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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
package opentracing
import (
"errors"
"net/http"
)
///////////////////////////////////////////////////////////////////////////////
// CORE PROPAGATION INTERFACES:
///////////////////////////////////////////////////////////////////////////////
var (
// ErrUnsupportedFormat occurs when the `format` passed to Tracer.Inject() or
// Tracer.Extract() is not recognized by the Tracer implementation.
ErrUnsupportedFormat = errors.New("opentracing: Unknown or unsupported Inject/Extract format")
// ErrSpanContextNotFound occurs when the `carrier` passed to
// Tracer.Extract() is valid and uncorrupted but has insufficient
// information to extract a SpanContext.
ErrSpanContextNotFound = errors.New("opentracing: SpanContext not found in Extract carrier")
// ErrInvalidSpanContext errors occur when Tracer.Inject() is asked to
// operate on a SpanContext which it is not prepared to handle (for
// example, since it was created by a different tracer implementation).
ErrInvalidSpanContext = errors.New("opentracing: SpanContext type incompatible with tracer")
// ErrInvalidCarrier errors occur when Tracer.Inject() or Tracer.Extract()
// implementations expect a different type of `carrier` than they are
// given.
ErrInvalidCarrier = errors.New("opentracing: Invalid Inject/Extract carrier")
// ErrSpanContextCorrupted occurs when the `carrier` passed to
// Tracer.Extract() is of the expected type but is corrupted.
ErrSpanContextCorrupted = errors.New("opentracing: SpanContext data corrupted in Extract carrier")
)
///////////////////////////////////////////////////////////////////////////////
// BUILTIN PROPAGATION FORMATS:
///////////////////////////////////////////////////////////////////////////////
// BuiltinFormat is used to demarcate the values within package `opentracing`
// that are intended for use with the Tracer.Inject() and Tracer.Extract()
// methods.
type BuiltinFormat byte
const (
// Binary represents SpanContexts as opaque binary data.
//
// For Tracer.Inject(): the carrier must be an `io.Writer`.
//
// For Tracer.Extract(): the carrier must be an `io.Reader`.
Binary BuiltinFormat = iota
// TextMap represents SpanContexts as key:value string pairs.
//
// Unlike HTTPHeaders, the TextMap format does not restrict the key or
// value character sets in any way.
//
// For Tracer.Inject(): the carrier must be a `TextMapWriter`.
//
// For Tracer.Extract(): the carrier must be a `TextMapReader`.
TextMap
// HTTPHeaders represents SpanContexts as HTTP header string pairs.
//
// Unlike TextMap, the HTTPHeaders format requires that the keys and values
// be valid as HTTP headers as-is (i.e., character casing may be unstable
// and special characters are disallowed in keys, values should be
// URL-escaped, etc).
//
// For Tracer.Inject(): the carrier must be a `TextMapWriter`.
//
// For Tracer.Extract(): the carrier must be a `TextMapReader`.
//
// See HTTPHeadersCarrier for an implementation of both TextMapWriter
// and TextMapReader that defers to an http.Header instance for storage.
// For example, Inject():
//
// carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
// err := span.Tracer().Inject(
// span.Context(), opentracing.HTTPHeaders, carrier)
//
// Or Extract():
//
// carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
// clientContext, err := tracer.Extract(
// opentracing.HTTPHeaders, carrier)
//
HTTPHeaders
)
// TextMapWriter is the Inject() carrier for the TextMap builtin format. With
// it, the caller can encode a SpanContext for propagation as entries in a map
// of unicode strings.
type TextMapWriter interface {
// Set a key:value pair to the carrier. Multiple calls to Set() for the
// same key leads to undefined behavior.
//
// NOTE: The backing store for the TextMapWriter may contain data unrelated
// to SpanContext. As such, Inject() and Extract() implementations that
// call the TextMapWriter and TextMapReader interfaces must agree on a
// prefix or other convention to distinguish their own key:value pairs.
Set(key, val string)
}
// TextMapReader is the Extract() carrier for the TextMap builtin format. With it,
// the caller can decode a propagated SpanContext as entries in a map of
// unicode strings.
type TextMapReader interface {
// ForeachKey returns TextMap contents via repeated calls to the `handler`
// function. If any call to `handler` returns a non-nil error, ForeachKey
// terminates and returns that error.
//
// NOTE: The backing store for the TextMapReader may contain data unrelated
// to SpanContext. As such, Inject() and Extract() implementations that
// call the TextMapWriter and TextMapReader interfaces must agree on a
// prefix or other convention to distinguish their own key:value pairs.
//
// The "foreach" callback pattern reduces unnecessary copying in some cases
// and also allows implementations to hold locks while the map is read.
ForeachKey(handler func(key, val string) error) error
}
// TextMapCarrier allows the use of regular map[string]string
// as both TextMapWriter and TextMapReader.
type TextMapCarrier map[string]string
// ForeachKey conforms to the TextMapReader interface.
func (c TextMapCarrier) ForeachKey(handler func(key, val string) error) error {
for k, v := range c {
if err := handler(k, v); err != nil {
return err
}
}
return nil
}
// Set implements Set() of opentracing.TextMapWriter
func (c TextMapCarrier) Set(key, val string) {
c[key] = val
}
// HTTPHeadersCarrier satisfies both TextMapWriter and TextMapReader.
//
// Example usage for server side:
//
// carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
// clientContext, err := tracer.Extract(opentracing.HTTPHeaders, carrier)
//
// Example usage for client side:
//
// carrier := opentracing.HTTPHeadersCarrier(httpReq.Header)
// err := tracer.Inject(
// span.Context(),
// opentracing.HTTPHeaders,
// carrier)
//
type HTTPHeadersCarrier http.Header
// Set conforms to the TextMapWriter interface.
func (c HTTPHeadersCarrier) Set(key, val string) {
h := http.Header(c)
h.Set(key, val)
}
// ForeachKey conforms to the TextMapReader interface.
func (c HTTPHeadersCarrier) ForeachKey(handler func(key, val string) error) error {
for k, vals := range c {
for _, v := range vals {
if err := handler(k, v); err != nil {
return err
}
}
}
return nil
}
|
