[8.2] Fix incoming edges ghost memory leak (MOD-13761)

.github/workflows/benchmark.yml

@@ -45,6 +45,7 @@ on:
           - bm-svs-train-fp16
           - bm-basics-svs-fp32-single
           - bm-spaces
+          - bm-hnsw-internals-incoming-edges
         description: 'Benchmarks set to run'
         default: benchmarks-all
       architecture:

src/VecSim/algorithms/hnsw/graph_data.h

@@ -6,6 +6,10 @@
 #include <mutex>
 #include "VecSim/utils/vec_utils.h"
 
+// Amortized shrink thresholds for incoming edges vectors.
+// Shrink is triggered when: capacity > SHRINK_RATIO * size
+constexpr size_t INCOMING_EDGES_SHRINK_RATIO = 2;
+
 template <typename DistType>
 using candidatesList = vecsim_stl::vector<std::pair<DistType, idType>>;
 
@@ -73,7 +77,16 @@ struct ElementLevelData {
         this->incomingUnidirectionalEdges->push_back(node_id);
     }
     bool removeIncomingUnidirectionalEdgeIfExists(idType node_id) {
-        return this->incomingUnidirectionalEdges->remove(node_id);
+        bool result = this->incomingUnidirectionalEdges->remove(node_id);
+
+        if (result) {
+            auto &vec = *this->incomingUnidirectionalEdges;
+            if (vec.capacity() > INCOMING_EDGES_SHRINK_RATIO * vec.size()) {
+                vec.shrink_to_fit();
+            }
+        }
+
+        return result;
     }
     void swapNodeIdInIncomingEdges(idType id_before, idType id_after) {
         auto it = std::find(this->incomingUnidirectionalEdges->begin(),

src/VecSim/algorithms/hnsw/hnsw_tiered_tests_friends.h

@@ -74,3 +74,5 @@ friend class CommonTypeMetricTieredTests_TestDataSizeTieredHNSW_Test;
 
 INDEX_TEST_FRIEND_CLASS(BM_VecSimBasics)
 INDEX_TEST_FRIEND_CLASS(BM_VecSimCommon)
+
+friend class BM_IncomingEdgesBase;

tests/benchmark/benchmarks.sh

@@ -9,6 +9,7 @@ if [ -z "$BM_TYPE"  ] || [ "$BM_TYPE" = "benchmarks-all" ]; then
         done
     done
     echo updated_index_single_fp32
+    echo index_internals_incoming_edges_fp32
     echo svs_training_fp32
     echo svs_training_fp16
     echo basics_svs_single_fp32
@@ -89,6 +90,10 @@ elif [ "$BM_TYPE" = "bm-batch-iter-uint8-multi" ] ; then
 elif [ "$BM_TYPE" = "bm-updated-fp32-single" ] ; then
     echo updated_index_single_fp32
 
+# hnsw internals benchmarks
+elif [ "$BM_TYPE" = "bm-hnsw-internals-incoming-edges" ] ; then
+    echo index_internals_incoming_edges_fp32
+
 # SVS benchmarks
 elif [ "$BM_TYPE" = "bm-svs-train-fp32" ] ; then
     echo svs_training_fp32