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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 <boost/optional.hpp>
#include <map>
#include <vector>
#include "mongo/bson/bsonobj.h"
#include "mongo/db/repl/oplog_entry.h"
#include "mongo/db/session/logical_session_id.h"
#include "mongo/util/uuid.h"
namespace mongo {
namespace repl {
/**
* Keeps tracks of oplog operations that would require changes to the config.transactions and
* provides functions to create oplog entries that would contain the writes to update
* config.transactions.
*
* Assumption: it is not allowed to do transactions/retryable writes against config.transactions.
*/
class SessionUpdateTracker {
public:
/**
* Converts all stored transaction infos to oplog writes to config.transactions.
* Can return an empty vector if there is nothing to flush.
*/
std::vector<OplogEntry> flushAll();
/**
* If 'entry' is part of a transaction, then return an update to the transaction table
* corresponding to the operation. Otherwise, inspect the entry to determine whether to buffer
* or flush the stored transaction information as part of retryable writes.
*/
boost::optional<std::vector<OplogEntry>> updateSession(const OplogEntry& entry);
/**
* Returns true if the oplog entry represents an operation in a transaction and false otherwise.
* No-ops representing migrated transactions are considered transaction operations.
*/
static bool isTransactionEntry(const OplogEntry& entry);
private:
/**
* Analyzes the given oplog entry and determines which transactions stored so far needs to be
* converted to oplog writes.
*
* Note: should only be called when oplog entry's ns target config.transactions or config.$cmd.
*/
std::vector<OplogEntry> _flush(const OplogEntry& entry);
/**
* Converts stored transaction infos that has a matching transcation id with the given
* query predicate. Can return an empty vector if there is nothing to flush.
*/
std::vector<OplogEntry> _flushForQueryPredicate(const BSONObj& queryPredicate);
/**
* Extract transaction information from the oplog if any and records them internally. Returns
* a list of 'config.transactions' table updates to be flushed if 'entry' has a 'txnNumber'
* greater than the currently stored session information.
*/
boost::optional<std::vector<OplogEntry>> _updateSessionInfo(const OplogEntry& entry);
/**
* Inspects the oplog entry and determines whether this needs to update the session info or
* flush stored transaction information to oplog writes.
*/
boost::optional<std::vector<OplogEntry>> _updateOrFlush(const OplogEntry& entry);
/**
* Returns an update to the transaction table generated by a transaction operation. This returns
* boost::none if the operation is a partialTxn operation that is not the first of the
* transaction.
*/
boost::optional<OplogEntry> _createTransactionTableUpdateFromTransactionOp(
const repl::OplogEntry& entry);
LogicalSessionIdMap<OplogEntry> _sessionsToUpdate;
};
} // namespace repl
} // namespace mongo
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