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arangodb/arangod/Agency/Inception.h

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C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2018 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Kaveh Vahedipour
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_CONSENSUS_INCEPTION_H
#define ARANGOD_CONSENSUS_INCEPTION_H 1
#include <memory>
#include "Agency/AgencyCommon.h"
#include "Basics/Common.h"
#include "Basics/ConditionVariable.h"
#include "Basics/Mutex.h"
#include "Basics/Thread.h"
#include <velocypack/Builder.h>
#include <velocypack/velocypack-aliases.h>
namespace arangodb {
namespace consensus {
class Agent;
/// @brief This class organizes the startup of the agency until the point
/// where the RAFT implementation can commence function
class Inception : public Thread {
public:
/// @brief Construct with agent
explicit Inception(Agent&);
/// @brief Defualt dtor
virtual ~Inception();
/// @brief Report acknowledged version for peer id
void reportVersionForEp(std::string const&, size_t);
void beginShutdown() override;
void run() override;
void signalConditionVar();
private:
/// @brief We are a restarting active RAFT agent
///
/// Make sure that majority of agents agrees on pool and active list.
/// Subsequently, start agency. The exception to agreement over active agent
/// list among peers is if an agent joins with empty active list. This allows
/// for a peer with empty list to join nevertheless.
/// The formation of an agency is tried for an hour before giving up.
bool restartingActiveAgent();
/// @brief Gossip your way into the agency
///
/// No persistence: gossip an agency together.
void gossip();
Agent& _agent; //< @brief The agent
arangodb::basics::ConditionVariable _cv; //< @brief For proper shutdown
std::unordered_map<std::string, size_t> _acked; //< @brief acknowledged config version
mutable arangodb::Mutex _vLock; //< @brieg Guard _acked
};
} // namespace consensus
} // namespace arangodb
#endif