MINOR: Add configurable logger per package

[stanislavkozlovski]

This patch extends log.go to provide prefix-logging functionality, allowing each file/struct/component to define their own logger that'll get prepended to every log message:

    log, _ := logger.GetLogger("clustered_data.go")
    log.Debug("Something happened!")
    => "[clustered_data.go] Something happened!"

I hacked around with zap's own benchmark suite and ran the suite 3 times comparing against the usual Zap Sugar logger and this Tektite wrapper. Long-story short:

• for simple messages (like "Test logging, but use a somewhat realistic message length. (10)), it's 2x slower - 58 ns/op to 114 ns/op. This is still better than libraries like apex/log that do 639 ns/op, go-kit/kit/log which does 142 ns/op, logrus which does 1129 ns/op and slog which does 140 ns/op

• for large messages, like logger.Infof("%v %v %v %s %v %v %v %v %v %s\n", fakeFmtArgs()...), it's roughly the same - 1275 ns/op to 1338 ns/op

| Benchmark                               | ns/op      |
|-----------------------------------------|------------|
| Zap.Sugar                               | 58.57      |
| Zap.Sugar_with_TektiteLogger            | 114.00     |
| Zap.SugarFormatting                     | 1275.67    |
| Zap.SugarFormatting_with_TektiteLogger  | 1338.00    |

• The suite: https://github.com/uber-go/zap/blob/master/benchmarks/scenario_bench_test.go
• My fork: https://github.com/stanislavkozlovski/zap/commit/5075d2f8651cd1550ab82eda5e9fd162a8e64708

[stanislavkozlovski]

I also played around with some other ways to write the message - e.g as per this SO suggestion

• https://stackoverflow.com/questions/76326437/add-a-prefix-to-zap-logger-for-all-message

But it wouldn't work, and when I added a lock - it was 2x slower as well, with more complexity. I figured it's not worth it.

[stanislavkozlovski]

oops... some tests fail

[stanislavkozlovski]

ha ok, I found why some tests were failing. I had removed the

func init() {
    initialise(zapcore.InfoLevel, "console", false)
}

method because I thought it was unused. Learning Go as I go...

[purplefox]

Looks good!

One of the tests is failing: TestTektiteLoggerReturnsErrorIfGlobalLoggerUninitialized- this is because the logger is initialised in a package init() method. I think you will need to move this test to another package without the init() to get this to work.

[stanislavkozlovski]

From some research, it seems like I can't avoid calling the init() method. I put the test elsewhere too and still the same failure.

So I guess this scenario can never happen - which is good. Now I get why you had the override flag