break out Step from Solver

include/caffe/solver.hpp

@@ -26,6 +26,7 @@ class Solver {
   // in a non-zero iter number to resume training for a pre-trained net.
   virtual void Solve(const char* resume_file = NULL);
   inline void Solve(const string resume_file) { Solve(resume_file.c_str()); }
+  void Step(int iters);
   virtual ~Solver() {}
   inline shared_ptr<Net<Dtype> > net() { return net_; }
   inline const vector<shared_ptr<Net<Dtype> > >& test_nets() {
@@ -36,7 +37,7 @@ class Solver {
  protected:
   // PreSolve is run before any solving iteration starts, allowing one to
   // put up some scaffold.
-  virtual void PreSolve() {}
+  virtual void PreSolve();
   // Get the update value for the current iteration.
   virtual void ComputeUpdateValue() = 0;
   // The Solver::Snapshot function implements the basic snapshotting utility
@@ -57,9 +58,11 @@ class Solver {
 
   SolverParameter param_;
   int iter_;
+  int start_iter_;
   int current_step_;
   shared_ptr<Net<Dtype> > net_;
   vector<shared_ptr<Net<Dtype> > > test_nets_;
+  bool initialized_;
 
   DISABLE_COPY_AND_ASSIGN(Solver);
 };

src/caffe/solver.cpp

@@ -29,9 +29,11 @@ Solver<Dtype>::Solver(const string& param_file)
 
 template <typename Dtype>
 void Solver<Dtype>::Init(const SolverParameter& param) {
+  initialized_ = false;
   LOG(INFO) << "Initializing solver from parameters: " << std::endl
             << param.DebugString();
   param_ = param;
+  CHECK_GE(param_.average_loss, 1) << "average_loss should be non-negative.";
   if (param_.random_seed() >= 0) {
     Caffe::set_random_seed(param_.random_seed());
   }
@@ -155,35 +157,20 @@ void Solver<Dtype>::InitTestNets() {
 }
 
 template <typename Dtype>
-void Solver<Dtype>::Solve(const char* resume_file) {
-  Caffe::set_phase(Caffe::TRAIN);
-  LOG(INFO) << "Solving " << net_->name();
-  LOG(INFO) << "Learning Rate Policy: " << param_.lr_policy();
-  PreSolve();
-
-  iter_ = 0;
-  current_step_ = 0;
-  if (resume_file) {
-    LOG(INFO) << "Restoring previous solver status from " << resume_file;
-    Restore(resume_file);
+void Solver<Dtype>::Step(int iters) {
+  if (!initialized_) {
+    PreSolve();
   }
-  // Remember the initial iter_ value; will be non-zero if we loaded from a
-  // resume_file above.
-  const int start_iter = iter_;
 
+  vector<Blob<Dtype>*> bottom_vec;
+  const int stop_iter = iter_ + iters;
   int average_loss = this->param_.average_loss();
-
-  CHECK_GE(average_loss, 1) << "average_loss should be non-negative.";
-
   vector<Dtype> losses;
   Dtype smoothed_loss = 0;
 
-  // For a network that is trained by the solver, no bottom or top vecs
-  // should be given, and we will just provide dummy vecs.
-  vector<Blob<Dtype>*> bottom_vec;
-  for (; iter_ < param_.max_iter(); ++iter_) {
+  for (; iter_ < stop_iter; ++iter_) {
     // Save a snapshot if needed.
-    if (param_.snapshot() && iter_ > start_iter &&
+    if (param_.snapshot() && iter_ > start_iter_ &&
         iter_ % param_.snapshot() == 0) {
       Snapshot();
     }
@@ -227,10 +214,33 @@ void Solver<Dtype>::Solve(const char* resume_file) {
         }
       }
     }
-
     ComputeUpdateValue();
     net_->Update();
   }
+}
+
+template <typename Dtype>
+void Solver<Dtype>::PreSolve() {
+  initialized_ = true;
+  start_iter_ = iter_ = 0;
+  current_state_ = 0;
+}
+
+template <typename Dtype>
+void Solver<Dtype>::Solve(const char* resume_file) {
+  Caffe::set_phase(Caffe::TRAIN);
+  LOG(INFO) << "Solving " << net_->name();
+  LOG(INFO) << "Learning Rate Policy: " << param_.lr_policy();
+
+  PreSolve();
+  if (resume_file) {
+    LOG(INFO) << "Restoring previous solver status from " << resume_file;
+    Restore(resume_file);
+  }
+
+  // For a network that is trained by the solver, no bottom or top vecs
+  // should be given, and we will just provide dummy vecs.
+  Step(param_.max_iter() - iter_);
   // Always save a snapshot after optimization, unless overridden by setting
   // snapshot_after_train := false.
   if (param_.snapshot_after_train()) { Snapshot(); }
@@ -242,7 +252,7 @@ void Solver<Dtype>::Solve(const char* resume_file) {
   // display the loss, which is computed in the forward pass.
   if (param_.display() && iter_ % param_.display() == 0) {
     Dtype loss;
-    net_->Forward(bottom_vec, &loss);
+    net_->ForwardPrefilled(&loss);
     LOG(INFO) << "Iteration " << iter_ << ", loss = " << loss;
   }
   if (param_.test_interval() && iter_ % param_.test_interval() == 0) {
@@ -352,7 +362,7 @@ void Solver<Dtype>::Restore(const char* state_file) {
     ReadProtoFromBinaryFile(state.learned_net().c_str(), &net_param);
     net_->CopyTrainedLayersFrom(net_param);
   }
-  iter_ = state.iter();
+  start_iter_ = iter_ = state.iter();
   current_step_ = state.current_step();
   RestoreSolverState(state);
 }
@@ -414,6 +424,7 @@ Dtype SGDSolver<Dtype>::GetLearningRate() {
 
 template <typename Dtype>
 void SGDSolver<Dtype>::PreSolve() {
+  Solver<Dtype>::PreSolve();
   // Initialize the history
   vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
   history_.clear();