From c92fcdb3d68f0fb00aad18d58f2f786da8aaa687 Mon Sep 17 00:00:00 2001
From: Krzesimir Nowak <krzesimir@kinvolk.io>
Date: Mon, 19 Aug 2019 10:38:46 +0200
Subject: [PATCH] Allow specifying custom timestamps for events

Adding event with timestamp is not yet a part of the OpenTelemetry
specification, but this function will come in handy when implementing
the OpenTracing bridge.
---
 api/trace/api.go                   | 3 +++
 api/trace/current_test.go          | 5 +++++
 api/trace/noop_span.go             | 5 +++++
 experimental/streaming/sdk/span.go | 4 ++++
 sdk/trace/span.go                  | 7 +++++++
 5 files changed, 24 insertions(+)

diff --git a/api/trace/api.go b/api/trace/api.go
index afb49fa42a54..0167fd25581e 100644
--- a/api/trace/api.go
+++ b/api/trace/api.go
@@ -71,6 +71,9 @@ type Span interface {
 
 	// AddEvent adds an event to the span.
 	AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue)
+	// AddEventWithTimestamp adds an event with a custom timestamp
+	// to the span.
+	AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue)
 
 	// IsRecordingEvents returns true if the span is active and recording events is enabled.
 	IsRecordingEvents() bool
diff --git a/api/trace/current_test.go b/api/trace/current_test.go
index 599a1b5142f4..7da2b3e71fc0 100644
--- a/api/trace/current_test.go
+++ b/api/trace/current_test.go
@@ -3,6 +3,7 @@ package trace_test
 import (
 	"context"
 	"testing"
+	"time"
 
 	"google.golang.org/grpc/codes"
 
@@ -108,6 +109,10 @@ func (mockSpan) Tracer() trace.Tracer {
 func (mockSpan) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue) {
 }
 
+// AddEventWithTimestamp does nothing.
+func (mockSpan) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+}
+
 // AddLink does nothing.
 func (mockSpan) AddLink(link trace.Link) {
 }
diff --git a/api/trace/noop_span.go b/api/trace/noop_span.go
index c4be98ab5e88..cc1b260e1b05 100644
--- a/api/trace/noop_span.go
+++ b/api/trace/noop_span.go
@@ -16,6 +16,7 @@ package trace
 
 import (
 	"context"
+	"time"
 
 	"google.golang.org/grpc/codes"
 
@@ -75,6 +76,10 @@ func (NoopSpan) Tracer() Tracer {
 func (NoopSpan) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue) {
 }
 
+// AddEventWithTimestamp does nothing.
+func (NoopSpan) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+}
+
 // SetName does nothing.
 func (NoopSpan) SetName(name string) {
 }
diff --git a/experimental/streaming/sdk/span.go b/experimental/streaming/sdk/span.go
index 477e764bb9bb..46ad9dc47ed3 100644
--- a/experimental/streaming/sdk/span.go
+++ b/experimental/streaming/sdk/span.go
@@ -112,6 +112,10 @@ func (sp *span) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue
 	sp.addEventWithTime(ctx, time.Time{}, msg, attrs...)
 }
 
+func (sp *span) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+	sp.addEventWithTime(ctx, timestamp, msg, attrs...)
+}
+
 func (sp *span) addEventWithTime(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
 	observer.Record(observer.Event{
 		Time:       timestamp,
diff --git a/sdk/trace/span.go b/sdk/trace/span.go
index 38e6fd949314..f0347f9481e9 100644
--- a/sdk/trace/span.go
+++ b/sdk/trace/span.go
@@ -158,6 +158,13 @@ func (s *span) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue)
 	s.addEventWithTimestamp(time.Now(), msg, attrs...)
 }
 
+func (s *span) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+	if !s.IsRecordingEvents() {
+		return
+	}
+	s.addEventWithTimestamp(timestamp, msg, attrs...)
+}
+
 func (s *span) addEventWithTimestamp(timestamp time.Time, msg string, attrs ...core.KeyValue) {
 	s.mu.Lock()
 	defer s.mu.Unlock()