swarm: integrate OpenTracing; propagate ctx to internal APIs (#17169)

* swarm: propagate ctx, enable opentracing

* swarm/tracing: log error when tracing is misconfigured

vendor/github.com/uber/jaeger-client-go/span.go

@@ -0,0 +1,249 @@
+// Copyright (c) 2017-2018 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 (
+	"sync"
+	"time"
+
+	"github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
+	"github.com/opentracing/opentracing-go/log"
+)
+
+// Span implements opentracing.Span
+type Span struct {
+	sync.RWMutex
+
+	tracer *Tracer
+
+	context SpanContext
+
+	// The name of the "operation" this span is an instance of.
+	// Known as a "span name" in some implementations.
+	operationName string
+
+	// firstInProcess, if true, indicates that this span is the root of the (sub)tree
+	// of spans in the current process. In other words it's true for the root spans,
+	// and the ingress spans when the process joins another trace.
+	firstInProcess bool
+
+	// startTime is the timestamp indicating when the span began, with microseconds precision.
+	startTime time.Time
+
+	// duration returns duration of the span with microseconds precision.
+	// Zero value means duration is unknown.
+	duration time.Duration
+
+	// tags attached to this span
+	tags []Tag
+
+	// The span's "micro-log"
+	logs []opentracing.LogRecord
+
+	// references for this span
+	references []Reference
+
+	observer ContribSpanObserver
+}
+
+// Tag is a simple key value wrapper.
+// TODO deprecate in the next major release, use opentracing.Tag instead.
+type Tag struct {
+	key   string
+	value interface{}
+}
+
+// SetOperationName sets or changes the operation name.
+func (s *Span) SetOperationName(operationName string) opentracing.Span {
+	s.Lock()
+	defer s.Unlock()
+	if s.context.IsSampled() {
+		s.operationName = operationName
+	}
+	s.observer.OnSetOperationName(operationName)
+	return s
+}
+
+// SetTag implements SetTag() of opentracing.Span
+func (s *Span) SetTag(key string, value interface{}) opentracing.Span {
+	s.observer.OnSetTag(key, value)
+	if key == string(ext.SamplingPriority) && !setSamplingPriority(s, value) {
+		return s
+	}
+	s.Lock()
+	defer s.Unlock()
+	if s.context.IsSampled() {
+		s.setTagNoLocking(key, value)
+	}
+	return s
+}
+
+func (s *Span) setTagNoLocking(key string, value interface{}) {
+	s.tags = append(s.tags, Tag{key: key, value: value})
+}
+
+// LogFields implements opentracing.Span API
+func (s *Span) LogFields(fields ...log.Field) {
+	s.Lock()
+	defer s.Unlock()
+	if !s.context.IsSampled() {
+		return
+	}
+	s.logFieldsNoLocking(fields...)
+}
+
+// this function should only be called while holding a Write lock
+func (s *Span) logFieldsNoLocking(fields ...log.Field) {
+	lr := opentracing.LogRecord{
+		Fields:    fields,
+		Timestamp: time.Now(),
+	}
+	s.appendLog(lr)
+}
+
+// LogKV implements opentracing.Span API
+func (s *Span) LogKV(alternatingKeyValues ...interface{}) {
+	s.RLock()
+	sampled := s.context.IsSampled()
+	s.RUnlock()
+	if !sampled {
+		return
+	}
+	fields, err := log.InterleavedKVToFields(alternatingKeyValues...)
+	if err != nil {
+		s.LogFields(log.Error(err), log.String("function", "LogKV"))
+		return
+	}
+	s.LogFields(fields...)
+}
+
+// LogEvent implements opentracing.Span API
+func (s *Span) LogEvent(event string) {
+	s.Log(opentracing.LogData{Event: event})
+}
+
+// LogEventWithPayload implements opentracing.Span API
+func (s *Span) LogEventWithPayload(event string, payload interface{}) {
+	s.Log(opentracing.LogData{Event: event, Payload: payload})
+}
+
+// Log implements opentracing.Span API
+func (s *Span) Log(ld opentracing.LogData) {
+	s.Lock()
+	defer s.Unlock()
+	if s.context.IsSampled() {
+		if ld.Timestamp.IsZero() {
+			ld.Timestamp = s.tracer.timeNow()
+		}
+		s.appendLog(ld.ToLogRecord())
+	}
+}
+
+// this function should only be called while holding a Write lock
+func (s *Span) appendLog(lr opentracing.LogRecord) {
+	// TODO add logic to limit number of logs per span (issue #46)
+	s.logs = append(s.logs, lr)
+}
+
+// SetBaggageItem implements SetBaggageItem() of opentracing.SpanContext
+func (s *Span) SetBaggageItem(key, value string) opentracing.Span {
+	s.Lock()
+	defer s.Unlock()
+	s.tracer.setBaggage(s, key, value)
+	return s
+}
+
+// BaggageItem implements BaggageItem() of opentracing.SpanContext
+func (s *Span) BaggageItem(key string) string {
+	s.RLock()
+	defer s.RUnlock()
+	return s.context.baggage[key]
+}
+
+// Finish implements opentracing.Span API
+func (s *Span) Finish() {
+	s.FinishWithOptions(opentracing.FinishOptions{})
+}
+
+// FinishWithOptions implements opentracing.Span API
+func (s *Span) FinishWithOptions(options opentracing.FinishOptions) {
+	if options.FinishTime.IsZero() {
+		options.FinishTime = s.tracer.timeNow()
+	}
+	s.observer.OnFinish(options)
+	s.Lock()
+	if s.context.IsSampled() {
+		s.duration = options.FinishTime.Sub(s.startTime)
+		// Note: bulk logs are not subject to maxLogsPerSpan limit
+		if options.LogRecords != nil {
+			s.logs = append(s.logs, options.LogRecords...)
+		}
+		for _, ld := range options.BulkLogData {
+			s.logs = append(s.logs, ld.ToLogRecord())
+		}
+	}
+	s.Unlock()
+	// call reportSpan even for non-sampled traces, to return span to the pool
+	s.tracer.reportSpan(s)
+}
+
+// Context implements opentracing.Span API
+func (s *Span) Context() opentracing.SpanContext {
+	s.Lock()
+	defer s.Unlock()
+	return s.context
+}
+
+// Tracer implements opentracing.Span API
+func (s *Span) Tracer() opentracing.Tracer {
+	return s.tracer
+}
+
+func (s *Span) String() string {
+	s.RLock()
+	defer s.RUnlock()
+	return s.context.String()
+}
+
+// OperationName allows retrieving current operation name.
+func (s *Span) OperationName() string {
+	s.RLock()
+	defer s.RUnlock()
+	return s.operationName
+}
+
+func (s *Span) serviceName() string {
+	return s.tracer.serviceName
+}
+
+// setSamplingPriority returns true if the flag was updated successfully, false otherwise.
+func setSamplingPriority(s *Span, value interface{}) bool {
+	s.Lock()
+	defer s.Unlock()
+	val, ok := value.(uint16)
+	if !ok {
+		return false
+	}
+	if val == 0 {
+		s.context.flags = s.context.flags & (^flagSampled)
+		return true
+	}
+	if s.tracer.isDebugAllowed(s.operationName) {
+		s.context.flags = s.context.flags | flagDebug | flagSampled
+		return true
+	}
+	return false
+}