blob: 3163653159f78b5b641b82f4867eaed5d30864e7 [file] [log] [blame]
package log15
import (
const timeKey = "t"
const lvlKey = "lvl"
const msgKey = "msg"
const errorKey = "LOG15_ERROR"
type Lvl int
const (
LvlCrit Lvl = iota
// Returns the name of a Lvl
func (l Lvl) String() string {
switch l {
case LvlDebug:
return "dbug"
case LvlInfo:
return "info"
case LvlWarn:
return "warn"
case LvlError:
return "eror"
case LvlCrit:
return "crit"
panic("bad level")
// Returns the appropriate Lvl from a string name.
// Useful for parsing command line args and configuration files.
func LvlFromString(lvlString string) (Lvl, error) {
switch lvlString {
case "debug", "dbug":
return LvlDebug, nil
case "info":
return LvlInfo, nil
case "warn":
return LvlWarn, nil
case "error", "eror":
return LvlError, nil
case "crit":
return LvlCrit, nil
return LvlDebug, fmt.Errorf("Unknown level: %v", lvlString)
// A Record is what a Logger asks its handler to write
type Record struct {
Time time.Time
Lvl Lvl
Msg string
Ctx []interface{}
Call stack.Call
KeyNames RecordKeyNames
type RecordKeyNames struct {
Time string
Msg string
Lvl string
// A Logger writes key/value pairs to a Handler
type Logger interface {
// New returns a new Logger that has this logger's context plus the given context
New(ctx ...interface{}) Logger
// GetHandler gets the handler associated with the logger.
GetHandler() Handler
// SetHandler updates the logger to write records to the specified handler.
SetHandler(h Handler)
// Log a message at the given level with context key/value pairs
Debug(msg string, ctx ...interface{})
Info(msg string, ctx ...interface{})
Warn(msg string, ctx ...interface{})
Error(msg string, ctx ...interface{})
Crit(msg string, ctx ...interface{})
type logger struct {
ctx []interface{}
h *swapHandler
func (l *logger) write(msg string, lvl Lvl, ctx []interface{}) {
Time: time.Now(),
Lvl: lvl,
Msg: msg,
Ctx: newContext(l.ctx, ctx),
Call: stack.Caller(2),
KeyNames: RecordKeyNames{
Time: timeKey,
Msg: msgKey,
Lvl: lvlKey,
func (l *logger) New(ctx ...interface{}) Logger {
child := &logger{newContext(l.ctx, ctx), new(swapHandler)}
return child
func newContext(prefix []interface{}, suffix []interface{}) []interface{} {
normalizedSuffix := normalize(suffix)
newCtx := make([]interface{}, len(prefix)+len(normalizedSuffix))
n := copy(newCtx, prefix)
copy(newCtx[n:], normalizedSuffix)
return newCtx
func (l *logger) Debug(msg string, ctx ...interface{}) {
l.write(msg, LvlDebug, ctx)
func (l *logger) Info(msg string, ctx ...interface{}) {
l.write(msg, LvlInfo, ctx)
func (l *logger) Warn(msg string, ctx ...interface{}) {
l.write(msg, LvlWarn, ctx)
func (l *logger) Error(msg string, ctx ...interface{}) {
l.write(msg, LvlError, ctx)
func (l *logger) Crit(msg string, ctx ...interface{}) {
l.write(msg, LvlCrit, ctx)
func (l *logger) GetHandler() Handler {
return l.h.Get()
func (l *logger) SetHandler(h Handler) {
func normalize(ctx []interface{}) []interface{} {
// if the caller passed a Ctx object, then expand it
if len(ctx) == 1 {
if ctxMap, ok := ctx[0].(Ctx); ok {
ctx = ctxMap.toArray()
// ctx needs to be even because it's a series of key/value pairs
// no one wants to check for errors on logging functions,
// so instead of erroring on bad input, we'll just make sure
// that things are the right length and users can fix bugs
// when they see the output looks wrong
if len(ctx)%2 != 0 {
ctx = append(ctx, nil, errorKey, "Normalized odd number of arguments by adding nil")
return ctx
// Lazy allows you to defer calculation of a logged value that is expensive
// to compute until it is certain that it must be evaluated with the given filters.
// Lazy may also be used in conjunction with a Logger's New() function
// to generate a child logger which always reports the current value of changing
// state.
// You may wrap any function which takes no arguments to Lazy. It may return any
// number of values of any type.
type Lazy struct {
Fn interface{}
// Ctx is a map of key/value pairs to pass as context to a log function
// Use this only if you really need greater safety around the arguments you pass
// to the logging functions.
type Ctx map[string]interface{}
func (c Ctx) toArray() []interface{} {
arr := make([]interface{}, len(c)*2)
i := 0
for k, v := range c {
arr[i] = k
arr[i+1] = v
i += 2
return arr