pomerium/internal/telemetry/trace/queue.go
2025-01-03 23:19:23 +00:00

817 lines
24 KiB
Go

package trace
import (
"context"
"encoding/json"
"errors"
"fmt"
"os"
"slices"
"strconv"
"sync"
"sync/atomic"
"time"
"unique"
lru "github.com/hashicorp/golang-lru/v2"
"github.com/pomerium/pomerium/internal/log"
"github.com/rs/zerolog"
"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
sdktrace "go.opentelemetry.io/otel/sdk/trace"
oteltrace "go.opentelemetry.io/otel/trace"
coltracepb "go.opentelemetry.io/proto/otlp/collector/trace/v1"
tracev1 "go.opentelemetry.io/proto/otlp/trace/v1"
"google.golang.org/protobuf/encoding/protojson"
"google.golang.org/protobuf/proto"
)
var (
maxPendingTraces atomic.Int32
maxCachedTraceIDs atomic.Int32
)
func init() {
envOrDefault := func(envName string, def int32) int32 {
if val, ok := os.LookupEnv(envName); ok {
if num, err := strconv.ParseInt(val, 10, 32); err == nil {
return int32(num)
}
}
return def
}
maxPendingTraces.Store(envOrDefault("POMERIUM_OTEL_MAX_PENDING_TRACES", 8192))
maxCachedTraceIDs.Store(envOrDefault("POMERIUM_OTEL_MAX_CACHED_TRACE_IDS", 16384))
}
func SetMaxPendingTraces(num int32) {
maxPendingTraces.Store(max(num, 0))
}
func SetMaxCachedTraceIDs(num int32) {
maxCachedTraceIDs.Store(max(num, 0))
}
type SpanExportQueue struct {
mu sync.Mutex
logger *zerolog.Logger
client otlptrace.Client
pendingResourcesByTraceID *lru.Cache[unique.Handle[oteltrace.TraceID], *Buffer]
knownTraceIDMappings *lru.Cache[unique.Handle[oteltrace.TraceID], unique.Handle[oteltrace.TraceID]]
uploadC chan []*tracev1.ResourceSpans
closing bool
closed chan struct{}
debugFlags DebugFlags
debugAllEnqueuedSpans map[oteltrace.SpanID]*tracev1.Span
tracker *spanTracker
observer *spanObserver
debugEvents []DebugEvent
}
func NewSpanExportQueue(ctx context.Context, client otlptrace.Client) *SpanExportQueue {
debug := DebugFlagsFromContext(ctx)
var observer *spanObserver
if debug.Check(TrackSpanReferences) {
observer = newSpanObserver()
}
q := &SpanExportQueue{
logger: log.Ctx(ctx),
client: client,
uploadC: make(chan []*tracev1.ResourceSpans, 64),
closed: make(chan struct{}),
debugFlags: debug,
debugAllEnqueuedSpans: make(map[oteltrace.SpanID]*tracev1.Span),
tracker: newSpanTracker(observer, debug),
observer: observer,
}
var err error
q.pendingResourcesByTraceID, err = lru.NewWithEvict(int(maxPendingTraces.Load()), q.onEvict)
if err != nil {
panic(err)
}
q.knownTraceIDMappings, err = lru.New[unique.Handle[oteltrace.TraceID], unique.Handle[oteltrace.TraceID]](int(maxCachedTraceIDs.Load()))
if err != nil {
panic(err)
}
go q.runUploader()
return q
}
func (q *SpanExportQueue) runUploader() {
defer close(q.closed)
for resourceSpans := range q.uploadC {
ctx, ca := context.WithTimeout(context.Background(), 10*time.Second)
if err := q.client.UploadTraces(ctx, resourceSpans); err != nil {
q.logger.Err(err).Msg("error uploading traces")
}
ca()
}
}
func (q *SpanExportQueue) onEvict(traceID unique.Handle[oteltrace.TraceID], buf *Buffer) {
if buf.IsEmpty() {
// if the buffer is not empty, it was evicted automatically
return
} else if mapping, ok := q.knownTraceIDMappings.Get(traceID); ok && mapping == zeroTraceID {
q.logger.Debug().
Str("traceID", traceID.Value().String()).
Msg("dropping unsampled trace")
return
}
select {
case q.uploadC <- buf.Flush():
q.logger.Warn().
Str("traceID", traceID.Value().String()).
Msg("trace export buffer is full, uploading oldest incomplete trace")
default:
q.logger.Warn().
Str("traceID", traceID.Value().String()).
Msg("trace export buffer and upload queues are full, dropping trace")
}
}
func (q *SpanExportQueue) insertPendingSpanLocked(
resource *ResourceInfo,
scope *ScopeInfo,
traceID unique.Handle[oteltrace.TraceID],
span *tracev1.Span,
) {
var pendingTraceResources *Buffer
if ptr, ok := q.pendingResourcesByTraceID.Get(traceID); ok {
pendingTraceResources = ptr
} else {
pendingTraceResources = NewBuffer()
q.pendingResourcesByTraceID.Add(traceID, pendingTraceResources)
}
pendingTraceResources.Insert(resource, scope, span)
}
func (q *SpanExportQueue) resolveTraceIDMappingLocked(out *Buffer, original, target unique.Handle[oteltrace.TraceID]) {
q.knownTraceIDMappings.Add(original, target)
if target == zeroTraceID && original != zeroTraceID {
// mapping a trace id to zero indicates we should drop the trace
q.pendingResourcesByTraceID.Remove(original)
return
}
if originalPending, ok := q.pendingResourcesByTraceID.Peek(original); ok {
if original == target {
out.Merge(originalPending)
} else {
// check if the target id is also pending
if targetPending, ok := q.pendingResourcesByTraceID.Peek(target); ok {
targetPending.MergeAs(originalPending, target)
} else {
out.MergeAs(originalPending, target)
}
}
q.pendingResourcesByTraceID.Remove(original)
}
}
func (q *SpanExportQueue) getTraceIDMappingLocked(id unique.Handle[oteltrace.TraceID]) (unique.Handle[oteltrace.TraceID], bool) {
v, ok := q.knownTraceIDMappings.Get(id)
return v, ok
}
func (q *SpanExportQueue) isKnownTracePendingLocked(id unique.Handle[oteltrace.TraceID]) bool {
_, ok := q.pendingResourcesByTraceID.Get(id) // will update the key's recent-ness in the lru
return ok
}
var ErrShuttingDown = errors.New("exporter is shutting down")
func (q *SpanExportQueue) Enqueue(ctx context.Context, req *coltracepb.ExportTraceServiceRequest) error {
q.mu.Lock()
defer q.mu.Unlock()
if q.closing {
return ErrShuttingDown
}
if q.debugFlags.Check(LogAllEvents) {
q.debugEvents = append(q.debugEvents, DebugEvent{
Timestamp: time.Now(),
Request: proto.Clone(req).(*coltracepb.ExportTraceServiceRequest),
})
}
// Spans are processed in two passes:
// 1. Look through each span to check if we have not yet seen its trace ID.
// If we haven't, and the span is a root span (no parent, or marked as such
// by us), mark the trace as observed, and (if indicated) keep track of the
// trace ID we need to rewrite it as, so that other spans we see later in
// this trace can also be rewritten the same way.
// If we find a new trace ID for which there are pending non-root spans,
// collect them and rewrite their trace IDs (if necessary), and prepare
// them to be uploaded.
//
// At this point, all trace IDs for the spans in the request are known.
//
// 2. Look through each span again, this time to filter out any spans in
// the request which belong to "pending" traces (known trace IDs for which
// we have not yet seen a root span), adding them to the list of pending
// spans for their corresponding trace IDs. They will be uploaded in the
// future once we have observed a root span for those traces, or if they
// are evicted by the queue.
// Pass 1
toUpload := NewBuffer()
for _, resource := range req.ResourceSpans {
for _, scope := range resource.ScopeSpans {
SPANS:
for _, span := range scope.Spans {
FormatSpanName(span)
spanID, ok := ToSpanID(span.SpanId)
if !ok {
continue
}
if q.debugFlags.Check(TrackAllSpans) {
q.debugAllEnqueuedSpans[spanID] = span
}
trackSpanReferences := q.debugFlags.Check(TrackSpanReferences)
parentSpanID, ok := ToSpanID(span.ParentSpanId)
if !ok {
continue
}
traceID, ok := ToTraceID(span.TraceId)
if !ok {
continue
}
if trackSpanReferences {
q.observer.Observe(spanID)
}
if mapping, ok := q.getTraceIDMappingLocked(traceID); ok {
if trackSpanReferences && mapping != zeroTraceID && parentSpanID.IsValid() {
q.observer.ObserveReference(parentSpanID, spanID)
}
} else {
// Observed a new trace ID. Check if the span is a root span
isRootSpan := !parentSpanID.IsValid() // no parent == root span
// Assume the trace is sampled, because it was exported. span.Flags
// is an unreliable way to detect whether the span was sampled,
// because neither envoy nor opentelemetry-go encode the sampling
// decision there, assuming unsampled spans would not be exported
// (this was not taking into account tail-based sampling strategies)
// https://github.com/open-telemetry/opentelemetry-proto/issues/166
isSampled := true
mappedTraceID := traceID
for _, attr := range span.Attributes {
switch attr.Key {
case "pomerium.traceparent":
tp, err := ParseTraceparent(attr.GetValue().GetStringValue())
if err != nil {
data, _ := protojson.Marshal(span)
log.Ctx(ctx).
Err(err).
Str("span", string(data)).
Msg("error processing span")
continue SPANS
}
mappedTraceID = unique.Make(tp.TraceID())
// use the sampling decision from pomerium.traceparent instead
isSampled = tp.IsSampled()
case "pomerium.external-parent-span":
// This is a non-root span whose parent we do not expect to see
// here. For example, if a request originated externally from a
// system that is uploading its own spans out-of-band from us,
// we will never observe a root span for this trace and it would
// otherwise get stuck in the queue.
if !isRootSpan && q.debugFlags.Check(TrackSpanReferences) {
value, err := oteltrace.SpanIDFromHex(attr.GetValue().GetStringValue())
if err != nil {
data, _ := protojson.Marshal(span)
log.Ctx(ctx).
Err(err).
Str("span", string(data)).
Msg("error processing span: invalid value for pomerium.external-parent-span")
} else {
q.observer.Observe(value) // mark this id as observed
}
}
isRootSpan = true
}
}
if q.debugFlags.Check(TrackSpanReferences) {
if isSampled && parentSpanID.IsValid() {
q.observer.ObserveReference(parentSpanID, spanID)
}
}
if !isSampled {
// We have observed a new trace that is not sampled (regardless of
// whether or not it is a root span). Resolve it using the zero
// trace ID to indicate that all spans for this trace should be
// dropped.
q.resolveTraceIDMappingLocked(toUpload, traceID, zeroTraceID)
} else if isRootSpan {
// We have observed a new trace that is sampled and is a root span.
// Resolve it using the mapped trace ID (if present), or its own
// trace ID (indicating it does not need to be rewritten).
// If the mapped trace is pending, this does not flush pending
// spans to the output buffer (toUpload), but instead merges them
// into the mapped trace's pending buffer.
q.resolveTraceIDMappingLocked(toUpload, traceID, mappedTraceID)
}
}
}
}
}
// Pass 2
for _, resource := range req.ResourceSpans {
resourceInfo := NewResourceInfo(resource.Resource, resource.SchemaUrl)
for _, scope := range resource.ScopeSpans {
scopeInfo := NewScopeInfo(scope.Scope, scope.SchemaUrl)
for _, span := range scope.Spans {
traceID, ok := ToTraceID(span.TraceId)
if !ok {
continue
}
if mapping, hasMapping := q.getTraceIDMappingLocked(traceID); hasMapping {
if mapping == zeroTraceID {
continue // the trace has been dropped
}
id := mapping.Value()
copy(span.TraceId, id[:])
// traceID = mapping
if q.isKnownTracePendingLocked(mapping) {
q.insertPendingSpanLocked(resourceInfo, scopeInfo, mapping, span)
} else {
toUpload.Insert(resourceInfo, scopeInfo, span)
}
} else {
q.insertPendingSpanLocked(resourceInfo, scopeInfo, traceID, span)
}
}
}
}
if resourceSpans := toUpload.Flush(); len(resourceSpans) > 0 {
q.uploadC <- resourceSpans
}
return nil
}
var (
ErrIncompleteTraces = errors.New("exporter shut down with incomplete traces")
ErrIncompleteSpans = errors.New("exporter shut down with incomplete spans")
ErrIncompleteUploads = errors.New("exporter shut down with pending trace uploads")
ErrMissingParentSpans = errors.New("exporter shut down with missing parent spans")
)
func (q *SpanExportQueue) WaitForSpans(maxDuration time.Duration) error {
if !q.debugFlags.Check(TrackSpanReferences) {
return nil
}
done := make(chan struct{})
go func() {
defer close(done)
q.observer.wait(q.debugAllEnqueuedSpans, 10*time.Second)
}()
select {
case <-done:
return nil
case <-time.After(maxDuration):
return ErrMissingParentSpans
}
}
func (q *SpanExportQueue) Close(ctx context.Context) error {
q.mu.Lock()
q.closing = true
close(q.uploadC)
q.mu.Unlock()
select {
case <-ctx.Done():
log.Ctx(ctx).Error().Msg("exporter stopped before all traces could be exported")
// drain uploadC
for range q.uploadC {
}
return context.Cause(ctx)
case <-q.closed:
q.mu.Lock()
defer q.mu.Unlock()
err := q.runOnCloseChecksLocked()
log.Ctx(ctx).Debug().Err(err).Msg("exporter stopped")
return err
}
}
func (q *SpanExportQueue) runOnCloseChecksLocked() error {
didWarn := false
if q.debugFlags.Check(TrackSpanReferences) {
var unknownParentIDs []string
for id, via := range q.observer.referencedIDs {
if via.IsValid() {
if q.debugFlags.Check(TrackAllSpans) {
if viaSpan, ok := q.debugAllEnqueuedSpans[via]; ok {
unknownParentIDs = append(unknownParentIDs, fmt.Sprintf("%s via %s (%s)", id, via, viaSpan.Name))
} else {
unknownParentIDs = append(unknownParentIDs, fmt.Sprintf("%s via %s", id, via))
}
}
}
}
if len(unknownParentIDs) > 0 {
didWarn = true
msg := startMsg("WARNING: parent spans referenced but never seen:\n")
for _, str := range unknownParentIDs {
msg.WriteString(str)
msg.WriteString("\n")
}
endMsg(msg)
}
}
incomplete := q.pendingResourcesByTraceID.Len() > 0
if incomplete && q.debugFlags.Check(WarnOnIncompleteTraces) {
didWarn = true
msg := startMsg("WARNING: exporter shut down with incomplete traces\n")
keys := q.pendingResourcesByTraceID.Keys()
values := q.pendingResourcesByTraceID.Values()
for i, k := range keys {
v := values[i]
fmt.Fprintf(msg, "- Trace: %s\n", k.Value())
for _, pendingScope := range v.scopesByResourceID {
msg.WriteString(" - Resource:\n")
for _, v := range pendingScope.resource.Resource.Attributes {
fmt.Fprintf(msg, " %s=%s\n", v.Key, v.Value.String())
}
for _, spanBuffer := range pendingScope.spansByScope {
if spanBuffer.scope != nil {
fmt.Fprintf(msg, " Scope: %s\n", spanBuffer.scope.ID())
} else {
msg.WriteString(" Scope: (unknown)\n")
}
msg.WriteString(" Spans:\n")
longestName := 0
for _, span := range spanBuffer.spans {
longestName = max(longestName, len(span.Name)+2)
}
for _, span := range spanBuffer.spans {
spanID, ok := ToSpanID(span.SpanId)
if !ok {
continue
}
traceID, ok := ToTraceID(span.TraceId)
if !ok {
continue
}
parentSpanID, ok := ToSpanID(span.ParentSpanId)
if !ok {
continue
}
_, seenParent := q.debugAllEnqueuedSpans[parentSpanID]
var missing string
if !seenParent {
missing = " [missing]"
}
fmt.Fprintf(msg, " - %-*s (trace: %s | span: %s | parent:%s %s)\n", longestName,
"'"+span.Name+"'", traceID.Value(), spanID, missing, parentSpanID)
for _, attr := range span.Attributes {
if attr.Key == "caller" {
fmt.Fprintf(msg, " => caller: '%s'\n", attr.Value.GetStringValue())
break
}
}
}
}
}
}
endMsg(msg)
}
if q.debugFlags.Check(LogTraceIDMappings) || (didWarn && q.debugFlags.Check(LogTraceIDMappingsOnWarn)) {
msg := startMsg("Known trace ids:\n")
keys := q.knownTraceIDMappings.Keys()
values := q.knownTraceIDMappings.Values()
for i, k := range keys {
v := values[i]
if k != v {
if v == zeroTraceID {
fmt.Fprintf(msg, "%s (dropped)\n", k.Value())
} else {
fmt.Fprintf(msg, "%s => %s\n", k.Value(), v.Value())
}
} else {
fmt.Fprintf(msg, "%s (no change)\n", k.Value())
}
}
endMsg(msg)
}
if q.debugFlags.Check(LogAllSpans) || (didWarn && q.debugFlags.Check(LogAllSpansOnWarn)) {
msg := startMsg("All exported spans:\n")
longestName := 0
for _, span := range q.debugAllEnqueuedSpans {
longestName = max(longestName, len(span.Name)+2)
}
for _, span := range q.debugAllEnqueuedSpans {
spanID, ok := ToSpanID(span.SpanId)
if !ok {
continue
}
traceID, ok := ToTraceID(span.TraceId)
if !ok {
continue
}
parentSpanID, ok := ToSpanID(span.ParentSpanId)
if !ok {
continue
}
fmt.Fprintf(msg, "%-*s (trace: %s | span: %s | parent: %s)", longestName,
"'"+span.Name+"'", traceID.Value(), spanID, parentSpanID)
var foundCaller bool
for _, attr := range span.Attributes {
if attr.Key == "caller" {
fmt.Fprintf(msg, " => %s\n", attr.Value.GetStringValue())
foundCaller = true
break
}
}
if !foundCaller {
msg.WriteString("\n")
}
}
endMsg(msg)
}
if q.debugFlags.Check(LogAllEvents) {
msg := startMsg("All Events:\n")
msg.WriteByte('[')
for i, event := range q.debugEvents {
msg.WriteString("\n ")
eventData, _ := json.Marshal(event)
msg.Write(eventData)
if i < len(q.debugEvents)-1 {
msg.WriteByte(',')
} else {
msg.WriteString("\n]")
}
}
msg.WriteByte('\n')
endMsg(msg)
}
if incomplete {
return ErrIncompleteTraces
}
return nil
}
type DebugEvent struct {
Timestamp time.Time `json:"timestamp"`
Request *coltracepb.ExportTraceServiceRequest `json:"request"`
}
func (e DebugEvent) MarshalJSON() ([]byte, error) {
type debugEvent struct {
Timestamp time.Time `json:"timestamp"`
Request json.RawMessage `json:"request"`
}
reqData, _ := protojson.Marshal(e.Request)
return json.Marshal(debugEvent{
Timestamp: e.Timestamp,
Request: reqData,
})
}
func (e *DebugEvent) UnmarshalJSON(b []byte) error {
type debugEvent struct {
Timestamp time.Time `json:"timestamp"`
Request json.RawMessage `json:"request"`
}
var ev debugEvent
if err := json.Unmarshal(b, &ev); err != nil {
return err
}
e.Timestamp = ev.Timestamp
var msg coltracepb.ExportTraceServiceRequest
if err := protojson.Unmarshal(ev.Request, &msg); err != nil {
return err
}
e.Request = &msg
return nil
}
type spanTracker struct {
inflightSpans sync.Map
allSpans sync.Map
debugFlags DebugFlags
observer *spanObserver
shutdownOnce sync.Once
}
func newSpanTracker(observer *spanObserver, debugFlags DebugFlags) *spanTracker {
return &spanTracker{
observer: observer,
debugFlags: debugFlags,
}
}
type spanInfo struct {
Name string
SpanContext oteltrace.SpanContext
Parent oteltrace.SpanContext
caller string
startTime time.Time
}
// ForceFlush implements trace.SpanProcessor.
func (t *spanTracker) ForceFlush(context.Context) error {
return nil
}
// OnEnd implements trace.SpanProcessor.
func (t *spanTracker) OnEnd(s sdktrace.ReadOnlySpan) {
id := s.SpanContext().SpanID()
t.inflightSpans.Delete(id)
}
// OnStart implements trace.SpanProcessor.
func (t *spanTracker) OnStart(_ context.Context, s sdktrace.ReadWriteSpan) {
id := s.SpanContext().SpanID()
t.inflightSpans.Store(id, struct{}{})
if t.debugFlags.Check(TrackSpanReferences) {
t.observer.Observe(id)
}
if t.debugFlags.Check(TrackAllSpans) {
var caller string
for _, attr := range s.Attributes() {
if attr.Key == "caller" {
caller = attr.Value.AsString()
break
}
}
t.allSpans.Store(id, &spanInfo{
Name: s.Name(),
SpanContext: s.SpanContext(),
Parent: s.Parent(),
caller: caller,
startTime: s.StartTime(),
})
}
}
// Shutdown implements trace.SpanProcessor.
func (t *spanTracker) Shutdown(_ context.Context) error {
if t.debugFlags == 0 {
return nil
}
didWarn := false
t.shutdownOnce.Do(func() {
if t.debugFlags.Check(WarnOnIncompleteSpans) {
if t.debugFlags.Check(TrackAllSpans) {
incompleteSpans := []*spanInfo{}
t.inflightSpans.Range(func(key, _ any) bool {
if info, ok := t.allSpans.Load(key); ok {
incompleteSpans = append(incompleteSpans, info.(*spanInfo))
}
return true
})
if len(incompleteSpans) > 0 {
didWarn = true
msg := startMsg("WARNING: spans not ended:\n")
longestName := 0
for _, span := range incompleteSpans {
longestName = max(longestName, len(span.Name)+2)
}
for _, span := range incompleteSpans {
var startedAt string
if span.caller != "" {
startedAt = " | started at: " + span.caller
}
fmt.Fprintf(msg, "%-*s (trace: %s | span: %s | parent: %s%s)\n", longestName, "'"+span.Name+"'",
span.SpanContext.TraceID(), span.SpanContext.SpanID(), span.Parent.SpanID(), startedAt)
}
endMsg(msg)
}
} else {
incompleteSpans := []oteltrace.SpanID{}
t.inflightSpans.Range(func(key, _ any) bool {
incompleteSpans = append(incompleteSpans, key.(oteltrace.SpanID))
return true
})
if len(incompleteSpans) > 0 {
didWarn = true
msg := startMsg("WARNING: spans not ended:\n")
for _, span := range incompleteSpans {
fmt.Fprintf(msg, "%s\n", span)
}
msg.WriteString("Note: set TrackAllSpans flag for more info\n")
endMsg(msg)
}
}
}
if t.debugFlags.Check(LogAllSpans) || (t.debugFlags.Check(LogAllSpansOnWarn) && didWarn) {
allSpans := []*spanInfo{}
t.allSpans.Range(func(_, value any) bool {
allSpans = append(allSpans, value.(*spanInfo))
return true
})
slices.SortFunc(allSpans, func(a, b *spanInfo) int {
return a.startTime.Compare(b.startTime)
})
msg := startMsg("All observed spans:\n")
longestName := 0
for _, span := range allSpans {
longestName = max(longestName, len(span.Name)+2)
}
for _, span := range allSpans {
var startedAt string
if span.caller != "" {
startedAt = " | started at: " + span.caller
}
fmt.Fprintf(msg, "%-*s (trace: %s | span: %s | parent: %s%s)\n", longestName, "'"+span.Name+"'",
span.SpanContext.TraceID(), span.SpanContext.SpanID(), span.Parent.SpanID(), startedAt)
}
endMsg(msg)
}
})
if didWarn {
return ErrIncompleteSpans
}
return nil
}
func newSpanObserver() *spanObserver {
return &spanObserver{
referencedIDs: map[oteltrace.SpanID]oteltrace.SpanID{},
cond: sync.NewCond(&sync.Mutex{}),
}
}
type spanObserver struct {
cond *sync.Cond
referencedIDs map[oteltrace.SpanID]oteltrace.SpanID
unobservedIDs int
}
func (obs *spanObserver) ObserveReference(id oteltrace.SpanID, via oteltrace.SpanID) {
obs.cond.L.Lock()
defer obs.cond.L.Unlock()
if _, referenced := obs.referencedIDs[id]; !referenced {
obs.referencedIDs[id] = via // referenced, but not observed
// It is possible for new unobserved references to come in while waiting,
// but incrementing the counter wouldn't satisfy the condition so we don't
// need to signal the waiters
obs.unobservedIDs++
}
}
func (obs *spanObserver) Observe(id oteltrace.SpanID) {
obs.cond.L.Lock()
defer obs.cond.L.Unlock()
if observed, referenced := obs.referencedIDs[id]; !referenced || observed.IsValid() { // NB: subtle condition
obs.referencedIDs[id] = zeroSpanID
if referenced {
obs.unobservedIDs--
obs.cond.Broadcast()
}
}
}
func (obs *spanObserver) wait(debugAllEnqueuedSpans map[oteltrace.SpanID]*tracev1.Span, warnAfter time.Duration) {
done := make(chan struct{})
defer close(done)
go func() {
select {
case <-done:
return
case <-time.After(warnAfter):
obs.debugWarnWaiting(debugAllEnqueuedSpans)
}
}()
obs.cond.L.Lock()
for obs.unobservedIDs > 0 {
obs.cond.Wait()
}
obs.cond.L.Unlock()
}
func (obs *spanObserver) debugWarnWaiting(debugAllEnqueuedSpans map[oteltrace.SpanID]*tracev1.Span) {
obs.cond.L.Lock()
msg := startMsg(fmt.Sprintf("Waiting on %d unobserved spans:\n", obs.unobservedIDs))
for id, via := range obs.referencedIDs {
if via.IsValid() {
fmt.Fprintf(msg, "%s via %s", id, via)
if span := debugAllEnqueuedSpans[id]; span != nil {
createdAt := "(unknown)"
for _, attr := range span.Attributes {
if attr.Key == "caller" {
createdAt = attr.Value.GetStringValue()
break
}
}
fmt.Fprintf(msg, "'%s' (trace: %s | created: %s)\n", span.GetName(), span.TraceId, createdAt)
} else {
msg.WriteString("\n")
}
}
}
endMsg(msg)
obs.cond.L.Unlock()
}