Naveen Sampath | 04696f7 | 2022-06-13 15:19:14 +0530 | [diff] [blame^] | 1 | // Copyright (c) 2017 Uber Technologies, Inc. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package jaeger |
| 16 | |
| 17 | import ( |
| 18 | "errors" |
| 19 | "fmt" |
| 20 | "strconv" |
| 21 | "strings" |
| 22 | "sync" |
| 23 | |
| 24 | "go.uber.org/atomic" |
| 25 | ) |
| 26 | |
| 27 | const ( |
| 28 | flagSampled = 1 |
| 29 | flagDebug = 2 |
| 30 | flagFirehose = 8 |
| 31 | ) |
| 32 | |
| 33 | var ( |
| 34 | errEmptyTracerStateString = errors.New("Cannot convert empty string to tracer state") |
| 35 | errMalformedTracerStateString = errors.New("String does not match tracer state format") |
| 36 | |
| 37 | emptyContext = SpanContext{} |
| 38 | ) |
| 39 | |
| 40 | // TraceID represents unique 128bit identifier of a trace |
| 41 | type TraceID struct { |
| 42 | High, Low uint64 |
| 43 | } |
| 44 | |
| 45 | // SpanID represents unique 64bit identifier of a span |
| 46 | type SpanID uint64 |
| 47 | |
| 48 | // SpanContext represents propagated span identity and state |
| 49 | type SpanContext struct { |
| 50 | // traceID represents globally unique ID of the trace. |
| 51 | // Usually generated as a random number. |
| 52 | traceID TraceID |
| 53 | |
| 54 | // spanID represents span ID that must be unique within its trace, |
| 55 | // but does not have to be globally unique. |
| 56 | spanID SpanID |
| 57 | |
| 58 | // parentID refers to the ID of the parent span. |
| 59 | // Should be 0 if the current span is a root span. |
| 60 | parentID SpanID |
| 61 | |
| 62 | // Distributed Context baggage. The is a snapshot in time. |
| 63 | baggage map[string]string |
| 64 | |
| 65 | // debugID can be set to some correlation ID when the context is being |
| 66 | // extracted from a TextMap carrier. |
| 67 | // |
| 68 | // See JaegerDebugHeader in constants.go |
| 69 | debugID string |
| 70 | |
| 71 | // samplingState is shared across all spans |
| 72 | samplingState *samplingState |
| 73 | |
| 74 | // remote indicates that span context represents a remote parent |
| 75 | remote bool |
| 76 | } |
| 77 | |
| 78 | type samplingState struct { |
| 79 | // Span context's state flags that are propagated across processes. Only lower 8 bits are used. |
| 80 | // We use an int32 instead of byte to be able to use CAS operations. |
| 81 | stateFlags atomic.Int32 |
| 82 | |
| 83 | // When state is not final, sampling will be retried on other span write operations, |
| 84 | // like SetOperationName / SetTag, and the spans will remain writable. |
| 85 | final atomic.Bool |
| 86 | |
| 87 | // localRootSpan stores the SpanID of the first span created in this process for a given trace. |
| 88 | localRootSpan SpanID |
| 89 | |
| 90 | // extendedState allows samplers to keep intermediate state. |
| 91 | // The keys and values in this map are completely opaque: interface{} -> interface{}. |
| 92 | extendedState sync.Map |
| 93 | } |
| 94 | |
| 95 | func (s *samplingState) isLocalRootSpan(id SpanID) bool { |
| 96 | return id == s.localRootSpan |
| 97 | } |
| 98 | |
| 99 | func (s *samplingState) setFlag(newFlag int32) { |
| 100 | swapped := false |
| 101 | for !swapped { |
| 102 | old := s.stateFlags.Load() |
| 103 | swapped = s.stateFlags.CAS(old, old|newFlag) |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | func (s *samplingState) unsetFlag(newFlag int32) { |
| 108 | swapped := false |
| 109 | for !swapped { |
| 110 | old := s.stateFlags.Load() |
| 111 | swapped = s.stateFlags.CAS(old, old&^newFlag) |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | func (s *samplingState) setSampled() { |
| 116 | s.setFlag(flagSampled) |
| 117 | } |
| 118 | |
| 119 | func (s *samplingState) unsetSampled() { |
| 120 | s.unsetFlag(flagSampled) |
| 121 | } |
| 122 | |
| 123 | func (s *samplingState) setDebugAndSampled() { |
| 124 | s.setFlag(flagDebug | flagSampled) |
| 125 | } |
| 126 | |
| 127 | func (s *samplingState) setFirehose() { |
| 128 | s.setFlag(flagFirehose) |
| 129 | } |
| 130 | |
| 131 | func (s *samplingState) setFlags(flags byte) { |
| 132 | s.stateFlags.Store(int32(flags)) |
| 133 | } |
| 134 | |
| 135 | func (s *samplingState) setFinal() { |
| 136 | s.final.Store(true) |
| 137 | } |
| 138 | |
| 139 | func (s *samplingState) flags() byte { |
| 140 | return byte(s.stateFlags.Load()) |
| 141 | } |
| 142 | |
| 143 | func (s *samplingState) isSampled() bool { |
| 144 | return s.stateFlags.Load()&flagSampled == flagSampled |
| 145 | } |
| 146 | |
| 147 | func (s *samplingState) isDebug() bool { |
| 148 | return s.stateFlags.Load()&flagDebug == flagDebug |
| 149 | } |
| 150 | |
| 151 | func (s *samplingState) isFirehose() bool { |
| 152 | return s.stateFlags.Load()&flagFirehose == flagFirehose |
| 153 | } |
| 154 | |
| 155 | func (s *samplingState) isFinal() bool { |
| 156 | return s.final.Load() |
| 157 | } |
| 158 | |
| 159 | func (s *samplingState) extendedStateForKey(key interface{}, initValue func() interface{}) interface{} { |
| 160 | if value, ok := s.extendedState.Load(key); ok { |
| 161 | return value |
| 162 | } |
| 163 | value := initValue() |
| 164 | value, _ = s.extendedState.LoadOrStore(key, value) |
| 165 | return value |
| 166 | } |
| 167 | |
| 168 | // ForeachBaggageItem implements ForeachBaggageItem() of opentracing.SpanContext |
| 169 | func (c SpanContext) ForeachBaggageItem(handler func(k, v string) bool) { |
| 170 | for k, v := range c.baggage { |
| 171 | if !handler(k, v) { |
| 172 | break |
| 173 | } |
| 174 | } |
| 175 | } |
| 176 | |
| 177 | // IsSampled returns whether this trace was chosen for permanent storage |
| 178 | // by the sampling mechanism of the tracer. |
| 179 | func (c SpanContext) IsSampled() bool { |
| 180 | return c.samplingState.isSampled() |
| 181 | } |
| 182 | |
| 183 | // IsDebug indicates whether sampling was explicitly requested by the service. |
| 184 | func (c SpanContext) IsDebug() bool { |
| 185 | return c.samplingState.isDebug() |
| 186 | } |
| 187 | |
| 188 | // IsSamplingFinalized indicates whether the sampling decision has been finalized. |
| 189 | func (c SpanContext) IsSamplingFinalized() bool { |
| 190 | return c.samplingState.isFinal() |
| 191 | } |
| 192 | |
| 193 | // IsFirehose indicates whether the firehose flag was set |
| 194 | func (c SpanContext) IsFirehose() bool { |
| 195 | return c.samplingState.isFirehose() |
| 196 | } |
| 197 | |
| 198 | // ExtendedSamplingState returns the custom state object for a given key. If the value for this key does not exist, |
| 199 | // it is initialized via initValue function. This state can be used by samplers (e.g. x.PrioritySampler). |
| 200 | func (c SpanContext) ExtendedSamplingState(key interface{}, initValue func() interface{}) interface{} { |
| 201 | return c.samplingState.extendedStateForKey(key, initValue) |
| 202 | } |
| 203 | |
| 204 | // IsValid indicates whether this context actually represents a valid trace. |
| 205 | func (c SpanContext) IsValid() bool { |
| 206 | return c.traceID.IsValid() && c.spanID != 0 |
| 207 | } |
| 208 | |
| 209 | // SetFirehose enables firehose mode for this trace. |
| 210 | func (c SpanContext) SetFirehose() { |
| 211 | c.samplingState.setFirehose() |
| 212 | } |
| 213 | |
| 214 | func (c SpanContext) String() string { |
| 215 | var flags int32 |
| 216 | if c.samplingState != nil { |
| 217 | flags = c.samplingState.stateFlags.Load() |
| 218 | } |
| 219 | if c.traceID.High == 0 { |
| 220 | return fmt.Sprintf("%016x:%016x:%016x:%x", c.traceID.Low, uint64(c.spanID), uint64(c.parentID), flags) |
| 221 | } |
| 222 | return fmt.Sprintf("%016x%016x:%016x:%016x:%x", c.traceID.High, c.traceID.Low, uint64(c.spanID), uint64(c.parentID), flags) |
| 223 | } |
| 224 | |
| 225 | // ContextFromString reconstructs the Context encoded in a string |
| 226 | func ContextFromString(value string) (SpanContext, error) { |
| 227 | var context SpanContext |
| 228 | if value == "" { |
| 229 | return emptyContext, errEmptyTracerStateString |
| 230 | } |
| 231 | parts := strings.Split(value, ":") |
| 232 | if len(parts) != 4 { |
| 233 | return emptyContext, errMalformedTracerStateString |
| 234 | } |
| 235 | var err error |
| 236 | if context.traceID, err = TraceIDFromString(parts[0]); err != nil { |
| 237 | return emptyContext, err |
| 238 | } |
| 239 | if context.spanID, err = SpanIDFromString(parts[1]); err != nil { |
| 240 | return emptyContext, err |
| 241 | } |
| 242 | if context.parentID, err = SpanIDFromString(parts[2]); err != nil { |
| 243 | return emptyContext, err |
| 244 | } |
| 245 | flags, err := strconv.ParseUint(parts[3], 10, 8) |
| 246 | if err != nil { |
| 247 | return emptyContext, err |
| 248 | } |
| 249 | context.samplingState = &samplingState{} |
| 250 | context.samplingState.setFlags(byte(flags)) |
| 251 | return context, nil |
| 252 | } |
| 253 | |
| 254 | // TraceID returns the trace ID of this span context |
| 255 | func (c SpanContext) TraceID() TraceID { |
| 256 | return c.traceID |
| 257 | } |
| 258 | |
| 259 | // SpanID returns the span ID of this span context |
| 260 | func (c SpanContext) SpanID() SpanID { |
| 261 | return c.spanID |
| 262 | } |
| 263 | |
| 264 | // ParentID returns the parent span ID of this span context |
| 265 | func (c SpanContext) ParentID() SpanID { |
| 266 | return c.parentID |
| 267 | } |
| 268 | |
| 269 | // Flags returns the bitmap containing such bits as 'sampled' and 'debug'. |
| 270 | func (c SpanContext) Flags() byte { |
| 271 | return c.samplingState.flags() |
| 272 | } |
| 273 | |
| 274 | // Span can be written to if it is sampled or the sampling decision has not been finalized. |
| 275 | func (c SpanContext) isWriteable() bool { |
| 276 | state := c.samplingState |
| 277 | return !state.isFinal() || state.isSampled() |
| 278 | } |
| 279 | |
| 280 | func (c SpanContext) isSamplingFinalized() bool { |
| 281 | return c.samplingState.isFinal() |
| 282 | } |
| 283 | |
| 284 | // NewSpanContext creates a new instance of SpanContext |
| 285 | func NewSpanContext(traceID TraceID, spanID, parentID SpanID, sampled bool, baggage map[string]string) SpanContext { |
| 286 | samplingState := &samplingState{} |
| 287 | if sampled { |
| 288 | samplingState.setSampled() |
| 289 | } |
| 290 | |
| 291 | return SpanContext{ |
| 292 | traceID: traceID, |
| 293 | spanID: spanID, |
| 294 | parentID: parentID, |
| 295 | samplingState: samplingState, |
| 296 | baggage: baggage} |
| 297 | } |
| 298 | |
| 299 | // CopyFrom copies data from ctx into this context, including span identity and baggage. |
| 300 | // TODO This is only used by interop.go. Remove once TChannel Go supports OpenTracing. |
| 301 | func (c *SpanContext) CopyFrom(ctx *SpanContext) { |
| 302 | c.traceID = ctx.traceID |
| 303 | c.spanID = ctx.spanID |
| 304 | c.parentID = ctx.parentID |
| 305 | c.samplingState = ctx.samplingState |
| 306 | if l := len(ctx.baggage); l > 0 { |
| 307 | c.baggage = make(map[string]string, l) |
| 308 | for k, v := range ctx.baggage { |
| 309 | c.baggage[k] = v |
| 310 | } |
| 311 | } else { |
| 312 | c.baggage = nil |
| 313 | } |
| 314 | } |
| 315 | |
| 316 | // WithBaggageItem creates a new context with an extra baggage item. |
| 317 | // Delete a baggage item if provided blank value. |
| 318 | // |
| 319 | // The SpanContext is designed to be immutable and passed by value. As such, |
| 320 | // it cannot contain any locks, and should only hold immutable data, including baggage. |
| 321 | // Another reason for why baggage is immutable is when the span context is passed |
| 322 | // as a parent when starting a new span. The new span's baggage cannot affect the parent |
| 323 | // span's baggage, so the child span either needs to take a copy of the parent baggage |
| 324 | // (which is expensive and unnecessary since baggage rarely changes in the life span of |
| 325 | // a trace), or it needs to do a copy-on-write, which is the approach taken here. |
| 326 | func (c SpanContext) WithBaggageItem(key, value string) SpanContext { |
| 327 | var newBaggage map[string]string |
| 328 | // unset baggage item |
| 329 | if value == "" { |
| 330 | if _, ok := c.baggage[key]; !ok { |
| 331 | return c |
| 332 | } |
| 333 | newBaggage = make(map[string]string, len(c.baggage)) |
| 334 | for k, v := range c.baggage { |
| 335 | newBaggage[k] = v |
| 336 | } |
| 337 | delete(newBaggage, key) |
| 338 | return SpanContext{c.traceID, c.spanID, c.parentID, newBaggage, "", c.samplingState, c.remote} |
| 339 | } |
| 340 | if c.baggage == nil { |
| 341 | newBaggage = map[string]string{key: value} |
| 342 | } else { |
| 343 | newBaggage = make(map[string]string, len(c.baggage)+1) |
| 344 | for k, v := range c.baggage { |
| 345 | newBaggage[k] = v |
| 346 | } |
| 347 | newBaggage[key] = value |
| 348 | } |
| 349 | // Use positional parameters so the compiler will help catch new fields. |
| 350 | return SpanContext{c.traceID, c.spanID, c.parentID, newBaggage, "", c.samplingState, c.remote} |
| 351 | } |
| 352 | |
| 353 | // isDebugIDContainerOnly returns true when the instance of the context is only |
| 354 | // used to return the debug/correlation ID from extract() method. This happens |
| 355 | // in the situation when "jaeger-debug-id" header is passed in the carrier to |
| 356 | // the extract() method, but the request otherwise has no span context in it. |
| 357 | // Previously this would've returned opentracing.ErrSpanContextNotFound from the |
| 358 | // extract method, but now it returns a dummy context with only debugID filled in. |
| 359 | // |
| 360 | // See JaegerDebugHeader in constants.go |
| 361 | // See TextMapPropagator#Extract |
| 362 | func (c *SpanContext) isDebugIDContainerOnly() bool { |
| 363 | return !c.traceID.IsValid() && c.debugID != "" |
| 364 | } |
| 365 | |
| 366 | // ------- TraceID ------- |
| 367 | |
| 368 | func (t TraceID) String() string { |
| 369 | if t.High == 0 { |
| 370 | return fmt.Sprintf("%016x", t.Low) |
| 371 | } |
| 372 | return fmt.Sprintf("%016x%016x", t.High, t.Low) |
| 373 | } |
| 374 | |
| 375 | // TraceIDFromString creates a TraceID from a hexadecimal string |
| 376 | func TraceIDFromString(s string) (TraceID, error) { |
| 377 | var hi, lo uint64 |
| 378 | var err error |
| 379 | if len(s) > 32 { |
| 380 | return TraceID{}, fmt.Errorf("TraceID cannot be longer than 32 hex characters: %s", s) |
| 381 | } else if len(s) > 16 { |
| 382 | hiLen := len(s) - 16 |
| 383 | if hi, err = strconv.ParseUint(s[0:hiLen], 16, 64); err != nil { |
| 384 | return TraceID{}, err |
| 385 | } |
| 386 | if lo, err = strconv.ParseUint(s[hiLen:], 16, 64); err != nil { |
| 387 | return TraceID{}, err |
| 388 | } |
| 389 | } else { |
| 390 | if lo, err = strconv.ParseUint(s, 16, 64); err != nil { |
| 391 | return TraceID{}, err |
| 392 | } |
| 393 | } |
| 394 | return TraceID{High: hi, Low: lo}, nil |
| 395 | } |
| 396 | |
| 397 | // IsValid checks if the trace ID is valid, i.e. not zero. |
| 398 | func (t TraceID) IsValid() bool { |
| 399 | return t.High != 0 || t.Low != 0 |
| 400 | } |
| 401 | |
| 402 | // ------- SpanID ------- |
| 403 | |
| 404 | func (s SpanID) String() string { |
| 405 | return fmt.Sprintf("%016x", uint64(s)) |
| 406 | } |
| 407 | |
| 408 | // SpanIDFromString creates a SpanID from a hexadecimal string |
| 409 | func SpanIDFromString(s string) (SpanID, error) { |
| 410 | if len(s) > 16 { |
| 411 | return SpanID(0), fmt.Errorf("SpanID cannot be longer than 16 hex characters: %s", s) |
| 412 | } |
| 413 | id, err := strconv.ParseUint(s, 16, 64) |
| 414 | if err != nil { |
| 415 | return SpanID(0), err |
| 416 | } |
| 417 | return SpanID(id), nil |
| 418 | } |