Feat[plugins]: report queue depth per appId to prometheus

[678098]

Introduced try-catch block for plugins:

10OCT2024_14:04:34.987 (139982138242624) ERROR bmqprometheus_prometheusstatconsumer.cpp:263 #PLUGIN_ERROR Invalid metric name
10OCT2024_14:04:35.987 (139982138242624) ERROR bmqprometheus_prometheusstatconsumer.cpp:263 #PLUGIN_ERROR Invalid metric name
10OCT2024_14:04:36.987 (139982138242624) ERROR bmqprometheus_prometheusstatconsumer.cpp:263 #PLUGIN_ERROR Invalid metric name

[bmq-oss-ci]

Build 295 of commit 332313a has completed with FAILURE

[waldgange]

Looks a bit confusing as we already have value in outer sope. Let's either reassign the existing variable or change the name of this one

[678098]

I replaced it by introducing another for-loop for conflicting value.

[678098]

@waldgange back to you, also note that I changed metric names:

1. Use a common dot notation everywhere, so queue_gc_msgs -> queue.gc_msgs
2. Renamed confusing metrics queue_content_msgs -> queue.content_msgs_max and the same with content_bytes (both of these metrics had implicit max value reported).

[alexander-e1off]

@waldgange back to you, also note that I changed metric names:

1. Use a common dot notation everywhere, so queue_gc_msgs -> queue.gc_msgs
2. Renamed confusing metrics queue_content_msgs -> queue.content_msgs_max and the same with content_bytes (both of these metrics had implicit max value reported).

Prometheus does not support dot in metric names:

Metric names may contain ASCII letters, digits, underscores, and colons. It must match the regex [a-zA-Z_:][a-zA-Z0-9_:]*.

[waldgange]

@waldgange back to you, also note that I changed metric names:

1. Use a common dot notation everywhere, so queue_gc_msgs -> queue.gc_msgs
2. Renamed confusing metrics queue_content_msgs -> queue.content_msgs_max and the same with content_bytes (both of these metrics had implicit max value reported).

It's OK to change the suffixes, but metric names can't contain dots. This is a Prometheus-specific restriction, so we use underscores.
Moreover If you pass these names to prometheus-cpp it will raise an exception. And it will crash the broker.
Actually it does not look safe. I think it's worth wrapping the code in onSnapshot() method with a try/catch block to prevent the broker from crashing in future. Although metric names are constant, it's definitely possible to specify label names that also have the same restrictions.

[678098]

@alexander-e1off @waldgange thanks, I will revert underscore change then.
I added a try-catch block around the code which operates metrics.
I am sure that it can throw std::invalid_argument, std::runtime_error or std::length_error, but to be more safe in the future, I catch a general exception type.

[bmq-oss-ci]

Build 303 of commit cea6f9c has completed with FAILURE

[waldgange]

LGTM

[waldgange]

I like this change! I was surprised we didn't have this wrapper before