Change Interface to unique_ptr

Author: reyoung

doc/design/register_grad_op.md

@@ -42,7 +42,7 @@ The `GradOpDescMaker` will be registered in `OpInfo`, to replace `grad_op_type_`
 
 ```cpp
 struct OpInfo {
-  std::function<std::vector<OpDescBind>(const OpDescBind&)>  grad_op_maker_;
+  std::function<std::vector<std::unique_ptr<OpDescBind>>(const OpDescBind&)>  grad_op_maker_;
   ...
 };
 ```
@@ -55,11 +55,11 @@ We propose a base class called `GradOpDescMakerBase` to let operator developers
 class GradOpDescMakerBase {
 public:
   GradOpDescMakerBase(const OpDescBind& );
-  virtual std::vector<OpDescBind> operator()()const = 0;
+  virtual std::vector<std::unique_ptr<OpDescBind>> operator()()const = 0;
 };
 ```
 
-We can convert `GradOpDescMakerBase` to `std::function<std::vector<OpDescBind>(const OpDescBind&)>` by
+We can convert `GradOpDescMakerBase` to `std::function<std::vector<std::unique_ptr<OpDescBind>>(const OpDescBind&)>` by
 
 ```cpp
 using GradOpMaker = ...;

paddle/framework/grad_op_desc_maker.h

@@ -24,7 +24,7 @@ class GradOpDescMakerBase {
   explicit GradOpDescMakerBase(const OpDescBind& fwd_op) : fwd_op_(fwd_op) {}
 
   virtual ~GradOpDescMakerBase() = default;
-  virtual std::vector<OpDescBind> operator()() const = 0;
+  virtual std::vector<std::unique_ptr<OpDescBind>> operator()() const = 0;
 
  protected:
   static std::vector<std::string> ToGradNames(
@@ -81,34 +81,38 @@ class SingleGradOpDescMaker : public GradOpDescMakerBase {
  public:
   using GradOpDescMakerBase::GradOpDescMakerBase;
 
-  std::vector<OpDescBind> operator()() const { return {this->Apply()}; }
+  std::vector<std::unique_ptr<OpDescBind>> operator()() const {
+    std::vector<std::unique_ptr<OpDescBind>> retv;
+    retv.emplace_back(this->Apply());
+    return retv;
+  }
 
  protected:
-  virtual OpDescBind Apply() const = 0;
+  virtual std::unique_ptr<OpDescBind> Apply() const = 0;
 };
 
 class DefaultGradOpDescMaker : public SingleGradOpDescMaker {
  public:
   using SingleGradOpDescMaker::SingleGradOpDescMaker;
 
  protected:
-  virtual OpDescBind Apply() const {
-    OpDescBind grad;
-    grad.SetType(this->GradOpType());
+  virtual std::unique_ptr<OpDescBind> Apply() const {
+    auto* grad = new OpDescBind();
+    grad->SetType(this->GradOpType());
 
     for (auto& input_param : this->InputNames()) {
-      grad.SetInput(input_param, this->Input(input_param));
-      grad.SetOutput(GradVarName(input_param), this->InputGrad(input_param));
+      grad->SetInput(input_param, this->Input(input_param));
+      grad->SetOutput(GradVarName(input_param), this->InputGrad(input_param));
     }
 
     for (auto& output_param : this->OutputNames()) {
-      grad.SetInput(output_param, this->Output(output_param));
-      grad.SetInput(GradVarName(output_param), this->OutputGrad(output_param));
+      grad->SetInput(output_param, this->Output(output_param));
+      grad->SetInput(GradVarName(output_param), this->OutputGrad(output_param));
     }
 
-    grad.SetAttrMap(this->Attrs());
+    grad->SetAttrMap(this->Attrs());
 
-    return grad;
+    return std::unique_ptr<OpDescBind>(grad);
   }
 
   virtual std::string GradOpType() const {

paddle/framework/op_info.h

@@ -28,7 +28,7 @@ namespace framework {
 struct OpInfo {
   OpCreator creator_;
   std::string grad_op_type_;
-  std::function<std::vector<OpDescBind>(const OpDescBind&)> grad_op_maker_;
+  GradOpMakerFN grad_op_maker_;
   OpProto* proto_{nullptr};
   OpAttrChecker* checker_{nullptr};
 

paddle/framework/type_defs.h

@@ -20,6 +20,7 @@
 namespace paddle {
 namespace framework {
 class OperatorBase;
+class OpDescBind;
 using VariableNameMap = std::map<std::string, std::vector<std::string>>;
 
 // The order should be as same as framework.proto
@@ -34,5 +35,8 @@ using OpCreator = std::function<OperatorBase*(
     const std::string& /*type*/, const VariableNameMap& /*inputs*/,
     const VariableNameMap& /*outputs*/, const AttributeMap& /*attrs*/)>;
 
+using GradOpMakerFN =
+    std::function<std::vector<std::unique_ptr<OpDescBind>>(const OpDescBind&)>;
+
 }  // namespace framework
 }  // namespace paddle