DataDog and StatsD Metrics Support

* Added support for DataDog and StatsD monitoring
* Added documentation

vendor/github.com/kr/logfmt/scanner.go

@@ -0,0 +1,149 @@
+package logfmt
+
+import (
+	"errors"
+	"fmt"
+)
+
+var ErrUnterminatedString = errors.New("logfmt: unterminated string")
+
+func gotoScanner(data []byte, h Handler) (err error) {
+	saveError := func(e error) {
+		if err == nil {
+			err = e
+		}
+	}
+
+	var c byte
+	var i int
+	var m int
+	var key []byte
+	var val []byte
+	var ok bool
+	var esc bool
+
+garbage:
+	if i == len(data) {
+		return
+	}
+
+	c = data[i]
+	switch {
+	case c > ' ' && c != '"' && c != '=':
+		key, val = nil, nil
+		m = i
+		i++
+		goto key
+	default:
+		i++
+		goto garbage
+	}
+
+key:
+	if i >= len(data) {
+		if m >= 0 {
+			key = data[m:i]
+			saveError(h.HandleLogfmt(key, nil))
+		}
+		return
+	}
+
+	c = data[i]
+	switch {
+	case c > ' ' && c != '"' && c != '=':
+		i++
+		goto key
+	case c == '=':
+		key = data[m:i]
+		i++
+		goto equal
+	default:
+		key = data[m:i]
+		i++
+		saveError(h.HandleLogfmt(key, nil))
+		goto garbage
+	}
+
+equal:
+	if i >= len(data) {
+		if m >= 0 {
+			i--
+			key = data[m:i]
+			saveError(h.HandleLogfmt(key, nil))
+		}
+		return
+	}
+
+	c = data[i]
+	switch {
+	case c > ' ' && c != '"' && c != '=':
+		m = i
+		i++
+		goto ivalue
+	case c == '"':
+		m = i
+		i++
+		esc = false
+		goto qvalue
+	default:
+		if key != nil {
+			saveError(h.HandleLogfmt(key, val))
+		}
+		i++
+		goto garbage
+	}
+
+ivalue:
+	if i >= len(data) {
+		if m >= 0 {
+			val = data[m:i]
+			saveError(h.HandleLogfmt(key, val))
+		}
+		return
+	}
+
+	c = data[i]
+	switch {
+	case c > ' ' && c != '"' && c != '=':
+		i++
+		goto ivalue
+	default:
+		val = data[m:i]
+		saveError(h.HandleLogfmt(key, val))
+		i++
+		goto garbage
+	}
+
+qvalue:
+	if i >= len(data) {
+		if m >= 0 {
+			saveError(ErrUnterminatedString)
+		}
+		return
+	}
+
+	c = data[i]
+	switch c {
+	case '\\':
+		i += 2
+		esc = true
+		goto qvalue
+	case '"':
+		i++
+		val = data[m:i]
+		if esc {
+			val, ok = unquoteBytes(val)
+			if !ok {
+				saveError(fmt.Errorf("logfmt: error unquoting bytes %q", string(val)))
+				goto garbage
+			}
+		} else {
+			val = val[1 : len(val)-1]
+		}
+		saveError(h.HandleLogfmt(key, val))
+		goto garbage
+	default:
+		i++
+		goto qvalue
+	}
+}