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// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package baggage // import "go.opentelemetry.io/otel/internal/baggage"
import "context"
type baggageContextKeyType int
const baggageKey baggageContextKeyType = iota
// SetHookFunc is a callback called when storing baggage in the context.
type SetHookFunc func(context.Context, List) context.Context
// GetHookFunc is a callback called when getting baggage from the context.
type GetHookFunc func(context.Context, List) List
type baggageState struct {
list List
setHook SetHookFunc
getHook GetHookFunc
}
// ContextWithSetHook returns a copy of parent with hook configured to be
// invoked every time ContextWithBaggage is called.
//
// Passing nil SetHookFunc creates a context with no set hook to call.
func ContextWithSetHook(parent context.Context, hook SetHookFunc) context.Context {
var s baggageState
if v, ok := parent.Value(baggageKey).(baggageState); ok {
s = v
}
s.setHook = hook
return context.WithValue(parent, baggageKey, s)
}
// ContextWithGetHook returns a copy of parent with hook configured to be
// invoked every time FromContext is called.
//
// Passing nil GetHookFunc creates a context with no get hook to call.
func ContextWithGetHook(parent context.Context, hook GetHookFunc) context.Context {
var s baggageState
if v, ok := parent.Value(baggageKey).(baggageState); ok {
s = v
}
s.getHook = hook
return context.WithValue(parent, baggageKey, s)
}
// ContextWithList returns a copy of parent with baggage. Passing nil list
// returns a context without any baggage.
func ContextWithList(parent context.Context, list List) context.Context {
var s baggageState
if v, ok := parent.Value(baggageKey).(baggageState); ok {
s = v
}
s.list = list
ctx := context.WithValue(parent, baggageKey, s)
if s.setHook != nil {
ctx = s.setHook(ctx, list)
}
return ctx
}
// ListFromContext returns the baggage contained in ctx.
func ListFromContext(ctx context.Context) List {
switch v := ctx.Value(baggageKey).(type) {
case baggageState:
if v.getHook != nil {
return v.getHook(ctx, v.list)
}
return v.list
default:
return nil
}
}
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