Opentracing support

vendor/github.com/uber/jaeger-client-go/rpcmetrics/normalizer.go

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+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package rpcmetrics
+
+// NameNormalizer is used to convert the endpoint names to strings
+// that can be safely used as tags in the metrics.
+type NameNormalizer interface {
+	Normalize(name string) string
+}
+
+// DefaultNameNormalizer converts endpoint names so that they contain only characters
+// from the safe charset [a-zA-Z0-9-./_]. All other characters are replaced with '-'.
+var DefaultNameNormalizer = &SimpleNameNormalizer{
+	SafeSets: []SafeCharacterSet{
+		&Range{From: 'a', To: 'z'},
+		&Range{From: 'A', To: 'Z'},
+		&Range{From: '0', To: '9'},
+		&Char{'-'},
+		&Char{'_'},
+		&Char{'/'},
+		&Char{'.'},
+	},
+	Replacement: '-',
+}
+
+// SimpleNameNormalizer uses a set of safe character sets.
+type SimpleNameNormalizer struct {
+	SafeSets    []SafeCharacterSet
+	Replacement byte
+}
+
+// SafeCharacterSet determines if the given character is "safe"
+type SafeCharacterSet interface {
+	IsSafe(c byte) bool
+}
+
+// Range implements SafeCharacterSet
+type Range struct {
+	From, To byte
+}
+
+// IsSafe implements SafeCharacterSet
+func (r *Range) IsSafe(c byte) bool {
+	return c >= r.From && c <= r.To
+}
+
+// Char implements SafeCharacterSet
+type Char struct {
+	Val byte
+}
+
+// IsSafe implements SafeCharacterSet
+func (ch *Char) IsSafe(c byte) bool {
+	return c == ch.Val
+}
+
+// Normalize checks each character in the string against SafeSets,
+// and if it's not safe substitutes it with Replacement.
+func (n *SimpleNameNormalizer) Normalize(name string) string {
+	var retMe []byte
+	nameBytes := []byte(name)
+	for i, b := range nameBytes {
+		if n.safeByte(b) {
+			if retMe != nil {
+				retMe[i] = b
+			}
+		} else {
+			if retMe == nil {
+				retMe = make([]byte, len(nameBytes))
+				copy(retMe[0:i], nameBytes[0:i])
+			}
+			retMe[i] = n.Replacement
+		}
+	}
+	if retMe == nil {
+		return name
+	}
+	return string(retMe)
+}
+
+// safeByte checks if b against all safe charsets.
+func (n *SimpleNameNormalizer) safeByte(b byte) bool {
+	for i := range n.SafeSets {
+		if n.SafeSets[i].IsSafe(b) {
+			return true
+		}
+	}
+	return false
+}