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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 <boost/optional.hpp>
#include "mongo/base/disallow_copying.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/session_catalog.h"
#include "mongo/util/time_support.h"
namespace mongo {
namespace repl {
/**
* This object handles acquiring the global exclusive lock for replication state transitions, as
* well as any actions that need to happen in between enqueuing the global lock request and waiting
* for it to be granted. One of the main such actions is aborting all in-progress transactions and
* causing all prepared transaction to yield their locks during the transition and restoring them
* when the transition is complete.
*/
class ReplicationStateTransitionLockGuard {
MONGO_DISALLOW_COPYING(ReplicationStateTransitionLockGuard);
public:
struct Args {
// How long to wait for the global X lock.
Date_t lockDeadline = Date_t::max();
// If true, will kill all user operations in between enqueuing the global lock request and
// waiting for it to be granted.
bool killUserOperations = false;
};
/**
* Acquires the global X lock while yielding the locks held by any prepared transactions.
* Also performs any other actions required according to the Args provided.
*/
ReplicationStateTransitionLockGuard(OperationContext* opCtx, const Args& args);
/**
* Releases the global X lock and atomically restores the locks for prepared transactions that
* were yielded in the constructor.
*/
~ReplicationStateTransitionLockGuard();
/**
* Temporarily releases the global X lock. Must be followed by a call to
* reacquireGlobalLockForStepdownAttempt().
*/
void releaseGlobalLockForStepdownAttempt();
/**
* Requires the global X lock after it was released via a call to
* releaseGlobalLockForStepdownAttempt(). Ignores the configured 'lockDeadline' and instead
* waits forever for the lock to be acquired.
*/
void reacquireGlobalLockForStepdownAttempt();
private:
// OperationContext of the thread driving the state transition.
OperationContext* const _opCtx;
// Args to configure what behaviors need to be taken while acquiring the global X lock for the
// state transition.
Args _args;
// The global X lock that this object is responsible for acquiring as part of the state
// transition.
boost::optional<Lock::GlobalLock> _globalLock;
// Used to prevent Sessions from being checked out, so that we can wait for all sessions to be
// checked in and iterate over all Sessions to get Sessions with prepared transactions to yield
// their locks.
boost::optional<SessionCatalog::PreventCheckingOutSessionsBlock> _preventCheckingOutSessions;
// Locks that were held by prepared transactions and were yielded in order to allow taking the
// global X lock.
std::vector<std::pair<Locker*, Locker::LockSnapshot>> _yieldedLocks;
};
} // namespace repl
} // namespace mongo
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