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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 "mongo/db/repl/primary_only_service.h"
#include "mongo/db/s/resharding/donor_document_gen.h"
#include "mongo/s/resharding/type_collection_fields_gen.h"
namespace mongo {
class ReshardingDonorService final : public repl::PrimaryOnlyService {
public:
static constexpr StringData kServiceName = "ReshardingDonorService"_sd;
explicit ReshardingDonorService(ServiceContext* serviceContext)
: PrimaryOnlyService(serviceContext) {}
~ReshardingDonorService() = default;
class DonorStateMachine;
StringData getServiceName() const override {
return kServiceName;
}
NamespaceString getStateDocumentsNS() const override {
return NamespaceString::kDonorReshardingOperationsNamespace;
}
ThreadPool::Limits getThreadPoolLimits() const override {
// TODO Limit the size of ReshardingDonorService thread pool.
return ThreadPool::Limits();
}
std::shared_ptr<PrimaryOnlyService::Instance> constructInstance(
BSONObj initialState) const override;
};
/**
* Represents the current state of a resharding donor operation on this shard. This class drives
* state transitions and updates to underlying on-disk metadata.
*/
class ReshardingDonorService::DonorStateMachine final
: public repl::PrimaryOnlyService::TypedInstance<DonorStateMachine> {
public:
explicit DonorStateMachine(const BSONObj& donorDoc);
~DonorStateMachine();
SemiFuture<void> run(std::shared_ptr<executor::ScopedTaskExecutor> executor,
const CancelationToken& token) noexcept override;
void interrupt(Status status) override;
/**
* Returns a Future that will be resolved when all work associated with this Instance has
* completed running.
*/
SharedSemiFuture<void> getCompletionFuture() const {
return _completionPromise.getFuture();
}
/**
* TODO(SERVER-50978) Report ReshardingDonorService Instances in currentOp().
*/
boost::optional<BSONObj> reportForCurrentOp(
MongoProcessInterface::CurrentOpConnectionsMode connMode,
MongoProcessInterface::CurrentOpSessionsMode sessionMode) noexcept override {
return boost::none;
}
void onReshardingFieldsChanges(const TypeCollectionReshardingFields& reshardingFields);
private:
// The following functions correspond to the actions to take at a particular donor state.
void _transitionToPreparingToDonate();
void _onPreparingToDonateCalculateTimestampThenTransitionToDonatingInitialData();
ExecutorFuture<void> _awaitAllRecipientsDoneCloningThenTransitionToDonatingOplogEntries(
const std::shared_ptr<executor::ScopedTaskExecutor>& executor);
ExecutorFuture<void> _awaitAllRecipientsDoneApplyingThenTransitionToPreparingToMirror(
const std::shared_ptr<executor::ScopedTaskExecutor>& executor);
void _writeTransactionOplogEntryThenTransitionToMirroring();
ExecutorFuture<void> _awaitCoordinatorHasCommittedThenTransitionToDropping(
const std::shared_ptr<executor::ScopedTaskExecutor>& executor);
void _dropOriginalCollectionThenDeleteLocalState();
// Drops the original collection and throws if the returned status is not either Status::OK()
// or NamespaceNotFound.
void _dropOriginalCollection();
// Transitions the state on-disk and in-memory to 'endState'.
void _transitionState(DonorStateEnum endState,
boost::optional<Timestamp> minFetchTimestamp = boost::none);
void _transitionStateAndUpdateCoordinator(
DonorStateEnum endState, boost::optional<Timestamp> minFetchTimestamp = boost::none);
// Transitions the state on-disk and in-memory to kError.
void _transitionStateToError(const Status& status);
// Inserts 'doc' on-disk and sets '_donorDoc' in-memory.
void _insertDonorDocument(const ReshardingDonorDocument& doc);
// Updates the donor document on-disk and in-memory with the 'replacementDoc.'
void _updateDonorDocument(ReshardingDonorDocument&& replacementDoc);
// Removes the local donor document from disk and clears the in-memory state.
void _removeDonorDocument();
// The in-memory representation of the underlying document in
// config.localReshardingOperations.donor.
ReshardingDonorDocument _donorDoc;
// The id both for the resharding operation and for the primary-only-service instance.
const UUID _id;
// Protects the promises below
Mutex _mutex = MONGO_MAKE_LATCH("ReshardingDonor::_mutex");
// Each promise below corresponds to a state on the donor state machine. They are listed in
// ascending order, such that the first promise below will be the first promise fulfilled.
SharedPromise<void> _allRecipientsDoneCloning;
SharedPromise<void> _allRecipientsDoneApplying;
SharedPromise<void> _coordinatorHasCommitted;
SharedPromise<void> _completionPromise;
};
} // namespace mongo
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