qLog

Blazing fast, structured, leveled logging in Go. Like zap or zerolog but more flexible

Installation

go get -u github.com/karantin2020/qlog

Library was tested with go versions => 1.9.

Quick Start

Examples are available in the folder ./examples.

To use default logger.

import (
	"github.com/karantin2020/qlog"
	"github.com/karantin2020/qlog/log"
)

func example_default() {
	log.Debug("failed to fetch URL")
	log.Info("failed to fetch URL")
	log.Error("failed to fetch URL")
	log.INFO.Fields(
		qlog.F{"service", "new"},
		qlog.F{"source", "after"},
	).Msgf("failed to fetch %s", "URL")
	log.Warn("failed to fetch URL")
	log.Critical("failed to fetch URL")
	log.Panic("failed to fetch URL")
}

Output is:

2017-11-19T01:12:20.569+0500    INFO    failed to fetch URL     {}
2017-11-19T01:12:20.569+0500    ERROR   failed to fetch URL     {"error":"failed to fetch URL"}
2017-11-19T01:12:20.569+0500    INFO    failed to fetch URL     {"service":"new","source":"after"}
2017-11-19T01:12:20.569+0500    WARN    failed to fetch URL     {}
2017-11-19T01:12:20.569+0500    CRITICAL        failed to fetch URL     {"error":"failed to fetch URL"}
2017-11-19T01:12:20.569+0500    PANIC   failed to fetch URL     {"error":"failed to fetch URL"}
panic: failed to fetch URL

goroutine 1 [running]:
github.com/karantin2020/qlog.(*Entry).errMsg(0xc467284400, 0x4fe87d, 0x13, 0xc467280001)
        $GOPATH/github.com/karantin2020/qlog/entry.go:125 +0x1ab
github.com/karantin2020/qlog.(*Entry).Panic(0xc467284400, 0x4fe87d, 0x13)
        $GOPATH/github.com/karantin2020/qlog/entry.go:156 +0x65
github.com/karantin2020/qlog.(*Notepad).Panic(0xc467280000, 0x4fe87d, 0x13)
        $GOPATH/github.com/karantin2020/qlog/qlog.go:298 +0x56
github.com/karantin2020/qlog/log.Panic(0x4fe87d, 0x13)
        $GOPATH/github.com/karantin2020/qlog/log/log.go:97 +0x41
main.example_default()
        $GOPATH/github.com/karantin2020/qlog/examples/default.go:22 +0x1c8
main.main()
        $GOPATH/github.com/karantin2020/qlog/examples/main.go:4 +0x20

If you need to change some configs then use customized version of logger.

import (
	"github.com/karantin2020/qlog"
)

func example_new() {
	nlog := qlog.New(InfoLevel).
		SetOutput(qlog.Template("${time}\t${LEVEL}\t${message}\t${fields}\n"))
	nlog.INFO.Msgf("failed to fetch %s", "URL")
	nlog.INFO.Msg("failed to fetch 'URL'")

	newlog := nlog.WithFields(
		qlog.F{"service", "new"},
		qlog.F{"source", "after"},
	)
	newlog.INFO.Msgf("failed to fetch %s", "URL")
	newlog.INFO.Msg("failed to fetch 'URL'")
}

Output is:

2017-11-19T01:15:42.822+0500    info    failed to fetch URL     {}
2017-11-19T01:15:42.822+0500    info    failed to fetch 'URL'   {}
2017-11-19T01:15:42.822+0500    info    failed to fetch URL     {"service":"new","source":"after"}
2017-11-19T01:15:42.822+0500    info    failed to fetch 'URL'   {"service":"new","source":"after"}

qlog.Template takes template string as the first argument. Substrings in ${...} are interpreted as field names or reserved words (fields, message...). If fields name (${...}) is in capital case then output will be formatted in capital case too (see level name in examples).

Instead of using qlog.Template("${time}\t${LEVEL}\t${message}\t${fields}\n") you can use variables qlog.DefaultTemplate and qlog.ColorTemplate.

See documentation in code.

Performance

For now only text output is implemented. It's performance is equal to uber/zap and zerolog.

Benchmark results:

go1.9

$ go test -benchmem  -bench=. -benchtime 5s
goos: linux
goarch: amd64
pkg: github.com/karantin2020/qlog
BenchmarkLogNoOutput-3      	30000000	       208 ns/op	       0 B/op	       0 allocs/op
BenchmarkLogEmpty-3         	20000000	       509 ns/op	      68 B/op	       2 allocs/op
BenchmarkLogDisabled-3      	3000000000	         1.64 ns/op	       0 B/op	       0 allocs/op
BenchmarkInfo-3             	20000000	       649 ns/op	      68 B/op	       2 allocs/op
BenchmarkError-3            	10000000	       765 ns/op	      85 B/op	       3 allocs/op
BenchmarkInfoLower-3        	20000000	       479 ns/op	      64 B/op	       1 allocs/op
BenchmarkDiscard-3          	30000000	       224 ns/op	       0 B/op	       0 allocs/op
BenchmarkOneField-3         	10000000	       575 ns/op	      68 B/op	       2 allocs/op
BenchmarkTwoFields-3        	10000000	       688 ns/op	      68 B/op	       2 allocs/op
BenchmarkOneFieldLower-3    	20000000	       551 ns/op	      64 B/op	       1 allocs/op
BenchmarkTwoFieldsLower-3   	10000000	       626 ns/op	      64 B/op	       1 allocs/op
BenchmarkWithFields-3       	20000000	       534 ns/op	      68 B/op	       2 allocs/op
PASS
ok github.com/karantin2020/qlog 105.338s

go1.10

$ go test -benchmem  -bench=. -benchtime 5s
goos: linux
goarch: amd64
pkg: github.com/karantin2020/qlog
BenchmarkLogNoOutput-3      	30000000	       220 ns/op	       0 B/op	       0 allocs/op
BenchmarkLogEmpty-3         	20000000	       531 ns/op	      68 B/op	       2 allocs/op
BenchmarkLogDisabled-3      	10000000000	         1.74 ns/op	       0 B/op	       0 allocs/op
BenchmarkInfo-3             	20000000	       602 ns/op	      68 B/op	       2 allocs/op
BenchmarkError-3            	10000000	       721 ns/op	      85 B/op	       3 allocs/op
BenchmarkInfoLower-3        	20000000	       480 ns/op	      64 B/op	       1 allocs/op
BenchmarkDiscard-3          	30000000	       236 ns/op	       0 B/op	       0 allocs/op
BenchmarkOneField-3         	10000000	       677 ns/op	      68 B/op	       2 allocs/op
BenchmarkTwoFields-3        	10000000	       804 ns/op	      68 B/op	       2 allocs/op
BenchmarkOneFieldLower-3    	10000000	       684 ns/op	      64 B/op	       1 allocs/op
BenchmarkTwoFieldsLower-3   	10000000	       669 ns/op	      64 B/op	       1 allocs/op
BenchmarkWithFields-3       	20000000	       618 ns/op	      68 B/op	       2 allocs/op
PASS
ok github.com/karantin2020/qlog 123.175s

Development Status: Stable

All APIs of qlog and log packages are stable before version 2.

Contributing

Contributing is welcome.

---

Released under the MIT License.