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opentelemetry-go/sdk/trace/span.go
Tyler Yahn fe363be399
Move Span Event to API (#1452)
* Move Span Event to API

* Add changes to CHANGELOG
2021-01-14 09:07:25 -08:00

562 lines
14 KiB
Go

// Copyright The OpenTelemetry 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 "go.opentelemetry.io/otel/sdk/trace"
import (
"context"
"fmt"
"reflect"
"sync"
"time"
"go.opentelemetry.io/otel/codes"
"go.opentelemetry.io/otel/label"
"go.opentelemetry.io/otel/trace"
export "go.opentelemetry.io/otel/sdk/export/trace"
"go.opentelemetry.io/otel/sdk/instrumentation"
"go.opentelemetry.io/otel/sdk/internal"
"go.opentelemetry.io/otel/sdk/resource"
)
const (
errorTypeKey = label.Key("error.type")
errorMessageKey = label.Key("error.message")
errorEventName = "error"
)
// ReadOnlySpan allows reading information from the data structure underlying a
// trace.Span. It is used in places where reading information from a span is
// necessary but changing the span isn't necessary or allowed.
// TODO: Should we make the methods unexported? The purpose of this interface
// is controlling access to `span` fields, not having multiple implementations.
type ReadOnlySpan interface {
Name() string
SpanContext() trace.SpanContext
Parent() trace.SpanContext
SpanKind() trace.SpanKind
StartTime() time.Time
EndTime() time.Time
Attributes() []label.KeyValue
Links() []trace.Link
Events() []trace.Event
StatusCode() codes.Code
StatusMessage() string
Tracer() trace.Tracer
IsRecording() bool
InstrumentationLibrary() instrumentation.Library
Resource() *resource.Resource
Snapshot() *export.SpanSnapshot
}
// ReadWriteSpan exposes the same methods as trace.Span and in addition allows
// reading information from the underlying data structure.
// This interface exposes the union of the methods of trace.Span (which is a
// "write-only" span) and ReadOnlySpan. New methods for writing or reading span
// information should be added under trace.Span or ReadOnlySpan, respectively.
type ReadWriteSpan interface {
trace.Span
ReadOnlySpan
}
var emptySpanContext = trace.SpanContext{}
// span is an implementation of the OpenTelemetry Span API representing the
// individual component of a trace.
type span struct {
// mu protects the contents of this span.
mu sync.Mutex
// parent holds the parent span of this span as a trace.SpanContext.
parent trace.SpanContext
// spanKind represents the kind of this span as a trace.SpanKind.
spanKind trace.SpanKind
// name is the name of this span.
name string
// startTime is the time at which this span was started.
startTime time.Time
// endTime is the time at which this span was ended. It contains the zero
// value of time.Time until the span is ended.
endTime time.Time
// statusCode represents the status of this span as a codes.Code value.
statusCode codes.Code
// statusMessage represents the status of this span as a string.
statusMessage string
// hasRemoteParent is true when this span has a remote parent span.
hasRemoteParent bool
// childSpanCount holds the number of child spans created for this span.
childSpanCount int
// resource contains attributes representing an entity that produced this
// span.
resource *resource.Resource
// instrumentationLibrary defines the instrumentation library used to
// provide instrumentation.
instrumentationLibrary instrumentation.Library
// spanContext holds the SpanContext of this span.
spanContext trace.SpanContext
// attributes are capped at configured limit. When the capacity is reached
// an oldest entry is removed to create room for a new entry.
attributes *attributesMap
// messageEvents are stored in FIFO queue capped by configured limit.
messageEvents *evictedQueue
// links are stored in FIFO queue capped by configured limit.
links *evictedQueue
// executionTracerTaskEnd ends the execution tracer span.
executionTracerTaskEnd func()
// tracer is the SDK tracer that created this span.
tracer *tracer
}
var _ trace.Span = &span{}
func (s *span) SpanContext() trace.SpanContext {
if s == nil {
return trace.SpanContext{}
}
return s.spanContext
}
func (s *span) IsRecording() bool {
if s == nil {
return false
}
s.mu.Lock()
defer s.mu.Unlock()
return s.endTime.IsZero()
}
func (s *span) SetStatus(code codes.Code, msg string) {
if s == nil {
return
}
if !s.IsRecording() {
return
}
s.mu.Lock()
s.statusCode = code
s.statusMessage = msg
s.mu.Unlock()
}
func (s *span) SetAttributes(attributes ...label.KeyValue) {
if !s.IsRecording() {
return
}
s.copyToCappedAttributes(attributes...)
}
// End ends the span.
//
// The only SpanOption currently supported is WithTimestamp which will set the
// end time for a Span's life-cycle.
//
// If this method is called while panicking an error event is added to the
// Span before ending it and the panic is continued.
func (s *span) End(options ...trace.SpanOption) {
if s == nil {
return
}
// Store the end time as soon as possible to avoid artificially increasing
// the span's duration in case some operation below takes a while.
et := internal.MonotonicEndTime(s.startTime)
if recovered := recover(); recovered != nil {
// Record but don't stop the panic.
defer panic(recovered)
s.addEvent(
errorEventName,
trace.WithAttributes(
errorTypeKey.String(typeStr(recovered)),
errorMessageKey.String(fmt.Sprint(recovered)),
),
)
}
if s.executionTracerTaskEnd != nil {
s.executionTracerTaskEnd()
}
if !s.IsRecording() {
return
}
config := trace.NewSpanConfig(options...)
s.mu.Lock()
if config.Timestamp.IsZero() {
s.endTime = et
} else {
s.endTime = config.Timestamp
}
s.mu.Unlock()
sps, ok := s.tracer.provider.spanProcessors.Load().(spanProcessorStates)
mustExportOrProcess := ok && len(sps) > 0
if mustExportOrProcess {
for _, sp := range sps {
sp.sp.OnEnd(s)
}
}
}
func (s *span) RecordError(err error, opts ...trace.EventOption) {
if s == nil || err == nil || !s.IsRecording() {
return
}
s.SetStatus(codes.Error, "")
opts = append(opts, trace.WithAttributes(
errorTypeKey.String(typeStr(err)),
errorMessageKey.String(err.Error()),
))
s.addEvent(errorEventName, opts...)
}
func typeStr(i interface{}) string {
t := reflect.TypeOf(i)
if t.PkgPath() == "" && t.Name() == "" {
// Likely a builtin type.
return t.String()
}
return fmt.Sprintf("%s.%s", t.PkgPath(), t.Name())
}
func (s *span) Tracer() trace.Tracer {
return s.tracer
}
func (s *span) AddEvent(name string, o ...trace.EventOption) {
if !s.IsRecording() {
return
}
s.addEvent(name, o...)
}
func (s *span) addEvent(name string, o ...trace.EventOption) {
c := trace.NewEventConfig(o...)
s.mu.Lock()
defer s.mu.Unlock()
s.messageEvents.add(trace.Event{
Name: name,
Attributes: c.Attributes,
Time: c.Timestamp,
})
}
func (s *span) SetName(name string) {
s.mu.Lock()
defer s.mu.Unlock()
s.name = name
// SAMPLING
noParent := !s.parent.SpanID.IsValid()
var ctx trace.SpanContext
if noParent {
ctx = trace.SpanContext{}
} else {
// FIXME: Where do we get the parent context from?
ctx = s.spanContext
}
data := samplingData{
noParent: noParent,
remoteParent: s.hasRemoteParent,
parent: ctx,
name: name,
cfg: s.tracer.provider.config.Load().(*Config),
span: s,
attributes: s.attributes.toKeyValue(),
links: s.interfaceArrayToLinksArray(),
kind: s.spanKind,
}
sampled := makeSamplingDecision(data)
// Adding attributes directly rather than using s.SetAttributes()
// as s.mu is already locked and attempting to do so would deadlock.
for _, a := range sampled.Attributes {
s.attributes.add(a)
}
}
func (s *span) Name() string {
s.mu.Lock()
defer s.mu.Unlock()
return s.name
}
func (s *span) Parent() trace.SpanContext {
s.mu.Lock()
defer s.mu.Unlock()
return s.parent
}
func (s *span) SpanKind() trace.SpanKind {
s.mu.Lock()
defer s.mu.Unlock()
return s.spanKind
}
func (s *span) StartTime() time.Time {
s.mu.Lock()
defer s.mu.Unlock()
return s.startTime
}
func (s *span) EndTime() time.Time {
s.mu.Lock()
defer s.mu.Unlock()
return s.endTime
}
func (s *span) Attributes() []label.KeyValue {
s.mu.Lock()
defer s.mu.Unlock()
if s.attributes.evictList.Len() == 0 {
return []label.KeyValue{}
}
return s.attributes.toKeyValue()
}
func (s *span) Links() []trace.Link {
s.mu.Lock()
defer s.mu.Unlock()
if len(s.links.queue) == 0 {
return []trace.Link{}
}
return s.interfaceArrayToLinksArray()
}
func (s *span) Events() []trace.Event {
s.mu.Lock()
defer s.mu.Unlock()
if len(s.messageEvents.queue) == 0 {
return []trace.Event{}
}
return s.interfaceArrayToMessageEventArray()
}
func (s *span) StatusCode() codes.Code {
s.mu.Lock()
defer s.mu.Unlock()
return s.statusCode
}
func (s *span) StatusMessage() string {
s.mu.Lock()
defer s.mu.Unlock()
return s.statusMessage
}
func (s *span) InstrumentationLibrary() instrumentation.Library {
s.mu.Lock()
defer s.mu.Unlock()
return s.instrumentationLibrary
}
func (s *span) Resource() *resource.Resource {
s.mu.Lock()
defer s.mu.Unlock()
return s.resource
}
func (s *span) addLink(link trace.Link) {
if !s.IsRecording() {
return
}
s.mu.Lock()
defer s.mu.Unlock()
s.links.add(link)
}
// Snapshot creates a snapshot representing the current state of the span as an
// export.SpanSnapshot and returns a pointer to it.
func (s *span) Snapshot() *export.SpanSnapshot {
var sd export.SpanSnapshot
s.mu.Lock()
defer s.mu.Unlock()
sd.ChildSpanCount = s.childSpanCount
sd.EndTime = s.endTime
sd.HasRemoteParent = s.hasRemoteParent
sd.InstrumentationLibrary = s.instrumentationLibrary
sd.Name = s.name
sd.ParentSpanID = s.parent.SpanID
sd.Resource = s.resource
sd.SpanContext = s.spanContext
sd.SpanKind = s.spanKind
sd.StartTime = s.startTime
sd.StatusCode = s.statusCode
sd.StatusMessage = s.statusMessage
if s.attributes.evictList.Len() > 0 {
sd.Attributes = s.attributes.toKeyValue()
sd.DroppedAttributeCount = s.attributes.droppedCount
}
if len(s.messageEvents.queue) > 0 {
sd.MessageEvents = s.interfaceArrayToMessageEventArray()
sd.DroppedMessageEventCount = s.messageEvents.droppedCount
}
if len(s.links.queue) > 0 {
sd.Links = s.interfaceArrayToLinksArray()
sd.DroppedLinkCount = s.links.droppedCount
}
return &sd
}
func (s *span) interfaceArrayToLinksArray() []trace.Link {
linkArr := make([]trace.Link, 0)
for _, value := range s.links.queue {
linkArr = append(linkArr, value.(trace.Link))
}
return linkArr
}
func (s *span) interfaceArrayToMessageEventArray() []trace.Event {
messageEventArr := make([]trace.Event, 0)
for _, value := range s.messageEvents.queue {
messageEventArr = append(messageEventArr, value.(trace.Event))
}
return messageEventArr
}
func (s *span) copyToCappedAttributes(attributes ...label.KeyValue) {
s.mu.Lock()
defer s.mu.Unlock()
for _, a := range attributes {
if a.Value.Type() != label.INVALID {
s.attributes.add(a)
}
}
}
func (s *span) addChild() {
if !s.IsRecording() {
return
}
s.mu.Lock()
s.childSpanCount++
s.mu.Unlock()
}
func startSpanInternal(ctx context.Context, tr *tracer, name string, parent trace.SpanContext, remoteParent bool, o *trace.SpanConfig) *span {
span := &span{}
span.spanContext = parent
cfg := tr.provider.config.Load().(*Config)
if hasEmptySpanContext(parent) {
// Generate both TraceID and SpanID
span.spanContext.TraceID, span.spanContext.SpanID = cfg.IDGenerator.NewIDs(ctx)
} else {
// TraceID already exists, just generate a SpanID
span.spanContext.SpanID = cfg.IDGenerator.NewSpanID(ctx, parent.TraceID)
}
span.attributes = newAttributesMap(cfg.MaxAttributesPerSpan)
span.messageEvents = newEvictedQueue(cfg.MaxEventsPerSpan)
span.links = newEvictedQueue(cfg.MaxLinksPerSpan)
data := samplingData{
noParent: hasEmptySpanContext(parent),
remoteParent: remoteParent,
parent: parent,
name: name,
cfg: cfg,
span: span,
attributes: o.Attributes,
links: o.Links,
kind: o.SpanKind,
}
sampled := makeSamplingDecision(data)
if !span.spanContext.IsSampled() && !o.Record {
return span
}
startTime := o.Timestamp
if startTime.IsZero() {
startTime = time.Now()
}
span.startTime = startTime
span.spanKind = trace.ValidateSpanKind(o.SpanKind)
span.name = name
span.hasRemoteParent = remoteParent
span.resource = cfg.Resource
span.instrumentationLibrary = tr.instrumentationLibrary
span.SetAttributes(sampled.Attributes...)
span.parent = parent
return span
}
func hasEmptySpanContext(parent trace.SpanContext) bool {
return parent.SpanID == emptySpanContext.SpanID &&
parent.TraceID == emptySpanContext.TraceID &&
parent.TraceFlags == emptySpanContext.TraceFlags &&
parent.TraceState.IsEmpty()
}
type samplingData struct {
noParent bool
remoteParent bool
parent trace.SpanContext
name string
cfg *Config
span *span
attributes []label.KeyValue
links []trace.Link
kind trace.SpanKind
}
func makeSamplingDecision(data samplingData) SamplingResult {
sampler := data.cfg.DefaultSampler
spanContext := &data.span.spanContext
sampled := sampler.ShouldSample(SamplingParameters{
ParentContext: data.parent,
TraceID: spanContext.TraceID,
Name: data.name,
HasRemoteParent: data.remoteParent,
Kind: data.kind,
Attributes: data.attributes,
Links: data.links,
})
if sampled.Decision == RecordAndSample {
spanContext.TraceFlags |= trace.FlagsSampled
} else {
spanContext.TraceFlags &^= trace.FlagsSampled
}
return sampled
}