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/**
* Copyright (C) 2021-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 "mongo/db/matcher/expression.h"
namespace mongo {
namespace change_stream_filter {
/**
* Produce a timestamp filter that starts an oplog scan at a specific time.
*/
std::unique_ptr<MatchExpression> buildTsFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
Timestamp startFromInclusive,
const MatchExpression* userMatch);
/**
* Produce a filter that rejects any operations marked with the "fromMigrate" flag. These operations
* occurs as part of chunk migration and should not be visible to user change streams, because they
* don't reflect user operations to the database.
*/
std::unique_ptr<MatchExpression> buildNotFromMigrateFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const MatchExpression* userMatch);
/**
* Produce a filter that includes operations marked fromMigrate:true when showSystemEvents feature
* is set.
*/
std::unique_ptr<MatchExpression> buildFromMigrateSystemOpFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const MatchExpression* userMatch);
/**
* Produce an oplog filter which captures all operations relevant to change streams, including CRUD
* events and certain commands. Depending on the 'userMatch' $match expression, this filter may be
* able to reject some entries before they get transformed into change stream entries.
*/
std::unique_ptr<MatchExpression> buildOperationFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const MatchExpression* userMatch);
/**
* Produce an oplog filter which captures DDL operations for views (i.e. create, drop and modify).
*/
std::unique_ptr<MatchExpression> buildViewDefinitionEventFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const MatchExpression* userMatch);
/**
* Produce an oplog filter which matches any operation that should cause the change stream to be
* invalidated. The filter generated by this function will differ depending on the type of change
* stream being constructed.
*/
std::unique_ptr<MatchExpression> buildInvalidationFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const MatchExpression* userMatch);
/**
* Produce a filter matching any 'applyOps' or 'commitTransaction' commands that commit a
* transaction. An 'applyOps' command implicitly commits a transaction if _both_ of the following
* are true: 1) it is not marked with the 'partialTxn' field, which would indicate that there are
* more entries to come in the transaction and 2) it is not marked with the 'prepare' field, which
* would indicate that the transaction is only committed if there is a follow-up 'commitTransaction'
* command in the oplog.
*
* This filter will ignore all but the last 'applyOps' command in a transaction comprising multiple
* 'applyOps' commands, and it will ignore all 'applyOps' commands in a prepared transaction. The
* change stream traverses back through the oplog to recover the ignored commands when it sees an
* entry that commits a transaction.
*
* As an optimization, this filter also ignores any transaction with just a single 'applyOps' if
* that 'applyOps' does not contain any updates that modify the namespace that the change stream is
* watching.
*/
std::unique_ptr<MatchExpression> buildTransactionFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const MatchExpression* userMatch);
/**
* Produce a filter matching any operations for internal change stream use. These events must not be
* filtered out by the change stream's oplog scan, even if they are not ultimately returned to the
* user.
*/
std::unique_ptr<MatchExpression> buildInternalOpFilter(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const MatchExpression* userMatch);
/**
* Returns the match filter for the classic changestream operations.
*/
BSONObj getMatchFilterForClassicOperationTypes();
} // namespace change_stream_filter
} // namespace mongo
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