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104 lines
3.0 KiB
104 lines
3.0 KiB
// Copyright (c) 2015 Uber Technologies, Inc.
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package tchannel
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import (
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"strings"
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"sync"
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)
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// tracingKeyPrefix is used to prefix all keys used by the OpenTracing Tracer to represent
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// its trace context and baggage. The prefixing is done in order to distinguish tracing
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// headers from the actual application headers and to hide the former from the user code.
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const tracingKeyPrefix = "$tracing$"
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// tracingKeyMappingSize is the maximum number of tracing key mappings we cache.
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const tracingKeyMappingSize = 100
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type tracingKeysMapping struct {
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sync.RWMutex
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mapping map[string]string
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mapper func(key string) string
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}
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var tracingKeyEncoding = &tracingKeysMapping{
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mapping: make(map[string]string),
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mapper: func(key string) string {
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return tracingKeyPrefix + key
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},
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}
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var tracingKeyDecoding = &tracingKeysMapping{
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mapping: make(map[string]string),
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mapper: func(key string) string {
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return key[len(tracingKeyPrefix):]
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},
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}
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func (m *tracingKeysMapping) mapAndCache(key string) string {
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m.RLock()
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v, ok := m.mapping[key]
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m.RUnlock()
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if ok {
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return v
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}
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m.Lock()
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defer m.Unlock()
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if v, ok := m.mapping[key]; ok {
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return v
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}
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mappedKey := m.mapper(key)
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if len(m.mapping) < tracingKeyMappingSize {
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m.mapping[key] = mappedKey
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}
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return mappedKey
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}
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type tracingHeadersCarrier map[string]string
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// Set implements Set() of opentracing.TextMapWriter
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func (c tracingHeadersCarrier) Set(key, val string) {
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prefixedKey := tracingKeyEncoding.mapAndCache(key)
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c[prefixedKey] = val
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}
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// ForeachKey conforms to the TextMapReader interface.
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func (c tracingHeadersCarrier) ForeachKey(handler func(key, val string) error) error {
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for k, v := range c {
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if !strings.HasPrefix(k, tracingKeyPrefix) {
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continue
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}
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noPrefixKey := tracingKeyDecoding.mapAndCache(k)
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if err := handler(noPrefixKey, v); err != nil {
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return err
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}
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}
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return nil
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}
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func (c tracingHeadersCarrier) RemoveTracingKeys() {
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for key := range c {
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if strings.HasPrefix(key, tracingKeyPrefix) {
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delete(c, key)
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}
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}
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}
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