go_goutils/logging/funcs_std.go

package logging

import (
	"fmt"
	"io"
	"log"
	"os"
	"strings"
)

/*
Setup sets up/configures a StdLogger and prepares it for use.
err will always be nil; it's there for interface-compat.
*/
func (l *StdLogger) Setup() (err error) {

	var multi io.Writer

	// This uses a shared handle across the import. We don't want that.
	// l.Logger = log.Default()
	if l.Prefix != "" {
		l.Prefix = strings.TrimRight(l.Prefix, " ") + " "
		// l.Logger.SetPrefix(l.Prefix)
	}
	// (stdlib).log.std is returned by log.Default(), which uses os.Stderr but we have flags for that.
	// https://stackoverflow.com/a/36719588/733214
	switch {
	case l.EnableStdErr && l.EnableStdOut:
		multi = io.MultiWriter(os.Stdout, os.Stderr)
	case l.EnableStdErr:
		multi = os.Stderr
	case l.EnableStdOut:
		multi = os.Stdout
	default:
		multi = nil
	}
	if multi != nil {
		l.Logger = log.New(multi, l.Prefix, l.LogFlags)
	} else {
		// This honestly should throw an error.
		l.Logger = &log.Logger{}
		l.Logger.SetPrefix(l.Prefix)
		l.Logger.SetFlags(l.LogFlags)
	}

	return
}

/*
Shutdown cleanly shuts down a StdLogger.
err will always be nil; it's there for interface-compat.
*/
func (l *StdLogger) Shutdown() (err error) {

	// NOOP

	return
}

/*
GetPrefix returns the prefix used by this StdLogger.
err will always be nil; it's there for interface-compat.
*/
func (l *StdLogger) GetPrefix() (prefix string, err error) {

	prefix = l.Prefix

	return
}

/*
DoDebug sets the debug state of this StdLogger.
Note that this merely acts as a *safety filter* for debug messages to avoid sensitive information being written to the log.
err will always be nil; it's there for interface-compat.
*/
func (l *StdLogger) DoDebug(d bool) (err error) {

	l.EnableDebug = d

	return
}

// GetDebug returns the debug status of this StdLogger.
func (l *StdLogger) GetDebug() (d bool) {

	d = l.EnableDebug

	return
}

/*
SetPrefix sets the prefix for this StdLogger.
err will always be nil; it's there for interface-compat.
*/
func (l *StdLogger) SetPrefix(prefix string) (err error) {

	l.Prefix = prefix
	if prefix != "" {
		l.Prefix = strings.TrimRight(l.Prefix, " ") + " "
	}
	l.Logger.SetPrefix(l.Prefix)

	return
}

// Alert writes an ALERT-level message to this StdLogger.
func (l *StdLogger) Alert(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "ALERT")

	return
}

// Crit writes an CRITICAL-level message to this StdLogger.
func (l *StdLogger) Crit(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "CRITICAL")

	return
}

// Debug writes a DEBUG-level message to this StdLogger.
func (l *StdLogger) Debug(s string, v ...interface{}) (err error) {

	if !l.EnableDebug {
		return
	}

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "DEBUG")

	return
}

// Emerg writes an EMERGENCY-level message to this StdLogger.
func (l *StdLogger) Emerg(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "EMERGENCY")

	return
}

// Err writes an ERROR-level message to this StdLogger.
func (l *StdLogger) Err(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "ERROR")

	return
}

// Info writes an INFO-level message to this StdLogger.
func (l *StdLogger) Info(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "INFO")

	return
}

// Notice writes a NOTICE-level message to this StdLogger.
func (l *StdLogger) Notice(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "NOTICE")

	return
}

// Warning writes a WARNING/WARN-level message to this StdLogger.
func (l *StdLogger) Warning(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "WARNING")

	return
}

// renderWrite prepares/formats a log message to be written to this StdLogger.
func (l *StdLogger) renderWrite(msg, prio string) {

	s := fmt.Sprintf("[%v] %v", prio, msg)

	l.Logger.Println(s)

	return
}