335 lines
9.0 KiB
Go
335 lines
9.0 KiB
Go
// Package mlog is a generic logging library. The log methods come in different
|
|
// severities: Debug, Info, Warn, Error, and Fatal.
|
|
//
|
|
// The log methods take in a string describing the error, and a set of key/value
|
|
// pairs giving the specific context around the error. The string is intended to
|
|
// always be the same no matter what, while the key/value pairs give information
|
|
// like which userID the error happened to, or any other relevant contextual
|
|
// information.
|
|
//
|
|
// Examples:
|
|
//
|
|
// Info("Something important has occurred")
|
|
// Error("Could not open file", llog.KV{"filename": filename}, llog.ErrKV(err))
|
|
//
|
|
package mlog
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
"os"
|
|
"sort"
|
|
"strconv"
|
|
"strings"
|
|
"sync"
|
|
)
|
|
|
|
// Truncate is a helper function to truncate a string to a given size. It will
|
|
// add 3 trailing elipses, so the returned string will be at most size+3
|
|
// characters long
|
|
func Truncate(s string, size int) string {
|
|
if len(s) <= size {
|
|
return s
|
|
}
|
|
return s[:size] + "..."
|
|
}
|
|
|
|
// Level describes the severity of a particular log message, and can be compared
|
|
// to the severity of any other Level
|
|
type Level interface {
|
|
// String gives the string form of the level, e.g. "INFO" or "ERROR"
|
|
String() string
|
|
|
|
// Uint gives an integer indicator of the severity of the level, with zero
|
|
// being most severe. If a Level with Uint of zero is logged then the Logger
|
|
// implementation provided by this package will exit the process (i.e. zero
|
|
// is used as Fatal).
|
|
Uint() uint
|
|
}
|
|
|
|
type level struct {
|
|
s string
|
|
i uint
|
|
}
|
|
|
|
func (l level) String() string {
|
|
return l.s
|
|
}
|
|
|
|
func (l level) Uint() uint {
|
|
return l.i
|
|
}
|
|
|
|
// All pre-defined log levels
|
|
var (
|
|
DebugLevel Level = level{s: "DEBUG", i: 40}
|
|
InfoLevel Level = level{s: "INFO", i: 30}
|
|
WarnLevel Level = level{s: "WARN", i: 20}
|
|
ErrorLevel Level = level{s: "ERROR", i: 10}
|
|
FatalLevel Level = level{s: "FATAL", i: 0}
|
|
)
|
|
|
|
// LevelFromString parses a string, possibly lowercase, and returns the Level
|
|
// identified by it, or an error.
|
|
//
|
|
// Note that this only works for the Levels pre-defined in this package, if
|
|
// you've extended the package to use your own levels you'll have to implement
|
|
// your own LevelFromString method.
|
|
func LevelFromString(ls string) (Level, error) {
|
|
var l Level
|
|
switch strings.ToUpper(ls) {
|
|
case "DEBUG":
|
|
l = DebugLevel
|
|
case "INFO":
|
|
l = InfoLevel
|
|
case "WARN":
|
|
l = WarnLevel
|
|
case "ERROR":
|
|
l = ErrorLevel
|
|
case "FATAL":
|
|
l = FatalLevel
|
|
default:
|
|
return nil, fmt.Errorf("unknown log level %q", ls)
|
|
}
|
|
|
|
return l, nil
|
|
}
|
|
|
|
// KVer is used to provide context to a log entry in the form of a dynamic set
|
|
// of key/value pairs which can be different for every entry.
|
|
//
|
|
// Each returned map should be modifiable.
|
|
type KVer interface {
|
|
KV() map[string]interface{}
|
|
}
|
|
|
|
// KV is a simple and convenient implementation of KVer
|
|
type KV map[string]interface{}
|
|
|
|
// KV implements the KVer method by returning a copy of the casted KV
|
|
func (kv KV) KV() map[string]interface{} {
|
|
nkv := make(map[string]interface{}, len(kv))
|
|
for k, v := range kv {
|
|
nkv[k] = v
|
|
}
|
|
return nkv
|
|
}
|
|
|
|
// Set returns a copy of the KV being called on with the given key/val set on
|
|
// it. The original KV is unaffected
|
|
func (kv KV) Set(k string, v interface{}) KV {
|
|
nkv := kv.KV()
|
|
nkv[k] = v
|
|
return nkv
|
|
}
|
|
|
|
// separate from Merge because it's convenient to not return a KVer if that KVer
|
|
// is going to immediately have KV called on it (and thereby create a copy for
|
|
// no reason).
|
|
func merge(kvs ...KVer) KV {
|
|
kvm := kvs[0].KV()
|
|
for _, kv := range kvs[1:] {
|
|
for k, v := range kv.KV() {
|
|
kvm[k] = v
|
|
}
|
|
}
|
|
return KV(kvm)
|
|
}
|
|
|
|
// Merge takes in multiple KVers and returns a single KVer which is the union of
|
|
// all the passed in ones. Key/vals on the rightmost of the set take precedence
|
|
// over conflicting ones to the left.
|
|
func Merge(kvs ...KVer) KVer {
|
|
return merge(kvs...)
|
|
}
|
|
|
|
// Message describes a message to be logged, after having already resolved the
|
|
// KVer
|
|
type Message struct {
|
|
Level
|
|
Msg string
|
|
KV KV
|
|
}
|
|
|
|
// WriteFn describes a function which formats a single log message and writes it
|
|
// to the given io.Writer. If the io.Writer returns an error this should return
|
|
// that error.
|
|
type WriteFn func(w io.Writer, msg Message) error
|
|
|
|
func stringSlice(kv KV) [][2]string {
|
|
slice := make([][2]string, 0, len(kv))
|
|
for k, v := range kv {
|
|
slice = append(slice, [2]string{
|
|
k,
|
|
strconv.QuoteToGraphic(fmt.Sprint(v)),
|
|
})
|
|
}
|
|
sort.Slice(slice, func(i, j int) bool {
|
|
return slice[i][0] < slice[j][0]
|
|
})
|
|
return slice
|
|
}
|
|
|
|
// DefaultWriteFn is the default implementation of WriteFn.
|
|
func DefaultWriteFn(w io.Writer, msg Message) error {
|
|
var err error
|
|
write := func(s string, args ...interface{}) {
|
|
if err == nil {
|
|
_, err = fmt.Fprintf(w, s, args...)
|
|
}
|
|
}
|
|
write("~ %s -- %s", msg.Level.String(), msg.Msg)
|
|
if len(msg.KV) > 0 {
|
|
write(" --")
|
|
for _, kve := range stringSlice(msg.KV) {
|
|
write(" %s=%s", kve[0], kve[1])
|
|
}
|
|
}
|
|
write("\n")
|
|
return err
|
|
}
|
|
|
|
// Logger wraps a WriteFn and an io.WriteCloser such that logging calls on the
|
|
// Logger will use them (in a thread-safe manner) to write out log messages.
|
|
//
|
|
// Logger will auto-initialize itself on the first method call.
|
|
type Logger struct {
|
|
WriteFn // Defaults to DefaultWriteFn
|
|
io.WriteCloser // Defaults to os.Stderr
|
|
|
|
levelL sync.RWMutex
|
|
maxLevel uint
|
|
maxLevelSet bool
|
|
|
|
init sync.Once
|
|
msgCh chan Message
|
|
testMsgWrittenCh chan struct{} // only initialized/used in tests
|
|
}
|
|
|
|
func (l *Logger) getMaxLevel() uint {
|
|
l.levelL.RLock()
|
|
defer l.levelL.RUnlock()
|
|
if !l.maxLevelSet {
|
|
return InfoLevel.Uint()
|
|
}
|
|
return l.maxLevel
|
|
}
|
|
|
|
// SetMaxLevelUint sets the maximum (up-to-and-including) level priority which
|
|
// the Logger will output a log for. Any Levels with an Uint value higher than
|
|
// this will not be logged. This may be called at any time.
|
|
func (l *Logger) SetMaxLevelUint(i uint) {
|
|
l.levelL.Lock()
|
|
l.maxLevel = i
|
|
l.maxLevelSet = true
|
|
l.levelL.Unlock()
|
|
}
|
|
|
|
// SetMaxLevel sets the maximum (up-to-and-including) Level which the Logger
|
|
// will output a log for. Any Levels whose Uint value is higher than this one's
|
|
// will not be logged. This may be called at any time.
|
|
func (l *Logger) SetMaxLevel(lvl Level) {
|
|
l.SetMaxLevelUint(lvl.Uint())
|
|
}
|
|
|
|
func (l *Logger) spin() {
|
|
for msg := range l.msgCh {
|
|
if err := l.WriteFn(l.WriteCloser, msg); err != nil {
|
|
go l.Error("could not write to Logger.WriteCloser", ErrKV(err))
|
|
}
|
|
if l.testMsgWrittenCh != nil {
|
|
l.testMsgWrittenCh <- struct{}{}
|
|
}
|
|
if msg.Level.Uint() == 0 {
|
|
l.WriteCloser.Close()
|
|
os.Exit(1)
|
|
}
|
|
}
|
|
l.WriteCloser.Close()
|
|
}
|
|
|
|
func (l *Logger) initDo() {
|
|
l.init.Do(func() {
|
|
if l.WriteFn == nil {
|
|
l.WriteFn = DefaultWriteFn
|
|
}
|
|
if l.WriteCloser == nil {
|
|
l.WriteCloser = os.Stderr
|
|
}
|
|
// maxLevel's default is implicitly handled by getMaxLevel
|
|
l.msgCh = make(chan Message, 1000)
|
|
go l.spin()
|
|
})
|
|
}
|
|
|
|
// Stop stops and cleans up any running go-routines and resources held by the
|
|
// Logger, allowing it to be garbage-collected. The Logger should not be used
|
|
// after Stop is called
|
|
func (l *Logger) Stop() {
|
|
l.initDo()
|
|
close(l.msgCh)
|
|
}
|
|
|
|
// Log can be used to manually log a message of some custom defined Level. kvs
|
|
// will be Merge'd automatically. If the Level is a fatal (Uint() == 0) then
|
|
// calling this will never return, and the process will have os.Exit(1) called.
|
|
func (l *Logger) Log(lvl Level, msg string, kvs ...KVer) {
|
|
if maxLevel := l.getMaxLevel(); maxLevel < lvl.Uint() {
|
|
return
|
|
}
|
|
|
|
var kv KV
|
|
if len(kvs) > 0 {
|
|
kv = merge(kvs...)
|
|
}
|
|
|
|
l.initDo()
|
|
l.msgCh <- Message{Level: lvl, Msg: msg, KV: kv}
|
|
|
|
// if a Fatal is logged then we're merely waiting here for spin to call
|
|
// os.Exit, and this go-routine shouldn't be allowed to continue
|
|
if lvl.Uint() == 0 {
|
|
select {}
|
|
}
|
|
}
|
|
|
|
// Debug logs a DebugLevel message, merging the KVers together first
|
|
func (l *Logger) Debug(msg string, kvs ...KVer) {
|
|
l.Log(DebugLevel, msg, kvs...)
|
|
}
|
|
|
|
// Info logs a InfoLevel message, merging the KVers together first
|
|
func (l *Logger) Info(msg string, kvs ...KVer) {
|
|
l.Log(InfoLevel, msg, kvs...)
|
|
}
|
|
|
|
// Warn logs a WarnLevel message, merging the KVers together first
|
|
func (l *Logger) Warn(msg string, kvs ...KVer) {
|
|
l.Log(WarnLevel, msg, kvs...)
|
|
}
|
|
|
|
// Error logs a ErrorLevel message, merging the KVers together first
|
|
func (l *Logger) Error(msg string, kvs ...KVer) {
|
|
l.Log(ErrorLevel, msg, kvs...)
|
|
}
|
|
|
|
// Fatal logs a FatalLevel message, merging the KVers together first. A Fatal
|
|
// message automatically stops the process with an os.Exit(1)
|
|
func (l *Logger) Fatal(msg string, kvs ...KVer) {
|
|
l.Log(FatalLevel, msg, kvs...)
|
|
}
|
|
|
|
// DefaultLogger is a Logger using the default configuration (which will log to
|
|
// stderr). The Debug, Info, Warn, etc... methods from DefaultLogger are exposed
|
|
// as global functions for convenience. Because Logger is not truly initialized
|
|
// till the first time it is called any of DefaultLogger's fields may be
|
|
// modified before using one of the Debug, Info, Warn, etc... global functions.
|
|
var (
|
|
DefaultLogger = new(Logger)
|
|
Debug = DefaultLogger.Debug
|
|
Info = DefaultLogger.Info
|
|
Warn = DefaultLogger.Warn
|
|
Error = DefaultLogger.Error
|
|
Fatal = DefaultLogger.Fatal
|
|
)
|