log

Simple, customizable, leveled and efficient logging in Go

Installation

go get -u github.com/ermanimer/log

Features

log is a simple logging package for Go.

• You can set output
• You can set internal error output (slog writes Log method's errors to internal error output instead of returning them.)
• You can set time format and prefixes
• You can set logging level to filter out log messages
• You can set a hook function to be called after each log

log isn't the fastest logging solution, but log is efficient while being customizable. Please see benchmark tests.

Usage

package main

import (
	"os"

	"github.com/ermanimer/log/v2"
)

func main() {
	// create a new logger instance with output and default parameters
	l := log.NewLogger()

	// log a message
	l.Debug("this is a debug message")

	// log a formatted message
	l.Debugf("this is a %s debug message", "formatted")
}

Output:

2021-06-07T16:46:26+03:00 debug this is a debug message
2021-06-07T16:46:26+03:00 debug this is a formatted debug message

Logging Levels

• Debug
• Info
• Warning
• Error
• Fatal

Default Parameters:

Parameter	Value
Output	os.Stdout
Internal Error Output	os.Stderr
Time Format	RFC3339
Debug Prefix	debug
Info Prefix	info
Warning Prefix	warning
Error Prefix	error
Fatal Prefix	fatal
Logging Level	Debug

Set Output

l.SetOutput(os.Stderr)

Set Internal Error Output

l.SetOutput(io.Discard)

Set Logging Level

l.SetLoggingLevel(InfoLevel)

Set Time Format

l.SetTimeFormat(time.RFC3339Nano)

Set Prefixes

l.SetDebugPrefix("DEB")
l.SetInfoPrefix("INF")
l.SetWarningPrefix("WAR")
l.SetErrorPrefix("ERR")
l.SetFatalPrefix("FAT")

Set Hook Function:

l.SetHookFunction(func(prefix, message string) {
  //you can filter messages with prefix and capture for Sentry.io
})

Benchmark Tests

Test Codes:

func BenchmarkDebug(b *testing.B) {
	// create logger
	l := NewLogger(ioutil.Discard)

	// start benchmark test
	b.RunParallel(func(pb *testing.PB) {
		for pb.Next() {
			l.Debug("test")
		}
	})
}

func BenchmarkDebugf(b *testing.B) {
	// create logger
	l := NewLogger(ioutil.Discard)

	// start benchmark test
	b.RunParallel(func(pb *testing.PB) {
		for pb.Next() {
			l.Debugf("%s", "test")
		}
	})
}

Results:

Function	Time	Bytes Allocated	Objects Allocated
Debug	410.7 ns/op	4 B/op	1 allocs/op
Debugf	408.7 ns/op	4 B/op	1 allocs/op
Info	404.0 ns/op	4 B/op	1 allocs/op
Infof	403.9 ns/op	4 B/op	1 allocs/op
Warning	407.0 ns/op	4 B/op	1 allocs/op
Warningf	409.4 ns/op	4 B/op	1 allocs/op
Error	404.6 ns/op	4 B/op	1 allocs/op
Errorf	406.2 ns/op	4 B/op	1 allocs/op
Fatal	402.1 ns/op	4 B/op	1 allocs/op
Fatalf	406.0 ns/op	4 B/op	1 allocs/op