Compressed log

[acajic]

This idea is similar to the one already suggested here #2064

Basically, if now I have a line like this:
logger->info("test {}", var);

I will find the following lines in my log file:

test 1
test 46
test 413
...

I would like to be able to pass additional argument what is the minimal time period between two logs of this type:
logger->infoCompressed(5 * 60 /*5 minutes*/, "test {}", var);

And in the log file I will find something like this:
test 1 (+133 similar messages)

and then after five minutes, we get another line like this:
test 31 (+42 similar messages)

What would be the best way to go about implementing this?

[tt4g]

It depends on whether the "similar messages" are log messages before or after formatting.
If it is a post-format message, this can only be implemented by sink with a formatter.

[acajic]

So, pre-format is "test {}" and post-format is "test 1"?
I need the pre-format.

[tt4g]

So, pre-format is "test {}" and post-format is "test 1"?

Yes. And you can use dup_filter_sink, which has a very similar feature.
See dup_filter_sink section in Wiki: https://github.com/gabime/spdlog/wiki/4.-Sinks

You can also implement a custom sink by referring to dup_filter_sink.
See: https://github.com/gabime/spdlog/wiki/4.-Sinks#implementing-your-own-sink

[acajic]

Nice. Thank you.

Each sink should be responsible for only single target (e.g file, console, db)

This may be a stupid question, but can multiple sinks point to the same target?

[tt4g]

Use dist_sink to proxy for multiple sinks.
By the way, dup_filter_sink inherits dist_sink.

[FilipWeisser]

I tried implementing this idea and ended up overloading and duplicating many functions. I had to add 2 parameters, "id" and "skip_duration", for all of info, warn, ..., log and sink_it functions. These 2 parameters are then used in a custom filter_similar_sink to keep count of the messages with the same id, and log them only if skip_duration has passed, with the (+x similar messages) message following it. eb2cb46

Is there a better way?