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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/vector_clock.h"
namespace mongo {
/**
* A vector clock service that additionally permits being advanced authoritatively ("ticking").
*
* Only linked in contexts where ticking is allowed, ie. mongod, embedded, mongod-based unittests.
*/
class VectorClockMutable : public VectorClock {
public:
// Decorate ServiceContext with VectorClockMutable*, that will resolve to the mutable vector
// clock implementation.
static VectorClockMutable* get(ServiceContext* service);
static VectorClockMutable* get(OperationContext* ctx);
static void registerVectorClockOnServiceContext(ServiceContext* service,
VectorClockMutable* vectorClockMutable);
/**
* Returns the next time value for the component, and provides a guarantee that any future call
* to tick() will return a value at least 'nTicks' ticks in the future from the current time.
*/
LogicalTime tickClusterTime(uint64_t nTicks) {
return _tick(Component::ClusterTime, nTicks);
}
LogicalTime tickConfigTime(uint64_t nTicks) {
return _tick(Component::ConfigTime, nTicks);
}
LogicalTime tickTopologyTime(uint64_t nTicks) {
return _tick(Component::TopologyTime, nTicks);
}
/**
* Authoritatively ticks the current time of the specified component to newTime.
*
* For ClusterTime, this should only be used for initializing from a trusted source, eg. from an
* oplog timestamp.
*/
void tickClusterTimeTo(LogicalTime newTime) {
_tickTo(Component::ClusterTime, newTime);
}
void tickConfigTimeTo(LogicalTime newTime) {
_tickTo(Component::ConfigTime, newTime);
}
void tickTopologyTimeTo(LogicalTime newTime) {
_tickTo(Component::TopologyTime, newTime);
}
/**
* These methods ensure that the values of the specified vector clock components as of the time
* of the call have been durably persisted to disk, before setting the returned future.
* Persisting the vector clock ensures that subsequent calls to `recover()` below will bring the
* components to at least the persisted time.
*/
virtual SharedSemiFuture<void> waitForDurableConfigTime() = 0;
virtual SharedSemiFuture<void> waitForDurableTopologyTime() = 0;
virtual SharedSemiFuture<void> waitForDurable() = 0;
/**
* Ensures that the values of the vector clock are at least equal to those from the last
* successfully persisted ones.
*/
virtual SharedSemiFuture<void> recover() = 0;
protected:
VectorClockMutable();
virtual ~VectorClockMutable();
/**
* Called by sub-classes in order to actually tick a Component time, once they have determined
* that doing so is permissible.
*
* Returns as per tick(), ie. returns the next time value, and guarantees that future calls will
* return at least nTicks later.
*/
LogicalTime _advanceComponentTimeByTicks(Component component, uint64_t nTicks);
/**
* Called by sublclasses in order to actually tickTo a Component time, once they have determined
* that doing so is permissible.
*/
void _advanceComponentTimeTo(Component component, LogicalTime&& newTime);
/**
* Returns the next time value for the component, and provides a guarantee that any future call
* to tick() will return a value at least 'nTicks' ticks in the future from the current time.
*/
virtual LogicalTime _tick(Component component, uint64_t nTicks) = 0;
/**
* Authoritatively ticks the current time of the Component to newTime.
*
* For ClusterTime, this should only be used for initializing from a trusted source, eg. from an
* oplog timestamp.
*/
virtual void _tickTo(Component component, LogicalTime newTime) = 0;
};
} // namespace mongo
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