Add const for getLayerOutput

paddle/gserver/gradientmachines/GradientMachine.h

@@ -134,7 +134,7 @@ public:
     backward(callback);
   }
 
-  virtual MatrixPtr getLayerOutput(const std::string& layerName) {
+  virtual MatrixPtr getLayerOutput(const std::string& layerName) const {
     return nullptr;
   }
 

paddle/gserver/gradientmachines/MultiGradientMachine.cpp

@@ -282,7 +282,8 @@ void MultiGradientMachine::forwardBackward(const std::vector<Argument>& inArgs,
   backwardImp(callback);
 }
 
-MatrixPtr MultiGradientMachine::getLayerOutput(const std::string& layerName) {
+MatrixPtr MultiGradientMachine::getLayerOutput(
+    const std::string& layerName) const {
   // each thread has the same neural network
   auto nn = threads_[0]->getGradientMachine();
   size_t height = 0;
@@ -301,11 +302,10 @@ MatrixPtr MultiGradientMachine::getLayerOutput(const std::string& layerName) {
 
   // copy one layer output from one trainer thread at each time
   size_t startRow = 0;
-
-  for (size_t i = 0; i < threads_.size(); i++) {
-    auto tmpMatrix = layerOutput->subMatrix(startRow, mats[i]->getHeight());
-    tmpMatrix->copyFrom(*mats[i]);
-    startRow += mats[i]->getHeight();
+  for (auto& mat : mats) {
+    auto tmpMatrix = layerOutput->subMatrix(startRow, mat->getHeight());
+    tmpMatrix->copyFrom(*mat);
+    startRow += mat->getHeight();
   }
 
   return layerOutput;

paddle/gserver/gradientmachines/MultiGradientMachine.h

@@ -189,7 +189,7 @@ public:
                        PassType passType,
                        const UpdateCallback& callback);
 
-  virtual MatrixPtr getLayerOutput(const std::string& layerName);
+  virtual MatrixPtr getLayerOutput(const std::string& layerName) const;
 
   virtual void onPassEnd();
 

paddle/gserver/gradientmachines/NeuralNetwork.cpp

@@ -293,7 +293,7 @@ void NeuralNetwork::backward(const UpdateCallback& callback) {
   }
 }
 
-MatrixPtr NeuralNetwork::getLayerOutput(const std::string& layerName) {
+MatrixPtr NeuralNetwork::getLayerOutput(const std::string& layerName) const {
   auto it = layerMap_.find(layerName);
   CHECK(it != layerMap_.end()) << "Cannot find layer: " << layerName;
   return it->second->getOutputValue();

paddle/gserver/gradientmachines/NeuralNetwork.h

@@ -87,7 +87,7 @@ public:
 
   virtual void backward(const UpdateCallback& callback = nullptr);
 
-  virtual MatrixPtr getLayerOutput(const std::string& layerName);
+  virtual MatrixPtr getLayerOutput(const std::string& layerName) const;
 
   const LayerPtr& getLayer(const std::string& layerName) const {
     auto it = layerMap_.find(layerName);