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/**
* Copyright (C) 2022-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/exec/document_value/document.h"
#include "mongo/db/pipeline/document_source_change_stream_gen.h"
#include "mongo/db/pipeline/expression_context.h"
namespace mongo {
/**
* An abstract class responsible for building a change stream event from an oplog entry.
*/
class ChangeStreamEventTransformation {
public:
ChangeStreamEventTransformation(const boost::intrusive_ptr<ExpressionContext>& expCtx,
const DocumentSourceChangeStreamSpec& spec);
virtual ~ChangeStreamEventTransformation() {}
/**
* Returns the change stream event build from an oplog entry.
*/
virtual Document applyTransformation(const Document& fromDoc) const = 0;
/**
* Returns all the fields names that could be potentially access by the event builder.
*/
virtual std::set<std::string> getFieldNameDependencies() const = 0;
protected:
// Construct a resume token for the specified event.
ResumeTokenData makeResumeToken(Value tsVal,
Value txnOpIndexVal,
Value uuidVal,
StringData operationType,
Value documentKey,
Value opDescription) const;
const DocumentSourceChangeStreamSpec _changeStreamSpec;
boost::intrusive_ptr<ExpressionContext> _expCtx;
ResumeTokenData _resumeToken;
// Set to true if the pre-image should be included in the output documents.
bool _preImageRequested = false;
// Set to true if the post-image should be included in the output documents.
bool _postImageRequested = false;
};
/*
* The event builder class to be used for oplog entries with no special behavior.
*/
class ChangeStreamDefaultEventTransformation final : public ChangeStreamEventTransformation {
public:
ChangeStreamDefaultEventTransformation(const boost::intrusive_ptr<ExpressionContext>& expCtx,
const DocumentSourceChangeStreamSpec& spec);
Document applyTransformation(const Document& fromDoc) const override;
std::set<std::string> getFieldNameDependencies() const override;
};
/**
* The event builder class to be used for oplog entries with the 'system.views' namespace.
*/
class ChangeStreamViewDefinitionEventTransformation final : public ChangeStreamEventTransformation {
public:
ChangeStreamViewDefinitionEventTransformation(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
const DocumentSourceChangeStreamSpec& spec);
Document applyTransformation(const Document& fromDoc) const override;
std::set<std::string> getFieldNameDependencies() const override;
};
/**
* Responsible for deciding which 'ChangeStreamEventTransformation' implementation to use for a
* given oplog entry. Also holds the ownership of all the 'ChangeStreamEventTransformation'
* implementations.
*/
class ChangeStreamEventTransformer {
public:
ChangeStreamEventTransformer(const boost::intrusive_ptr<ExpressionContext>& expCtx,
const DocumentSourceChangeStreamSpec& spec);
Document applyTransformation(const Document& oplog) const {
return getBuilder(oplog)->applyTransformation(oplog);
}
std::set<std::string> getFieldNameDependencies() const {
auto accessedFields = _defaultEventBuilder->getFieldNameDependencies();
accessedFields.merge(_viewNsEventBuilder->getFieldNameDependencies());
return accessedFields;
}
private:
ChangeStreamEventTransformation* getBuilder(const Document& oplog) const;
std::unique_ptr<ChangeStreamDefaultEventTransformation> _defaultEventBuilder;
std::unique_ptr<ChangeStreamViewDefinitionEventTransformation> _viewNsEventBuilder;
bool _isSingleCollStream;
};
} // namespace mongo
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