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/**
* Copyright (C) 2019-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/migration_coordinator_document_gen.h"
#include "mongo/db/session/logical_session_id.h"
#include "mongo/s/catalog/type_chunk.h"
#include "mongo/util/future.h"
namespace mongo {
namespace migrationutil {
/**
* Manages the migration commit/abort process, including updates to config.rangeDeletions on the
* donor and the recipient, and updates to the routing table on the config server.
*/
class MigrationCoordinator {
public:
MigrationCoordinator(MigrationSessionId sessionId,
ShardId donorShard,
ShardId recipientShard,
NamespaceString collectionNamespace,
UUID collectionUuid,
ChunkRange range,
ChunkVersion preMigrationChunkVersion,
const KeyPattern& shardKeyPattern,
bool waitForDelete);
MigrationCoordinator(const MigrationCoordinatorDocument& doc);
MigrationCoordinator(const MigrationCoordinator&) = delete;
MigrationCoordinator& operator=(const MigrationCoordinator&) = delete;
MigrationCoordinator(MigrationCoordinator&&) = delete;
MigrationCoordinator& operator=(MigrationCoordinator&&) = delete;
~MigrationCoordinator();
const UUID& getMigrationId() const;
const LogicalSessionId& getLsid() const;
TxnNumber getTxnNumber() const;
/**
* Sets the shard key pattern on the coordinator. Needs to be called by migration recovery to
* allow the range deletion task to access the shard key pattern.
*/
void setShardKeyPattern(const boost::optional<KeyPattern>& shardKeyPattern);
/**
* Initializes persistent state required to ensure that orphaned ranges are properly handled,
* even after failover, by doing the following:
*
* 1) Inserts a document into the local config.migrationCoordinators with the lsid and
* recipientId and waits for majority writeConcern. 2) Inserts a document into the local
* config.rangeDeletions with the collectionUUID, range to delete, and "pending: true" and waits
* for majority writeConcern.
*/
void startMigration(OperationContext* opCtx);
/**
* Saves the decision.
*
* This method is non-blocking and does not perform any I/O.
*/
void setMigrationDecision(DecisionEnum decision);
/**
* If a decision has been set, makes the decision durable, then communicates the decision by
* updating the local (donor's) and remote (recipient's) config.rangeDeletions entries.
*
* If the decision was to commit, returns a future that is set when range deletion for
* the donated range completes.
*/
boost::optional<SharedSemiFuture<void>> completeMigration(OperationContext* opCtx);
/**
* Deletes the persistent state for this migration from config.migrationCoordinators.
*/
void forgetMigration(OperationContext* opCtx);
/**
* Asynchronously releases the recipient critical section without waiting for it to finish. Sets
* the _releaseRecipientCriticalSectionFuture future that will be readied once the recipient
* critical section has been released.
*/
void launchReleaseRecipientCriticalSection(OperationContext* opCtx);
private:
/**
* Deletes the range deletion task from the recipient node and marks the range deletion task on
* the donor as ready to be processed. Returns a future that is set when range deletion for
* the donated range completes.
*/
SharedSemiFuture<void> _commitMigrationOnDonorAndRecipient(OperationContext* opCtx);
/**
* Deletes the range deletion task from the donor node and marks the range deletion task on the
* recipient node as ready to be processed.
*/
void _abortMigrationOnDonorAndRecipient(OperationContext* opCtx);
/**
* Waits for the completion of _releaseRecipientCriticalSectionFuture and ignores ShardNotFound
* exceptions.
*/
void _waitForReleaseRecipientCriticalSectionFutureIgnoreShardNotFound(OperationContext* opCtx);
MigrationCoordinatorDocument _migrationInfo;
boost::optional<KeyPattern> _shardKeyPattern;
bool _waitForDelete = false;
boost::optional<ExecutorFuture<void>> _releaseRecipientCriticalSectionFuture;
};
} // namespace migrationutil
} // namespace mongo
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