refactor useless copy to const reference.

Author: LindaSummer

src/types/redis_tdigest.cc

@@ -49,8 +49,8 @@ namespace redis {
 // It should be replaced by a iteration of the rocksdb iterator
 class DummyCentroids {
  public:
-  DummyCentroids(const TDigestMetadata& meta_data, std::vector<Centroid> centroids)
-      : meta_data_(meta_data), centroids_(std::move(centroids)) {}
+  DummyCentroids(const TDigestMetadata& meta_data, const std::vector<Centroid>& centroids)
+      : meta_data_(meta_data), centroids_(centroids) {}
   class Iterator {
    public:
     Iterator(std::vector<Centroid>::const_iterator&& iter, const std::vector<Centroid>& centroids)
@@ -98,7 +98,7 @@ class DummyCentroids {
 
  private:
   const TDigestMetadata& meta_data_;
-  std::vector<Centroid> centroids_;
+  const std::vector<Centroid>& centroids_;
 };
 
 uint64_t constexpr kMaxElements = 1 * 1024;  // 1k doubles

src/types/tdigest.h

@@ -38,8 +38,7 @@ struct Centroid {
 
   std::string ToString() const { return fmt::format("centroid<mean: {}, weight: {}>", mean, weight); }
 
-  template <typename T>
-  explicit Centroid(T&& centroid) : mean(centroid.mean), weight(centroid.weight) {}
+  Centroid(const Centroid& centroid) = default;
 
   explicit Centroid() = default;
   explicit Centroid(double mean, double weight) : mean(mean), weight(weight) {}