//   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 "paddle/fluid/framework/reader.h"
#include <deque>

namespace paddle {
namespace framework {

void ReaderBase::ReadNext(std::vector<LoDTensor> *out) {
  std::lock_guard<std::mutex> lock(mu_);
  PADDLE_ENFORCE_EQ(status_, ReaderStatus::kRunning,
                    platform::errors::Unavailable(
                        "The current reader has stopped running and cannot "
                        "continue to read the next batch of data."));
  ReadNextImpl(out);
}

void ReaderBase::InsertDecoratedReader(
    const std::shared_ptr<ReaderBase> &decorated_reader) {
  std::lock_guard<std::mutex> guard(mu_);
  decorated_readers_.emplace_back(decorated_reader);
}

std::unordered_set<ReaderBase *> ReaderBase::GetEndPoints() {
  std::unordered_set<ReaderBase *> result;
  std::deque<ReaderBase *> queue;
  queue.emplace_back(this);
  while (!queue.empty()) {  // BFS search
    auto *front = queue.front();
    queue.pop_front();
    if (front->decorated_readers_.empty()) {
      result.emplace(front);
    } else {
      for (auto &reader : front->decorated_readers_) {
        if (auto *reader_ptr = reader.lock().get()) {
          queue.emplace_back(reader_ptr);
        }
      }
    }
  }

  return result;
}

void ReaderBase::Shutdown() {
  std::lock_guard<std::mutex> lock(mu_);
  if (status_ != ReaderStatus::kStopped) {
    ShutdownImpl();
    status_ = ReaderStatus::kStopped;
  }
}

void ReaderBase::Start() {
  std::lock_guard<std::mutex> lock(mu_);
  if (status_ != ReaderStatus::kRunning) {
    StartImpl();
    status_ = ReaderStatus::kRunning;
  }
}

ReaderBase::~ReaderBase() {}

DecoratedReader::~DecoratedReader() {
  VLOG(1) << "~DecoratedReader";
  reader_->Shutdown();
}
}  // namespace framework
}  // namespace paddle
