Fix bug: Exclude hosts with missing or 404 HTTP check status

The bug was that when HTTP check results were missing from the map (value = 0),
hosts were incorrectly included in lag calculations.

Fixed by checking for both StatusNotFound (404) AND zero (missing map entry).

- Updated aggregateMySQLProbes to check: httpStatus == StatusNotFound || httpStatus == 0
- Added test case TestAggregateMySQLProbesWithMissingHttpChecks to validate fix
- All existing tests pass

Co-authored-by: alexisjcarr <34029816+alexisjcarr@users.noreply.github.com>

Author: Copilot

pkg/throttle/mysql.go

@@ -21,7 +21,8 @@ func aggregateMySQLProbes(
 	// so it's safe to iterate it
 	probeValues := []float64{}
 	for _, probe := range *probes {
-		if clusterInstanceHttpChecksMap[mysql.MySQLHttpCheckHashKey(clusterName, &probe.Key)] == http.StatusNotFound {
+		httpStatus := clusterInstanceHttpChecksMap[mysql.MySQLHttpCheckHashKey(clusterName, &probe.Key)]
+		if httpStatus == http.StatusNotFound || httpStatus == 0 {
 			continue
 		}
 		instanceMetricResult, ok := instanceResultsMap[mysql.GetClusterInstanceKey(clusterName, &probe.Key)]

pkg/throttle/mysql_test.go

@@ -265,3 +265,34 @@ func TestAggregateMySQLProbesWithHttpChecks(t *testing.T) {
 		test.S(t).ExpectNotNil(err)
 	}
 }
+
+func TestAggregateMySQLProbesWithMissingHttpChecks(t *testing.T) {
+clusterName := "c0"
+k1 := mysql.GetClusterInstanceKey(clusterName, &key1)
+k2 := mysql.GetClusterInstanceKey(clusterName, &key2)
+k3 := mysql.GetClusterInstanceKey(clusterName, &key3)
+
+results := mysql.InstanceMetricResultMap{
+k1: base.NewSimpleMetricResult(1.2),
+k2: base.NewSimpleMetricResult(2.5),
+k3: base.NewSimpleMetricResult(0.3),
+}
+
+// Test with missing HTTP check entry (will return 0 from map)
+checksWithMissing := mysql.ClusterInstanceHttpCheckResultMap{
+mysql.MySQLHttpCheckHashKey(clusterName, &key1): http.StatusOK,
+mysql.MySQLHttpCheckHashKey(clusterName, &key3): http.StatusOK,
+// key2 is missing - should be excluded
+}
+
+var probeSet mysql.Probes = map[mysql.InstanceKey](*mysql.Probe){}
+for ck := range results {
+probeSet[ck.Key] = &mysql.Probe{Key: ck.Key}
+}
+
+metric := aggregateMySQLProbes(&probeSet, clusterName, results, checksWithMissing, 0, false, 0)
+val, err := metric.Get()
+test.S(t).ExpectNil(err)
+// key2 (2.5) should be excluded due to missing HTTP check, worst should be 1.2
+test.S(t).ExpectEquals(val, 1.2)
+}