1 files changed, 516 insertions, 0 deletions

diff --git a/vendor/go.opencensus.io/trace/trace.go b/vendor/go.opencensus.io/trace/trace.go
new file mode 100644
index 0000000..9e5e5f0
--- /dev/null
+++ b/vendor/go.opencensus.io/trace/trace.go
@@ -0,0 +1,516 @@
+// Copyright 2017, OpenCensus Authors
+//
+// 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 trace
+
+import (
+        "context"
+        crand "crypto/rand"
+        "encoding/binary"
+        "fmt"
+        "math/rand"
+        "sync"
+        "sync/atomic"
+        "time"
+
+        "go.opencensus.io/internal"
+        "go.opencensus.io/trace/tracestate"
+)
+
+// Span represents a span of a trace.  It has an associated SpanContext, and
+// stores data accumulated while the span is active.
+//
+// Ideally users should interact with Spans by calling the functions in this
+// package that take a Context parameter.
+type Span struct {
+        // data contains information recorded about the span.
+        //
+        // It will be non-nil if we are exporting the span or recording events for it.
+        // Otherwise, data is nil, and the Span is simply a carrier for the
+        // SpanContext, so that the trace ID is propagated.
+        data        *SpanData
+        mu          sync.Mutex // protects the contents of *data (but not the pointer value.)
+        spanContext SpanContext
+        // spanStore is the spanStore this span belongs to, if any, otherwise it is nil.
+        *spanStore
+        endOnce sync.Once
+
+        executionTracerTaskEnd func() // ends the execution tracer span
+}
+
+// IsRecordingEvents returns true if events are being recorded for this span.
+// Use this check to avoid computing expensive annotations when they will never
+// be used.
+func (s *Span) IsRecordingEvents() bool {
+        if s == nil {
+                return false
+        }
+        return s.data != nil
+}
+
+// TraceOptions contains options associated with a trace span.
+type TraceOptions uint32
+
+// IsSampled returns true if the span will be exported.
+func (sc SpanContext) IsSampled() bool {
+        return sc.TraceOptions.IsSampled()
+}
+
+// setIsSampled sets the TraceOptions bit that determines whether the span will be exported.
+func (sc *SpanContext) setIsSampled(sampled bool) {
+        if sampled {
+                sc.TraceOptions |= 1
+        } else {
+                sc.TraceOptions &= ^TraceOptions(1)
+        }
+}
+
+// IsSampled returns true if the span will be exported.
+func (t TraceOptions) IsSampled() bool {
+        return t&1 == 1
+}
+
+// SpanContext contains the state that must propagate across process boundaries.
+//
+// SpanContext is not an implementation of context.Context.
+// TODO: add reference to external Census docs for SpanContext.
+type SpanContext struct {
+        TraceID      TraceID
+        SpanID       SpanID
+        TraceOptions TraceOptions
+        Tracestate   *tracestate.Tracestate
+}
+
+type contextKey struct{}
+
+// FromContext returns the Span stored in a context, or nil if there isn't one.
+func FromContext(ctx context.Context) *Span {
+        s, _ := ctx.Value(contextKey{}).(*Span)
+        return s
+}
+
+// NewContext returns a new context with the given Span attached.
+func NewContext(parent context.Context, s *Span) context.Context {
+        return context.WithValue(parent, contextKey{}, s)
+}
+
+// All available span kinds. Span kind must be either one of these values.
+const (
+        SpanKindUnspecified = iota
+        SpanKindServer
+        SpanKindClient
+)
+
+// StartOptions contains options concerning how a span is started.
+type StartOptions struct {
+        // Sampler to consult for this Span. If provided, it is always consulted.
+        //
+        // If not provided, then the behavior differs based on whether
+        // the parent of this Span is remote, local, or there is no parent.
+        // In the case of a remote parent or no parent, the
+        // default sampler (see Config) will be consulted. Otherwise,
+        // when there is a non-remote parent, no new sampling decision will be made:
+        // we will preserve the sampling of the parent.
+        Sampler Sampler
+
+        // SpanKind represents the kind of a span. If none is set,
+        // SpanKindUnspecified is used.
+        SpanKind int
+}
+
+// StartOption apply changes to StartOptions.
+type StartOption func(*StartOptions)
+
+// WithSpanKind makes new spans to be created with the given kind.
+func WithSpanKind(spanKind int) StartOption {
+        return func(o *StartOptions) {
+                o.SpanKind = spanKind
+        }
+}
+
+// WithSampler makes new spans to be be created with a custom sampler.
+// Otherwise, the global sampler is used.
+func WithSampler(sampler Sampler) StartOption {
+        return func(o *StartOptions) {
+                o.Sampler = sampler
+        }
+}
+
+// StartSpan starts a new child span of the current span in the context. If
+// there is no span in the context, creates a new trace and span.
+//
+// Returned context contains the newly created span. You can use it to
+// propagate the returned span in process.
+func StartSpan(ctx context.Context, name string, o ...StartOption) (context.Context, *Span) {
+        var opts StartOptions
+        var parent SpanContext
+        if p := FromContext(ctx); p != nil {
+                parent = p.spanContext
+        }
+        for _, op := range o {
+                op(&opts)
+        }
+        span := startSpanInternal(name, parent != SpanContext{}, parent, false, opts)
+
+        ctx, end := startExecutionTracerTask(ctx, name)
+        span.executionTracerTaskEnd = end
+        return NewContext(ctx, span), span
+}
+
+// StartSpanWithRemoteParent starts a new child span of the span from the given parent.
+//
+// If the incoming context contains a parent, it ignores. StartSpanWithRemoteParent is
+// preferred for cases where the parent is propagated via an incoming request.
+//
+// Returned context contains the newly created span. You can use it to
+// propagate the returned span in process.
+func StartSpanWithRemoteParent(ctx context.Context, name string, parent SpanContext, o ...StartOption) (context.Context, *Span) {
+        var opts StartOptions
+        for _, op := range o {
+                op(&opts)
+        }
+        span := startSpanInternal(name, parent != SpanContext{}, parent, true, opts)
+        ctx, end := startExecutionTracerTask(ctx, name)
+        span.executionTracerTaskEnd = end
+        return NewContext(ctx, span), span
+}
+
+func startSpanInternal(name string, hasParent bool, parent SpanContext, remoteParent bool, o StartOptions) *Span {
+        span := &Span{}
+        span.spanContext = parent
+
+        cfg := config.Load().(*Config)
+
+        if !hasParent {
+                span.spanContext.TraceID = cfg.IDGenerator.NewTraceID()
+        }
+        span.spanContext.SpanID = cfg.IDGenerator.NewSpanID()
+        sampler := cfg.DefaultSampler
+
+        if !hasParent || remoteParent || o.Sampler != nil {
+                // If this span is the child of a local span and no Sampler is set in the
+                // options, keep the parent's TraceOptions.
+                //
+                // Otherwise, consult the Sampler in the options if it is non-nil, otherwise
+                // the default sampler.
+                if o.Sampler != nil {
+                        sampler = o.Sampler
+                }
+                span.spanContext.setIsSampled(sampler(SamplingParameters{
+                        ParentContext:   parent,
+                        TraceID:         span.spanContext.TraceID,
+                        SpanID:          span.spanContext.SpanID,
+                        Name:            name,
+                        HasRemoteParent: remoteParent}).Sample)
+        }
+
+        if !internal.LocalSpanStoreEnabled && !span.spanContext.IsSampled() {
+                return span
+        }
+
+        span.data = &SpanData{
+                SpanContext:     span.spanContext,
+                StartTime:       time.Now(),
+                SpanKind:        o.SpanKind,
+                Name:            name,
+                HasRemoteParent: remoteParent,
+        }
+        if hasParent {
+                span.data.ParentSpanID = parent.SpanID
+        }
+        if internal.LocalSpanStoreEnabled {
+                var ss *spanStore
+                ss = spanStoreForNameCreateIfNew(name)
+                if ss != nil {
+                        span.spanStore = ss
+                        ss.add(span)
+                }
+        }
+
+        return span
+}
+
+// End ends the span.
+func (s *Span) End() {
+        if s == nil {
+                return
+        }
+        if s.executionTracerTaskEnd != nil {
+                s.executionTracerTaskEnd()
+        }
+        if !s.IsRecordingEvents() {
+                return
+        }
+        s.endOnce.Do(func() {
+                exp, _ := exporters.Load().(exportersMap)
+                mustExport := s.spanContext.IsSampled() && len(exp) > 0
+                if s.spanStore != nil || mustExport {
+                        sd := s.makeSpanData()
+                        sd.EndTime = internal.MonotonicEndTime(sd.StartTime)
+                        if s.spanStore != nil {
+                                s.spanStore.finished(s, sd)
+                        }
+                        if mustExport {
+                                for e := range exp {
+                                        e.ExportSpan(sd)
+                                }
+                        }
+                }
+        })
+}
+
+// makeSpanData produces a SpanData representing the current state of the Span.
+// It requires that s.data is non-nil.
+func (s *Span) makeSpanData() *SpanData {
+        var sd SpanData
+        s.mu.Lock()
+        sd = *s.data
+        if s.data.Attributes != nil {
+                sd.Attributes = make(map[string]interface{})
+                for k, v := range s.data.Attributes {
+                        sd.Attributes[k] = v
+                }
+        }
+        s.mu.Unlock()
+        return &sd
+}
+
+// SpanContext returns the SpanContext of the span.
+func (s *Span) SpanContext() SpanContext {
+        if s == nil {
+                return SpanContext{}
+        }
+        return s.spanContext
+}
+
+// SetName sets the name of the span, if it is recording events.
+func (s *Span) SetName(name string) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        s.mu.Lock()
+        s.data.Name = name
+        s.mu.Unlock()
+}
+
+// SetStatus sets the status of the span, if it is recording events.
+func (s *Span) SetStatus(status Status) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        s.mu.Lock()
+        s.data.Status = status
+        s.mu.Unlock()
+}
+
+// AddAttributes sets attributes in the span.
+//
+// Existing attributes whose keys appear in the attributes parameter are overwritten.
+func (s *Span) AddAttributes(attributes ...Attribute) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        s.mu.Lock()
+        if s.data.Attributes == nil {
+                s.data.Attributes = make(map[string]interface{})
+        }
+        copyAttributes(s.data.Attributes, attributes)
+        s.mu.Unlock()
+}
+
+// copyAttributes copies a slice of Attributes into a map.
+func copyAttributes(m map[string]interface{}, attributes []Attribute) {
+        for _, a := range attributes {
+                m[a.key] = a.value
+        }
+}
+
+func (s *Span) lazyPrintfInternal(attributes []Attribute, format string, a ...interface{}) {
+        now := time.Now()
+        msg := fmt.Sprintf(format, a...)
+        var m map[string]interface{}
+        s.mu.Lock()
+        if len(attributes) != 0 {
+                m = make(map[string]interface{})
+                copyAttributes(m, attributes)
+        }
+        s.data.Annotations = append(s.data.Annotations, Annotation{
+                Time:       now,
+                Message:    msg,
+                Attributes: m,
+        })
+        s.mu.Unlock()
+}
+
+func (s *Span) printStringInternal(attributes []Attribute, str string) {
+        now := time.Now()
+        var a map[string]interface{}
+        s.mu.Lock()
+        if len(attributes) != 0 {
+                a = make(map[string]interface{})
+                copyAttributes(a, attributes)
+        }
+        s.data.Annotations = append(s.data.Annotations, Annotation{
+                Time:       now,
+                Message:    str,
+                Attributes: a,
+        })
+        s.mu.Unlock()
+}
+
+// Annotate adds an annotation with attributes.
+// Attributes can be nil.
+func (s *Span) Annotate(attributes []Attribute, str string) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        s.printStringInternal(attributes, str)
+}
+
+// Annotatef adds an annotation with attributes.
+func (s *Span) Annotatef(attributes []Attribute, format string, a ...interface{}) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        s.lazyPrintfInternal(attributes, format, a...)
+}
+
+// AddMessageSendEvent adds a message send event to the span.
+//
+// messageID is an identifier for the message, which is recommended to be
+// unique in this span and the same between the send event and the receive
+// event (this allows to identify a message between the sender and receiver).
+// For example, this could be a sequence id.
+func (s *Span) AddMessageSendEvent(messageID, uncompressedByteSize, compressedByteSize int64) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        now := time.Now()
+        s.mu.Lock()
+        s.data.MessageEvents = append(s.data.MessageEvents, MessageEvent{
+                Time:                 now,
+                EventType:            MessageEventTypeSent,
+                MessageID:            messageID,
+                UncompressedByteSize: uncompressedByteSize,
+                CompressedByteSize:   compressedByteSize,
+        })
+        s.mu.Unlock()
+}
+
+// AddMessageReceiveEvent adds a message receive event to the span.
+//
+// messageID is an identifier for the message, which is recommended to be
+// unique in this span and the same between the send event and the receive
+// event (this allows to identify a message between the sender and receiver).
+// For example, this could be a sequence id.
+func (s *Span) AddMessageReceiveEvent(messageID, uncompressedByteSize, compressedByteSize int64) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        now := time.Now()
+        s.mu.Lock()
+        s.data.MessageEvents = append(s.data.MessageEvents, MessageEvent{
+                Time:                 now,
+                EventType:            MessageEventTypeRecv,
+                MessageID:            messageID,
+                UncompressedByteSize: uncompressedByteSize,
+                CompressedByteSize:   compressedByteSize,
+        })
+        s.mu.Unlock()
+}
+
+// AddLink adds a link to the span.
+func (s *Span) AddLink(l Link) {
+        if !s.IsRecordingEvents() {
+                return
+        }
+        s.mu.Lock()
+        s.data.Links = append(s.data.Links, l)
+        s.mu.Unlock()
+}
+
+func (s *Span) String() string {
+        if s == nil {
+                return "<nil>"
+        }
+        if s.data == nil {
+                return fmt.Sprintf("span %s", s.spanContext.SpanID)
+        }
+        s.mu.Lock()
+        str := fmt.Sprintf("span %s %q", s.spanContext.SpanID, s.data.Name)
+        s.mu.Unlock()
+        return str
+}
+
+var config atomic.Value // access atomically
+
+func init() {
+        gen := &defaultIDGenerator{}
+        // initialize traceID and spanID generators.
+        var rngSeed int64
+        for _, p := range []interface{}{
+                &rngSeed, &gen.traceIDAdd, &gen.nextSpanID, &gen.spanIDInc,
+        } {
+                binary.Read(crand.Reader, binary.LittleEndian, p)
+        }
+        gen.traceIDRand = rand.New(rand.NewSource(rngSeed))
+        gen.spanIDInc |= 1
+
+        config.Store(&Config{
+                DefaultSampler: ProbabilitySampler(defaultSamplingProbability),
+                IDGenerator:    gen,
+        })
+}
+
+type defaultIDGenerator struct {
+        sync.Mutex
+
+        // Please keep these as the first fields
+        // so that these 8 byte fields will be aligned on addresses
+        // divisible by 8, on both 32-bit and 64-bit machines when
+        // performing atomic increments and accesses.
+        // See:
+        // * https://github.com/census-instrumentation/opencensus-go/issues/587
+        // * https://github.com/census-instrumentation/opencensus-go/issues/865
+        // * https://golang.org/pkg/sync/atomic/#pkg-note-BUG
+        nextSpanID uint64
+        spanIDInc  uint64
+
+        traceIDAdd  [2]uint64
+        traceIDRand *rand.Rand
+}
+
+// NewSpanID returns a non-zero span ID from a randomly-chosen sequence.
+func (gen *defaultIDGenerator) NewSpanID() [8]byte {
+        var id uint64
+        for id == 0 {
+                id = atomic.AddUint64(&gen.nextSpanID, gen.spanIDInc)
+        }
+        var sid [8]byte
+        binary.LittleEndian.PutUint64(sid[:], id)
+        return sid
+}
+
+// NewTraceID returns a non-zero trace ID from a randomly-chosen sequence.
+// mu should be held while this function is called.
+func (gen *defaultIDGenerator) NewTraceID() [16]byte {
+        var tid [16]byte
+        // Construct the trace ID from two outputs of traceIDRand, with a constant
+        // added to each half for additional entropy.
+        gen.Lock()
+        binary.LittleEndian.PutUint64(tid[0:8], gen.traceIDRand.Uint64()+gen.traceIDAdd[0])
+        binary.LittleEndian.PutUint64(tid[8:16], gen.traceIDRand.Uint64()+gen.traceIDAdd[1])
+        gen.Unlock()
+        return tid
+}