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/**
* Copyright (C) 2018 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/pipeline/document_source.h"
#include "mongo/db/pipeline/document_source_change_stream.h"
#include "mongo/db/pipeline/document_source_change_stream_gen.h"
#include "mongo/db/pipeline/document_source_match.h"
#include "mongo/db/pipeline/field_path.h"
namespace mongo {
class DocumentSourceChangeStreamTransform : public DocumentSource {
public:
/**
* Creates a new transformation stage from the given specification.
*/
static boost::intrusive_ptr<DocumentSourceChangeStreamTransform> create(
const boost::intrusive_ptr<ExpressionContext>&,
const ServerGlobalParams::FeatureCompatibility::Version&,
BSONObj changeStreamSpec);
Document applyTransformation(const Document& input);
DepsTracker::State getDependencies(DepsTracker* deps) const final;
DocumentSource::GetModPathsReturn getModifiedPaths() const final;
Value serialize(boost::optional<ExplainOptions::Verbosity> explain) const;
DocumentSource::StageConstraints constraints(Pipeline::SplitState pipeState) const final;
DocumentSource::GetNextResult getNext();
const char* getSourceName() const {
return DocumentSourceChangeStream::kStageName.rawData();
}
private:
// This constructor is private, callers should use the 'create()' method above.
DocumentSourceChangeStreamTransform(const boost::intrusive_ptr<ExpressionContext>&,
const ServerGlobalParams::FeatureCompatibility::Version&,
BSONObj changeStreamSpec);
struct DocumentKeyCacheEntry {
DocumentKeyCacheEntry() = default;
DocumentKeyCacheEntry(std::pair<std::vector<FieldPath>, bool> documentKeyFieldsIn)
: documentKeyFields(documentKeyFieldsIn.first), isFinal(documentKeyFieldsIn.second){};
// Fields of the document key, in order, including "_id" and the shard key if the
// collection is sharded. Empty until the first oplog entry with a uuid is encountered.
// Needed for transforming 'insert' oplog entries.
std::vector<FieldPath> documentKeyFields;
// Set to true if the document key fields for this entry are definitively known and will
// not change. This implies that either the collection has become sharded or has been
// dropped.
bool isFinal;
};
/**
* Represents the DocumentSource's state if it's currently reading from an 'applyOps' entry
* which was created as part of a transaction.
*/
struct TransactionContext {
MONGO_DISALLOW_COPYING(TransactionContext);
// The array of oplog entries from an 'applyOps' representing the transaction. Only kept
// around so that the underlying memory of 'arr' isn't freed.
Value opArray;
// Array representation of the 'opArray' field. Stored like this to avoid re-typechecking
// each call to next(), or copying the entire array.
const std::vector<Value>& arr;
// Our current place in the 'opArray'.
size_t pos;
// The clusterTime of the applyOps.
Timestamp clusterTime;
// Fields that were taken from the 'applyOps' oplog entry.
Document lsid;
TxnNumber txnNumber;
TransactionContext(const Value& applyOpsVal,
Timestamp ts,
const Document& lsidDoc,
TxnNumber n)
: opArray(applyOpsVal),
arr(opArray.getArray()),
pos(0),
clusterTime(ts),
lsid(lsidDoc),
txnNumber(n) {}
};
/**
* Helper used for determining what resume token to return.
*/
ResumeTokenData getResumeToken(Value ts, Value uuid, Value documentKey);
void initializeTransactionContext(const Document& input);
/**
* Gets the next relevant applyOps entry that should be returned. If there is none, returns
* empty document.
*/
boost::optional<Document> extractNextApplyOpsEntry();
/**
* Helper for extractNextApplyOpsEntry(). Checks the namespace of the given document to see
* if it should be returned in the change stream.
*/
bool isDocumentRelevant(const Document& d);
BSONObj _changeStreamSpec;
// Map of collection UUID to document key fields.
std::map<UUID, DocumentKeyCacheEntry> _documentKeyCache;
// Regex for matching the "ns" field in applyOps sub-entries. Only used when we have a
// change stream on the entire DB. When watching just a single collection, this field is
// boost::none, and an exact string equality check is used instead.
boost::optional<pcrecpp::RE> _nsRegex;
// Represents if the current 'applyOps' we're unwinding, if any.
boost::optional<TransactionContext> _txnContext;
// Set to true if this transformation stage can be run on the collectionless namespace.
bool _isIndependentOfAnyCollection;
// '_fcv' is used to determine which version of the resume token to generate for each change.
// This is a snapshot of what the feature compatibility version was at the time the stream was
// opened or resumed.
ServerGlobalParams::FeatureCompatibility::Version _fcv;
};
} // namespace mongo
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