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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/transaction_coordinator_catalog.h"
namespace mongo {
class TransactionCoordinatorService {
TransactionCoordinatorService(const TransactionCoordinatorService&) = delete;
TransactionCoordinatorService& operator=(const TransactionCoordinatorService&) = delete;
public:
TransactionCoordinatorService();
~TransactionCoordinatorService();
/**
* Retrieves the TransactionCoordinatorService associated with the service or operation context.
*/
static TransactionCoordinatorService* get(OperationContext* opCtx);
static TransactionCoordinatorService* get(ServiceContext* serviceContext);
/**
* Creates a new TransactionCoordinator for the given session id and transaction number, with a
* deadline for the commit decision. If the coordinator has not decided to commit by that
* deadline, it will abort.
*/
void createCoordinator(OperationContext* opCtx,
LogicalSessionId lsid,
TxnNumber txnNumber,
Date_t commitDeadline);
/**
* Outputs a vector of BSON documents to the ops out-param containing information about active
* and idle coordinators in the system.
*/
void reportCoordinators(OperationContext* opCtx, bool includeIdle, std::vector<BSONObj>* ops);
/**
* If a coordinator for the (lsid, txnNumber) exists, delivers the participant list to the
* coordinator, which will cause the coordinator to start coordinating the commit if the
* coordinator had not yet received a list, and returns a Future that will contain the decision
* when the transaction finishes committing or aborting.
*
* If no coordinator for the (lsid, txnNumber) exists, returns boost::none.
*/
boost::optional<SharedSemiFuture<txn::CommitDecision>> coordinateCommit(
OperationContext* opCtx,
LogicalSessionId lsid,
TxnNumber txnNumber,
const std::set<ShardId>& participantList);
/**
* If a coordinator for the (lsid, txnNumber) exists, returns a Future that will contain the
* decision when the transaction finishes committing or aborting.
*
* If no coordinator for the (lsid, txnNumber) exists, returns boost::none.
*/
boost::optional<SharedSemiFuture<txn::CommitDecision>> recoverCommit(OperationContext* opCtx,
LogicalSessionId lsid,
TxnNumber txnNumber);
/**
* Marks the coordinator catalog as stepping up, which blocks all incoming requests for
* coordinators, and launches an async task to:
* 1. Wait for the coordinators in the catalog to complete (successfully or with an error) and
* be removed from the catalog.
* 2. Read all pending commit tasks from the config.transactionCoordinators collection.
* 3. Create TransactionCoordinator objects in memory for each pending commit and launch an
* async task to continue coordinating its commit.
*
* The 'recoveryDelay' argument is only used for testing in order to simulate recovery taking
* long time.
*/
void onStepUp(OperationContext* opCtx, Milliseconds recoveryDelayForTesting = Milliseconds(0));
void onStepDown();
/**
* Called when an already established replica set is added as a shard to a cluster. Ensures that
* the TransactionCoordinator service is started up if the replica set is currently primary.
*/
void onShardingInitialization(OperationContext* opCtx, bool isPrimary);
/**
* Cancel commit on the coordinator for the given transaction only if it has not started yet.
*/
void cancelIfCommitNotYetStarted(OperationContext* opCtx,
LogicalSessionId lsid,
TxnNumber txnNumber);
/**
* Blocking call which waits for the previous stepUp/stepDown round to join and ensures all
* tasks scheduled by that round have completed.
*/
void joinPreviousRound();
private:
struct CatalogAndScheduler {
CatalogAndScheduler(ServiceContext* service) : scheduler(service) {}
void onStepDown();
void join();
txn::AsyncWorkScheduler scheduler;
TransactionCoordinatorCatalog catalog;
boost::optional<Future<void>> recoveryTaskCompleted;
};
/**
* Returns the current catalog + scheduler if stepUp has started, otherwise throws a NotMaster
* exception.
*/
std::shared_ptr<CatalogAndScheduler> _getCatalogAndScheduler(OperationContext* opCtx);
// Contains the catalog + scheduler, which was active at the last step-down attempt (if any).
// Set at onStepDown and destroyed at onStepUp, which are always invoked sequentially by the
// replication machinery, so there is no need to explicitly synchronize it
std::shared_ptr<CatalogAndScheduler> _catalogAndSchedulerToCleanup;
// Protects the state below
mutable stdx::mutex _mutex;
// The catalog + scheduler instantiated at the last step-up attempt. When nullptr, it means
// onStepUp has not been called yet after the last stepDown (or construction).
std::shared_ptr<CatalogAndScheduler> _catalogAndScheduler;
};
} // namespace mongo
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