add checkpoint_load, update checkpoint save

paddle/fluid/operators/CMakeLists.txt

@@ -243,6 +243,7 @@ op_library(load_op DEPS lod_tensor)
 op_library(save_combine_op DEPS lod_tensor)
 op_library(load_combine_op DEPS lod_tensor)
 op_library(checkpoint_save_op DEPS lod_tensor)
+op_library(checkpoint_load_op DEPS lod_tensor)
 op_library(concat_op DEPS concat)
 
 # FIXME(thuan): Move CSP operators to paddle/fluid/framework/operators/concurrency
@@ -278,6 +279,6 @@ cc_test(beam_search_op_test SRCS beam_search_op_test.cc DEPS lod_tensor beam_sea
 cc_test(strided_memcpy_test SRCS strided_memcpy_test.cc DEPS tensor memory)
 cc_test(save_load_op_test SRCS save_load_op_test.cc DEPS save_op load_op)
 cc_test(save_load_combine_op_test SRCS save_load_combine_op_test.cc DEPS save_combine_op load_combine_op)
-cc_test(checkpoint_save_op_test SRCS checkpoint_save_op_test.cc DEPS checkpoint_save_op)
+cc_test(checkpoint_op_test SRCS checkpoint_op_test.cc DEPS checkpoint_save_op checkpoint_load_op)
 nv_test(nccl_op_test SRCS nccl_op_test.cu.cc DEPS nccl_op gpu_info device_context)
 nv_test(dropout_op_test SRCS dropout_op_test.cc DEPS dropout_op tensor)

paddle/fluid/operators/checkpoint_load_op.cc

@@ -0,0 +1,87 @@
+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#include <stdint.h>
+#include <sys/stat.h>
+#include <fstream>
+#include <numeric>
+#include <sstream>
+#include "paddle/fluid/framework/data_type.h"
+#include "paddle/fluid/framework/data_type_transform.h"
+#include "paddle/fluid/framework/framework.pb.h"
+#include "paddle/fluid/framework/lod_tensor.h"
+#include "paddle/fluid/framework/op_registry.h"
+#include "paddle/fluid/platform/device_context.h"
+
+namespace paddle {
+namespace operators {
+
+constexpr char kSEP = '/';
+// write empty file named _SUCCESS
+const char SUCCESS[] = "_SUCCESS";
+
+static bool FileExists(const std::string &filepath) {
+  struct stat buffer;
+  return (stat(filepath.c_str(), &buffer) == 0);
+}
+
+static std::string DirName(const std::string &filepath) {
+  auto pos = filepath.rfind(kSEP);
+  if (pos == std::string::npos) {
+    return "";
+  }
+  return filepath.substr(0, pos);
+}
+
+class CheckpointLoadOp : public framework::OperatorBase {
+ public:
+  CheckpointLoadOp(const std::string &type,
+                   const framework::VariableNameMap &inputs,
+                   const framework::VariableNameMap &outputs,
+                   const framework::AttributeMap &attrs)
+      : OperatorBase(type, inputs, outputs, attrs) {}
+
+ private:
+  void RunImpl(const framework::Scope &scope,
+               const platform::Place &place) const override {
+    auto dir = Attr<std::string>("dir");
+    bool is_present = FileExists(dir);
+    if (!is_present) {
+      return;
+    }
+
+    // UPDATE LATER ...
+  }
+};
+
+class CheckpointLoadOpProtoMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  CheckpointLoadOpProtoMaker(OpProto *proto, OpAttrChecker *op_checker)
+      : OpProtoAndCheckerMaker(proto, op_checker) {
+    AddAttr<std::string>(
+        "dir",
+        "(string)"
+        "The \"file_path\" where the LoDTensor variables will be saved.")
+        .AddCustomChecker(
+            [](const std::string &path) { return !path.empty(); });
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+
+REGISTER_OPERATOR(checkpoint_load, ops::CheckpointLoadOp,
+                  ops::CheckpointLoadOpProtoMaker);

paddle/fluid/operators/checkpoint_save_op.cc

@@ -27,8 +27,6 @@ limitations under the License. */
 namespace paddle {
 namespace operators {
 
-// TODO(sidgoyal78): These function are needed by other files (save_op), move
-// them to paddle::filesystem namespace. (as noted by yuyang18 in save_op).
 constexpr char kSEP = '/';
 // write empty file named _SUCCESS
 const char SUCCESS[] = "_SUCCESS";
@@ -82,7 +80,14 @@ class CheckpointSaveOp : public framework::OperatorBase {
       // overwrite=false",
       //              dir, overwrite);
     }
+    MkDirRecursively(dir.c_str());
 
+    auto serial_var_name = Output("Serial");
+    auto *serial_var = scope.FindVar(serial_var_name);
+    std::string *serial_num = serial_var->GetMutable<std::string>();
+    serial_num->append("0");
+    dir.append("/");
+    dir.append(serial_num);
     MkDirRecursively(dir.c_str());
 
     auto inp_var_names = Inputs("X");
@@ -93,6 +98,7 @@ class CheckpointSaveOp : public framework::OperatorBase {
     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]);
       std::string var_file;
@@ -132,19 +138,20 @@ class CheckpointSaveOpProtoMaker : public framework::OpProtoAndCheckerMaker {
         "X",
         "(vector) Input LoDTensors that need to be saved together in a file.")
         .AsDuplicable();
+    AddOutput("Serial", "the serial number");
     AddComment(R"DOC(
-SaveCombine operator
+CheckpointSave operator
 
 This operator will serialize and write a list of input LoDTensor variables 
 to a file on disk.
 )DOC");
     AddAttr<bool>("overwrite",
-                  "(boolean, default true)"
-                  "Overwrite the output file if it exists.")
-        .SetDefault(true);
+                  "(boolean, default false)"
+                  "Delete the output dir if it exists.")
+        .SetDefault(false);
 
     AddAttr<std::string>(
-        "file_path",
+        "dir",
         "(string)"
         "The \"file_path\" where the LoDTensor variables will be saved.")
         .AddCustomChecker(