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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 (
"bytes"
"errors"
"fmt"
"io"
"os"
"path"
"path/filepath"
"regexp"
"runtime"
"strconv"
"strings"
"sync"
"time"
)
// TODO see Formatter interface in fmt/print.go
// TODO try text/template, maybe it have enough performance
// TODO other template systems?
// TODO make it possible to specify formats per backend?
type fmtVerb int
const (
fmtVerbTime fmtVerb = iota
fmtVerbLevel
fmtVerbID
fmtVerbPid
fmtVerbProgram
fmtVerbModule
fmtVerbMessage
fmtVerbLongfile
fmtVerbShortfile
fmtVerbLongpkg
fmtVerbShortpkg
fmtVerbLongfunc
fmtVerbShortfunc
fmtVerbCallpath
fmtVerbLevelColor
// Keep last, there are no match for these below.
fmtVerbUnknown
fmtVerbStatic
)
var fmtVerbs = []string{
"time",
"level",
"id",
"pid",
"program",
"module",
"message",
"longfile",
"shortfile",
"longpkg",
"shortpkg",
"longfunc",
"shortfunc",
"callpath",
"color",
}
const rfc3339Milli = "2006-01-02T15:04:05.999Z07:00"
var defaultVerbsLayout = []string{
rfc3339Milli,
"s",
"d",
"d",
"s",
"s",
"s",
"s",
"s",
"s",
"s",
"s",
"s",
"0",
"",
}
var (
pid = os.Getpid()
program = filepath.Base(os.Args[0])
)
func getFmtVerbByName(name string) fmtVerb {
for i, verb := range fmtVerbs {
if name == verb {
return fmtVerb(i)
}
}
return fmtVerbUnknown
}
// Formatter is the required interface for a custom log record formatter.
type Formatter interface {
Format(calldepth int, r *Record, w io.Writer) error
}
// formatter is used by all backends unless otherwise overriden.
var formatter struct {
sync.RWMutex
def Formatter
}
func getFormatter() Formatter {
formatter.RLock()
defer formatter.RUnlock()
return formatter.def
}
var (
// DefaultFormatter is the default formatter used and is only the message.
DefaultFormatter = MustStringFormatter("%{message}")
// GlogFormatter mimics the glog format
GlogFormatter = MustStringFormatter("%{level:.1s}%{time:0102 15:04:05.999999} %{pid} %{shortfile}] %{message}")
)
// SetFormatter sets the default formatter for all new backends. A backend will
// fetch this value once it is needed to format a record. Note that backends
// will cache the formatter after the first point. For now, make sure to set
// the formatter before logging.
func SetFormatter(f Formatter) {
formatter.Lock()
defer formatter.Unlock()
formatter.def = f
}
var formatRe = regexp.MustCompile(`%{([a-z]+)(?::(.*?[^\\]))?}`)
type part struct {
verb fmtVerb
layout string
}
// stringFormatter contains a list of parts which explains how to build the
// formatted string passed on to the logging backend.
type stringFormatter struct {
parts []part
}
// NewStringFormatter returns a new Formatter which outputs the log record as a
// string based on the 'verbs' specified in the format string.
//
// The verbs:
//
// General:
// %{id} Sequence number for log message (uint64).
// %{pid} Process id (int)
// %{time} Time when log occurred (time.Time)
// %{level} Log level (Level)
// %{module} Module (string)
// %{program} Basename of os.Args[0] (string)
// %{message} Message (string)
// %{longfile} Full file name and line number: /a/b/c/d.go:23
// %{shortfile} Final file name element and line number: d.go:23
// %{callpath} Callpath like main.a.b.c...c "..." meaning recursive call ~. meaning truncated path
// %{color} ANSI color based on log level
//
// For normal types, the output can be customized by using the 'verbs' defined
// in the fmt package, eg. '%{id:04d}' to make the id output be '%04d' as the
// format string.
//
// For time.Time, use the same layout as time.Format to change the time format
// when output, eg "2006-01-02T15:04:05.999Z-07:00".
//
// For the 'color' verb, the output can be adjusted to either use bold colors,
// i.e., '%{color:bold}' or to reset the ANSI attributes, i.e.,
// '%{color:reset}' Note that if you use the color verb explicitly, be sure to
// reset it or else the color state will persist past your log message. e.g.,
// "%{color:bold}%{time:15:04:05} %{level:-8s}%{color:reset} %{message}" will
// just colorize the time and level, leaving the message uncolored.
//
// For the 'callpath' verb, the output can be adjusted to limit the printing
// the stack depth. i.e. '%{callpath:3}' will print '~.a.b.c'
//
// Colors on Windows is unfortunately not supported right now and is currently
// a no-op.
//
// There's also a couple of experimental 'verbs'. These are exposed to get
// feedback and needs a bit of tinkering. Hence, they might change in the
// future.
//
// Experimental:
// %{longpkg} Full package path, eg. github.com/go-logging
// %{shortpkg} Base package path, eg. go-logging
// %{longfunc} Full function name, eg. littleEndian.PutUint32
// %{shortfunc} Base function name, eg. PutUint32
// %{callpath} Call function path, eg. main.a.b.c
func NewStringFormatter(format string) (Formatter, error) {
var fmter = &stringFormatter{}
// Find the boundaries of all %{vars}
matches := formatRe.FindAllStringSubmatchIndex(format, -1)
if matches == nil {
return nil, errors.New("logger: invalid log format: " + format)
}
// Collect all variables and static text for the format
prev := 0
for _, m := range matches {
start, end := m[0], m[1]
if start > prev {
fmter.add(fmtVerbStatic, format[prev:start])
}
name := format[m[2]:m[3]]
verb := getFmtVerbByName(name)
if verb == fmtVerbUnknown {
return nil, errors.New("logger: unknown variable: " + name)
}
// Handle layout customizations or use the default. If this is not for the
// time, color formatting or callpath, we need to prefix with %.
layout := defaultVerbsLayout[verb]
if m[4] != -1 {
layout = format[m[4]:m[5]]
}
if verb != fmtVerbTime && verb != fmtVerbLevelColor && verb != fmtVerbCallpath {
layout = "%" + layout
}
fmter.add(verb, layout)
prev = end
}
end := format[prev:]
if end != "" {
fmter.add(fmtVerbStatic, end)
}
// Make a test run to make sure we can format it correctly.
t, err := time.Parse(time.RFC3339, "2010-02-04T21:00:57-08:00")
if err != nil {
panic(err)
}
testFmt := "hello %s"
r := &Record{
ID: 12345,
Time: t,
Module: "logger",
Args: []interface{}{"go"},
fmt: &testFmt,
}
if err := fmter.Format(0, r, &bytes.Buffer{}); err != nil {
return nil, err
}
return fmter, nil
}
// MustStringFormatter is equivalent to NewStringFormatter with a call to panic
// on error.
func MustStringFormatter(format string) Formatter {
f, err := NewStringFormatter(format)
if err != nil {
panic("Failed to initialized string formatter: " + err.Error())
}
return f
}
func (f *stringFormatter) add(verb fmtVerb, layout string) {
f.parts = append(f.parts, part{verb, layout})
}
func (f *stringFormatter) Format(calldepth int, r *Record, output io.Writer) error {
for _, part := range f.parts {
if part.verb == fmtVerbStatic {
output.Write([]byte(part.layout))
} else if part.verb == fmtVerbTime {
output.Write([]byte(r.Time.Format(part.layout)))
} else if part.verb == fmtVerbLevelColor {
doFmtVerbLevelColor(part.layout, r.Level, output)
} else if part.verb == fmtVerbCallpath {
depth, err := strconv.Atoi(part.layout)
if err != nil {
depth = 0
}
output.Write([]byte(formatCallpath(calldepth+1, depth)))
} else {
var v interface{}
switch part.verb {
case fmtVerbLevel:
v = r.Level
break
case fmtVerbID:
v = r.ID
break
case fmtVerbPid:
v = pid
break
case fmtVerbProgram:
v = program
break
case fmtVerbModule:
v = r.Module
break
case fmtVerbMessage:
v = r.Message()
break
case fmtVerbLongfile, fmtVerbShortfile:
_, file, line, ok := runtime.Caller(calldepth + 1)
if !ok {
file = "???"
line = 0
} else if part.verb == fmtVerbShortfile {
file = filepath.Base(file)
}
v = fmt.Sprintf("%s:%d", file, line)
case fmtVerbLongfunc, fmtVerbShortfunc,
fmtVerbLongpkg, fmtVerbShortpkg:
// TODO cache pc
v = "???"
if pc, _, _, ok := runtime.Caller(calldepth + 1); ok {
if f := runtime.FuncForPC(pc); f != nil {
v = formatFuncName(part.verb, f.Name())
}
}
default:
panic("unhandled format part")
}
fmt.Fprintf(output, part.layout, v)
}
}
return nil
}
// formatFuncName tries to extract certain part of the runtime formatted
// function name to some pre-defined variation.
//
// This function is known to not work properly if the package path or name
// contains a dot.
func formatFuncName(v fmtVerb, f string) string {
i := strings.LastIndex(f, "/")
j := strings.Index(f[i+1:], ".")
if j < 1 {
return "???"
}
pkg, fun := f[:i+j+1], f[i+j+2:]
switch v {
case fmtVerbLongpkg:
return pkg
case fmtVerbShortpkg:
return path.Base(pkg)
case fmtVerbLongfunc:
return fun
case fmtVerbShortfunc:
i = strings.LastIndex(fun, ".")
return fun[i+1:]
}
panic("unexpected func formatter")
}
func formatCallpath(calldepth int, depth int) string {
v := ""
callers := make([]uintptr, 64)
n := runtime.Callers(calldepth+2, callers)
oldPc := callers[n-1]
start := n - 3
if depth > 0 && start >= depth {
start = depth - 1
v += "~."
}
recursiveCall := false
for i := start; i >= 0; i-- {
pc := callers[i]
if oldPc == pc {
recursiveCall = true
continue
}
oldPc = pc
if recursiveCall {
recursiveCall = false
v += ".."
}
if i < start {
v += "."
}
if f := runtime.FuncForPC(pc); f != nil {
v += formatFuncName(fmtVerbShortfunc, f.Name())
}
}
return v
}
// backendFormatter combines a backend with a specific formatter making it
// possible to have different log formats for different backends.
type backendFormatter struct {
b Backend
f Formatter
}
// NewBackendFormatter creates a new backend which makes all records that
// passes through it beeing formatted by the specific formatter.
func NewBackendFormatter(b Backend, f Formatter) Backend {
return &backendFormatter{b, f}
}
// Log implements the Log function required by the Backend interface.
func (bf *backendFormatter) Log(level Level, calldepth int, r *Record) error {
// Make a shallow copy of the record and replace any formatter
r2 := *r
r2.formatter = bf.f
return bf.b.Log(level, calldepth+1, &r2)
}
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