[#1629] fix(operator): Support parsing NaN float value in metrics (#1630

)

### What changes were proposed in this pull request?
When parsing json, handle special cases where the value might be NaN

### Why are the changes needed?
Fix: #1629 

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
test in real cluster and add unit test

deploy/kubernetes/operator/pkg/webhook/util/util.go

@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"math"
 	"net/http"
 	"time"
 
@@ -158,12 +159,40 @@ func NeedInspectPod(pod *corev1.Pod) bool {
 	return false
 }
 
+// JSONFloat is used to parse the float64 which may be NaN
+type JSONFloat float64
+
+// MarshalJSON return bytes representing JSONFloat
+func (j JSONFloat) MarshalJSON() ([]byte, error) {
+	v := float64(j)
+	if math.IsNaN(v) {
+		s := "\"NaN\""
+		return []byte(s), nil
+	}
+	return json.Marshal(v) // marshal result as standard float64
+}
+
+// UnmarshalJSON return the parsed JSONFloat
+func (j *JSONFloat) UnmarshalJSON(v []byte) error {
+	if s := string(v); s == "\"NaN\"" {
+		*j = JSONFloat(math.NaN())
+		return nil
+	}
+	// just a regular float value
+	var fv float64
+	if err := json.Unmarshal(v, &fv); err != nil {
+		return err
+	}
+	*j = JSONFloat(fv)
+	return nil
+}
+
 // MetricItem records an item of metric information of shuffle servers.
 type MetricItem struct {
-	Name        string   `json:"name"`
-	LabelNames  []string `json:"labelNames"`
-	LabelValues []string `json:"labelValues"`
-	Value       float32  `json:"value"`
+	Name        string    `json:"name"`
+	LabelNames  []string  `json:"labelNames"`
+	LabelValues []string  `json:"labelValues"`
+	Value       JSONFloat `json:"value"`
 }
 
 // MetricList records all items of metric information of shuffle servers.

deploy/kubernetes/operator/pkg/webhook/util/util_test.go

@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package util
+
+import (
+	"encoding/json"
+	"math"
+	"testing"
+)
+
+// JSONFloatWrapper is struct which contain JSONFloat
+type JSONFloatWrapper struct {
+	Value1 JSONFloat `json:"value1"`
+	Value2 JSONFloat `json:"value2"`
+}
+
+func TestParseJsonFloat(t *testing.T) {
+	wrapper := JSONFloatWrapper{Value1: JSONFloat(math.NaN()), Value2: 9.99}
+	bytes, err := json.Marshal(wrapper)
+	if err != nil {
+		t.Fatal("Marshal JsonFloat failed, caused by ", err.Error())
+	}
+	parsed := &JSONFloatWrapper{}
+	if err := json.Unmarshal(bytes, parsed); err != nil {
+		t.Fatal("Unmarshal JsonFloat failed, caused by ", err.Error())
+	} else if !math.IsNaN(float64(parsed.Value1)) {
+		t.Fatal("Value1 should be Nan")
+	} else if math.Abs(float64(parsed.Value2)-9.99) > 1e-9 {
+		t.Fatal("Value1 should be 9.99")
+	}
+}
+
+func TestGetLastAppNum(t *testing.T) {
+	jsonString := `
+		{
+			"metrics": [{
+				"name": "app_num_with_node",
+				"labelNames": ["tags"],
+				"labelValues": ["ss_v5,GRPC"],
+				"value": 10.0,
+				"timestampMs": null
+			}, {
+				"name": "total_remove_resource_time",
+				"labelNames": ["quantile"],
+				"labelValues": ["0.5"],
+				"value": "NaN",
+				"timestampMs": null
+			}],
+			"timeStamp": 1712575271639
+		}
+	`
+	if num, err := getLastAppNum([]byte(jsonString)); err != nil {
+		t.Fatal("getLastAppNum failed, casued by ", err.Error())
+	} else if num != 10 {
+		t.Fatal("Get wrong app number: ", num)
+	}
+}