heron/tmaster/src/cpp/manager/stateful-checkpointer.h

/*
 * Copyright 2015 Twitter, Inc.
 *
 * 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 __TMASTER_STATEFUL_CHECKPOINTER_H_
#define __TMASTER_STATEFUL_CHECKPOINTER_H_

#include <string>
#include <unordered_set>
#include "network/network.h"
#include "proto/tmaster.pb.h"
#include "manager/tmaster.h"
#include "basics/basics.h"


namespace heron {
namespace proto {
class PhysicalPlan;
}
}

namespace heron {
namespace tmaster {

/**
 * A StatefulCheckpointer is responsible for sending NewStatefulCheckpoint
 * requests to stmgrs to start checkpoints and keep tracking of the ongoing
 * checkpointing progress.
 *
 */
class StatefulCheckpointer {
 public:
  explicit StatefulCheckpointer(std::chrono::high_resolution_clock::time_point _tmaster_start_time);
  virtual ~StatefulCheckpointer();
  void RegisterNewPhysicalPlan(const proto::system::PhysicalPlan& _pplan);

  void StartCheckpoint(const StMgrMap& _stmgrs);

  // Called by tmaster when a InstanceStateStored message is received
  // Return true if this completes a globally consistent checkpoint
  // for this _checkpoint_id
  bool HandleInstanceStateStored(const std::string& _checkpoint_id,
                                 const proto::system::Instance& _instance);

 private:
  sp_string GenerateCheckpointId();

  std::chrono::high_resolution_clock::time_point tmaster_start_time_;

  // Current partially consistent checkpoint
  // for which still some more states need to be saved
  std::string current_partial_checkpoint_;

  // The set of all tasks
  std::unordered_set<sp_int32> all_tasks_;

  // The set of tasks from which we still need confirmation
  // of state storage before we can declare it a globally
  // consistent checkpoint
  std::unordered_set<sp_int32> partial_checkpoint_remaining_tasks_;
};
}  // namespace tmaster
}  // namespace heron

#endif