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/**
* Copyright (C) 2020-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 <queue>
#include "mongo/db/exec/document_value/document.h"
#include "mongo/db/pipeline/pipeline.h"
#include "mongo/db/query/plan_executor.h"
namespace mongo {
/**
* A plan executor which is used to execute a Pipeline of DocumentSources.
*/
class PlanExecutorPipeline final : public PlanExecutor {
public:
PlanExecutorPipeline(boost::intrusive_ptr<ExpressionContext> expCtx,
std::unique_ptr<Pipeline, PipelineDeleter> pipeline,
bool isChangeStream);
CanonicalQuery* getCanonicalQuery() const override {
return nullptr;
}
const NamespaceString& nss() const override {
return _expCtx->ns;
}
OperationContext* getOpCtx() const override {
return _expCtx->opCtx;
}
// Pipeline execution does not support the saveState()/restoreState() interface. Instead, the
// underlying data access plan is saved/restored internally in between DocumentSourceCursor
// batches, or when the underlying PlanStage tree yields.
void saveState() override {}
void restoreState() override {}
void detachFromOperationContext() override {
_pipeline->detachFromOperationContext();
}
void reattachToOperationContext(OperationContext* opCtx) override {
_pipeline->reattachToOperationContext(opCtx);
}
ExecState getNext(BSONObj* objOut, RecordId* recordIdOut) override;
ExecState getNextDocument(Document* docOut, RecordId* recordIdOut) override;
bool isEOF() override;
// DocumentSource execution is only used for executing aggregation commands, so the interfaces
// for executing other CRUD operations are not supported.
long long executeCount() override {
MONGO_UNREACHABLE;
}
UpdateResult executeUpdate() override {
MONGO_UNREACHABLE;
}
UpdateResult getUpdateResult() const override {
MONGO_UNREACHABLE;
}
long long executeDelete() override {
MONGO_UNREACHABLE;
}
void dispose(OperationContext* opCtx) override {
_pipeline->dispose(opCtx);
}
void enqueue(const BSONObj& obj) override {
_stash.push(obj.getOwned());
}
void markAsKilled(Status killStatus) override;
bool isMarkedAsKilled() const override {
return !_killStatus.isOK();
}
Status getKillStatus() override {
invariant(isMarkedAsKilled());
return _killStatus;
}
bool isDisposed() const override {
return _pipeline->isDisposed();
}
Timestamp getLatestOplogTimestamp() const override {
return _latestOplogTimestamp;
}
BSONObj getPostBatchResumeToken() const override {
return _postBatchResumeToken;
}
LockPolicy lockPolicy() const override {
return LockPolicy::kLocksInternally;
}
std::string getPlanSummary() const override;
void getSummaryStats(PlanSummaryStats* statsOut) const override;
/**
* Writes the explain information about the underlying pipeline to a std::vector<Value>,
* providing the level of detail specified by 'verbosity'.
*/
std::vector<Value> writeExplainOps(ExplainOptions::Verbosity verbosity) const {
return _pipeline->writeExplainOps(verbosity);
}
BSONObj getStats() const override {
// TODO SERVER-49808: Report execution stats for the pipeline.
return BSONObj{};
}
private:
/**
* Obtains the next document from the underlying Pipeline, and does change streams-related
* accounting if needed.
*/
boost::optional<Document> _getNext();
/**
* If this is a change stream, advance the cluster time and post batch resume token based on the
* latest document returned by the underlying pipeline.
*/
void _performChangeStreamsAccounting(const boost::optional<Document>);
/**
* Verifies that the docs's resume token has not been modified.
*/
void _validateResumeToken(const Document& event) const;
/**
* Set the speculative majority read timestamp if we have scanned up to a certain oplog
* timestamp.
*/
void _setSpeculativeReadTimestamp();
boost::intrusive_ptr<ExpressionContext> _expCtx;
std::unique_ptr<Pipeline, PipelineDeleter> _pipeline;
const bool _isChangeStream;
std::queue<BSONObj> _stash;
// If _killStatus has a non-OK value, then we have been killed and the value represents the
// reason for the kill.
Status _killStatus = Status::OK();
size_t _nReturned = 0;
// Set to true once we have received all results from the underlying '_pipeline', and the
// pipeline has indicated end-of-stream.
bool _pipelineIsEof = false;
// If '_pipeline' is a change stream, these track the latest timestamp seen while scanning the
// oplog, as well as the most recent PBRT.
Timestamp _latestOplogTimestamp;
BSONObj _postBatchResumeToken;
};
} // namespace mongo
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