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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 <tuple>
#include "mongo/bson/timestamp.h"
namespace mongo {
class BSONObj;
class BSONObjBuilder;
class BSONObjBuilderValueStream;
template <typename T>
class StatusWith;
namespace repl {
/**
* OpTime encompasses a Timestamp (which itself is composed of two 32-bit integers, which can
* represent a time_t and a counter), and a 64-bit Term number. OpTime can be used to
* label every op in an oplog with a unique identifier.
*/
class OpTime {
public:
static const char kTimestampFieldName[];
static const char kTermFieldName[];
// The term of an OpTime generated by old protocol version.
static const long long kUninitializedTerm = -1;
// The initial term after the first time upgrading from protocol version 0.
//
// This is also the initial term for nodes that were recently started up but have not
// yet joined the cluster, all in protocol version 1.
static const long long kInitialTerm;
/**
* Returns maximum OpTime value.
*/
static OpTime max();
// Default OpTime, also the smallest one.
OpTime() : _timestamp(Timestamp(0, 0)), _term(kUninitializedTerm) {}
OpTime(Timestamp ts, long long term) : _timestamp(std::move(ts)), _term(term) {}
Timestamp getTimestamp() const {
return _timestamp;
}
long long getSecs() const {
return _timestamp.getSecs();
}
long long getTerm() const {
return _term;
}
/**
* Serializes the contents of this optime to the specified builder in the form:
* subObjName : { ts: <timestamp>, t: <term> }
*/
void append(BSONObjBuilder* builder, const std::string& subObjName) const;
BSONObj toBSON() const;
static StatusWith<Date_t> parseWallTimeFromOplogEntry(const BSONObj& obj);
static StatusWith<OpTime> parseFromOplogEntry(const BSONObj& obj);
/**
* Parses OpTime from a document in the form:
* { ts: <timestamp>, t: <term> }
*
* Throws an exception on error.
*/
static OpTime parse(const BSONObj& obj);
std::string toString() const;
// Returns true when this OpTime is not yet initialized.
bool isNull() const {
return _timestamp.isNull();
}
inline bool operator==(const OpTime& rhs) const {
// Only compare timestamp if either of the two OpTimes is generated by old protocol,
// so that (Timestamp(), 0) == (Timestamp(), -1)
if (_term == kUninitializedTerm || rhs._term == kUninitializedTerm) {
return _timestamp == rhs._timestamp;
}
// Compare term first, then the timestamps.
return std::tie(_term, _timestamp) == std::tie(rhs._term, rhs._timestamp);
}
// Since the term will be reset to 0 after upgrade protocol version -> downgrade
// -> upgrade again, comparison of arbitrary OpTimes may not be safe. However it's safe
// to compare OpTimes generated in same or successive replset configs.
// Upgrade / downgrade process will make sure the last oplog entries on all nodes are from
// the same protocol version to avoid problematic scenarios.
inline bool operator<(const OpTime& rhs) const {
// Only compare timestamp if either of the two OpTimes is generated by old protocol.
if (_term == kUninitializedTerm || rhs._term == kUninitializedTerm) {
return _timestamp < rhs._timestamp;
}
// Compare term first, then the timestamps.
return std::tie(_term, _timestamp) < std::tie(rhs._term, rhs._timestamp);
}
inline bool operator!=(const OpTime& rhs) const {
return !(*this == rhs);
}
inline bool operator<=(const OpTime& rhs) const {
return *this < rhs || *this == rhs;
}
inline bool operator>(const OpTime& rhs) const {
return !(*this <= rhs);
}
inline bool operator>=(const OpTime& rhs) const {
return !(*this < rhs);
}
friend std::ostream& operator<<(std::ostream& out, const OpTime& opTime);
void appendAsQuery(BSONObjBuilder* builder) const;
BSONObj asQuery() const;
private:
Timestamp _timestamp;
long long _term = kInitialTerm;
};
struct OpTimeAndWallTime {
OpTime opTime;
Date_t wallTime = Date_t();
inline bool operator==(const OpTimeAndWallTime& rhs) const {
return opTime == rhs.opTime && wallTime == rhs.wallTime;
}
inline bool operator<(const OpTimeAndWallTime& rhs) const {
// Wall clock time ordering should not matter for calculations of the commit point.
return opTime < rhs.opTime;
}
std::string toString() const {
return opTime.toString() + ", " + wallTime.toString();
}
};
std::ostream& operator<<(std::ostream& out, const OpTimeAndWallTime& opTime);
} // namespace repl
/**
* Support BSONObjBuilder and BSONArrayBuilder "stream" API.
*/
BSONObjBuilder& operator<<(BSONObjBuilderValueStream& builder, const repl::OpTime& value);
} // namespace mongo
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