102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
// Copyright (c) 2017 Uber Technologies, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package rpcmetrics
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// NameNormalizer is used to convert the endpoint names to strings
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// that can be safely used as tags in the metrics.
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type NameNormalizer interface {
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Normalize(name string) string
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}
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// DefaultNameNormalizer converts endpoint names so that they contain only characters
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// from the safe charset [a-zA-Z0-9-./_]. All other characters are replaced with '-'.
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var DefaultNameNormalizer = &SimpleNameNormalizer{
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SafeSets: []SafeCharacterSet{
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&Range{From: 'a', To: 'z'},
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&Range{From: 'A', To: 'Z'},
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&Range{From: '0', To: '9'},
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&Char{'-'},
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&Char{'_'},
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&Char{'/'},
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&Char{'.'},
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},
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Replacement: '-',
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}
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// SimpleNameNormalizer uses a set of safe character sets.
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type SimpleNameNormalizer struct {
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SafeSets []SafeCharacterSet
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Replacement byte
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}
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// SafeCharacterSet determines if the given character is "safe"
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type SafeCharacterSet interface {
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IsSafe(c byte) bool
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}
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// Range implements SafeCharacterSet
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type Range struct {
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From, To byte
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}
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// IsSafe implements SafeCharacterSet
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func (r *Range) IsSafe(c byte) bool {
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return c >= r.From && c <= r.To
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}
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// Char implements SafeCharacterSet
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type Char struct {
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Val byte
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}
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// IsSafe implements SafeCharacterSet
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func (ch *Char) IsSafe(c byte) bool {
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return c == ch.Val
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}
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// Normalize checks each character in the string against SafeSets,
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// and if it's not safe substitutes it with Replacement.
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func (n *SimpleNameNormalizer) Normalize(name string) string {
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var retMe []byte
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nameBytes := []byte(name)
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for i, b := range nameBytes {
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if n.safeByte(b) {
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if retMe != nil {
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retMe[i] = b
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}
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} else {
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if retMe == nil {
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retMe = make([]byte, len(nameBytes))
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copy(retMe[0:i], nameBytes[0:i])
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}
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retMe[i] = n.Replacement
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}
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}
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if retMe == nil {
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return name
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}
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return string(retMe)
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}
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// safeByte checks if b against all safe charsets.
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func (n *SimpleNameNormalizer) safeByte(b byte) bool {
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for i := range n.SafeSets {
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if n.SafeSets[i].IsSafe(b) {
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return true
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}
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}
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return false
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}
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