fix growing allocation of pendingOffsets when no offsetManager is in …

…use (#436)

* fix growing allocation of pendingOffsets when no offsetManager is in use

* dont close writeResult channel, avoids potential panic if used as a lib

pipeline/node.go

@@ -544,9 +544,11 @@ func (n *Node) write(msg message.Msg, off offset.Offset) (message.Msg, error) {
 		return nil, err
 	}
 
-	n.offsetLock.Lock()
-	n.pendingOffsets = append(n.pendingOffsets, off)
-	n.offsetLock.Unlock()
+	if n.om != nil {
+		n.offsetLock.Lock()
+		n.pendingOffsets = append(n.pendingOffsets, off)
+		n.offsetLock.Unlock()
+	}
 	ctx, cancel := context.WithTimeout(context.Background(), n.writeTimeout)
 	defer cancel()
 	c := make(chan writeResult)

pipeline/node_bench_test.go

@@ -0,0 +1,25 @@
+package pipeline
+
+import (
+	"testing"
+
+	"github.com/compose/transporter/offset"
+
+	"github.com/compose/transporter/message"
+)
+
+func BenchmarkNodeWrite(b *testing.B) {
+	node, err := NewNodeWithOptions("benchwriter", "test", ".*",
+		WithWriteTimeout("500ms"),
+	)
+	if err != nil {
+		b.Error(err)
+	}
+
+	msg := &message.Base{}
+	off := offset.Offset{}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		node.write(msg, off)
+	}
+}