feat(go): batch nats fast writer tdengine writes

go/vehicle-gateway/cmd/nats-fast-writer/main_test.go

@@ -80,9 +80,44 @@ func TestProcessFastMessageRecordsStageDurationMetrics(t *testing.T) {
 	}
 }
 
+func TestProcessFastBatchAppendsTDengineBatchBeforeRedisAndAck(t *testing.T) {
+	first := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, VIN: "VIN001", EventID: "evt-4"}
+	second := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, VIN: "VIN002", EventID: "evt-5"}
+	firstPayload, err := first.MarshalJSONBytes()
+	if err != nil {
+		t.Fatal(err)
+	}
+	secondPayload, err := second.MarshalJSONBytes()
+	if err != nil {
+		t.Fatal(err)
+	}
+	appender := &recordingFastAppender{}
+	updater := &recordingFastUpdater{}
+	ackCount := 0
+	msgs := []*fastMessage{
+		{subject: "vehicle.raw.go.jt808.v1", data: firstPayload, ack: func() error { ackCount++; return nil }},
+		{subject: "vehicle.raw.go.jt808.v1", data: secondPayload, ack: func() error { ackCount++; return nil }},
+	}
+
+	if err := processFastBatch(context.Background(), nil, appender, updater, msgs); err != nil {
+		t.Fatalf("processFastBatch() error = %v", err)
+	}
+	if appender.count != 0 {
+		t.Fatalf("AppendAll count = %d, want 0", appender.count)
+	}
+	if appender.batchCount != 1 || appender.batchRows != 2 {
+		t.Fatalf("AppendAllBatch count=%d rows=%d, want count=1 rows=2", appender.batchCount, appender.batchRows)
+	}
+	if updater.count != 2 || ackCount != 2 {
+		t.Fatalf("updates=%d acks=%d, want 2/2", updater.count, ackCount)
+	}
+}
+
 type recordingFastAppender struct {
-	count int
-	err   error
+	count      int
+	batchCount int
+	batchRows  int
+	err        error
 }
 
 func (a *recordingFastAppender) AppendAll(context.Context, envelope.FrameEnvelope) error {
@@ -90,6 +125,12 @@ func (a *recordingFastAppender) AppendAll(context.Context, envelope.FrameEnvelop
 	return a.err
 }
 
+func (a *recordingFastAppender) AppendAllBatch(_ context.Context, envs []envelope.FrameEnvelope) error {
+	a.batchCount++
+	a.batchRows += len(envs)
+	return a.err
+}
+
 type recordingFastUpdater struct {
 	count int
 	err   error