379 lines
9.1 KiB
Go
379 lines
9.1 KiB
Go
// Copyright (C) 2014 Jakob Borg. All rights reserved. Use of this source code
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// is governed by an MIT-style license that can be found in the LICENSE file.
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// Package logger implements a standardized logger with callback functionality
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package logger
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import (
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"os"
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"strings"
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"sync"
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"time"
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)
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// This package uses stdlib sync as it may be used to debug syncthing/lib/sync
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// and that would cause an implosion of the universe.
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type LogLevel int
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const (
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LevelDebug LogLevel = iota
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LevelVerbose
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LevelInfo
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LevelWarn
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LevelFatal
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NumLevels
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)
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const (
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DefaultFlags = log.Ltime
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DebugFlags = log.Ltime | log.Ldate | log.Lmicroseconds | log.Lshortfile
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)
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// A MessageHandler is called with the log level and message text.
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type MessageHandler func(l LogLevel, msg string)
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type Logger interface {
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AddHandler(level LogLevel, h MessageHandler)
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SetFlags(flag int)
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SetPrefix(prefix string)
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Debugln(vals ...interface{})
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Debugf(format string, vals ...interface{})
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Verboseln(vals ...interface{})
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Verbosef(format string, vals ...interface{})
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Infoln(vals ...interface{})
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Infof(format string, vals ...interface{})
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Warnln(vals ...interface{})
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Warnf(format string, vals ...interface{})
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Fatalln(vals ...interface{})
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Fatalf(format string, vals ...interface{})
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ShouldDebug(facility string) bool
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SetDebug(facility string, enabled bool)
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Facilities() map[string]string
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FacilityDebugging() []string
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NewFacility(facility, description string) Logger
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}
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type logger struct {
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logger *log.Logger
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handlers [NumLevels][]MessageHandler
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facilities map[string]string // facility name => description
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debug map[string]struct{} // only facility names with debugging enabled
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mut sync.Mutex
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}
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// DefaultLogger logs to standard output with a time prefix.
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var DefaultLogger = New()
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func New() Logger {
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return newLogger(os.Stdout)
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}
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func newLogger(w io.Writer) Logger {
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res := &logger{
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facilities: make(map[string]string),
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debug: make(map[string]struct{}),
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}
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if os.Getenv("LOGGER_DISCARD") != "" {
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// Hack to completely disable logging, for example when running benchmarks.
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res.logger = log.New(ioutil.Discard, "", 0)
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return res
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}
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res.logger = log.New(w, "", DefaultFlags)
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return res
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}
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// AddHandler registers a new MessageHandler to receive messages with the
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// specified log level or above.
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func (l *logger) AddHandler(level LogLevel, h MessageHandler) {
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l.mut.Lock()
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defer l.mut.Unlock()
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l.handlers[level] = append(l.handlers[level], h)
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}
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// See log.SetFlags
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func (l *logger) SetFlags(flag int) {
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l.logger.SetFlags(flag)
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}
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// See log.SetPrefix
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func (l *logger) SetPrefix(prefix string) {
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l.logger.SetPrefix(prefix)
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}
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func (l *logger) callHandlers(level LogLevel, s string) {
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for ll := LevelDebug; ll <= level; ll++ {
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for _, h := range l.handlers[ll] {
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h(level, strings.TrimSpace(s))
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}
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}
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}
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// Debugln logs a line with a DEBUG prefix.
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func (l *logger) Debugln(vals ...interface{}) {
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l.debugln(3, vals...)
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}
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func (l *logger) debugln(level int, vals ...interface{}) {
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s := fmt.Sprintln(vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(level, "DEBUG: "+s)
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l.callHandlers(LevelDebug, s)
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}
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// Debugf logs a formatted line with a DEBUG prefix.
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func (l *logger) Debugf(format string, vals ...interface{}) {
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l.debugf(3, format, vals...)
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}
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func (l *logger) debugf(level int, format string, vals ...interface{}) {
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s := fmt.Sprintf(format, vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(level, "DEBUG: "+s)
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l.callHandlers(LevelDebug, s)
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}
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// Infoln logs a line with a VERBOSE prefix.
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func (l *logger) Verboseln(vals ...interface{}) {
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s := fmt.Sprintln(vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "VERBOSE: "+s)
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l.callHandlers(LevelVerbose, s)
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}
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// Infof logs a formatted line with a VERBOSE prefix.
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func (l *logger) Verbosef(format string, vals ...interface{}) {
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s := fmt.Sprintf(format, vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "VERBOSE: "+s)
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l.callHandlers(LevelVerbose, s)
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}
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// Infoln logs a line with an INFO prefix.
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func (l *logger) Infoln(vals ...interface{}) {
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s := fmt.Sprintln(vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "INFO: "+s)
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l.callHandlers(LevelInfo, s)
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}
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// Infof logs a formatted line with an INFO prefix.
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func (l *logger) Infof(format string, vals ...interface{}) {
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s := fmt.Sprintf(format, vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "INFO: "+s)
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l.callHandlers(LevelInfo, s)
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}
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// Warnln logs a formatted line with a WARNING prefix.
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func (l *logger) Warnln(vals ...interface{}) {
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s := fmt.Sprintln(vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "WARNING: "+s)
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l.callHandlers(LevelWarn, s)
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}
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// Warnf logs a formatted line with a WARNING prefix.
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func (l *logger) Warnf(format string, vals ...interface{}) {
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s := fmt.Sprintf(format, vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "WARNING: "+s)
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l.callHandlers(LevelWarn, s)
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}
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// Fatalln logs a line with a FATAL prefix and exits the process with exit
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// code 1.
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func (l *logger) Fatalln(vals ...interface{}) {
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s := fmt.Sprintln(vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "FATAL: "+s)
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l.callHandlers(LevelFatal, s)
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os.Exit(1)
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}
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// Fatalf logs a formatted line with a FATAL prefix and exits the process with
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// exit code 1.
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func (l *logger) Fatalf(format string, vals ...interface{}) {
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s := fmt.Sprintf(format, vals...)
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l.mut.Lock()
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defer l.mut.Unlock()
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l.logger.Output(2, "FATAL: "+s)
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l.callHandlers(LevelFatal, s)
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os.Exit(1)
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}
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// ShouldDebug returns true if the given facility has debugging enabled.
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func (l *logger) ShouldDebug(facility string) bool {
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l.mut.Lock()
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_, res := l.debug[facility]
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l.mut.Unlock()
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return res
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}
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// SetDebug enabled or disables debugging for the given facility name.
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func (l *logger) SetDebug(facility string, enabled bool) {
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l.mut.Lock()
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defer l.mut.Unlock()
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if _, ok := l.debug[facility]; enabled && !ok {
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l.SetFlags(DebugFlags)
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l.debug[facility] = struct{}{}
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} else if !enabled && ok {
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delete(l.debug, facility)
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if len(l.debug) == 0 {
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l.SetFlags(DefaultFlags)
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}
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}
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}
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// FacilityDebugging returns the set of facilities that have debugging
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// enabled.
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func (l *logger) FacilityDebugging() []string {
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enabled := make([]string, 0, len(l.debug))
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l.mut.Lock()
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for facility := range l.debug {
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enabled = append(enabled, facility)
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}
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l.mut.Unlock()
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return enabled
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}
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// Facilities returns the currently known set of facilities and their
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// descriptions.
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func (l *logger) Facilities() map[string]string {
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l.mut.Lock()
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res := make(map[string]string, len(l.facilities))
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for facility, descr := range l.facilities {
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res[facility] = descr
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}
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l.mut.Unlock()
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return res
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}
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// NewFacility returns a new logger bound to the named facility.
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func (l *logger) NewFacility(facility, description string) Logger {
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l.mut.Lock()
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l.facilities[facility] = description
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l.mut.Unlock()
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return &facilityLogger{
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logger: l,
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facility: facility,
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}
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}
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// A facilityLogger is a regular logger but bound to a facility name. The
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// Debugln and Debugf methods are no-ops unless debugging has been enabled for
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// this facility on the parent logger.
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type facilityLogger struct {
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*logger
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facility string
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}
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// Debugln logs a line with a DEBUG prefix.
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func (l *facilityLogger) Debugln(vals ...interface{}) {
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if !l.ShouldDebug(l.facility) {
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return
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}
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l.logger.debugln(3, vals...)
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}
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// Debugf logs a formatted line with a DEBUG prefix.
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func (l *facilityLogger) Debugf(format string, vals ...interface{}) {
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if !l.ShouldDebug(l.facility) {
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return
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}
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l.logger.debugf(3, format, vals...)
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}
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// A Recorder keeps a size limited record of log events.
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type Recorder interface {
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Since(t time.Time) []Line
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Clear()
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}
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type recorder struct {
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lines []Line
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initial int
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mut sync.Mutex
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}
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// A Line represents a single log entry.
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type Line struct {
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When time.Time `json:"when"`
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Message string `json:"message"`
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Level LogLevel `json:"level"`
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}
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func NewRecorder(l Logger, level LogLevel, size, initial int) Recorder {
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r := &recorder{
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lines: make([]Line, 0, size),
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initial: initial,
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}
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l.AddHandler(level, r.append)
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return r
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}
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func (r *recorder) Since(t time.Time) []Line {
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r.mut.Lock()
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defer r.mut.Unlock()
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res := r.lines
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for i := 0; i < len(res); i++ {
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if res[i].When.After(t) {
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// We must copy the result as r.lines can be mutated as soon as the lock
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// is released.
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res = res[i:]
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cp := make([]Line, len(res))
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copy(cp, res)
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return cp
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}
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}
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return nil
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}
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func (r *recorder) Clear() {
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r.mut.Lock()
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r.lines = r.lines[:0]
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r.mut.Unlock()
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}
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func (r *recorder) append(l LogLevel, msg string) {
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line := Line{
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When: time.Now(),
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Message: msg,
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Level: l,
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}
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r.mut.Lock()
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defer r.mut.Unlock()
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if len(r.lines) == cap(r.lines) {
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if r.initial > 0 {
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// Shift all lines one step to the left, keeping the "initial" first intact.
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copy(r.lines[r.initial+1:], r.lines[r.initial+2:])
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} else {
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copy(r.lines, r.lines[1:])
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}
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// Add the new one at the end
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r.lines[len(r.lines)-1] = line
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return
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}
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r.lines = append(r.lines, line)
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if len(r.lines) == r.initial {
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r.lines = append(r.lines, Line{time.Now(), "...", l})
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}
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}
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