chore: refactor diag logger

[dyladan]

/cc @MSNev

Per request of @Flarna this is the diag refactoring split out of #6. There may be some relevant discussion in the previous PR.

This PR is a prerequisite for #10

• The filtered logger is now the only global that is saved
  • log level and the logger are now enclosed in the filtered logger
• setLogLevel is now removed in favor of a second optional argument to setLogger
• setLogger()/setLogger(undefined)/setLogger(null) are now disallowed and replaced with disable
  • Calling this way anyway results in a noop logger
• Constructing a log level filtered logger results in a logger which ignores the global log level and only uses the one it is specifically constructed with
• Methods to create log level loggers and noop loggers are now not exported to the user and treated as internal concerns. The only exports are diag, DiagLogger, DiagLogLevel, and LogFunction.

[codecov]

Codecov Report

Merging #9 (df18a12) into main (ed9ba80) will decrease coverage by 0.49%.
The diff coverage is 98.11%.

@@            Coverage Diff             @@
##             main       #9      +/-   ##
==========================================
- Coverage   94.27%   93.77%   -0.50%     
==========================================
  Files          35       37       +2     
  Lines         489      466      -23     
  Branches       78       75       -3     
==========================================
- Hits          461      437      -24     
- Misses         28       29       +1     

Impacted Files	Coverage Δ
src/diag/consoleLogger.ts	100.00% <ø> (ø)
src/api/diag.ts	97.43% <95.65%> (-2.57%)	⬇️
src/diag/index.ts	100.00% <100.00%> (ø)
src/diag/internal/logLevelLogger.ts	100.00% <100.00%> (ø)
src/diag/internal/noopLogger.ts	100.00% <100.00%> (ø)
src/diag/types.ts	100.00% <100.00%> (ø)
src/index.ts	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ed9ba80...ecc34e8. Read the comment docs.

[dyladan]

@MSNev I can't add you as a reviewer because it seems you aren't a member of the OpenTelemetry community?

[dyladan]

Ok, I know I said id mention that "m" word less, buuuutttt...

Does this result in smaller output? Looks like it might be close -- enough?

As this definitely looks easier to read. And while I can think of a few additional tricks, I'm not sure its worth it, basically

• keep the diagLoggerFunctions but don't export from main project (effectively keeping internal)
• still use for loop for diag.ts, here (which some funcky toUpper() for the level lookup) and in the noopLoger.ts.

The looping might trim a tiny bit off, but you also add the array itself, the log level map, and the import statements. I think the readability alone is a good argument to keep it this way, but the minification win just isn't big enough IMO.

[obecny]

lgtm

[MSNev]

looks good -- just added 1 suggestion

[MSNev]

@MSNev I can't add you as a reviewer because it seems you aren't a member of the OpenTelemetry community?

open-telemetry/community#666