From 8d2dc8a822e6e312de271dd75b4c9501e1ac64c3 Mon Sep 17 00:00:00 2001
From: Asim Aslam <asim@aslam.me>
Date: Fri, 24 Jan 2020 21:24:51 +0000
Subject: [PATCH] trace Read endpoint

---
 debug/trace/default.go | 22 ++++++++++++++++++++--
 debug/trace/options.go |  7 +++++++
 debug/trace/trace.go   |  4 ++--
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/debug/trace/default.go b/debug/trace/default.go
index abbf1c15..05fd9d97 100644
--- a/debug/trace/default.go
+++ b/debug/trace/default.go
@@ -16,7 +16,25 @@ type trace struct {
 }
 
 func (t *trace) Read(opts ...ReadOption) ([]*Span, error) {
-	return []*Span{}, nil
+	var options ReadOptions
+	for _, o := range opts {
+		o(&options)
+	}
+
+	sp := t.buffer.Get(t.buffer.Size())
+
+	var spans []*Span
+
+	for _, span := range sp {
+		val := span.Value.(*Span)
+		// skip if trace id is specified and doesn't match
+		if len(options.Trace) > 0 && val.Trace != options.Trace {
+			continue
+		}
+		spans = append(spans, val)
+	}
+
+	return spans, nil
 }
 
 func (t *trace) Start(ctx context.Context, name string) *Span {
@@ -49,7 +67,7 @@ func (t *trace) Start(ctx context.Context, name string) *Span {
 
 func (t *trace) Finish(s *Span) error {
 	// set finished time
-	s.Finished = time.Now()
+	s.Duration = time.Since(s.Started)
 
 	// save the span
 	t.buffer.Put(s)
diff --git a/debug/trace/options.go b/debug/trace/options.go
index d92abad9..7a0af631 100644
--- a/debug/trace/options.go
+++ b/debug/trace/options.go
@@ -10,3 +10,10 @@ type ReadOptions struct {
 }
 
 type ReadOption func(o *ReadOptions)
+
+// Read the given trace
+func ReadTrace(t string) ReadOption {
+	return func(o *ReadOptions) {
+		o.Trace = t
+	}
+}
diff --git a/debug/trace/trace.go b/debug/trace/trace.go
index 4a4471c3..5cefad2e 100644
--- a/debug/trace/trace.go
+++ b/debug/trace/trace.go
@@ -28,8 +28,8 @@ type Span struct {
 	Parent string
 	// Start time
 	Started time.Time
-	// Finish time
-	Finished time.Time
+	// Duration in nano seconds
+	Duration time.Duration
 	// associated data
 	Metadata map[string]string
 }