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swarm/tracing: Add comments

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lash 2019-02-15 11:42:49 +01:00
parent bfd3346532
commit c9fbfac7d5
1 changed files with 13 additions and 3 deletions
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16
swarm/tracing/tracing.go
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@ -22,11 +22,13 @@ var (
store = spanStore{}
)
// TracingEnabledFlag is the CLI flag name to use to enable trace collections.
const (
// TracingEnabledFlag is the CLI flag name to use to enable trace collections.
TracingEnabledFlag = "tracing"
StoreLabelId = "span_save_id"
StoreLabelMeta = "span_save_meta"
// StoreLabels are used to pass span information through context instances to the span store
StoreLabelId = "span_save_id"
StoreLabelMeta = "span_save_meta"
)
var (
@ -113,10 +115,14 @@ func initTracer(endpoint, svc string) (closer io.Closer) {
return closer
}
// spanStore holds saved spans
type spanStore struct {
spans sync.Map
}
// StartSaveSpan stores the span specified in the passed context for later retrieval
// The span object but be context value on the key StoreLabelId.
// It will be stored under the the following string key context.Value(StoreLabelId)|.|context.Value(StoreLabelMeta)
func StartSaveSpan(ctx context.Context) context.Context {
if !Enabled {
return ctx
@ -139,6 +145,8 @@ func StartSaveSpan(ctx context.Context) context.Context {
return ctx
}
// ShiftSpanByKey retrieves the span stored under the key of the string given as argument
// The span is then deleted from the store
func ShiftSpanByKey(k string) opentracing.Span {
if !Enabled {
return nil
@ -151,6 +159,8 @@ func ShiftSpanByKey(k string) opentracing.Span {
return span.(opentracing.Span)
}
// FinishSpans calls `Finish()` on all stored spans
// It should be called on instance shutdown
func FinishSpans() {
store.spans.Range(func(k, v interface{}) bool {
v.(opentracing.Span).Finish()