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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 <set>
#include "mongo/db/operation_context.h"
#include "mongo/db/repl/optime.h"
#include "mongo/db/service_context.h"
#include "mongo/db/transactions_stats_gen.h"
#include "mongo/util/concurrency/with_lock.h"
namespace mongo {
/**
* Container for server-wide multi-document transaction statistics.
*/
class ServerTransactionsMetrics {
MONGO_DISALLOW_COPYING(ServerTransactionsMetrics);
public:
ServerTransactionsMetrics() = default;
static ServerTransactionsMetrics* get(ServiceContext* service);
static ServerTransactionsMetrics* get(OperationContext* opCtx);
unsigned long long getCurrentActive() const;
void decrementCurrentActive();
void incrementCurrentActive();
unsigned long long getCurrentInactive() const;
void decrementCurrentInactive();
void incrementCurrentInactive();
unsigned long long getCurrentOpen() const;
void decrementCurrentOpen();
void incrementCurrentOpen();
unsigned long long getTotalStarted() const;
void incrementTotalStarted();
unsigned long long getTotalAborted() const;
void incrementTotalAborted();
unsigned long long getTotalCommitted() const;
void incrementTotalCommitted();
unsigned long long getTotalPrepared() const;
void incrementTotalPrepared();
unsigned long long getTotalPreparedThenCommitted() const;
void incrementTotalPreparedThenCommitted();
unsigned long long getTotalPreparedThenAborted() const;
void incrementTotalPreparedThenAborted();
unsigned long long getCurrentPrepared() const;
void incrementCurrentPrepared();
void decrementCurrentPrepared();
/**
* Returns the OpTime of the oldest oplog entry written across all open transactions.
* Returns boost::none if there are no transaction oplog entry OpTimes stored.
*/
boost::optional<repl::OpTime> getOldestActiveOpTime() const;
/**
* Add the transaction's oplog entry OpTime to oldestActiveOplogEntryOpTimes, a set of OpTimes.
* Also creates a pair with this OpTime and OpTime::max() as the corresponding commit/abort
* oplog entry OpTime. Finally, adds this to oldestNonMajorityCommittedOpTimes.
*/
void addActiveOpTime(repl::OpTime oldestOplogEntryOpTime);
/**
* Remove the corresponding transaction oplog entry OpTime if the transaction commits or
* aborts. Also updates the pair in oldestNonMajorityCommittedOpTimes with the
* oldestOplogEntryOpTime to have a valid finishOpTime instead of OpTime::max(). It's stored in
* the format: < oldestOplogEntryOpTime, finishOpTime >.
*/
void removeActiveOpTime(repl::OpTime oldestOplogEntryOpTime,
boost::optional<repl::OpTime> finishOpTime);
/**
* Returns the number of transaction oplog entry OpTimes currently stored.
*/
unsigned int getTotalActiveOpTimes() const;
/**
* Returns the oldest oplog entry OpTime across transactions whose corresponding commit or
* abort oplog entry has not been majority committed.
*/
boost::optional<repl::OpTime> getOldestNonMajorityCommittedOpTime() const;
/**
* Remove the corresponding transaction oplog entry OpTime pair from
* oldestNonMajorityCommittedOpTimes if the transaction is majority committed or aborted.
* We determine this by checking if there are any pairs in the set whose
* 'finishOpTime' <= 'committedOpTime'.
*/
void removeOpTimesLessThanOrEqToCommittedOpTime(repl::OpTime committedOpTime);
/**
* Testing function that adds an OpTime pair to oldestNonMajorityCommittedOpTimes.
*/
void addNonMajCommittedOpTimePair_forTest(std::pair<repl::OpTime, repl::OpTime> OpTimePair);
/**
* Testing function that returns the oldest non-majority committed OpTime pair in the form:
* < oldestOplogEntryOpTime, finishOpTime >.
*/
boost::optional<repl::OpTime> getFinishOpTimeOfOldestNonMajCommitted_forTest() const;
/**
* Appends the accumulated stats to a transactions stats object.
*/
void updateStats(TransactionsStats* stats, OperationContext* opCtx);
/**
* Invalidates the in-memory state of prepared transactions during replication rollback by
* clearing oldestActiveOplogEntryOpTime, oldestActiveOplogEntryOpTimes, and
* oldestNonMajorityCommittedOpTimes. These variables/data structures should be properly
* reconstructed during replication recovery.
*/
void clearOpTimes();
private:
/**
* Returns the first and oldest optime in the ordered set of active oplog entry optimes.
* Returns boost::none if there are no transaction oplog entry optimes stored.
*/
boost::optional<repl::OpTime> _calculateOldestActiveOpTime(WithLock) const;
/**
* Returns the oldest read timestamp in use by any open unprepared transaction. This will
* return a null timestamp if there is no oldest open unprepared read timestamp to be
* returned.
*/
static Timestamp _getOldestOpenUnpreparedReadTimestamp(OperationContext* opCtx);
//
// Member variables, excluding atomic variables, are labeled with the following code to
// indicate the synchronization rules for accessing them.
//
// (M) Reads and writes guarded by _mutex
//
mutable stdx::mutex _mutex;
// The number of multi-document transactions currently active.
AtomicWord<unsigned long long> _currentActive{0};
// The number of multi-document transactions currently inactive.
AtomicWord<unsigned long long> _currentInactive{0};
// The total number of open transactions.
AtomicWord<unsigned long long> _currentOpen{0};
// The total number of multi-document transactions started since the last server startup.
AtomicWord<unsigned long long> _totalStarted{0};
// The total number of multi-document transaction aborts.
AtomicWord<unsigned long long> _totalAborted{0};
// The total number of multi-document transaction commits.
AtomicWord<unsigned long long> _totalCommitted{0};
// The total number of prepared transactions since the last server startup.
AtomicWord<unsigned long long> _totalPrepared{0};
// The total number of prepared transaction commits.
AtomicWord<unsigned long long> _totalPreparedThenCommitted{0};
// The total number of prepared transaction aborts.
AtomicWord<unsigned long long> _totalPreparedThenAborted{0};
// The current number of transactions in the prepared state.
AtomicWord<unsigned long long> _currentPrepared{0};
// The optime of the oldest oplog entry for any active transaction.
boost::optional<repl::OpTime> _oldestActiveOplogEntryOpTime; // (M)
// Maintain the oldest oplog entry OpTime across all active transactions. Currently, we only
// write an oplog entry for an ongoing transaction if it is in the `prepare` state. By
// maintaining an ordered set of OpTimes, the OpTime at the beginning will be the oldest.
std::set<repl::OpTime> _oldestActiveOplogEntryOpTimes; // (M)
// Maintain the oldest oplog entry OpTime across transactions whose corresponding abort/commit
// oplog entries have not been majority committed. Since this is an ordered set, the first
// pair's oldestOplogEntryOpTime represents the earliest OpTime that we should pin the stable
// timestamp behind.
// Each pair is structured as follows: <oldestOplogEntryOpTime, finishOpTime>
// 'oldestOplogEntryOpTime': The first oplog entry OpTime written by a transaction.
// 'finishOpTime': The commit/abort oplog entry OpTime.
// Once the corresponding abort/commit entry has been majority committed, remove the pair from
// this set.
std::set<std::pair<repl::OpTime, repl::OpTime>> _oldestNonMajorityCommittedOpTimes; // (M)
};
} // namespace mongo
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