Files
log/formatter/formatter.go
T

553 lines
16 KiB
Go

// Package formatter provides buffered and append-style formatting of log
// entries in txt, json, and raw formats.
//
// Ownership and concurrency contract:
// - Configure via the fluent API (Type, TimestampFormat, ShowLevel,
// ShowTimestamp) before sharing an instance; configuration is not
// synchronized.
// - Buffered methods (Format, FormatWithOptions, FormatValue, FormatArgs)
// reuse an internal buffer. The returned slice is valid only until the
// next buffered call; copy before retention or async hand-off. Single
// goroutine only.
// - Append methods (AppendFormat, AppendFormatWithOptions, AppendValue,
// AppendArgs) write to a caller-provided buffer and are safe for
// concurrent use after configuration.
package formatter
import (
"encoding/json"
"fmt"
"strconv"
"time"
"unicode/utf8"
"github.com/lixenwraith/log/sanitizer"
)
// Format flags. Resolution in Format/AppendFormat: FlagNo* suppresses,
// FlagShow* enables, otherwise configured default applies; FlagNo* wins on conflict.
// FormatWithOptions/AppendFormatWithOptions are explicit: unset FlagShow* bits mean off.
const (
FlagRaw int64 = 0b0001
FlagShowTimestamp int64 = 0b0010
FlagShowLevel int64 = 0b0100
FlagStructuredJSON int64 = 0b1000
FlagNoTimestamp int64 = 0b010000
FlagNoLevel int64 = 0b100000
FlagKV int64 = 0b1000000 // args are alternating string keys and values
FlagDefault = FlagShowTimestamp | FlagShowLevel
)
// Formatter manages formatting of log entries
type Formatter struct {
sanitizer *sanitizer.Sanitizer
format string
timestampFormat string
showTimestamp bool
showLevel bool
ctxKeys ContextKeys
buf []byte
// Serializers are stateless and format-fixed; built once to keep the
// per-record path allocation-free
serTxt *sanitizer.Serializer
serJSON *sanitizer.Serializer
serRaw *sanitizer.Serializer
}
// ContextSlots is the number of correlation values a Context carries
const ContextSlots = 3
// Context carries caller-stamped values emitted with a record.
// Tag names the source; Vals are correlation counters keyed by ContextKeys.
type Context struct {
Tag string
Vals [ContextSlots]uint64
}
// ContextKeys names the record keys for Context fields; empty names are omitted.
// Names are emitted verbatim and must be plain identifiers.
type ContextKeys struct {
Tag string
Vals [ContextSlots]string
}
// New creates a formatter with the provided sanitizer
func New(s ...*sanitizer.Sanitizer) *Formatter {
var san *sanitizer.Sanitizer
if len(s) > 0 && s[0] != nil {
san = s[0]
} else {
san = sanitizer.New() // Default passthrough sanitizer
}
return &Formatter{
sanitizer: san,
format: "txt",
timestampFormat: time.RFC3339Nano,
showTimestamp: true,
showLevel: true,
buf: make([]byte, 0, 1024),
serTxt: sanitizer.NewSerializer("txt", san),
serJSON: sanitizer.NewSerializer("json", san),
serRaw: sanitizer.NewSerializer("raw", san),
}
}
// ContextKeys sets the record keys used for Context values
func (f *Formatter) ContextKeys(tag string, vals ...string) *Formatter {
f.ctxKeys = ContextKeys{Tag: tag}
for i := 0; i < len(vals) && i < ContextSlots; i++ {
f.ctxKeys.Vals[i] = vals[i]
}
return f
}
// serializerFor returns the cached serializer for a normalized format name
func (f *Formatter) serializerFor(format string) *sanitizer.Serializer {
switch format {
case "json":
return f.serJSON
case "raw":
return f.serRaw
default:
return f.serTxt
}
}
// Type sets the output format ("txt", "json", or "raw")
func (f *Formatter) Type(format string) *Formatter {
f.format = format
return f
}
// TimestampFormat sets the timestamp format string
func (f *Formatter) TimestampFormat(format string) *Formatter {
if format != "" {
f.timestampFormat = format
}
return f
}
// ShowLevel sets whether to include level in output
func (f *Formatter) ShowLevel(show bool) *Formatter {
f.showLevel = show
return f
}
// ShowTimestamp sets whether to include timestamp in output
func (f *Formatter) ShowTimestamp(show bool) *Formatter {
f.showTimestamp = show
return f
}
// Format formats using configured options resolved against explicit flags.
// Returned slice aliases the internal buffer.
func (f *Formatter) Format(flags int64, timestamp time.Time, level int64, trace string, args []any) []byte {
return f.FormatCtx(Context{}, flags, timestamp, level, trace, args)
}
// FormatCtx is Format with caller-stamped context.
// Returned slice aliases the internal buffer.
func (f *Formatter) FormatCtx(ctx Context, flags int64, timestamp time.Time, level int64, trace string, args []any) []byte {
f.buf = f.AppendFormatCtx(f.buf[:0], ctx, flags, timestamp, level, trace, args)
return f.buf
}
// AppendFormat appends a formatted entry to dst using configured options
// resolved against explicit flags. Safe for concurrent use.
func (f *Formatter) AppendFormat(dst []byte, flags int64, timestamp time.Time, level int64, trace string, args []any) []byte {
return f.AppendFormatCtx(dst, Context{}, flags, timestamp, level, trace, args)
}
// AppendFormatCtx is AppendFormat with caller-stamped context
func (f *Formatter) AppendFormatCtx(dst []byte, ctx Context, flags int64, timestamp time.Time, level int64, trace string, args []any) []byte {
eff := flags &^ (FlagShowTimestamp | FlagShowLevel)
if resolveShow(flags, FlagShowTimestamp, FlagNoTimestamp, f.showTimestamp) {
eff |= FlagShowTimestamp
}
if resolveShow(flags, FlagShowLevel, FlagNoLevel, f.showLevel) {
eff |= FlagShowLevel
}
return f.AppendFormatWithOptionsCtx(dst, f.format, ctx, eff, timestamp, level, trace, args)
}
// FormatWithOptions formats with explicit format and flags, ignoring
// configured display defaults. Returned slice aliases the internal buffer.
func (f *Formatter) FormatWithOptions(format string, flags int64, timestamp time.Time, level int64, trace string, args []any) []byte {
f.buf = f.AppendFormatWithOptionsCtx(f.buf[:0], format, Context{}, flags, timestamp, level, trace, args)
return f.buf
}
// AppendFormatWithOptions is the compatibility wrapper over the context core
func (f *Formatter) AppendFormatWithOptions(dst []byte, format string, flags int64, timestamp time.Time, level int64, trace string, args []any) []byte {
return f.AppendFormatWithOptionsCtx(dst, format, Context{}, flags, timestamp, level, trace, args)
}
// AppendFormatWithOptionsCtx is the allocation-explicit core. Safe for
// concurrent use. Unknown formats fall back to "txt".
func (f *Formatter) AppendFormatWithOptionsCtx(dst []byte, format string, ctx Context, flags int64, timestamp time.Time, level int64, trace string, args []any) []byte {
// FlagRaw completely bypasses formatting, context, and sanitization
if flags&FlagRaw != 0 {
for i, arg := range args {
if i > 0 {
dst = append(dst, ' ')
}
switch v := arg.(type) {
case string:
dst = append(dst, v...)
case []byte:
dst = append(dst, v...)
case fmt.Stringer:
dst = append(dst, v.String()...)
case error:
dst = append(dst, v.Error()...)
default:
dst = append(dst, fmt.Sprint(v)...)
}
}
return dst
}
format = normalizeFormat(format)
serializer := f.serializerFor(format)
switch format {
case "raw":
for i, arg := range args {
dst = f.appendValue(dst, arg, serializer, i > 0)
}
return dst
case "json":
return f.appendJSON(dst, ctx, flags, timestamp, level, trace, args, serializer)
default: // "txt"
return f.appendTxt(dst, ctx, flags, timestamp, level, trace, args, serializer)
}
}
func resolveShow(flags, show, no int64, configured bool) bool {
switch {
case flags&no != 0:
return false
case flags&show != 0:
return true
default:
return configured
}
}
func normalizeFormat(format string) string {
switch format {
case "raw", "json", "txt":
return format
default:
return "txt"
}
}
// FormatValue formats a single value. Returned slice aliases the internal buffer.
func (f *Formatter) FormatValue(v any) []byte {
f.buf = f.AppendValue(f.buf[:0], v)
return f.buf
}
// AppendValue appends a single formatted value to dst. Safe for concurrent use.
func (f *Formatter) AppendValue(dst []byte, v any) []byte {
return f.appendValue(dst, v, f.serializerFor(normalizeFormat(f.format)), false)
}
// FormatArgs formats multiple arguments. Returned slice aliases the internal buffer.
func (f *Formatter) FormatArgs(args ...any) []byte {
f.buf = f.AppendArgs(f.buf[:0], args...)
return f.buf
}
// AppendArgs appends multiple space-separated values to dst. Safe for
// concurrent use.
func (f *Formatter) AppendArgs(dst []byte, args ...any) []byte {
serializer := f.serializerFor(normalizeFormat(f.format))
for i, arg := range args {
dst = f.appendValue(dst, arg, serializer, i > 0)
}
return dst
}
// appendValue provides unified type conversion (was convertValue; now
// value-return style over caller buffer). Type switch body unchanged except
// buffer plumbing — replace every `serializer.WriteX(buf, ...)` with
// `serializer.WriteX(&dst, ...)` and `return dst`.
func (f *Formatter) appendValue(dst []byte, v any, serializer *sanitizer.Serializer, needsSpace bool) []byte {
if needsSpace && len(dst) > 0 {
dst = append(dst, ' ')
}
switch val := v.(type) {
case string:
serializer.WriteString(&dst, val)
case []byte:
serializer.WriteString(&dst, string(val))
case rune:
var runeStr [utf8.UTFMax]byte
n := utf8.EncodeRune(runeStr[:], val)
serializer.WriteString(&dst, string(runeStr[:n]))
case int:
serializer.WriteNumber(&dst, string(strconv.AppendInt(nil, int64(val), 10)))
case int64:
serializer.WriteNumber(&dst, string(strconv.AppendInt(nil, val, 10)))
case uint:
serializer.WriteNumber(&dst, string(strconv.AppendUint(nil, uint64(val), 10)))
case uint64:
serializer.WriteNumber(&dst, string(strconv.AppendUint(nil, val, 10)))
case float32:
serializer.WriteNumber(&dst, string(strconv.AppendFloat(nil, float64(val), 'f', -1, 32)))
case float64:
serializer.WriteNumber(&dst, string(strconv.AppendFloat(nil, val, 'f', -1, 64)))
case bool:
serializer.WriteBool(&dst, val)
case nil:
serializer.WriteNil(&dst)
case time.Time:
serializer.WriteString(&dst, val.Format(f.timestampFormat))
case error:
serializer.WriteString(&dst, val.Error())
case fmt.Stringer:
serializer.WriteString(&dst, val.String())
default:
serializer.WriteComplex(&dst, val)
}
return dst
}
// LevelToString converts integer level values to string
func LevelToString(level int64) string {
switch level {
case -4:
return "DEBUG"
case 0:
return "INFO"
case 4:
return "WARN"
case 8:
return "ERROR"
case 12:
return "PROC"
case 16:
return "DISK"
case 20:
return "SYS"
default:
return fmt.Sprintf("LEVEL(%d)", level)
}
}
// appendJSONKey writes a quoted literal key followed by ':'
func appendJSONKey(dst []byte, key string) []byte {
dst = append(dst, '"')
dst = append(dst, key...)
dst = append(dst, '"', ':')
return dst
}
// isKV reports whether args form an even-length list with string keys
func isKV(args []any) bool {
if len(args) == 0 || len(args)%2 != 0 {
return false
}
for i := 0; i < len(args); i += 2 {
if _, ok := args[i].(string); !ok {
return false
}
}
return true
}
// appendJSON unifies JSON output over a caller-provided buffer
func (f *Formatter) appendJSON(dst []byte, ctx Context, flags int64, timestamp time.Time, level int64, trace string, args []any, serializer *sanitizer.Serializer) []byte {
dst = append(dst, '{')
needsComma := false
if flags&FlagShowTimestamp != 0 {
dst = append(dst, `"time":"`...)
dst = timestamp.AppendFormat(dst, f.timestampFormat)
dst = append(dst, '"')
needsComma = true
}
if flags&FlagShowLevel != 0 {
if needsComma {
dst = append(dst, ',')
}
dst = append(dst, `"level":"`...)
dst = append(dst, LevelToString(level)...)
dst = append(dst, '"')
needsComma = true
}
// Caller-stamped context, emitted as top-level keys
if ctx.Tag != "" && f.ctxKeys.Tag != "" {
if needsComma {
dst = append(dst, ',')
}
dst = appendJSONKey(dst, f.ctxKeys.Tag)
serializer.WriteString(&dst, ctx.Tag)
needsComma = true
}
for i, key := range f.ctxKeys.Vals {
if key == "" {
continue
}
if needsComma {
dst = append(dst, ',')
}
dst = appendJSONKey(dst, key)
dst = strconv.AppendUint(dst, ctx.Vals[i], 10)
needsComma = true
}
if trace != "" {
if needsComma {
dst = append(dst, ',')
}
dst = append(dst, `"trace":`...)
serializer.WriteString(&dst, trace)
needsComma = true
}
// Handle structured JSON if flag is set and args match pattern
if flags&FlagStructuredJSON != 0 && len(args) >= 2 {
if message, ok := args[0].(string); ok {
if fields, ok := args[1].(map[string]any); ok {
if needsComma {
dst = append(dst, ',')
}
dst = append(dst, `"message":`...)
serializer.WriteString(&dst, message)
dst = append(dst, `,"fields":`...)
marshaledFields, err := json.Marshal(fields)
if err != nil {
dst = append(dst, `{"_marshal_error":"`...)
serializer.WriteString(&dst, err.Error())
dst = append(dst, `"}`...)
} else {
dst = append(dst, marshaledFields...)
}
dst = append(dst, '}', '\n')
return dst
}
}
}
if len(args) > 0 {
if needsComma {
dst = append(dst, ',')
}
// Keyed object when the caller declares k/v args, positional array otherwise
if flags&FlagKV != 0 && isKV(args) {
dst = append(dst, `"fields":{`...)
for i := 0; i < len(args); i += 2 {
if i > 0 {
dst = append(dst, ',')
}
serializer.WriteString(&dst, args[i].(string))
dst = append(dst, ':')
dst = f.appendValue(dst, args[i+1], serializer, false)
}
dst = append(dst, '}')
} else {
dst = append(dst, `"fields":[`...)
for i, arg := range args {
if i > 0 {
dst = append(dst, ',')
}
dst = f.appendValue(dst, arg, serializer, false)
}
dst = append(dst, ']')
}
}
dst = append(dst, '}', '\n')
return dst
}
// appendTxt handles txt format output over a caller-provided buffer
func (f *Formatter) appendTxt(dst []byte, ctx Context, flags int64, timestamp time.Time, level int64, trace string, args []any, serializer *sanitizer.Serializer) []byte {
needsSpace := false
if flags&FlagShowTimestamp != 0 {
dst = timestamp.AppendFormat(dst, f.timestampFormat)
needsSpace = true
}
if flags&FlagShowLevel != 0 {
if needsSpace {
dst = append(dst, ' ')
}
dst = append(dst, LevelToString(level)...)
needsSpace = true
}
if ctx.Tag != "" && f.ctxKeys.Tag != "" {
if needsSpace {
dst = append(dst, ' ')
}
dst = append(dst, f.ctxKeys.Tag...)
dst = append(dst, '=')
dst = f.appendValue(dst, ctx.Tag, serializer, false)
needsSpace = true
}
for i, key := range f.ctxKeys.Vals {
if key == "" {
continue
}
if needsSpace {
dst = append(dst, ' ')
}
dst = append(dst, key...)
dst = append(dst, '=')
dst = strconv.AppendUint(dst, ctx.Vals[i], 10)
needsSpace = true
}
if trace != "" {
if needsSpace {
dst = append(dst, ' ')
}
// Sanitize trace to prevent terminal control sequence injection
tempBuf := make([]byte, 0, len(trace)*2)
f.serTxt.WriteString(&tempBuf, trace)
// Extract content without quotes if added by txt serializer
if len(tempBuf) > 2 && tempBuf[0] == '"' && tempBuf[len(tempBuf)-1] == '"' {
dst = append(dst, tempBuf[1:len(tempBuf)-1]...)
} else {
dst = append(dst, tempBuf...)
}
needsSpace = true
}
if flags&FlagKV != 0 && isKV(args) {
for i := 0; i < len(args); i += 2 {
if needsSpace {
dst = append(dst, ' ')
}
dst = append(dst, args[i].(string)...)
dst = append(dst, '=')
dst = f.appendValue(dst, args[i+1], serializer, false)
needsSpace = true
}
} else {
for _, arg := range args {
dst = f.appendValue(dst, arg, serializer, needsSpace)
needsSpace = true
}
}
dst = append(dst, '\n')
return dst
}
// Reset clears the internal buffer for reuse
func (f *Formatter) Reset() {
f.buf = f.buf[:0]
}