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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/vector_clock_mutable.h"
#include "mongo/logv2/log.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kDefault
namespace mongo {
namespace {
const auto vectorClockMutableDecoration = ServiceContext::declareDecoration<VectorClockMutable*>();
} // namespace
VectorClockMutable* VectorClockMutable::get(ServiceContext* service) {
return vectorClockMutableDecoration(service);
}
VectorClockMutable* VectorClockMutable::get(OperationContext* ctx) {
return get(ctx->getClient()->getServiceContext());
}
VectorClockMutable::VectorClockMutable() = default;
VectorClockMutable::~VectorClockMutable() = default;
void VectorClockMutable::registerVectorClockOnServiceContext(
ServiceContext* service, VectorClockMutable* vectorClockMutable) {
VectorClock::registerVectorClockOnServiceContext(service, vectorClockMutable);
auto& clock = vectorClockMutableDecoration(service);
invariant(!clock);
clock = std::move(vectorClockMutable);
}
LogicalTime VectorClockMutable::_advanceComponentTimeByTicks(Component component, uint64_t nTicks) {
invariant(nTicks > 0 && nTicks <= kMaxValue);
stdx::lock_guard<Latch> lock(_mutex);
LogicalTime time = _vectorTime[component];
const unsigned wallClockSecs =
durationCount<Seconds>(_service->getFastClockSource()->now().toDurationSinceEpoch());
unsigned timeSecs = time.asTimestamp().getSecs();
// Synchronize time with wall clock time, if time was behind in seconds.
if (timeSecs < wallClockSecs) {
time = LogicalTime(Timestamp(wallClockSecs, 0));
}
// If reserving 'nTicks' would force the time's increment field to exceed (2^31-1),
// overflow by moving to the next second. We use the signed integer maximum as an overflow point
// in order to preserve compatibility with potentially signed or unsigned integral Timestamp
// increment types. It is also unlikely to tick a clock by more than 2^31 in the span of one
// second.
else if (time.asTimestamp().getInc() > (kMaxValue - nTicks)) {
LOGV2(20709,
"Exceeded maximum allowable increment value within one second. Moving time forward "
"to the next second.",
"vectorClockComponent"_attr = _componentName(component));
// Move time forward to the next second
time = LogicalTime(Timestamp(time.asTimestamp().getSecs() + 1, 0));
}
uassert(40482,
str::stream() << _componentName(component)
<< " cannot be advanced beyond the maximum logical time value",
_lessThanOrEqualToMaxPossibleTime(time, nTicks));
// Save the next time.
time.addTicks(1);
_vectorTime[component] = time;
// Add the rest of the requested ticks if needed.
if (nTicks > 1) {
_vectorTime[component].addTicks(nTicks - 1);
}
return time;
}
void VectorClockMutable::_advanceComponentTimeTo(Component component, LogicalTime&& newTime) {
stdx::lock_guard<Latch> lock(_mutex);
// Rate limit checks are skipped here so a server with no activity for longer than
// maxAcceptableLogicalClockDriftSecs seconds can still have its cluster time initialized.
uassert(40483,
str::stream() << _componentName(component)
<< " cannot be advanced beyond the maximum logical time value",
_lessThanOrEqualToMaxPossibleTime(newTime, 0));
if (newTime > _vectorTime[component]) {
_vectorTime[component] = std::move(newTime);
}
}
} // namespace mongo
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