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/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <memory>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/bson/timestamp.h"
#include "mongo/db/repl/optime.h"
#include "mongo/db/repl/replica_set_config.h"
#include "mongo/db/repl/replication_executor.h"
#include "mongo/db/repl/scatter_gather_algorithm.h"
#include "mongo/db/repl/scatter_gather_runner.h"
#include "mongo/stdx/functional.h"
namespace mongo {
class Status;
namespace repl {
class ScatterGatherRunner;
class FreshnessScanner {
MONGO_DISALLOW_COPYING(FreshnessScanner);
public:
struct FreshnessInfo {
// The index of node in ReplicaSetConfig.
int index;
// The latest applied opTime on that node.
OpTime opTime;
};
using Result = std::vector<FreshnessInfo>;
class Algorithm : public ScatterGatherAlgorithm {
public:
Algorithm(const ReplicaSetConfig& rsConfig, int myIndex, Milliseconds timeout);
virtual std::vector<executor::RemoteCommandRequest> getRequests() const;
virtual void processResponse(const executor::RemoteCommandRequest& request,
const ResponseStatus& response);
virtual bool hasReceivedSufficientResponses() const;
/**
* Returns a sorted list of nodes in descending lastAppliedOptime order.
*
* It is invalid to call this before hasReceivedSufficientResponses returns true.
*/
Result getResult() const;
private:
const ReplicaSetConfig _rsConfig;
std::vector<HostAndPort> _targets;
const int _myIndex;
const Milliseconds _timeout;
Result _freshnessInfos;
int _responsesProcessed = 0;
int _totalRequests = 0;
};
FreshnessScanner() = default;
virtual ~FreshnessScanner() = default;
/**
* Begins the process of sending replSetGetFreshness commands to all nodes
* in currentConfig, in attempt to find the most up-to-date oplog.
*
* evh can be used to schedule a callback when the process is complete.
* If this function returns Status::OK(), evh is then guaranteed to be signaled.
**/
StatusWith<ReplicationExecutor::EventHandle> start(ReplicationExecutor* executor,
const ReplicaSetConfig& rsConfig,
int myIndex,
Milliseconds timeout);
/**
* Informs the FreshnessScanner to cancel further processing.
*/
void cancel();
Result getResult() const;
private:
std::unique_ptr<Algorithm> _algorithm;
std::unique_ptr<ScatterGatherRunner> _runner;
};
} // namespace repl
} // namespace mongo
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