perf(go): decouple realtime mysql projection

go/vehicle-gateway/cmd/realtime-api/main_test.go

@@ -5,7 +5,9 @@ import (
 	"encoding/json"
 	"os"
 	"strings"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/segmentio/kafka-go"
 
@@ -96,6 +98,31 @@ func TestCompositeRealtimeUpdaterUpdatesBothStores(t *testing.T) {
 	}
 }
 
+func TestAsyncSecondaryRealtimeUpdaterDoesNotBlockPrimaryPath(t *testing.T) {
+	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolGB32960, VIN: "VIN001"}
+	primary := &contextCheckingRealtimeUpdater{}
+	secondary := &blockingRealtimeUpdater{started: make(chan struct{}), release: make(chan struct{})}
+	updater := newAsyncSecondaryRealtimeUpdater(primary, secondary, 8, 1)
+	defer updater.Close()
+
+	start := time.Now()
+	if err := updater.Update(context.Background(), env); err != nil {
+		t.Fatalf("Update() error = %v", err)
+	}
+	if elapsed := time.Since(start); elapsed > 100*time.Millisecond {
+		t.Fatalf("async updater blocked primary path for %v", elapsed)
+	}
+	if primary.count != 1 {
+		t.Fatalf("primary updates = %d, want 1", primary.count)
+	}
+	select {
+	case <-secondary.started:
+	case <-time.After(time.Second):
+		t.Fatal("secondary update was not started asynchronously")
+	}
+	close(secondary.release)
+}
+
 func TestKafkaTopicsFromEnvDefaultsToGoRawTopics(t *testing.T) {
 	got := strings.Join(kafkaTopicsFromEnv(), ",")
 	want := "vehicle.raw.go.gb32960.v1,vehicle.raw.go.jt808.v1,vehicle.raw.go.yutong-mqtt.v1"
@@ -164,3 +191,15 @@ type discardRealtimeLogger struct{}
 func (discardRealtimeLogger) Info(string, ...any)  {}
 func (discardRealtimeLogger) Error(string, ...any) {}
 func (discardRealtimeLogger) Warn(string, ...any)  {}
+
+type blockingRealtimeUpdater struct {
+	started chan struct{}
+	release chan struct{}
+	once    sync.Once
+}
+
+func (u *blockingRealtimeUpdater) Update(context.Context, envelope.FrameEnvelope) error {
+	u.once.Do(func() { close(u.started) })
+	<-u.release
+	return nil
+}