summaryrefslogtreecommitdiff
path: root/vendor/github.com/uber/jaeger-client-go/span_context.go
blob: b7230abfeec1cac48cf8cf3479acb2a5d12621af (plain)
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
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
// Copyright (c) 2017 Uber Technologies, Inc.
//
// 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 jaeger

import (
	"errors"
	"fmt"
	"strconv"
	"strings"
	"sync"

	"go.uber.org/atomic"
)

const (
	flagSampled  = 1
	flagDebug    = 2
	flagFirehose = 8
)

var (
	errEmptyTracerStateString     = errors.New("Cannot convert empty string to tracer state")
	errMalformedTracerStateString = errors.New("String does not match tracer state format")

	emptyContext = SpanContext{}
)

// TraceID represents unique 128bit identifier of a trace
type TraceID struct {
	High, Low uint64
}

// SpanID represents unique 64bit identifier of a span
type SpanID uint64

// SpanContext represents propagated span identity and state
type SpanContext struct {
	// traceID represents globally unique ID of the trace.
	// Usually generated as a random number.
	traceID TraceID

	// spanID represents span ID that must be unique within its trace,
	// but does not have to be globally unique.
	spanID SpanID

	// parentID refers to the ID of the parent span.
	// Should be 0 if the current span is a root span.
	parentID SpanID

	// Distributed Context baggage. The is a snapshot in time.
	baggage map[string]string

	// debugID can be set to some correlation ID when the context is being
	// extracted from a TextMap carrier.
	//
	// See JaegerDebugHeader in constants.go
	debugID string

	// samplingState is shared across all spans
	samplingState *samplingState

	// remote indicates that span context represents a remote parent
	remote bool
}

type samplingState struct {
	// Span context's state flags that are propagated across processes. Only lower 8 bits are used.
	// We use an int32 instead of byte to be able to use CAS operations.
	stateFlags atomic.Int32

	// When state is not final, sampling will be retried on other span write operations,
	// like SetOperationName / SetTag, and the spans will remain writable.
	final atomic.Bool

	// localRootSpan stores the SpanID of the first span created in this process for a given trace.
	localRootSpan SpanID

	// extendedState allows samplers to keep intermediate state.
	// The keys and values in this map are completely opaque: interface{} -> interface{}.
	extendedState sync.Map
}

func (s *samplingState) isLocalRootSpan(id SpanID) bool {
	return id == s.localRootSpan
}

func (s *samplingState) setFlag(newFlag int32) {
	swapped := false
	for !swapped {
		old := s.stateFlags.Load()
		swapped = s.stateFlags.CAS(old, old|newFlag)
	}
}

func (s *samplingState) unsetFlag(newFlag int32) {
	swapped := false
	for !swapped {
		old := s.stateFlags.Load()
		swapped = s.stateFlags.CAS(old, old&^newFlag)
	}
}

func (s *samplingState) setSampled() {
	s.setFlag(flagSampled)
}

func (s *samplingState) unsetSampled() {
	s.unsetFlag(flagSampled)
}

func (s *samplingState) setDebugAndSampled() {
	s.setFlag(flagDebug | flagSampled)
}

func (s *samplingState) setFirehose() {
	s.setFlag(flagFirehose)
}

func (s *samplingState) setFlags(flags byte) {
	s.stateFlags.Store(int32(flags))
}

func (s *samplingState) setFinal() {
	s.final.Store(true)
}

func (s *samplingState) flags() byte {
	return byte(s.stateFlags.Load())
}

func (s *samplingState) isSampled() bool {
	return s.stateFlags.Load()&flagSampled == flagSampled
}

func (s *samplingState) isDebug() bool {
	return s.stateFlags.Load()&flagDebug == flagDebug
}

func (s *samplingState) isFirehose() bool {
	return s.stateFlags.Load()&flagFirehose == flagFirehose
}

func (s *samplingState) isFinal() bool {
	return s.final.Load()
}

func (s *samplingState) extendedStateForKey(key interface{}, initValue func() interface{}) interface{} {
	if value, ok := s.extendedState.Load(key); ok {
		return value
	}
	value := initValue()
	value, _ = s.extendedState.LoadOrStore(key, value)
	return value
}

// ForeachBaggageItem implements ForeachBaggageItem() of opentracing.SpanContext
func (c SpanContext) ForeachBaggageItem(handler func(k, v string) bool) {
	for k, v := range c.baggage {
		if !handler(k, v) {
			break
		}
	}
}

// IsSampled returns whether this trace was chosen for permanent storage
// by the sampling mechanism of the tracer.
func (c SpanContext) IsSampled() bool {
	return c.samplingState.isSampled()
}

// IsDebug indicates whether sampling was explicitly requested by the service.
func (c SpanContext) IsDebug() bool {
	return c.samplingState.isDebug()
}

// IsSamplingFinalized indicates whether the sampling decision has been finalized.
func (c SpanContext) IsSamplingFinalized() bool {
	return c.samplingState.isFinal()
}

// IsFirehose indicates whether the firehose flag was set
func (c SpanContext) IsFirehose() bool {
	return c.samplingState.isFirehose()
}

// ExtendedSamplingState returns the custom state object for a given key. If the value for this key does not exist,
// it is initialized via initValue function. This state can be used by samplers (e.g. x.PrioritySampler).
func (c SpanContext) ExtendedSamplingState(key interface{}, initValue func() interface{}) interface{} {
	return c.samplingState.extendedStateForKey(key, initValue)
}

// IsValid indicates whether this context actually represents a valid trace.
func (c SpanContext) IsValid() bool {
	return c.traceID.IsValid() && c.spanID != 0
}

// SetFirehose enables firehose mode for this trace.
func (c SpanContext) SetFirehose() {
	c.samplingState.setFirehose()
}

func (c SpanContext) String() string {
	if c.traceID.High == 0 {
		return fmt.Sprintf("%x:%x:%x:%x", c.traceID.Low, uint64(c.spanID), uint64(c.parentID), c.samplingState.stateFlags.Load())
	}
	return fmt.Sprintf("%x%016x:%x:%x:%x", c.traceID.High, c.traceID.Low, uint64(c.spanID), uint64(c.parentID), c.samplingState.stateFlags.Load())
}

// ContextFromString reconstructs the Context encoded in a string
func ContextFromString(value string) (SpanContext, error) {
	var context SpanContext
	if value == "" {
		return emptyContext, errEmptyTracerStateString
	}
	parts := strings.Split(value, ":")
	if len(parts) != 4 {
		return emptyContext, errMalformedTracerStateString
	}
	var err error
	if context.traceID, err = TraceIDFromString(parts[0]); err != nil {
		return emptyContext, err
	}
	if context.spanID, err = SpanIDFromString(parts[1]); err != nil {
		return emptyContext, err
	}
	if context.parentID, err = SpanIDFromString(parts[2]); err != nil {
		return emptyContext, err
	}
	flags, err := strconv.ParseUint(parts[3], 10, 8)
	if err != nil {
		return emptyContext, err
	}
	context.samplingState = &samplingState{}
	context.samplingState.setFlags(byte(flags))
	return context, nil
}

// TraceID returns the trace ID of this span context
func (c SpanContext) TraceID() TraceID {
	return c.traceID
}

// SpanID returns the span ID of this span context
func (c SpanContext) SpanID() SpanID {
	return c.spanID
}

// ParentID returns the parent span ID of this span context
func (c SpanContext) ParentID() SpanID {
	return c.parentID
}

// Flags returns the bitmap containing such bits as 'sampled' and 'debug'.
func (c SpanContext) Flags() byte {
	return c.samplingState.flags()
}

// NewSpanContext creates a new instance of SpanContext
func NewSpanContext(traceID TraceID, spanID, parentID SpanID, sampled bool, baggage map[string]string) SpanContext {
	samplingState := &samplingState{}
	if sampled {
		samplingState.setSampled()
	}

	return SpanContext{
		traceID:       traceID,
		spanID:        spanID,
		parentID:      parentID,
		samplingState: samplingState,
		baggage:       baggage}
}

// CopyFrom copies data from ctx into this context, including span identity and baggage.
// TODO This is only used by interop.go. Remove once TChannel Go supports OpenTracing.
func (c *SpanContext) CopyFrom(ctx *SpanContext) {
	c.traceID = ctx.traceID
	c.spanID = ctx.spanID
	c.parentID = ctx.parentID
	c.samplingState = ctx.samplingState
	if l := len(ctx.baggage); l > 0 {
		c.baggage = make(map[string]string, l)
		for k, v := range ctx.baggage {
			c.baggage[k] = v
		}
	} else {
		c.baggage = nil
	}
}

// WithBaggageItem creates a new context with an extra baggage item.
func (c SpanContext) WithBaggageItem(key, value string) SpanContext {
	var newBaggage map[string]string
	if c.baggage == nil {
		newBaggage = map[string]string{key: value}
	} else {
		newBaggage = make(map[string]string, len(c.baggage)+1)
		for k, v := range c.baggage {
			newBaggage[k] = v
		}
		newBaggage[key] = value
	}
	// Use positional parameters so the compiler will help catch new fields.
	return SpanContext{c.traceID, c.spanID, c.parentID, newBaggage, "", c.samplingState, c.remote}
}

// isDebugIDContainerOnly returns true when the instance of the context is only
// used to return the debug/correlation ID from extract() method. This happens
// in the situation when "jaeger-debug-id" header is passed in the carrier to
// the extract() method, but the request otherwise has no span context in it.
// Previously this would've returned opentracing.ErrSpanContextNotFound from the
// extract method, but now it returns a dummy context with only debugID filled in.
//
// See JaegerDebugHeader in constants.go
// See TextMapPropagator#Extract
func (c *SpanContext) isDebugIDContainerOnly() bool {
	return !c.traceID.IsValid() && c.debugID != ""
}

// ------- TraceID -------

func (t TraceID) String() string {
	if t.High == 0 {
		return fmt.Sprintf("%x", t.Low)
	}
	return fmt.Sprintf("%x%016x", t.High, t.Low)
}

// TraceIDFromString creates a TraceID from a hexadecimal string
func TraceIDFromString(s string) (TraceID, error) {
	var hi, lo uint64
	var err error
	if len(s) > 32 {
		return TraceID{}, fmt.Errorf("TraceID cannot be longer than 32 hex characters: %s", s)
	} else if len(s) > 16 {
		hiLen := len(s) - 16
		if hi, err = strconv.ParseUint(s[0:hiLen], 16, 64); err != nil {
			return TraceID{}, err
		}
		if lo, err = strconv.ParseUint(s[hiLen:], 16, 64); err != nil {
			return TraceID{}, err
		}
	} else {
		if lo, err = strconv.ParseUint(s, 16, 64); err != nil {
			return TraceID{}, err
		}
	}
	return TraceID{High: hi, Low: lo}, nil
}

// IsValid checks if the trace ID is valid, i.e. not zero.
func (t TraceID) IsValid() bool {
	return t.High != 0 || t.Low != 0
}

// ------- SpanID -------

func (s SpanID) String() string {
	return fmt.Sprintf("%x", uint64(s))
}

// SpanIDFromString creates a SpanID from a hexadecimal string
func SpanIDFromString(s string) (SpanID, error) {
	if len(s) > 16 {
		return SpanID(0), fmt.Errorf("SpanID cannot be longer than 16 hex characters: %s", s)
	}
	id, err := strconv.ParseUint(s, 16, 64)
	if err != nil {
		return SpanID(0), err
	}
	return SpanID(id), nil
}