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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 "mongo/db/pipeline/change_stream_constants.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/document_source_change_stream.h"
#include "mongo/db/pipeline/document_source_sort.h"
namespace mongo {
/**
* This stage is used internally for change notifications to close cursor after returning
* "invalidate" entries.
* It is not intended to be created by the user.
*/
class DocumentSourceCloseCursor final : public DocumentSource {
public:
static constexpr StringData kStageName = "$changeStream"_sd;
const char* getSourceName() const final {
// This is used in error reporting.
return DocumentSourceCloseCursor::kStageName.rawData();
}
StageConstraints constraints(Pipeline::SplitState pipeState) const final {
// This stage should never be in the shards part of a split pipeline.
invariant(pipeState != Pipeline::SplitState::kSplitForShards);
return {StreamType::kStreaming,
PositionRequirement::kNone,
// If this is parsed on mongos it should stay on mongos. If we're not in a sharded
// cluster then it's okay to run on mongod.
HostTypeRequirement::kLocalOnly,
DiskUseRequirement::kNoDiskUse,
FacetRequirement::kNotAllowed,
TransactionRequirement::kNotAllowed,
LookupRequirement::kNotAllowed,
ChangeStreamRequirement::kChangeStreamStage};
}
Value serialize(boost::optional<ExplainOptions::Verbosity> explain) const final {
// We only serialize this stage in the context of explain.
return explain ? Value(DOC(kStageName << Document())) : Value();
}
static boost::intrusive_ptr<DocumentSourceCloseCursor> create(
const boost::intrusive_ptr<ExpressionContext>& expCtx) {
return new DocumentSourceCloseCursor(expCtx);
}
boost::optional<DistributedPlanLogic> distributedPlanLogic() final {
// This stage must run on mongos to ensure it sees any invalidation in the correct order,
// and to ensure that all remote cursors are cleaned up properly.
// {shardsStage, mergingStage, sortPattern}
return DistributedPlanLogic{nullptr, this, change_stream_constants::kSortSpec};
}
private:
/**
* Use the create static method to create a DocumentSourceCloseCursor.
*/
DocumentSourceCloseCursor(const boost::intrusive_ptr<ExpressionContext>& expCtx)
: DocumentSource(kStageName, expCtx) {}
GetNextResult doGetNext() final;
bool _shouldCloseCursor = false;
};
} // namespace mongo
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