load implement

paddle/fluid/operators/checkpoint_load_op.cc

@@ -47,13 +47,54 @@ class CheckpointLoadOp : public framework::OperatorBase {
  private:
   void RunImpl(const framework::Scope &scope,
                const platform::Place &place) const override {
-    auto dir = Attr<std::string>("dir");
-    bool is_present = FileExists(dir);
+    std::string dir = Attr<std::string>("dir");
+
+    VLOG(3) << "Load checkpoint from dir: " << dir;
+
+    std::string success;
+    success.append(dir);
+    success.append("/");
+    success.append(SUCCESS);
+
+    bool is_present = FileExists(success);
     if (!is_present) {
+      VLOG(3) << "can not find _SUCCESS from  path: " << success;
       return;
     }
 
-    // UPDATE LATER ...
+    auto inp_var_names = Output("Out");
+    PADDLE_ENFORCE_GT(static_cast<int>(inp_var_names.size()), 0,
+                      "The number of input variables should be greater than 0");
+    // get device context from pool
+    platform::DeviceContextPool &pool = platform::DeviceContextPool::Instance();
+    auto &dev_ctx = *pool.Get(place);
+
+    // todo (tangwei) made it async
+    for (size_t i = 0; i < inp_var_names.size(); i++) {
+      auto *var = scope.FindVar(inp_var_names[i]);
+
+      PADDLE_ENFORCE(var != nullptr,
+                     "Cannot find variable %s for save_combine_op",
+                     inp_var_names[i]);
+      PADDLE_ENFORCE(var->IsType<framework::LoDTensor>(),
+                     "SaveCombineOp only supports LoDTensor, %s has wrong type",
+                     inp_var_names[i]);
+
+      std::string var_file;
+      var_file.append(dir);
+      var_file.append("/");
+      var_file.append(inp_var_names[i]);
+      VLOG(3) << "ready to load var: " << inp_var_names[i];
+
+      auto &tensor = var->Get<framework::LoDTensor>();
+
+      std::ifstream fin(var_file);
+      PADDLE_ENFORCE(static_cast<bool>(fin), "Cannot open file %s for load op",
+                     var_file);
+      DeserializeFromStream(fin, tensor, *dev_ctx);
+      fin.close();
+      VLOG(3) << " load var: " << inp_var_names[i] << " finished";
+    }
   }
 };
 
@@ -61,6 +102,7 @@ class CheckpointLoadOpProtoMaker : public framework::OpProtoAndCheckerMaker {
  public:
   CheckpointLoadOpProtoMaker(OpProto *proto, OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
+    AddOutput("Out", "(Tensor) The tensor need to be loaded");
     AddComment(R"DOC(
 CheckpointLoad operator