/* Copyright 2015 The TensorFlow 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.
==============================================================================*/

#ifndef TENSORFLOW_CORE_FRAMEWORK_HASH_TABLE_TENSOR_GENERATOR_H_
#define TENSORFLOW_CORE_FRAMEWORK_HASH_TABLE_TENSOR_GENERATOR_H_

#include <queue>
#include <mutex>
#include <functional>
#include <utility>

#include "tensorflow/core/lib/core/refcount.h"
#include "tensorflow/core/framework/tensor.h"
#include "tensorflow/core/lib/core/status.h"
#include "tensorflow/core/lib/core/spin_rw_lock.h"
#include "tensorflow/core/platform/mutex.h"

namespace tensorflow {

class TensorGenerator : public core::RefCounted {
 public:
  using Consumer = std::function<void(Status, const Tensor&)>;
  using Producer = std::function<void(const Consumer&)>;

  explicit TensorGenerator(const Producer& producer);
  void GetNextTensor(const Consumer& done);
  void SetProducer(const Producer& producer) {
    spin_wr_lock l(&spin_mu_);
    producer_ = producer;
  }
 private:
  void Produce();
  void Enque(Status st, const Tensor& tensor);
  void Deque(const Consumer& done);

  mutable mutex mu_;
  std::queue<std::pair<Status, Tensor>> results_;
  std::queue<Consumer> waiters_;
  Producer producer_;
  mutable easy_spinrwlock_t spin_mu_ = EASY_SPINRWLOCK_INITIALIZER;  
  static constexpr int kQueueSize = 5;
};

}  // namespace tensorflow

#endif  // TENSORFLOW_CORE_FRAMEWORK_HASH_TABLE_TENSOR_GENERATOR_H_

