Fix get_num_threads()

Author: rfsaliev

bindings/c/src/index.hpp

@@ -48,7 +48,7 @@ struct Index {
     virtual float get_distance(size_t id, std::span<const float> query) const = 0;
     virtual void
     reconstruct_at(svs::data::SimpleDataView<float> dst, std::span<const size_t> ids) = 0;
-    virtual size_t get_num_threads() { return pool_builder.get_threads_num(); };
+    virtual size_t get_num_threads() = 0;
     virtual void set_num_threads(size_t num_threads) = 0;
 };
 
@@ -105,6 +105,8 @@ struct IndexVamana : public Index {
         index.reconstruct_at(dst, ids);
     }
 
+    size_t get_num_threads() override { return index.get_num_threads(); }
+
     void set_num_threads(size_t num_threads) override {
         pool_builder.resize(num_threads);
         index.set_threadpool(pool_builder.build());
@@ -181,6 +183,8 @@ struct DynamicIndexVamana : public DynamicIndex {
         }
     }
 
+    size_t get_num_threads() override { return index.get_num_threads(); }
+
     void set_num_threads(size_t num_threads) override {
         pool_builder.resize(num_threads);
         index.set_threadpool(pool_builder.build());