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/**
* Copyright (C) 2020-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 <vector>
#include "mongo/base/status.h"
#include "mongo/bson/timestamp.h"
#include "mongo/db/s/resharding/coordinator_document_gen.h"
#include "mongo/platform/mutex.h"
#include "mongo/util/concurrency/with_lock.h"
#include "mongo/util/future.h"
#include "mongo/util/string_map.h"
namespace mongo {
class ChunkType;
class NamespaceString;
class OperationContext;
class ServiceContext;
class ShardId;
/**
* Observes writes that indicate state changes for a resharding operation. Holds promises that
* the ReshardingCoordinator waits on in order to transition to a new state.
*
* An instance of this object is specific to one resharding operation.
*/
class ReshardingCoordinatorObserver {
public:
ReshardingCoordinatorObserver();
~ReshardingCoordinatorObserver();
/**
* Called when a donor or recipient writes to its 'state' field. The updatedStateDoc is the
* post-image of the ReshardingCoordinatorDocument after the update.
*/
void onReshardingParticipantTransition(const ReshardingCoordinatorDocument& updatedStateDoc);
/**
* Fulfills the '_allRecipientsCreatedCollection' promise when the last recipient writes that it
* is in 'initializing' state.
*/
SharedSemiFuture<ReshardingCoordinatorDocument> awaitAllRecipientsCreatedCollection();
/**
* When the last donor reports its 'minFetchTimestamp', selects the highest 'minFetchTimestamp'
* of all donors to be the 'fetchTimestamp'. Fulfills the '_allDonorsReportedMinFetchTimestamp'
* promise with this 'fetchTimestamp'.
*/
SharedSemiFuture<ReshardingCoordinatorDocument> awaitAllDonorsReadyToDonate();
/**
* Fulfills the '_allRecipientsFinishedCloning' promise when the last recipient writes that it
* is in 'steady-state'.
*/
SharedSemiFuture<ReshardingCoordinatorDocument> awaitAllRecipientsFinishedCloning();
/**
* Fulfills the '_allRecipientsReportedStrictConsistencyTimestamp' promise when the last
* recipient writes that it is in 'strict-consistency' state as well as its
* 'strictConsistencyTimestamp'.
*/
SharedSemiFuture<ReshardingCoordinatorDocument> awaitAllRecipientsInStrictConsistency();
/**
* Fulfills the '_allDonorsDroppedOriginalCollection' promise when the last donor writes that it
* is in 'done' state.
*/
SharedSemiFuture<ReshardingCoordinatorDocument> awaitAllDonorsDroppedOriginalCollection();
/**
* Fulfills the '_allRecipientsRenamedCollection' promise when the last recipient writes
* that it is in 'done' state.
*/
SharedSemiFuture<ReshardingCoordinatorDocument> awaitAllRecipientsRenamedCollection();
/**
* Sets errors on any promises that have not yet been fulfilled.
*/
void interrupt(Status status);
private:
// Protects the state below
Mutex _mutex = MONGO_MAKE_LATCH("ReshardingCoordinatorObserver::_mutex");
/**
* Promises indicating that either all donors or all recipients have entered a specific state.
* The ReshardingCoordinator waits on these in order to transition states. Promises must be
* fulfilled in descending order.
*
* Below are the relationships between promise and expected state in
* format: {promiseToFulfill, expectedState}
*
* {_allRecipientsCreatedCollection, RecipientStateEnum::kInitialized}
* {_allDonorsReportedMinFetchTimestamp, DonorStateEnum::kDonating}
* {_allRecipientsFinishedCloning, RecipientStateEnum::kSteadyState}
* {_allRecipientsReportedStrictConsistencyTimestamp, RecipientStateEnum::kStrictConsistency}
* {_allRecipientsRenamedCollection, RecipientStateEnum::kDone}
* {_allDonorsDroppedOriginalCollection, DonorStateEnum::kDone}
*/
SharedPromise<ReshardingCoordinatorDocument> _allRecipientsCreatedCollection;
SharedPromise<ReshardingCoordinatorDocument> _allDonorsReportedMinFetchTimestamp;
SharedPromise<ReshardingCoordinatorDocument> _allRecipientsFinishedCloning;
SharedPromise<ReshardingCoordinatorDocument> _allRecipientsReportedStrictConsistencyTimestamp;
SharedPromise<ReshardingCoordinatorDocument> _allRecipientsRenamedCollection;
SharedPromise<ReshardingCoordinatorDocument> _allDonorsDroppedOriginalCollection;
};
} // namespace mongo
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