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Fix lint errors ddf3ed8 Nov 24, 2015
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// Copyright 2013, Örjan Persson. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package logging
import (
// ErrInvalidLogLevel is used when an invalid log level has been used.
var ErrInvalidLogLevel = errors.New("logger: invalid log level")
// Level defines all available log levels for log messages.
type Level int
// Log levels.
const (
CRITICAL Level = iota
var levelNames = []string{
// String returns the string representation of a logging level.
func (p Level) String() string {
return levelNames[p]
// LogLevel returns the log level from a string representation.
func LogLevel(level string) (Level, error) {
for i, name := range levelNames {
if strings.EqualFold(name, level) {
return Level(i), nil
return ERROR, ErrInvalidLogLevel
// Leveled interface is the interface required to be able to add leveled
// logging.
type Leveled interface {
GetLevel(string) Level
SetLevel(Level, string)
IsEnabledFor(Level, string) bool
// LeveledBackend is a log backend with additional knobs for setting levels on
// individual modules to different levels.
type LeveledBackend interface {
type moduleLeveled struct {
levels map[string]Level
backend Backend
formatter Formatter
once sync.Once
// AddModuleLevel wraps a log backend with knobs to have different log levels
// for different modules.
func AddModuleLevel(backend Backend) LeveledBackend {
var leveled LeveledBackend
var ok bool
if leveled, ok = backend.(LeveledBackend); !ok {
leveled = &moduleLeveled{
levels: make(map[string]Level),
backend: backend,
return leveled
// GetLevel returns the log level for the given module.
func (l *moduleLeveled) GetLevel(module string) Level {
level, exists := l.levels[module]
if exists == false {
level, exists = l.levels[""]
// no configuration exists, default to debug
if exists == false {
level = DEBUG
return level
// SetLevel sets the log level for the given module.
func (l *moduleLeveled) SetLevel(level Level, module string) {
l.levels[module] = level
// IsEnabledFor will return true if logging is enabled for the given module.
func (l *moduleLeveled) IsEnabledFor(level Level, module string) bool {
return level <= l.GetLevel(module)
func (l *moduleLeveled) Log(level Level, calldepth int, rec *Record) (err error) {
if l.IsEnabledFor(level, rec.Module) {
// TODO get rid of traces of formatter here. BackendFormatter should be used.
rec.formatter = l.getFormatterAndCacheCurrent()
err = l.backend.Log(level, calldepth+1, rec)
func (l *moduleLeveled) getFormatterAndCacheCurrent() Formatter {
l.once.Do(func() {
if l.formatter == nil {
l.formatter = getFormatter()
return l.formatter
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