Add helper method to (efficiently) format trace_id

[ioquatix]

What does this PR do?

It provides a helper method to format a trace_id, suitable for the wire protocol (mainly log correlation in my case). I don't have a strong opinion about the method name.

Motivation:

I don't want to create a Correlation object every time I log something.

Specifically, this code was previously working fine: https://github.com/socketry/console-output-datadog/blob/main/lib/console/output/datadog/wrapper.rb#L39-L54

But it appears to break with 128-bit trace IDs. I want to use the method introduced in this PR to correctly format the trace ID.

Additional Notes:

Should it always return a string, i.e. the format should be opaque to the user? If we agree to this, some changes to the Correlation class/related code might be required.

I wonder if, for the sake of compatibility, 128-bit integer trace ids should be accepted for the purpose of log correlation. As this code (console-output-datadog) worked previously but now appears broken. Actually, I believe this would cause problems, because it would be hard to differentiate 128-bit integer (decimal) from 16-byte hex (OpenTelemetry format).

Another option, or in addition to this, would be to consider supporting something like trace.correlation_id/trace.formatted_id/trace.id_string or something similar, OR if you really wanted to improve compatibility, have trace.id.to_s behave similarly, e.g. trace.id can return an opaque object that has #to_s that behaves similarly to the method in this PR.

[TonyCTHsu]

👋 @ioquatix ,

I have made the improvement in 2.0.0.beta2. Have you been able give it a try?

[ioquatix]

@TonyCTHsu is there any chance you can submit a PR to https://github.com/socketry/traces-backend-datadog

I imagine you want to edit this file: https://github.com/socketry/traces-backend-datadog/blob/main/lib/traces/backend/datadog/interface.rb

[ioquatix]

Actually, I think we need to modify this code: https://github.com/socketry/console-output-datadog/blob/main/lib/console/output/datadog/wrapper.rb#L41-L63 (this was my main pain point, see the format_trace_id method).

[ioquatix]

Also, I'd still like to avoid creating a correlation object for every log message, is that possible?

[TonyCTHsu]

@TonyCTHsu is there any chance you can submit a PR to https://github.com/socketry/traces-backend-datadog

👋 @ioquatix, I will put that on my TODO list 😉

One thing worth mentioning: Both traces-backend-datadog and console-output-datadog declares dependency to ddtrace. We've rename the gem to datadog in 2.0. So I will have to check how to make this transition.

Also, I'd still like to avoid creating a correlation object for every log message, is that possible?

Ah yes! I will further extract a stateless helper method for you! Shhhh.... its our secret.

[TonyCTHsu]

Implemented in #3670

[ioquatix]

Thanks!