Optimize rounding distances, avoid promoting to double (#22846)

Signed-off-by: yah01 <yang.cen@zilliz.com>

.clang-tidy

@@ -20,7 +20,7 @@ Checks: >
     -*, clang-diagnostic-*, -clang-diagnostic-error,
     clang-analyzer-*, -clang-analyzer-alpha*,
     google-*, -google-runtime-references, -google-readability-todo,
-    modernize-*, -modernize-use-trailing-return-type,
+    modernize-*, -modernize-use-trailing-return-type, -modernize-use-nodiscard,
     performance-*,
     bugprone-bool-pointer-implicit-conversion,
     bugprone-branch-clone,

internal/core/src/index/VectorDiskIndex.cpp

@@ -216,7 +216,7 @@ VectorDiskAnnIndex<T>::Query(const DatasetPtr dataset,
     if (round_decimal != -1) {
         const float multiplier = pow(10.0, round_decimal);
         for (int i = 0; i < total_num; i++) {
-            distances[i] = round(distances[i] * multiplier) / multiplier;
+            distances[i] = std::round(distances[i] * multiplier) / multiplier;
         }
     }
     auto result = std::make_unique<SearchResult>();

internal/core/src/index/VectorMemIndex.cpp

@@ -15,6 +15,8 @@
 // limitations under the License.
 
 #include "index/VectorMemIndex.h"
+
+#include <cmath>
 #include "index/Meta.h"
 #include "index/Utils.h"
 #include "exceptions/EasyAssert.h"
@@ -129,7 +131,7 @@ VectorMemIndex::Query(const DatasetPtr dataset,
     if (round_decimal != -1) {
         const float multiplier = pow(10.0, round_decimal);
         for (int i = 0; i < total_num; i++) {
-            distances[i] = round(distances[i] * multiplier) / multiplier;
+            distances[i] = std::round(distances[i] * multiplier) / multiplier;
         }
     }
     auto result = std::make_unique<SearchResult>();

internal/core/src/query/SearchOnSealed.cpp

@@ -58,7 +58,7 @@ SearchOnSealedIndex(const Schema& schema,
     if (round_decimal != -1) {
         const float multiplier = pow(10.0, round_decimal);
         for (int i = 0; i < total_num; i++) {
-            distances[i] = round(distances[i] * multiplier) / multiplier;
+            distances[i] = std::round(distances[i] * multiplier) / multiplier;
         }
     }
     result.seg_offsets_.resize(total_num);

internal/core/src/query/SubSearchResult.cpp

@@ -89,9 +89,8 @@ SubSearchResult::round_values() {
     if (round_decimal_ == -1)
         return;
     const float multiplier = pow(10.0, round_decimal_);
-    for (auto it = this->distances_.begin(); it != this->distances_.end();
-         it++) {
-        *it = round(*it * multiplier) / multiplier;
+    for (float& distance : this->distances_) {
+        distance = std::round(distance * multiplier) / multiplier;
     }
 }
 

internal/core/src/query/SubSearchResult.h

@@ -34,11 +34,11 @@ class SubSearchResult {
           distances_(num_queries * topk, init_value(metric_type)) {
     }
 
-    SubSearchResult(SubSearchResult&& other)
+    SubSearchResult(SubSearchResult&& other) noexcept
         : num_queries_(other.num_queries_),
           topk_(other.topk_),
           round_decimal_(other.round_decimal_),
-          metric_type_(other.metric_type_),
+          metric_type_(std::move(other.metric_type_)),
           seg_offsets_(std::move(other.seg_offsets_)),
           distances_(std::move(other.distances_)) {
     }

internal/core/src/segcore/ReduceStructure.h

@@ -12,6 +12,7 @@
 #pragma once
 
 #include <limits>
+#include <utility>
 
 #include "common/Consts.h"
 #include "common/Types.h"
@@ -33,7 +34,7 @@ struct SearchResultPair {
                      int64_t index,
                      int64_t lb,
                      int64_t rb)
-        : primary_key_(primary_key),
+        : primary_key_(std::move(primary_key)),
           distance_(distance),
           search_result_(result),
           segment_index_(index),
@@ -43,7 +44,7 @@ struct SearchResultPair {
 
     bool
     operator>(const SearchResultPair& other) const {
-        if (fabs(distance_ - other.distance_) < 0.000001f) {
+        if (std::fabs(distance_ - other.distance_) < 0.000001f) {
             return primary_key_ < other.primary_key_;
         }
         return distance_ > other.distance_;