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[](https://github.com/bep/logg/actions?query=workflow:Test)
[](https://goreportcard.com/report/github.com/bep/logg)
[](https://godoc.org/github.com/bep/logg)
This is a fork of the exellent [Apex Log](https://github.com/apex/log) library.
Main changes:
* Trim unneeded dependencies.
* Make `Fields` into a slice to preserve log order.
* Split the old `Interface` in two and remove all but one `Log` method (see below).
* This allows for lazy creation of messages in `Log(fmt.Stringer)` and ignoring fields added in `LevelLogger`s with levels below the `Logger`s.
* The pointer passed to `HandleLog` is not safe to use outside of the current log chain, and needs to be cloned with `Clone` first if that's needed.
* See [Benchmarks](#benchmarks) for more info.
This is probably the very fastest structured log library when logging is disabled:
<img width="492" alt="image" src="https://user-images.githubusercontent.com/394382/184383985-265a4b0e-ee36-405e-9dc1-4686d0cad57a.png">
> One can never have enough log libraries!
```go
// Logger is the main interface for the logger.
type Logger interface {
// WithLevel returns a new entry with `level` set.
WithLevel(Level) *Entry
}
// LevelLogger is the logger at a given level.
type LevelLogger interface {
// Log logs a message at the given level using the string from calling s.String().
// Note that s.String() will not be called if the level is not enabled.
Log(s fmt.Stringer)
// Logf logs a message at the given level using the format and args from calling fmt.Sprintf().
// Note that fmt.Sprintf() will not be called if the level is not enabled.
Logf(format string, a ...any)
// WithLevel returns a new entry with `level` set.
WithLevel(Level) *Entry
// WithFields returns a new entry with the`fields` in fields set.
// This is a noop if LevelLogger's level is less than Logger's.
WithFields(fields Fielder) *Entry
// WithLevel returns a new entry with the field f set with value v
// This is a noop if LevelLogger's level is less than Logger's.
WithField(f string, v any) *Entry
// WithDuration returns a new entry with the "duration" field set
// to the given duration in milliseconds.
// This is a noop if LevelLogger's level is less than Logger's.
WithDuration(time.Duration) *Entry
// WithError returns a new entry with the "error" set to `err`.
// This is a noop if err is nil or LevelLogger's level is less than Logger's.
WithError(error) *Entry
}
```
## Benchmarks
Benchmarks below are borrowed and adapted from [Zap](https://github.com/uber-go/zap/tree/master/benchmarks).
### Logging at a disabled level without any structured context
```
name time/op
DisabledWithoutFields/apex/log-10 33.9ns ± 0%
DisabledWithoutFields/bep/logg-10 0.28ns ± 0%
DisabledWithoutFields/sirupsen/logrus-10 6.54ns ± 0%
DisabledWithoutFields/rs/zerolog-10 0.31ns ± 0%
name alloc/op
DisabledWithoutFields/apex/log-10 112B ± 0%
DisabledWithoutFields/bep/logg-10 0.00B
DisabledWithoutFields/sirupsen/logrus-10 16.0B ± 0%
DisabledWithoutFields/rs/zerolog-10 0.00B
name allocs/op
DisabledWithoutFields/apex/log-10 1.00 ± 0%
DisabledWithoutFields/bep/logg-10 0.00
DisabledWithoutFields/sirupsen/logrus-10 1.00 ± 0%
DisabledWithoutFields/rs/zerolog-10 0.00
```
### Logging at a disabled level with some accumulated context
```
name time/op
DisabledAccumulatedContext/apex/log-10 0.29ns ± 0%
DisabledAccumulatedContext/bep/logg-10 0.27ns ± 0%
DisabledAccumulatedContext/sirupsen/logrus-10 6.61ns ± 0%
DisabledAccumulatedContext/rs/zerolog-10 0.32ns ± 0%
name alloc/op
DisabledAccumulatedContext/apex/log-10 0.00B
DisabledAccumulatedContext/bep/logg-10 0.00B
DisabledAccumulatedContext/sirupsen/logrus-10 16.0B ± 0%
DisabledAccumulatedContext/rs/zerolog-10 0.00B
name allocs/op
DisabledAccumulatedContext/apex/log-10 0.00
DisabledAccumulatedContext/bep/logg-10 0.00
DisabledAccumulatedContext/sirupsen/logrus-10 1.00 ± 0%
DisabledAccumulatedContext/rs/zerolog-10 0.00
```
### Logging at a disabled level, adding context at each log site
```
name time/op
DisabledAddingFields/apex/log-10 328ns ± 0%
DisabledAddingFields/bep/logg-10 0.38ns ± 0%
DisabledAddingFields/sirupsen/logrus-10 610ns ± 0%
DisabledAddingFields/rs/zerolog-10 10.5ns ± 0%
name alloc/op
DisabledAddingFields/apex/log-10 886B ± 0%
DisabledAddingFields/bep/logg-10 0.00B
DisabledAddingFields/sirupsen/logrus-10 1.52kB ± 0%
DisabledAddingFields/rs/zerolog-10 24.0B ± 0%
name allocs/op
DisabledAddingFields/apex/log-10 10.0 ± 0%
DisabledAddingFields/bep/logg-10 0.00
DisabledAddingFields/sirupsen/logrus-10 12.0 ± 0%
DisabledAddingFields/rs/zerolog-10 1.00 ± 0%
```
### Logging without any structured context
```
name time/op
WithoutFields/apex/log-10 964ns ± 0%
WithoutFields/bep/logg-10 100ns ± 0%
WithoutFields/go-kit/kit/log-10 232ns ± 0%
WithoutFields/inconshreveable/log15-10 2.13µs ± 0%
WithoutFields/sirupsen/logrus-10 866ns ± 0%
WithoutFields/stdlib.Println-10 7.08ns ± 0%
WithoutFields/stdlib.Printf-10 56.4ns ± 0%
WithoutFields/rs/zerolog-10 30.9ns ± 0%
WithoutFields/rs/zerolog.Formatting-10 1.33µs ± 0%
WithoutFields/rs/zerolog.Check-10 32.1ns ± 0%
name alloc/op
WithoutFields/apex/log-10 352B ± 0%
WithoutFields/bep/logg-10 56.0B ± 0%
WithoutFields/go-kit/kit/log-10 520B ± 0%
WithoutFields/inconshreveable/log15-10 1.43kB ± 0%
WithoutFields/sirupsen/logrus-10 1.14kB ± 0%
WithoutFields/stdlib.Println-10 16.0B ± 0%
WithoutFields/stdlib.Printf-10 136B ± 0%
WithoutFields/rs/zerolog-10 0.00B
WithoutFields/rs/zerolog.Formatting-10 1.92kB ± 0%
WithoutFields/rs/zerolog.Check-10 0.00B
name allocs/op
WithoutFields/apex/log-10 6.00 ± 0%
WithoutFields/bep/logg-10 2.00 ± 0%
WithoutFields/go-kit/kit/log-10 9.00 ± 0%
WithoutFields/inconshreveable/log15-10 20.0 ± 0%
WithoutFields/sirupsen/logrus-10 23.0 ± 0%
WithoutFields/stdlib.Println-10 1.00 ± 0%
WithoutFields/stdlib.Printf-10 6.00 ± 0%
WithoutFields/rs/zerolog-10 0.00
WithoutFields/rs/zerolog.Formatting-10 58.0 ± 0%
WithoutFields/rs/zerolog.Check-10 0.00
```
### Logging with some accumulated context
```
name time/op
AccumulatedContext/apex/log-10 12.7µs ± 0%
AccumulatedContext/bep/logg-10 1.52µs ± 0%
AccumulatedContext/go-kit/kit/log-10 2.52µs ± 0%
AccumulatedContext/inconshreveable/log15-10 9.36µs ± 0%
AccumulatedContext/sirupsen/logrus-10 3.41µs ± 0%
AccumulatedContext/rs/zerolog-10 37.9ns ± 0%
AccumulatedContext/rs/zerolog.Check-10 34.0ns ± 0%
AccumulatedContext/rs/zerolog.Formatting-10 1.36µs ± 0%
name alloc/op
AccumulatedContext/apex/log-10 3.30kB ± 0%
AccumulatedContext/bep/logg-10 1.16kB ± 0%
AccumulatedContext/go-kit/kit/log-10 3.67kB ± 0%
AccumulatedContext/inconshreveable/log15-10 3.31kB ± 0%
AccumulatedContext/sirupsen/logrus-10 4.73kB ± 0%
AccumulatedContext/rs/zerolog-10 0.00B
AccumulatedContext/rs/zerolog.Check-10 0.00B
AccumulatedContext/rs/zerolog.Formatting-10 1.92kB ± 0%
name allocs/op
AccumulatedContext/apex/log-10 53.0 ± 0%
AccumulatedContext/bep/logg-10 25.0 ± 0%
AccumulatedContext/go-kit/kit/log-10 56.0 ± 0%
AccumulatedContext/inconshreveable/log15-10 70.0 ± 0%
AccumulatedContext/sirupsen/logrus-10 68.0 ± 0%
AccumulatedContext/rs/zerolog-10 0.00
AccumulatedContext/rs/zerolog.Check-10 0.00
AccumulatedContext/rs/zerolog.Formatting-10 58.0 ± 0%
```
## Logging with additional context at each log site
```
name time/op
AddingFields/apex/log-10 13.2µs ± 0%
AddingFields/bep/logg-10 1.79µs ± 0%
AddingFields/go-kit/kit/log-10 2.23µs ± 0%
AddingFields/inconshreveable/log15-10 14.3µs ± 0%
AddingFields/sirupsen/logrus-10 4.46µs ± 0%
AddingFields/rs/zerolog-10 398ns ± 0%
AddingFields/rs/zerolog.Check-10 389ns ± 0%
name alloc/op
AddingFields/apex/log-10 4.19kB ± 0%
AddingFields/bep/logg-10 2.02kB ± 0%
AddingFields/go-kit/kit/log-10 3.31kB ± 0%
AddingFields/inconshreveable/log15-10 6.68kB ± 0%
AddingFields/sirupsen/logrus-10 6.27kB ± 0%
AddingFields/rs/zerolog-10 24.0B ± 0%
AddingFields/rs/zerolog.Check-10 24.0B ± 0%
name allocs/op
AddingFields/apex/log-10 63.0 ± 0%
AddingFields/bep/logg-10 34.0 ± 0%
AddingFields/go-kit/kit/log-10 57.0 ± 0%
AddingFields/inconshreveable/log15-10 74.0 ± 0%
AddingFields/sirupsen/logrus-10 79.0 ± 0%
AddingFields/rs/zerolog-10 1.00 ± 0%
AddingFields/rs/zerolog.Check-10 1.00 ± 0%
```
|
