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/**
* Copyright (C) 2022-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 <queue>
#include "mongo/db/cancelable_operation_context.h"
#include "mongo/db/repl/primary_only_service.h"
#include "mongo/db/s/global_index/global_index_cloner_fetcher_factory.h"
#include "mongo/db/s/global_index/global_index_cloner_gen.h"
#include "mongo/db/s/global_index/global_index_inserter.h"
#include "mongo/db/s/resharding/resharding_future_util.h"
#include "mongo/util/concurrency/thread_pool.h"
namespace mongo {
namespace global_index {
class GlobalIndexCloningService : public repl::PrimaryOnlyService {
public:
static constexpr StringData kServiceName = "GlobalIndexCloningService"_sd;
explicit GlobalIndexCloningService(ServiceContext* serviceContext);
class CloningExternalState;
class CloningStateMachine;
StringData getServiceName() const override {
return kServiceName;
}
NamespaceString getStateDocumentsNS() const override {
return NamespaceString::kGlobalIndexClonerNamespace;
}
ThreadPool::Limits getThreadPoolLimits() const override;
void checkIfConflictsWithOtherInstances(
OperationContext* opCtx,
BSONObj initialState,
const std::vector<const repl::PrimaryOnlyService::Instance*>& existingInstances) override;
std::shared_ptr<repl::PrimaryOnlyService::Instance> constructInstance(
BSONObj initialState) override;
private:
ServiceContext* const _serviceContext;
};
/**
* Represents the current state of a global index operation on this shard. This class drives state
* transitions and updates to underlying on-disk metadata.
*/
class GlobalIndexCloningService::CloningStateMachine final
: public repl::PrimaryOnlyService::TypedInstance<CloningStateMachine> {
public:
CloningStateMachine(
ServiceContext* service,
const GlobalIndexCloningService* cloningService,
std::unique_ptr<GlobalIndexCloningService::CloningExternalState> externalState,
std::unique_ptr<GlobalIndexClonerFetcherFactoryInterface> fetcherFactory,
GlobalIndexClonerDoc clonerDoc);
SemiFuture<void> run(std::shared_ptr<executor::ScopedTaskExecutor> executor,
const CancellationToken& token) noexcept override;
void interrupt(Status status) override;
void abort();
/**
* Returns a Future that will be resolved when all work associated with this Instance is done
* making forward progress.
*/
SharedSemiFuture<void> getCompletionFuture() const {
return _completionPromise.getFuture();
}
boost::optional<BSONObj> reportForCurrentOp(
MongoProcessInterface::CurrentOpConnectionsMode,
MongoProcessInterface::CurrentOpSessionsMode) noexcept override;
/**
* Initiates the cancellation of the cloning operation.
*/
void abort(bool isUserCancelled);
void checkIfOptionsConflict(const BSONObj& stateDoc) const final;
private:
/**
* Initializes the _abortSource and generates a token from it to return back the caller.
* Should only be called once per lifetime.
*/
CancellationToken _initAbortSource(const CancellationToken& stepdownToken);
/**
* Initializes the necessary components.
*/
void _init(const std::shared_ptr<executor::ScopedTaskExecutor>& executor);
/**
* Make sure that the necessary collections are created.
*/
void _initializeCollections(const CancelableOperationContextFactory& cancelableOpCtxFactory);
/**
* Inserts the state document to storage.
*/
ExecutorFuture<void> _persistStateDocument(
std::shared_ptr<executor::ScopedTaskExecutor> executor,
const CancellationToken& cancelToken);
/**
* Deletes the state document from storage.
*/
void _removeStateDocument(OperationContext* opCtx);
/**
* Performs the entire cloning process.
*/
ExecutorFuture<void> _runUntilDoneCloning(
std::shared_ptr<executor::ScopedTaskExecutor> executor,
const CancellationToken& stepdownToken);
/**
* Iterates over the documents from the source collection and convert them into global index
* entries.
*/
ExecutorFuture<void> _clone(std::shared_ptr<executor::ScopedTaskExecutor> executor,
const CancellationToken& cancelToken,
const CancelableOperationContextFactory& cancelableOpCtxFactory);
/**
* Removes the side collections created by this cloner.
*/
ExecutorFuture<void> _cleanup(std::shared_ptr<executor::ScopedTaskExecutor> executor,
const CancellationToken& stepdownToken);
/**
* Fetches documents from source collection and store them in a queue.
*/
void _fetchNextBatch(OperationContext* opCtx);
/**
* Convert fetched documents to global index entries.
*/
ExecutorFuture<void> _processBatch(
std::shared_ptr<executor::ScopedTaskExecutor> executor,
const CancellationToken& cancelToken,
const CancelableOperationContextFactory& cancelableOpCtxFactory);
/**
* Create collection with the given namespace only if it doesn't exist.
*/
void _ensureCollection(OperationContext* opCtx, const NamespaceString& nss);
ServiceContext* const _serviceContext;
// The primary-only service instance corresponding to the cloner instance. Not owned.
const GlobalIndexCloningService* const _cloningService;
// A separate executor different from the one supplied by the primary only service is needed
// because the one from POS can be shut down during step down. This will ensure that the
// operation context created from the cancelableOpCtxFactory can be interrupted when the cancel
// token is aborted during step down.
const std::shared_ptr<ThreadPool> _execForCancelableOpCtx;
boost::optional<resharding::RetryingCancelableOperationContextFactory>
_retryingCancelableOpCtxFactory;
Mutex _mutex = MONGO_MAKE_LATCH("GlobalIndexCloningStateMachine::_mutex");
GlobalIndexClonerDoc _clonerState;
// Canceled when there is an unrecoverable error or stepdown.
boost::optional<CancellationSource> _abortSource;
std::unique_ptr<GlobalIndexClonerFetcherFactoryInterface> _fetcherFactory;
std::unique_ptr<GlobalIndexClonerFetcherInterface> _fetcher;
std::unique_ptr<GlobalIndexInserter> _inserter;
// Keeps track if there is still a posibility that we still have documents that needs to be
// fetched from the source collection.
bool _hasMoreToFetch{true};
std::queue<GlobalIndexClonerFetcher::FetchedEntry> _fetchedDocs;
SharedPromise<void> _completionPromise;
const std::unique_ptr<CloningExternalState> _externalState;
};
} // namespace global_index
} // namespace mongo
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