.com/mcollina is that a mosca or ascoltatori
topic? I think in either case the fix shouldn't be too tough and I could
create a PR in a few days..

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#426.

[psorowka]

Ah.. sorry didn't even think about it could be backend specific. This is on redis.

And seems to be redis specific as well, at least it doesn't happen with mongo or memory backend

[mcollina]

Confirmed, it is redis specific.

[psorowka]

do you have an instant clue? I'm not familiar with the dedupe logic yet so would have to do some debugging first to understand things..

[mcollina]

https://github.com/mcollina/mosca/blob/master/lib/client.js#L51 and possibly https://github.com/mcollina/ascoltatori/blob/master/lib/redis_ascoltatore.js.

[psorowka]

mhh okay. unfortunately i have no capacities today