After v1.5.4: bridge doesn't queue up messages when connection not active

[beville]

We have a mobile device, using a cell modem for network connectivity. We are currently using mosquitto 1.5.1 to act a bridge to the remote broker. The idea is that local MQTT client apps can connect exclusively to the local bridge, and don't worry about mobile connectivity. We'd like to keep our version of mosquitto up to date, but have run into a problem. Here's what we see with regards to the bridge handing messages when connectivity is down.

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With 1.5.1 this works fine. The sequence I see is this:

1. Mosquitto starts up, reads the config which has this line under the bridge section:
   topic device/intro out 1 "" ""
2. Mosquitto seems to subscribe to the topic 'device/intro' immediately:
   mosquitto[1195]: Bridge local.device.bridge doing local SUBSCRIBE on topic device/intro
3. Client connects, and publishes message with topic 'device/intro', and mosquitto queues it up.
4. Data connection is established, and the device has an IP address on cell network.
5. Mosquitto connects to remote broker
6. Mosquitto publishes 'device/intro' message

This above seems true up to version 1.5.4.

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From 1.5.5 on, this is what I see:

1. Mosquitto starts up, reads the config which has this line under the bridge section:
   topic device/intro out 1 "" ""
2. Client connects, and publishes message with topic 'device/intro'
3. Data connection is established, and the device has an IP address on cell network.
4. Mosquitto connects to remote broker
5. Mosquitto seems to subscribe to the topic 'device/intro':
   mosquitto[1195]: Bridge local.device.bridge doing local SUBSCRIBE on topic device/intro
6. Mosquitto does not publish 'device/intro' message

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So it appears that the message is now being discarded because of the timing of the subscription relative to the connection the remote broker. It seems like the bridge shouldn't be discarding any configured outgoing message topics regardless of current connectivity.

[ralight]

Thanks, I'll take a look (I'm currently traveling though). Could you just confirming what platform you are running on?

[beville]

Linux, on an arm7.

I'm pretty the change is related to this commit: 464b12f

Some other info, config for the bridge has cleansession=false, and test messages are QoS=1

[ralight]

I've added some tests and a fix, and intend to make a release today.

[beville]

Fantastic, thanks for addressing this so quickly!