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93 lines
2.6 KiB
93 lines
2.6 KiB
// Copyright The OpenTelemetry Authors
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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 baggage // import "go.opentelemetry.io/otel/internal/baggage"
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import "context"
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type baggageContextKeyType int
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const baggageKey baggageContextKeyType = iota
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// SetHookFunc is a callback called when storing baggage in the context.
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type SetHookFunc func(context.Context, List) context.Context
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// GetHookFunc is a callback called when getting baggage from the context.
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type GetHookFunc func(context.Context, List) List
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type baggageState struct {
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list List
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setHook SetHookFunc
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getHook GetHookFunc
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}
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// ContextWithSetHook returns a copy of parent with hook configured to be
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// invoked every time ContextWithBaggage is called.
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//
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// Passing nil SetHookFunc creates a context with no set hook to call.
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func ContextWithSetHook(parent context.Context, hook SetHookFunc) context.Context {
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var s baggageState
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if v, ok := parent.Value(baggageKey).(baggageState); ok {
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s = v
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}
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s.setHook = hook
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return context.WithValue(parent, baggageKey, s)
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}
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// ContextWithGetHook returns a copy of parent with hook configured to be
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// invoked every time FromContext is called.
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//
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// Passing nil GetHookFunc creates a context with no get hook to call.
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func ContextWithGetHook(parent context.Context, hook GetHookFunc) context.Context {
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var s baggageState
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if v, ok := parent.Value(baggageKey).(baggageState); ok {
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s = v
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}
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s.getHook = hook
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return context.WithValue(parent, baggageKey, s)
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}
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// ContextWithList returns a copy of parent with baggage. Passing nil list
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// returns a context without any baggage.
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func ContextWithList(parent context.Context, list List) context.Context {
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var s baggageState
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if v, ok := parent.Value(baggageKey).(baggageState); ok {
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s = v
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}
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s.list = list
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ctx := context.WithValue(parent, baggageKey, s)
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if s.setHook != nil {
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ctx = s.setHook(ctx, list)
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}
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return ctx
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}
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// ListFromContext returns the baggage contained in ctx.
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func ListFromContext(ctx context.Context) List {
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switch v := ctx.Value(baggageKey).(type) {
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case baggageState:
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if v.getHook != nil {
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return v.getHook(ctx, v.list)
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}
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return v.list
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default:
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return nil
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}
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}
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