Remove Readers' HasNext()

paddle/fluid/framework/lod_tensor.cc

@@ -12,9 +12,14 @@ 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 "paddle/fluid/framework/lod_tensor.h"
+#include <stdint.h>
+#include <string.h>
+#include <algorithm>
+#include <iterator>
+
 #include "paddle/fluid/framework/data_type.h"
 #include "paddle/fluid/framework/framework.pb.h"
+#include "paddle/fluid/framework/lod_tensor.h"
 
 #include "paddle/fluid/memory/memcpy.h"
 #include "paddle/fluid/memory/memory.h"
@@ -22,11 +27,6 @@ limitations under the License. */
 #include "paddle/fluid/recordio/scanner.h"
 #include "paddle/fluid/recordio/writer.h"
 
-#include <stdint.h>
-#include <string.h>
-#include <algorithm>
-#include <iterator>
-
 namespace paddle {
 namespace framework {
 
@@ -294,7 +294,7 @@ void DeserializeFromStream(std::istream &is, LoDTensor *tensor,
   TensorFromStream(is, static_cast<Tensor *>(tensor), dev_ctx);
 }
 
-void WriteToRecordIO(recordio::Writer &writer,
+void WriteToRecordIO(recordio::Writer *writer,
                      const std::vector<LoDTensor> &tensor,
                      const platform::DeviceContext &dev_ctx) {
   std::stringstream buffer;
@@ -303,18 +303,20 @@ void WriteToRecordIO(recordio::Writer &writer,
   for (auto &each : tensor) {
     SerializeToStream(buffer, each, dev_ctx);
   }
-  writer.Write(buffer.str());
+  writer->Write(buffer.str());
 }
 
 std::vector<LoDTensor> ReadFromRecordIO(
-    recordio::Scanner &scanner, const platform::DeviceContext &dev_ctx) {
-  std::istringstream sin(scanner.Next());
-  uint32_t sz;
-  sin.read(reinterpret_cast<char *>(&sz), sizeof(uint32_t));
+    recordio::Scanner *scanner, const platform::DeviceContext &dev_ctx) {
   std::vector<LoDTensor> result;
-  result.resize(sz);
-  for (uint32_t i = 0; i < sz; ++i) {
-    DeserializeFromStream(sin, &result[i], dev_ctx);
+  if (scanner->HasNext()) {
+    std::istringstream sin(scanner->Next());
+    uint32_t sz;
+    sin.read(reinterpret_cast<char *>(&sz), sizeof(uint32_t));
+    result.resize(sz);
+    for (uint32_t i = 0; i < sz; ++i) {
+      DeserializeFromStream(sin, &result[i], dev_ctx);
+    }
   }
   return result;
 }

paddle/fluid/framework/lod_tensor.h

@@ -15,6 +15,9 @@ limitations under the License. */
 #pragma once
 
 #include <memory>
+#include <string>
+#include <utility>
+#include <vector>
 #ifdef PADDLE_WITH_CUDA
 #include <thrust/device_vector.h>
 #include <thrust/host_vector.h>
@@ -216,12 +219,12 @@ void SerializeToStream(std::ostream& os, const LoDTensor& tensor,
 void DeserializeFromStream(std::istream& is, LoDTensor* tensor,
                            const platform::DeviceContext& dev_ctx);
 
-extern void WriteToRecordIO(recordio::Writer& writer,
+extern void WriteToRecordIO(recordio::Writer* writer,
                             const std::vector<LoDTensor>& tensor,
                             const platform::DeviceContext& dev_ctx);
 
 extern std::vector<LoDTensor> ReadFromRecordIO(
-    recordio::Scanner& scanner, const platform::DeviceContext& dev_ctx);
+    recordio::Scanner* scanner, const platform::DeviceContext& dev_ctx);
 
 }  // namespace framework
 }  // namespace paddle

paddle/fluid/framework/lod_tensor_test.cc

@@ -12,17 +12,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "paddle/fluid/framework/lod_tensor.h"
-
-#include "paddle/fluid/recordio/scanner.h"
-#include "paddle/fluid/recordio/writer.h"
-
 #include <glog/logging.h>
 #include <gtest/gtest.h>
 #include <algorithm>
 #include <memory>
 #include <vector>
 
+#include "paddle/fluid/framework/lod_tensor.h"
+
+#include "paddle/fluid/recordio/scanner.h"
+#include "paddle/fluid/recordio/writer.h"
+
 namespace paddle {
 namespace framework {
 
@@ -240,8 +240,8 @@ TEST(LoDTensor, RecordIO) {
       *platform::DeviceContextPool::Instance().Get(platform::CPUPlace());
   {
     recordio::Writer writer(stream, recordio::Compressor::kSnappy);
-    WriteToRecordIO(writer, {tensor, tensor}, ctx);
-    WriteToRecordIO(writer, {tensor, tensor}, ctx);
+    WriteToRecordIO(&writer, {tensor, tensor}, ctx);
+    WriteToRecordIO(&writer, {tensor, tensor}, ctx);
     writer.Flush();
   }
 
@@ -254,11 +254,11 @@ TEST(LoDTensor, RecordIO) {
   {
     std::unique_ptr<std::istream> stream_ptr(stream);
     recordio::Scanner scanner(std::move(stream_ptr));
-    auto tensors = ReadFromRecordIO(scanner, ctx);
+    auto tensors = ReadFromRecordIO(&scanner, ctx);
     ASSERT_EQ(tensors.size(), 2);
     assert_tensor_ok(tensors[0]);
     assert_tensor_ok(tensors[1]);
-    tensors = ReadFromRecordIO(scanner, ctx);
+    tensors = ReadFromRecordIO(&scanner, ctx);
     ASSERT_EQ(tensors.size(), 2);
     assert_tensor_ok(tensors[0]);
     assert_tensor_ok(tensors[1]);

paddle/fluid/framework/reader.h

@@ -14,14 +14,13 @@
 
 #pragma once
 
+#include <memory>
+#include <vector>
+
 #include "paddle/fluid/framework/ddim.h"
 #include "paddle/fluid/framework/lod_tensor_array.h"
 #include "paddle/fluid/platform/place.h"
 
-#include <memory>
-#include <thread>
-#include <vector>
-
 namespace paddle {
 namespace framework {
 
@@ -31,8 +30,6 @@ class ReaderBase {
 
   virtual void ReInit() = 0;
 
-  virtual bool HasNext() const = 0;
-
   virtual ~ReaderBase();
 };
 
@@ -44,8 +41,6 @@ class DecoratedReader : public ReaderBase {
 
   void ReInit() override { reader_->ReInit(); }
 
-  bool HasNext() const override { return reader_->HasNext(); }
-
  protected:
   ReaderBase* reader_;
 };
@@ -80,8 +75,6 @@ class ReaderHolder {
     reader_->ReInit();
   }
 
-  bool HasNext() const { return reader_->HasNext(); }
-
  private:
   std::unique_ptr<ReaderBase> reader_;
 };

paddle/fluid/operators/reader/create_double_buffer_reader_op.cc

@@ -63,13 +63,14 @@ class DoubleBufferReader : public framework::DecoratedReader {
     StartPrefetcher();
   }
 
-  bool HasNext() const override;
   void ReadNext(std::vector<framework::LoDTensor>* out) override;
   void ReInit() override;
 
   ~DoubleBufferReader() { EndPrefetcher(); }
 
  private:
+  bool HasNext() const;
+
   void StartPrefetcher() {
     channel_ = framework::MakeChannel<Item>(kChannelSize);
     prefetcher_ = std::thread([this] { PrefetchThreadFunc(); });
@@ -149,22 +150,15 @@ class CreateDoubleBufferReaderOpMaker : public DecoratedReaderMakerBase {
   }
 };
 
-bool DoubleBufferReader::HasNext() const {
-  while (!channel_->IsClosed() && !channel_->CanReceive()) {
-  }
-  return channel_->CanReceive();
-}
-
 void DoubleBufferReader::ReadNext(std::vector<framework::LoDTensor>* out) {
-  if (!HasNext()) {
-    PADDLE_THROW("There is no next data!");
-  }
-
-  Item batch;
-  channel_->Receive(&batch);
-  *out = batch.payloads_;
-  if (batch.ctx_) {
-    batch.ctx_->Wait();
+  out->clear();
+  if (HasNext()) {
+    Item batch;
+    channel_->Receive(&batch);
+    *out = batch.payloads_;
+    if (batch.ctx_) {
+      batch.ctx_->Wait();
+    }
   }
 }
 
@@ -174,16 +168,26 @@ void DoubleBufferReader::ReInit() {
   StartPrefetcher();
 }
 
+bool DoubleBufferReader::HasNext() const {
+  while (!channel_->IsClosed() && !channel_->CanReceive()) {
+  }
+  return channel_->CanReceive();
+}
+
 void DoubleBufferReader::PrefetchThreadFunc() {
   VLOG(5) << "A new prefetch thread starts.";
   std::vector<std::vector<framework::LoDTensor>> cpu_tensor_cache(kCacheSize);
   std::vector<std::vector<framework::LoDTensor>> gpu_tensor_cache(kCacheSize);
   size_t cached_tensor_id = 0;
 
-  while (reader_->HasNext()) {
+  while (true) {
     Item batch;
     auto& cpu_batch = cpu_tensor_cache[cached_tensor_id];
     reader_->ReadNext(&cpu_batch);
+    if (cpu_batch.empty()) {
+      // The underlying reader have no next data.
+      break;
+    }
     if (platform::is_gpu_place(place_)) {
       auto& gpu_batch = gpu_tensor_cache[cached_tensor_id];
       auto* gpu_ctx = ctxs_[cached_tensor_id].get();

paddle/fluid/operators/reader/create_multi_pass_reader_op.cc

@@ -25,22 +25,12 @@ class MultiPassReader : public framework::DecoratedReader {
       : DecoratedReader(reader), pass_num_(pass_num), pass_count_(0) {}
 
   void ReadNext(std::vector<framework::LoDTensor>* out) override {
-    if (!HasNext()) {
-      PADDLE_THROW("There is no next data!");
-    }
     reader_->ReadNext(out);
-  }
-
-  bool HasNext() const override {
-    if (reader_->HasNext()) {
-      return true;
-    } else {
+    if (out->empty()) {
       ++pass_count_;
-      if (pass_count_ >= pass_num_) {
-        return false;
-      } else {
+      if (pass_count_ < pass_num_) {
         reader_->ReInit();
-        return true;
+        reader_->ReadNext(out);
       }
     }
   }

paddle/fluid/operators/reader/create_random_data_generator_op.cc

@@ -52,8 +52,6 @@ class RandomDataGenerator : public framework::ReaderBase {
 
   void ReInit() override { return; }
 
-  bool HasNext() const override { return true; }
-
  private:
   float min_;
   float max_;
@@ -74,7 +72,7 @@ class CreateRandomDataGeneratorOp : public framework::OperatorBase {
     const auto& ranks = Attr<std::vector<int>>("ranks");
     PADDLE_ENFORCE(!shape_concat.empty() && !ranks.empty());
     PADDLE_ENFORCE_EQ(std::accumulate(ranks.begin(), ranks.end(), 0),
-                      int(shape_concat.size()),
+                      static_cast<int>(shape_concat.size()),
                       "The accumulate of all ranks should be equal to the "
                       "shape concat's length.");
     std::vector<framework::DDim> shapes = RestoreShapes(shape_concat, ranks);

paddle/fluid/operators/reader/create_recordio_file_reader_op.cc

@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <mutex>
-#include <thread>
 #include "paddle/fluid/operators/reader/reader_op_registry.h"
 #include "paddle/fluid/recordio/scanner.h"
 
@@ -35,17 +33,15 @@ class RecordIOFileReader : public framework::FileReader {
     LOG(INFO) << "Creating file reader" << filename;
   }
 
-  bool HasNext() const override { return scanner_.HasNext(); }
-
   void ReInit() override { scanner_.Reset(); }
 
  protected:
   void ReadNextImpl(std::vector<framework::LoDTensor>* out) override {
     if (ThreadSafe) {
       std::lock_guard<std::mutex> guard(*mutex_);
-      *out = framework::ReadFromRecordIO(scanner_, dev_ctx_);
+      *out = framework::ReadFromRecordIO(&scanner_, dev_ctx_);
     } else {
-      *out = framework::ReadFromRecordIO(scanner_, dev_ctx_);
+      *out = framework::ReadFromRecordIO(&scanner_, dev_ctx_);
     }
   }
 
@@ -66,7 +62,7 @@ class CreateRecordIOReaderOp : public framework::OperatorBase {
     const auto& ranks = Attr<std::vector<int>>("ranks");
     PADDLE_ENFORCE(!shape_concat.empty() && !ranks.empty());
     PADDLE_ENFORCE_EQ(std::accumulate(ranks.begin(), ranks.end(), 0),
-                      int(shape_concat.size()),
+                      static_cast<int>(shape_concat.size()),
                       "The accumulate of all ranks should be equal to the "
                       "shape concat's length.");
     std::string filename = Attr<std::string>("filename");

paddle/fluid/operators/reader/create_shuffle_reader_op.cc

@@ -30,35 +30,33 @@ class ShuffleReader : public framework::DecoratedReader {
       std::random_device device;
       seed_ = device();
     }
-    ReadIntoBuffers();
+    ReloadBuffer();
   }
 
   void ReadNext(std::vector<framework::LoDTensor>* out) override {
-    if (!HasNext()) {
-      PADDLE_THROW("There is no next data!");
-    }
+    out->clear();
     if (iteration_pos_ >= buffer_.size()) {
       VLOG(10) << "Resetting shuffle buffer";
-      ReadIntoBuffers();
+      ReloadBuffer();
+      if (buffer_.empty()) {
+        return;
+      }
     }
     *out = buffer_[iteration_pos_++];
   }
 
-  bool HasNext() const override {
-    return iteration_pos_ < buffer_.size() || reader_->HasNext();
-  }
-
  private:
-  void ReadIntoBuffers() {
+  void ReloadBuffer() {
     buffer_.clear();
     buffer_.reserve(buffer_size_);
     iteration_pos_ = 0;
     for (size_t i = 0; i < buffer_size_; ++i) {
-      if (!reader_->HasNext()) {
+      std::vector<framework::LoDTensor> ins;
+      reader_->ReadNext(&ins);
+      if (ins.empty()) {
         break;
       }
-      buffer_.emplace_back();
-      reader_->ReadNext(&buffer_.back());
+      buffer_.emplace_back(ins);
     }
     std::mt19937 g(seed_);
     std::shuffle(buffer_.begin(), buffer_.end(), g);

paddle/fluid/operators/reader/create_threaded_reader_op.cc

@@ -21,67 +21,27 @@ namespace reader {
 
 class ThreadedReader : public framework::DecoratedReader {
  public:
-  ThreadedReader(ReaderBase* reader, bool unsafe_mode)
-      : DecoratedReader(reader), unsafe_mode_(unsafe_mode) {}
+  ThreadedReader(ReaderBase* reader, bool safe_mode)
+      : DecoratedReader(reader), safe_mode_(safe_mode) {}
 
   void ReadNext(std::vector<framework::LoDTensor>* out) override {
     std::lock_guard<std::mutex> lock(mutex_);
-    if (!unsafe_mode_) {
-      if (!reader_->HasNext()) {
-        PADDLE_THROW("There is no next data!");
-      }
-      reader_->ReadNext(out);
-    } else {
-      auto& thread_buffer = thread_buffers_[std::this_thread::get_id()];
-      if (thread_buffer.empty()) {
-        PADDLE_THROW(
-            "thread_buffer is empty! HasNext() must be invoked before "
-            "ReadNext() in the same thread.");
-      }
-      *out = thread_buffer;
-      thread_buffer.clear();
-    }
-  }
-
-  bool HasNext() const override {
-    if (!unsafe_mode_) {
-      PADDLE_THROW(
-          "ThreadedReader::HasNext() is disabled when 'unsafe_mode' is false.");
-    }
-    std::thread::id thread_id = std::this_thread::get_id();
-    std::lock_guard<std::mutex> lock(mutex_);
-    auto& thread_buffer = thread_buffers_[thread_id];
-    if (thread_buffer.empty() && reader_->HasNext()) {
-      reader_->ReadNext(&thread_buffer);
-    }
-    return !thread_buffer.empty();
+    reader_->ReadNext(out);
   }
 
   void ReInit() override {
-    if (!unsafe_mode_) {
+    if (safe_mode_) {
       PADDLE_THROW(
-          "ThreadedReader::ReInit() is disabled when 'unsafe_mode' is false.");
+          "ThreadedReader::ReInit() is disabled when 'safe_mode' is true.");
     }
     VLOG(5) << "ThreadedReader::ReInit() is invoked! It might be buggy in "
                "multi-thread environment.";
     reader_->ReInit();
   }
 
-  ~ThreadedReader() {
-    for (auto& p : thread_buffers_) {
-      if (!p.second.empty()) {
-        PADDLE_THROW(
-            "Find an unused data batch in ThreadedReader! Maybe one thread "
-            "invokes 'HasNext()' without subsequent 'ReadNext()'.");
-      }
-    }
-  }
-
  private:
-  bool unsafe_mode_;
-  mutable std::mutex mutex_;
-  mutable std::unordered_map<std::thread::id, std::vector<framework::LoDTensor>>
-      thread_buffers_;
+  bool safe_mode_;
+  std::mutex mutex_;
 };
 
 class CreateThreadedReaderOp : public framework::OperatorBase {
@@ -98,8 +58,8 @@ class CreateThreadedReaderOp : public framework::OperatorBase {
     }
     const auto& underlying_reader = scope.FindVar(Input("UnderlyingReader"))
                                         ->Get<framework::ReaderHolder>();
-    bool unsafe_mode = Attr<bool>("unsafe_mode");
-    out->Reset(new ThreadedReader(underlying_reader.Get(), unsafe_mode));
+    bool safe_mode = Attr<bool>("safe_mode");
+    out->Reset(new ThreadedReader(underlying_reader.Get(), safe_mode));
   }
 };
 
@@ -107,10 +67,9 @@ class CreateThreadedReaderOpMaker : public DecoratedReaderMakerBase {
  public:
   CreateThreadedReaderOpMaker(OpProto* op_proto, OpAttrChecker* op_checker)
       : DecoratedReaderMakerBase(op_proto, op_checker) {
-    AddAttr<bool>("unsafe_mode",
-                  "When 'unsafe_mode' is false, invoking 'HasNext()' or "
-                  "'ReInit()' is not allowed to avoid unexpected bugs in "
-                  "multi-thread environment.")
+    AddAttr<bool>("safe_mode",
+                  "When 'safe_mode' is true, 'ReInit()' is disabled to avoid "
+                  "unexpected bugs in multi-thread environment.")
         .SetDefault(true);
     AddComment(R"DOC(
       CreateThreadedReader Operator
@@ -118,13 +77,9 @@ class CreateThreadedReaderOpMaker : public DecoratedReaderMakerBase {
       This operator creates a threaded reader. A threaded reader's 
       'ReadNext()' can be invoked by several threads at the same 
       time. 
-      When the attribute 'unsafe_mode' is false, the threaded reader's 
-      'HasNext()' and 'ReInit()' will be disabled to avoid unexpected 
-      bugs in multi-thread environment. If you really need them, you 
-      can enable them by setting 'unsafe_mode' true. In this case, 
-      'HasNext()' returning true only guarantees the safety of 
-      invoking 'ReadNext()' in the same thread. Each thread must 
-      invoke 'HasNext()' and 'ReadNext()' in pairs.
+      When the attribute 'safe_mode' is true, the threaded reader's 
+      'ReInit()' is disabled to avoid unexpected bugs in multi-thread 
+      environment.
     )DOC");
   }
 };

paddle/fluid/operators/reader/open_files_op.cc

@@ -30,12 +30,12 @@ class MultiFileReader : public framework::ReaderBase {
   }
 
   void ReadNext(std::vector<framework::LoDTensor>* out) override;
-  bool HasNext() const override;
   void ReInit() override;
 
   ~MultiFileReader() { EndScheduler(); }
 
  private:
+  bool HasNext();
   void StartNewScheduler();
   void EndScheduler();
   void ScheduleThreadFunc();
@@ -52,16 +52,10 @@ class MultiFileReader : public framework::ReaderBase {
 };
 
 void MultiFileReader::ReadNext(std::vector<framework::LoDTensor>* out) {
-  if (!HasNext()) {
-    PADDLE_THROW("There is no next data!");
+  out->clear();
+  if (HasNext()) {
+    buffer_->Receive(out);
   }
-  buffer_->Receive(out);
-}
-
-bool MultiFileReader::HasNext() const {
-  while (!buffer_->IsClosed() && !buffer_->CanReceive()) {
-  }
-  return buffer_->CanReceive();
 }
 
 void MultiFileReader::ReInit() {
@@ -69,6 +63,12 @@ void MultiFileReader::ReInit() {
   StartNewScheduler();
 }
 
+bool MultiFileReader::HasNext() {
+  while (!buffer_->IsClosed() && !buffer_->CanReceive()) {
+  }
+  return buffer_->CanReceive();
+}
+
 void MultiFileReader::StartNewScheduler() {
   size_t thread_num = prefetchers_.size();
   waiting_file_idx_ = framework::MakeChannel<size_t>(file_names_.size());
@@ -140,9 +140,12 @@ void MultiFileReader::PrefetchThreadFunc(std::string file_name,
   VLOG(5) << "The prefetch thread of file '" << file_name << "' starts.";
   std::unique_ptr<framework::ReaderBase> reader =
       CreateReaderByFileName(file_name, dims_);
-  while (reader->HasNext()) {
+  while (true) {
     std::vector<framework::LoDTensor> ins;
     reader->ReadNext(&ins);
+    if (ins.empty()) {
+      break;
+    }
     try {
       buffer_->Send(&ins);
     } catch (paddle::platform::EnforceNotMet e) {

paddle/fluid/pybind/pybind.cc

@@ -252,7 +252,6 @@ All parameter, weight, gradient are variables in Paddle.
            py::return_value_policy::reference);
 
   py::class_<framework::ReaderHolder>(m, "Reader", "")
-      .def("has_next", &framework::ReaderHolder::HasNext)
       .def("reset", &framework::ReaderHolder::ReInit);
 
   py::class_<Scope>(m, "Scope", "")

paddle/fluid/pybind/recordio.cc

@@ -39,7 +39,7 @@ class RecordIOWriter {
   void CompleteAppendTensor() {
     auto& ctx =
         *platform::DeviceContextPool::Instance().Get(platform::CPUPlace());
-    framework::WriteToRecordIO(writer_, tensors_, ctx);
+    framework::WriteToRecordIO(&writer_, tensors_, ctx);
     tensors_.clear();
   }
 

python/paddle/fluid/layers/io.py

@@ -236,13 +236,9 @@ def monkey_patch_reader_methods(reader):
         var = scope.find_var(reader.name)
         return var.get_reader()
 
-    def eof():
-        return not __get_reader__().has_next()
-
     def reset():
         return __get_reader__().reset()
 
-    reader.eof = eof
     reader.reset = reset
     reader.stop_gradient = True
     reader.persistable = True
@@ -299,8 +295,7 @@ def open_recordio_file(filename,
        shapes(list): List of tuples which declaring data shapes.
        lod_levels(list): List of ints which declaring data lod_level.
        dtypes(list): List of strs which declaring data type.
-       pass_num(int): Number of passes to run. After completing the
-            given number of passes, 'has_next()' will return False.
+       pass_num(int): Number of passes to run.
        for_parallel(Bool): Set it as True if you are going to run
             subsequent operators in parallel.
 
@@ -377,8 +372,7 @@ def open_files(filenames,
        dtypes(list): List of strs which declaring data type.
        thread_num(int): The maximal concurrent prefetch thread number.
        buffer_size(int): The size of prefetch buffer.
-       pass_num(int): Number of passes to run. After completing the 
-            given number of passes, 'has_next()' will return False.
+       pass_num(int): Number of passes to run.
        for_parallel(Bool): Set it as True if you are going to run 
             subsequent operators in parallel.