1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
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
}
}
|
