/* 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_COMMON_RUNTIME_DEVICE_SET_H_
#define TENSORFLOW_CORE_COMMON_RUNTIME_DEVICE_SET_H_

#include <memory>
#include <unordered_map>
#include <vector>

#include "tensorflow/core/common_runtime/device.h"
#include "tensorflow/core/platform/macros.h"
#include "tensorflow/core/platform/types.h"
#include "tensorflow/core/util/device_name_utils.h"

namespace tensorflow {

// DeviceSet is a container class for managing the various types of
// devices used by a model.
class DeviceSet {
 public:
  DeviceSet();
  ~DeviceSet();

  // Does not take ownership of 'device'.
  void AddDevice(Device* device);

  // Set the device designated as the "client".  This device
  // must also be registered via AddDevice().
  void set_client_device(Device* device) {
    DCHECK(client_device_ == nullptr);
    client_device_ = device;
  }

  // Returns a pointer to the device designated as the "client".
  Device* client_device() const { return client_device_; }

  // Return the list of devices in this set.
  const std::vector<Device*>& devices() const { return devices_; }

  // Given a DeviceNameUtils::ParsedName (which may have some
  // wildcards for different components), fills "*devices" with all
  // devices in "*this" that match "spec".
  void FindMatchingDevices(const DeviceNameUtils::ParsedName& spec,
                           std::vector<Device*>* devices) const;

  // Finds the device with the given "fullname". Returns nullptr if
  // not found.
  Device* FindDeviceByName(const string& fullname) const;

  // Return the list of unique device types in this set, ordered
  // with more preferable devices earlier.
  std::vector<DeviceType> PrioritizedDeviceTypeList() const;

  // An order to sort by device types according to system-determined
  // priority.
  //
  // Higher result implies higher priority.
  static int DeviceTypeOrder(const DeviceType& d);

 private:
  // Not owned.
  std::vector<Device*> devices_;

  // Fullname -> device* for device in devices_.
  std::unordered_map<string, Device*> device_by_name_;

  // client_device_ points to an element of devices_ that we consider
  // to be the client device (in this local process).
  Device* client_device_ = nullptr;

  TF_DISALLOW_COPY_AND_ASSIGN(DeviceSet);
};

}  // namespace tensorflow

#endif  // TENSORFLOW_CORE_COMMON_RUNTIME_DEVICE_SET_H_