Throttler: CheckThrottlerResponseCode to replace HTTP status codes

go/vt/vttablet/tabletmanager/rpc_throttler.go

@@ -53,6 +53,7 @@ func (tm *TabletManager) CheckThrottler(ctx context.Context, req *tabletmanagerd
 		return nil, vterrors.Errorf(vtrpc.Code_INTERNAL, "nil checkResult")
 	}
 	resp := &tabletmanagerdatapb.CheckThrottlerResponse{
+		ResponseCode:    throttle.ResponseCodeFromStatus(checkResult.ResponseCode, checkResult.StatusCode),
 		StatusCode:      int32(checkResult.StatusCode),
 		Value:           checkResult.Value,
 		Threshold:       checkResult.Threshold,
@@ -64,22 +65,24 @@ func (tm *TabletManager) CheckThrottler(ctx context.Context, req *tabletmanagerd
 	}
 	for name, metric := range checkResult.Metrics {
 		resp.Metrics[name] = &tabletmanagerdatapb.CheckThrottlerResponse_Metric{
-			Name:       name,
-			Scope:      metric.Scope,
-			StatusCode: int32(metric.StatusCode),
-			Value:      metric.Value,
-			Threshold:  metric.Threshold,
-			Message:    metric.Message,
+			Name:         name,
+			Scope:        metric.Scope,
+			StatusCode:   int32(metric.StatusCode),
+			ResponseCode: throttle.ResponseCodeFromStatus(metric.ResponseCode, metric.StatusCode),
+			Value:        metric.Value,
+			Threshold:    metric.Threshold,
+			Message:      metric.Message,
 		}
 	}
 	if len(checkResult.Metrics) == 0 {
 		// For backwards compatibility, when the checked tablet is of lower version, it does not return a
 		// matrics map, but only the one metric.
 		resp.Metrics[base.DefaultMetricName.String()] = &tabletmanagerdatapb.CheckThrottlerResponse_Metric{
-			StatusCode: int32(checkResult.StatusCode),
-			Value:      checkResult.Value,
-			Threshold:  checkResult.Threshold,
-			Message:    checkResult.Message,
+			StatusCode:   int32(checkResult.StatusCode),
+			ResponseCode: throttle.ResponseCodeFromStatus(checkResult.ResponseCode, checkResult.StatusCode),
+			Value:        checkResult.Value,
+			Threshold:    checkResult.Threshold,
+			Message:      checkResult.Message,
 		}
 	}
 	if checkResult.Error != nil {
@@ -140,8 +143,9 @@ func (tm *TabletManager) GetThrottlerStatus(ctx context.Context, req *tabletmana
 	}
 	for _, recentApp := range status.RecentApps {
 		resp.RecentApps[recentApp.AppName] = &tabletmanagerdatapb.GetThrottlerStatusResponse_RecentApp{
-			CheckedAt:  protoutil.TimeToProto(recentApp.CheckedAt),
-			StatusCode: int32(recentApp.StatusCode),
+			CheckedAt:    protoutil.TimeToProto(recentApp.CheckedAt),
+			StatusCode:   int32(recentApp.StatusCode),
+			ResponseCode: recentApp.ResponseCode,
 		}
 	}
 	return resp, nil

go/vt/vttablet/tabletserver/tabletserver.go

@@ -46,6 +46,7 @@ import (
 	"vitess.io/vitess/go/vt/mysqlctl"
 	binlogdatapb "vitess.io/vitess/go/vt/proto/binlogdata"
 	querypb "vitess.io/vitess/go/vt/proto/query"
+	tabletmanagerdatapb "vitess.io/vitess/go/vt/proto/tabletmanagerdata"
 	topodatapb "vitess.io/vitess/go/vt/proto/topodata"
 	vtrpcpb "vitess.io/vitess/go/vt/proto/vtrpc"
 	"vitess.io/vitess/go/vt/servenv"
@@ -1800,8 +1801,9 @@ func (tsv *TabletServer) registerThrottlerCheckHandlers() {
 			}
 			metricNames := tsv.lagThrottler.MetricNames(r.URL.Query()["m"])
 			checkResult := tsv.lagThrottler.Check(ctx, appName, metricNames, flags)
-			if checkResult.StatusCode == http.StatusNotFound && flags.OKIfNotExists {
+			if checkResult.ResponseCode == tabletmanagerdatapb.CheckThrottlerResponseCode_UNKNOWN_METRIC && flags.OKIfNotExists {
 				checkResult.StatusCode = http.StatusOK // 200
+				checkResult.ResponseCode = tabletmanagerdatapb.CheckThrottlerResponseCode_OK
 			}
 
 			if r.Method == http.MethodGet {

go/vt/vttablet/tabletserver/throttle/base/recent_app.go

@@ -42,21 +42,25 @@ package base
 
 import (
 	"time"
+
+	tabletmanagerdatapb "vitess.io/vitess/go/vt/proto/tabletmanagerdata"
 )
 
 // RecentApp indicates when an app was last checked
 type RecentApp struct {
-	AppName    string
-	CheckedAt  time.Time
-	StatusCode int
+	AppName      string
+	CheckedAt    time.Time
+	StatusCode   int
+	ResponseCode tabletmanagerdatapb.CheckThrottlerResponseCode
 }
 
 // NewRecentApp creates a RecentApp
-func NewRecentApp(appName string, statusCode int) *RecentApp {
+func NewRecentApp(appName string, statusCode int, responseCode tabletmanagerdatapb.CheckThrottlerResponseCode) *RecentApp {
 	result := &RecentApp{
-		AppName:    appName,
-		CheckedAt:  time.Now(),
-		StatusCode: statusCode,
+		AppName:      appName,
+		CheckedAt:    time.Now(),
+		StatusCode:   statusCode,
+		ResponseCode: responseCode,
 	}
 	return result
 }