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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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 "mongo/db/s/balancer/balancer_chunk_selection_policy.h"
#include "mongo/db/s/balancer/balancer_random.h"
namespace mongo {
class ClusterStatistics;
class BalancerChunkSelectionPolicyImpl final : public BalancerChunkSelectionPolicy {
public:
BalancerChunkSelectionPolicyImpl(ClusterStatistics* clusterStats, BalancerRandomSource& random);
~BalancerChunkSelectionPolicyImpl();
StatusWith<SplitInfoVector> selectChunksToSplit(OperationContext* opCtx) override;
StatusWith<SplitInfoVector> selectChunksToSplit(OperationContext* opCtx,
const NamespaceString& ns) override;
StatusWith<MigrateInfoVector> selectChunksToMove(
OperationContext* opCtx, stdx::unordered_set<ShardId>* usedShards) override;
StatusWith<MigrateInfosWithReason> selectChunksToMove(OperationContext* opCtx,
const NamespaceString& ns) override;
StatusWith<boost::optional<MigrateInfo>> selectSpecificChunkToMove(
OperationContext* opCtx, const NamespaceString& nss, const ChunkType& chunk) override;
Status checkMoveAllowed(OperationContext* opCtx,
const ChunkType& chunk,
const ShardId& newShardId) override;
private:
/**
* Synchronous method, which iterates the collection's chunks and uses the tags information to
* figure out whether some of them validate the tag range boundaries and need to be split.
*/
StatusWith<SplitInfoVector> _getSplitCandidatesForCollection(
OperationContext* opCtx,
const NamespaceString& nss,
const ShardStatisticsVector& shardStats);
/**
* Synchronous method, which iterates the collection's chunks and uses the cluster statistics to
* figure out where to place them.
*/
StatusWith<MigrateInfosWithReason> _getMigrateCandidatesForCollection(
OperationContext* opCtx,
const NamespaceString& nss,
const ShardStatisticsVector& shardStats,
stdx::unordered_set<ShardId>* usedShards);
// Source for obtaining cluster statistics. Not owned and must not be destroyed before the
// policy object is destroyed.
ClusterStatistics* const _clusterStats;
// Source of randomness when metadata needs to be randomized.
BalancerRandomSource& _random;
};
} // namespace mongo
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