git-server/vendor/gopkg.in/clog.v1

Clog

Clog is a channel-based logging package for Go.

This package supports multiple logger adapters across different levels of logging. It uses Go's native channel feature to provide goroutine-safe mechanism on large concurrency.

Installation

To use a tagged revision:

go get gopkg.in/clog.v1

To use with latest changes:

go get github.com/go-clog/clog

Please apply -u flag to update in the future.

Testing

If you want to test on your machine, please apply -t flag:

go get -t gopkg.in/clog.v1

Please apply -u flag to update in the future.

Getting Started

Clog currently has two builtin logger adapters: console, file and slack.

It is extremely easy to create one with all default settings. Generally, you would want to create new logger inside init or main function.

...

import (
	"fmt"
	"os"

	log "gopkg.in/clog.v1"
)

func init() {
	err := log.New(log.CONSOLE, log.ConsoleConfig{})
	if err != nil {
		fmt.Printf("Fail to create new logger: %v\n", err)
		os.Exit(1)
	}

	log.Trace("Hello %s!", "Clog")
	// Output: Hello Clog!

	log.Info("Hello %s!", "Clog")
	log.Warn("Hello %s!", "Clog")
	...
}

...

The above code is equivalent to the follow settings:

...
	err := log.New(log.CONSOLE, log.ConsoleConfig{
		Level:      log.TRACE, // Record all logs
		BufferSize: 0,         // 0 means logging synchronously
	})
...

In production, you may want to make log less verbose and asynchronous:

...
	err := log.New(log.CONSOLE, log.ConsoleConfig{
		// Logs under INFO level (in this case TRACE) will be discarded
		Level:      log.INFO, 
		// Number mainly depends on how many logs will be produced by program, 100 is good enough
		BufferSize: 100,      
	})
...

Console logger comes with color output, but for non-colorable destination, the color output will be disabled automatically.

Error Location

When using log.Error and log.Fatal functions, the first argument allows you to indicate whether to print the code location or not.

...
	// 0 means disable printing code location
	log.Error(0, "So bad... %v", err)

	// To print appropriate code location mainly depends on how deep your call stack is, 
	// you need to try and verify
	log.Error(2, "So bad... %v", err)
	// Output: 2017/02/09 01:06:16 [ERROR] [...uban-builder/main.go:64 main()] ...
	log.Fatal(2, "Boom! %v", err)
	// Output: 2017/02/09 01:06:16 [FATAL] [...uban-builder/main.go:64 main()] ...
...

Calling log.Fatal will exit the program.

File

File logger is more complex than console, and it has ability to rotate:

...
	err := log.New(log.FILE, log.FileConfig{
		Level:              log.INFO, 
		BufferSize:         100,  
		Filename:           "clog.log",  
		FileRotationConfig: log.FileRotationConfig {
			Rotate: true,
			Daily:  true,
		},
	})
...

Slack

Slack logger is also supported in a simple way:

...
	err := log.New(log.SLACK, log.SlackConfig{
		Level:              log.INFO, 
		BufferSize:         100,  
		URL:                "https://url-to-slack-webhook",  
	})
...

Credits

• Avatar is a modified version based on egonelbre/gophers' scientist.

License

This project is under Apache v2 License. See the LICENSE file for the full license text.