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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/s/database_version.h"
namespace mongo {
AtomicWord<uint64_t> ComparableDatabaseVersion::_uuidDisambiguatingSequenceNumSource{1ULL};
AtomicWord<uint64_t> ComparableDatabaseVersion::_forcedRefreshSequenceNumSource{1ULL};
DatabaseVersion DatabaseVersion::makeFixed() {
DatabaseVersion dbVersion;
dbVersion.setLastMod(0);
dbVersion.setUuid(UUID::gen());
return dbVersion;
}
DatabaseVersion DatabaseVersion::makeUpdated() const {
DatabaseVersion newVersion = *this;
newVersion.setLastMod(newVersion.getLastMod() + 1);
return newVersion;
}
ComparableDatabaseVersion ComparableDatabaseVersion::makeComparableDatabaseVersion(
const boost::optional<DatabaseVersion>& version) {
return ComparableDatabaseVersion(version,
_uuidDisambiguatingSequenceNumSource.fetchAndAdd(1),
_forcedRefreshSequenceNumSource.load());
}
ComparableDatabaseVersion
ComparableDatabaseVersion::makeComparableDatabaseVersionForForcedRefresh() {
return ComparableDatabaseVersion(boost::none /* version */,
_uuidDisambiguatingSequenceNumSource.fetchAndAdd(1),
_forcedRefreshSequenceNumSource.addAndFetch(2) - 1);
}
void ComparableDatabaseVersion::setDatabaseVersion(const DatabaseVersion& version) {
_dbVersion = version;
}
BSONObj ComparableDatabaseVersion::toBSONForLogging() const {
BSONObjBuilder builder;
if (_dbVersion)
builder.append("dbVersion"_sd, _dbVersion->toBSON());
else
builder.append("dbVersion"_sd, "None");
builder.append("uuidDisambiguatingSequenceNum"_sd,
static_cast<int64_t>(_uuidDisambiguatingSequenceNum));
builder.append("forcedRefreshSequenceNum"_sd, static_cast<int64_t>(_forcedRefreshSequenceNum));
return builder.obj();
}
bool ComparableDatabaseVersion::operator==(const ComparableDatabaseVersion& other) const {
if (_forcedRefreshSequenceNum != other._forcedRefreshSequenceNum)
return false; // Values created on two sides of a forced refresh sequence number are always
// considered different
if (_forcedRefreshSequenceNum == 0)
return true; // Only default constructed values have _forcedRefreshSequenceNum == 0 and
// they are always equal
// Relying on the boost::optional<DatabaseVersion>::operator== comparison
return _dbVersion == other._dbVersion;
}
bool ComparableDatabaseVersion::operator<(const ComparableDatabaseVersion& other) const {
if (_forcedRefreshSequenceNum < other._forcedRefreshSequenceNum)
return true; // Values created on two sides of a forced refresh sequence number are always
// considered different
if (_forcedRefreshSequenceNum > other._forcedRefreshSequenceNum)
return false; // Values created on two sides of a forced refresh sequence number are always
// considered different
if (_forcedRefreshSequenceNum == 0)
return false; // Only default constructed values have _forcedRefreshSequenceNum == 0 and
// they are always equal
// 1. If both versions are valid and have timestamps
// 1.1. if their timestamps are the same -> rely on lastMod to define the order
// 1.2. Otherwise -> rely on the timestamps values to define order
// 2. If both versions are valid and have the same uuid -> rely on lastMod to define the order
// 3. Any other scenario -> rely on disambiguating sequence number
if (_dbVersion && other._dbVersion) {
const auto timestamp = _dbVersion->getTimestamp();
const auto otherTimestamp = other._dbVersion->getTimestamp();
if (timestamp && otherTimestamp) {
if (*timestamp == *otherTimestamp)
return _dbVersion->getLastMod() < other._dbVersion->getLastMod();
else
return *timestamp < *otherTimestamp;
} else if (_dbVersion->getUuid() == other._dbVersion->getUuid()) {
return _dbVersion->getLastMod() < other._dbVersion->getLastMod();
}
}
return _uuidDisambiguatingSequenceNum < other._uuidDisambiguatingSequenceNum;
}
} // namespace mongo
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