Add ToIndexData for CopyToIndexFileToGpu

Former-commit-id: 901d2113cb3530b7425f267b34f42e99439b6e0c

cpp/src/db/engine/ExecutionEngineImpl.cpp

@@ -243,12 +243,9 @@ ExecutionEngineImpl::CopyToGpu(uint64_t device_id) {
 
 Status
 ExecutionEngineImpl::CopyToIndexFileToGpu(uint64_t device_id) {
-    auto index = cache::GpuCacheMgr::GetInstance(device_id)->GetIndex(location_);
-    bool already_in_cache = (index != nullptr);
-    if (!already_in_cache) {
-        cache::DataObjPtr obj = std::make_shared<cache::DataObj>(nullptr, PhysicalSize());
-        milvus::cache::GpuCacheMgr::GetInstance(device_id)->InsertItem(location_, obj);
-    }
+    auto to_index_data = std::make_shared<ToIndexData>(PhysicalSize());
+    cache::DataObjPtr obj = std::static_pointer_cast<cache::DataObj>(to_index_data);
+    milvus::cache::GpuCacheMgr::GetInstance(device_id)->InsertItem(location_, obj);
     return Status::OK();
 }
 

cpp/src/wrapper/VecImpl.h

@@ -111,5 +111,16 @@ class BFIndex : public VecIndexImpl {
     GetRawIds();
 };
 
+class ToIndexData : public cache::DataObj {
+ public:
+    ToIndexData(int64_t size) : size_(size) {}
+
+    int64_t
+    Size() override {return size_;}
+
+ private:
+    int64_t size_;
+};
+
 }  // namespace engine
 }  // namespace milvus