follow comments, use unique_ptr and remove unused file

paddle/platform/device_context.cc

@@ -189,11 +189,11 @@ void MKLDNNDeviceContext::AddElement(const std::string& op_key,
   if (GetElement<T>(op_key)) {
     return;
   }
-  GetElementPool<T>().emplace(op_key, value);
+  GetElementPool<T>().emplace(op_key, std::move(value));
 }
 
 template <typename T>
-const T MKLDNNDeviceContext::GetElement(const std::string& op_key) const {
+const T& MKLDNNDeviceContext::GetElement(const std::string& op_key) const {
   auto it = GetElementPool<T>().find(op_key);
   return it == GetElementPool<T>().end() ? nullptr : it->second;
 }

paddle/platform/device_context.h

@@ -132,7 +132,7 @@ class MKLDNNDeviceContext : public CPUDeviceContext {
 
   /* \brief  Get existed element: memory, primitive or primitive desc */
   template <typename T>
-  const T GetElement(const std::string& op_key) const;
+  const T& GetElement(const std::string& op_key) const;
 
   /* \brief  Get element pool: memory, primitive or primitive desc pool */
   template <typename T>
@@ -140,7 +140,7 @@ class MKLDNNDeviceContext : public CPUDeviceContext {
   GetElementPool() const;
 
   /* \brief  Get the active engine */
-  const MKLDNNEnginePtr GetEngine() const { return engine_; }
+  const MKLDNNEngine& engine() const { return *engine_; }
 
   /* \brief  Submit primitive to pipeline */
   void Submit(const MKLDNNPrimitivePtr& p) { pipeline_.push_back(*p); }
@@ -163,7 +163,7 @@ class MKLDNNDeviceContext : public CPUDeviceContext {
                      std::hash<std::string>>
       primitive_desc_pool_;
   std::vector<MKLDNNPrimitive> pipeline_;
-  std::unique_ptr<MKLDNNStream> stream_;
+  MKLDNNStreamPtr stream_;
   MKLDNNEnginePtr engine_;
   bool ready_;
 };

paddle/platform/mkldnn_helper.h

@@ -25,10 +25,11 @@ using MKLDNNMemory = mkldnn::memory;
 using MKLDNNPrimitive = mkldnn::primitive;
 using MKLDNNPrimitiveDesc = mkldnn::handle<mkldnn_primitive_desc_t>;
 
-typedef std::shared_ptr<MKLDNNEngine> MKLDNNEnginePtr;
-typedef std::shared_ptr<MKLDNNMemory> MKLDNNMemoryPtr;
-typedef std::shared_ptr<MKLDNNPrimitive> MKLDNNPrimitivePtr;
-typedef std::shared_ptr<MKLDNNPrimitiveDesc> MKLDNNPrimitiveDescPtr;
+typedef std::unique_ptr<MKLDNNStream> MKLDNNStreamPtr;
+typedef std::unique_ptr<MKLDNNEngine> MKLDNNEnginePtr;
+typedef std::unique_ptr<MKLDNNMemory> MKLDNNMemoryPtr;
+typedef std::unique_ptr<MKLDNNPrimitive> MKLDNNPrimitivePtr;
+typedef std::unique_ptr<MKLDNNPrimitiveDesc> MKLDNNPrimitiveDescPtr;
 
 }  // namespace platform
 }  // namespace paddle