Fix data race problem on statistic module related to metric

Author: chenneal

BUILD

@@ -8,6 +8,7 @@ configure_make(
         "--enable-shared=no",
         "--disable-libevent-regress",
         "--disable-openssl",
+        "--with-pic",
     ],
     lib_source = "@com_github_libevent//:all",
     out_lib_dir = "lib",

sentinel-core/statistic/base/metric_bucket.cc

@@ -19,7 +19,7 @@ int64_t MetricBucket::Get(const MetricEvent& event) const {
   return counters_[i].load();
 }
 
-int64_t MetricBucket::MinRt() const { return min_rt_; }
+int64_t MetricBucket::MinRt() const { return min_rt_.load(); }
 
 void MetricBucket::Add(const MetricEvent& event, int64_t n) {
   int i = (int)event;
@@ -29,12 +29,12 @@ void MetricBucket::Add(const MetricEvent& event, int64_t n) {
 void MetricBucket::AddRt(int64_t rt) {
   Add(MetricEvent::RT, rt);
   // Not thread-safe, but it's okay.
-  if (rt < min_rt_) {
-    min_rt_ = rt;
+  if (rt < min_rt_.load()) {
+    min_rt_.store(rt);
   }
 }
 
-void MetricBucket::InitMinRt() { min_rt_ = Constants::kMaxAllowedRt; }
+void MetricBucket::InitMinRt() { min_rt_.store(Constants::kMaxAllowedRt); }
 
 }  // namespace Stat
 }  // namespace Sentinel

sentinel-core/statistic/base/metric_bucket.h

@@ -23,7 +23,7 @@ class MetricBucket {
   const std::unique_ptr<std::atomic<int64_t>[]> counters_ =
       std::make_unique<std::atomic<int64_t>[]>(
           static_cast<int>(MetricEvent::Count));
-  long min_rt_;
+  std::atomic<long> min_rt_;
 
   void InitMinRt();
 };

sentinel-core/statistic/base/window_wrap.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <atomic>
 #include <memory>
 
 namespace Sentinel {
@@ -21,7 +22,7 @@ class WindowWrap {
   bool IsTimeInBucket(int64_t time_millis) const;
 
  private:
-  int64_t bucket_start_;
+  std::atomic<int64_t> bucket_start_;
   const int64_t bucket_length_ms_;
   const std::shared_ptr<T> value_;
 };
@@ -36,7 +37,7 @@ int64_t WindowWrap<T>::BucketLengthInMs() const {
 
 template <typename T>
 int64_t WindowWrap<T>::BucketStart() const {
-  return bucket_start_;
+  return bucket_start_.load();
 }
 
 template <typename T>
@@ -46,7 +47,7 @@ std::shared_ptr<T> WindowWrap<T>::Value() const {
 
 template <typename T>
 void WindowWrap<T>::ResetTo(int64_t start_time) {
-  this->bucket_start_ = start_time;
+  this->bucket_start_.store(start_time);
 }
 
 template <typename T>