[Fix] coredump if add new c++ metrics (#666)

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# Purpose

What this PR does / why we need it?
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- Fixes #
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When adding new metric in c++, it would core dump and print "Please call
SetUp() first!"
# Modifications 

Does this PR introduce _any_ user-facing change?
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No using changes
# Test

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Tested with adding new metrics and online services

![img_v3_02u6_5dd8aa32-f951-44dd-8de8-fc22d634f34g](https://github.com/user-attachments/assets/31d12621-a885-44c2-97e9-43decc130ad8)

![img_v3_02u6_e73f6c7e-7f3f-416a-8852-f6f0eacdd6dg](https://github.com/user-attachments/assets/bdc1fc96-0ad8-49ec-8f64-8def75fa7a88)

Author: flesher0813

ucm/shared/metrics/cc/api/metrics_api.cc

@@ -24,7 +24,7 @@
 #include "metrics_api.h"
 namespace UC::Metrics {
 
-void SetUp(size_t maxVectorLen) { Metrics::SetUp(maxVectorLen); }
+void SetUp(size_t maxVectorLen) { Metrics::GetInstance().SetUp(maxVectorLen); }
 
 void CreateStats(const std::string& name, const std::string& type)
 {

ucm/shared/metrics/cc/domain/metrics.cc

@@ -29,14 +29,14 @@ thread_local std::shared_ptr<MetricBuffer> Metrics::threadBuffer_ =
     std::make_shared<MetricBuffer>();
 thread_local bool Metrics::isRegisteredThread_ = false;
 
-std::atomic<bool> Metrics::isInited_{false};
-size_t Metrics::maxVectorLen_{10000};
-
 void Metrics::CreateStats(const std::string& name, const std::string& type)
 {
-    std::unique_lock<std::shared_mutex> lock(mutex_);
+    if (!isInited_.load(std::memory_order_acquire)) {
+        throw std::runtime_error("Please call SetUp() first!");
+    }
     std::string typeUpper = type;
     std::transform(typeUpper.begin(), typeUpper.end(), typeUpper.begin(), ::toupper);
+    std::unique_lock<std::shared_mutex> lock(mutex_);
     if (statsType_.count(name)) {
         return;
     } else {

ucm/shared/metrics/cc/domain/metrics.h

@@ -35,7 +35,6 @@
 #include <tuple>
 #include <unordered_map>
 #include <vector>
-
 namespace UC::Metrics {
 struct MetricBuffer {
     struct InnerBuffer {
@@ -74,13 +73,13 @@ class Metrics {
 public:
     static Metrics& GetInstance()
     {
-        if (!isInited_) { throw std::runtime_error("Please call SetUp() first!"); }
         static Metrics inst;
         return inst;
     }
 
-    static void SetUp(size_t maxVectorLen)
+    void SetUp(size_t maxVectorLen)
     {
+        std::unique_lock<std::shared_mutex> lock(mutex_);
         if (isInited_.load(std::memory_order_acquire)) { return; }
         bool expected = false;
         if (isInited_.compare_exchange_strong(expected, true, std::memory_order_release,
@@ -113,8 +112,8 @@ class Metrics {
     Metrics() = default;
     Metrics(const Metrics&) = delete;
     Metrics& operator=(const Metrics&) = delete;
-    static std::atomic<bool> isInited_;
-    static size_t maxVectorLen_;
+    std::atomic<bool> isInited_{false};
+    size_t maxVectorLen_{10000};
 };
 }  // namespace UC::Metrics
 

ucm/shared/test/case/metrics/metrics_test.cc

@@ -35,7 +35,7 @@ class UCMetricsUT : public testing::Test {
     void SetUp() override
     {
         try {
-            Metrics::SetUp(1000000);
+            UC::Metrics::SetUp(1000000);
             CreateStats("stats1", "counter");
             CreateStats("stats2", "gauge");
             CreateStats("stats3", "histogram");