From d8fc5bd6e93e2e25309b86c8b2a0a72de02ce63d Mon Sep 17 00:00:00 2001
From: Daniel Bedrood <danielb@scribd.com>
Date: Wed, 22 Feb 2023 10:32:13 +0100
Subject: [PATCH 1/2] fix: Fix passing data using context in gorm

---
 pkg/instrumentation/database.go | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/pkg/instrumentation/database.go b/pkg/instrumentation/database.go
index 19922c2f..931f217b 100644
--- a/pkg/instrumentation/database.go
+++ b/pkg/instrumentation/database.go
@@ -10,11 +10,13 @@ import (
 	"gorm.io/gorm"
 )
 
-const (
+type spanContextKey string
+
+var (
 	// ParentSpanGormKey is the name of the parent span key
-	ParentSpanGormKey = "tracingParentSpan"
+	parentSpanGormKey = spanContextKey("trancingParentSpan")
 	// SpanGormKey is the name of the span key
-	SpanGormKey = "tracingSpan"
+	spanGormKey = spanContextKey("tracingSpan")
 )
 
 // TraceDatabase sets span to gorm settings, returns cloned DB
@@ -22,8 +24,12 @@ func TraceDatabase(ctx context.Context, db *gorm.DB) *gorm.DB {
 	if ctx == nil {
 		return db
 	}
+
 	parentSpan, _ := ddtrace.SpanFromContext(ctx)
-	return db.Set(ParentSpanGormKey, parentSpan)
+
+	return db.Session(&gorm.Session{
+		Context: context.WithValue(db.Statement.Context, parentSpanGormKey, parentSpan),
+	})
 }
 
 // InstrumentDatabase adds callbacks for tracing, call TraceDatabase to make it work
@@ -58,12 +64,15 @@ func (c *callbacks) afterDelete(db *gorm.DB)  { c.after(db) }
 func (c *callbacks) beforeRow(db *gorm.DB)    { c.before(db, "", c.serviceName) }
 func (c *callbacks) afterRow(db *gorm.DB)     { c.after(db) }
 func (c *callbacks) before(db *gorm.DB, operationName string, serviceName string) {
-	val, ok := db.Get(ParentSpanGormKey)
+	if db.Statement == nil || db.Statement.Context == nil {
+		return
+	}
+
+	parentSpan, ok := db.Statement.Context.Value(parentSpanGormKey).(ddtrace.Span)
 	if !ok {
 		return
 	}
 
-	parentSpan := val.(ddtrace.Span)
 	spanOpts := []ddtrace.StartSpanOption{
 		ddtrace.ChildOf(parentSpan.Context()),
 		ddtrace.SpanType(ext.SpanTypeSQL),
@@ -73,16 +82,19 @@ func (c *callbacks) before(db *gorm.DB, operationName string, serviceName string
 		operationName = strings.Split(db.Statement.SQL.String(), " ")[0]
 	}
 	sp := ddtrace.StartSpan(operationName, spanOpts...)
-	db.Set(SpanGormKey, sp)
+	db.Statement.Context = context.WithValue(db.Statement.Context, spanGormKey, sp)
 }
 
 func (c *callbacks) after(db *gorm.DB) {
-	val, ok := db.Get(SpanGormKey)
+	if db.Statement == nil || db.Statement.Context == nil {
+		return
+	}
+
+	sp, ok := db.Statement.Context.Value(spanGormKey).(ddtrace.Span)
 	if !ok {
 		return
 	}
 
-	sp := val.(ddtrace.Span)
 	sp.SetTag(ext.ResourceName, strings.ToUpper(db.Statement.SQL.String()))
 	sp.SetTag("db.table", db.Statement.Table)
 	sp.SetTag("db.query", strings.ToUpper(db.Statement.SQL.String()))

From d490f60344709f8f8767cd560cb0b1bf3f86739b Mon Sep 17 00:00:00 2001
From: Daniel Bedrood <danielb@scribd.com>
Date: Wed, 22 Feb 2023 11:06:45 +0100
Subject: [PATCH 2/2] test: New unit test for TraceDatabase function

---
 pkg/instrumentation/database_test.go | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/pkg/instrumentation/database_test.go b/pkg/instrumentation/database_test.go
index 8d7ce542..de7d2e31 100644
--- a/pkg/instrumentation/database_test.go
+++ b/pkg/instrumentation/database_test.go
@@ -135,3 +135,18 @@ func TestInstrumentDatabase(t *testing.T) {
 		}
 	}
 }
+
+func TestTraceDatabase(t *testing.T) {
+	dbFile := path.Join(t.TempDir(), "test_db")
+	db, err := gorm.Open(sqlite.Open(dbFile))
+	if err != nil {
+		t.Fatalf("Failed to open DB: %s", err)
+	}
+
+	InstrumentDatabase(db, "test_app_name")
+	db = TraceDatabase(context.Background(), db)
+
+	if sp := db.Statement.Context.Value(parentSpanGormKey); sp == nil {
+		t.Error("Parent span not set on statement")
+	}
+}