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/**
* Copyright (C) 2019-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 <boost/optional.hpp>
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
#include "mongo/db/pipeline/lite_parsed_pipeline.h"
#include "mongo/db/pipeline/stage_constraints.h"
#include "mongo/db/stats/counters.h"
namespace mongo {
class DocumentSourceUnionWith final : public DocumentSource {
public:
static constexpr StringData kStageName = "$unionWith"_sd;
static boost::intrusive_ptr<DocumentSource> createFromBson(
BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& expCtx);
class LiteParsed final : public LiteParsedDocumentSourceNestedPipelines {
public:
static std::unique_ptr<LiteParsed> parse(const NamespaceString& nss,
const BSONElement& spec);
LiteParsed(std::string parseTimeName,
NamespaceString foreignNss,
boost::optional<LiteParsedPipeline> pipeline)
: LiteParsedDocumentSourceNestedPipelines(
std::move(parseTimeName), std::move(foreignNss), std::move(pipeline)) {}
PrivilegeVector requiredPrivileges(bool isMongos,
bool bypassDocumentValidation) const override final;
};
DocumentSourceUnionWith(const boost::intrusive_ptr<ExpressionContext>& expCtx,
std::unique_ptr<Pipeline, PipelineDeleter> pipeline)
: DocumentSource(kStageName, expCtx), _pipeline(std::move(pipeline)) {
if (!_pipeline->getContext()->ns.isOnInternalDb()) {
globalOpCounters.gotNestedAggregate();
}
_pipeline->getContext()->inUnionWith = true;
// If this pipeline is being run as part of explain, then cache a copy to use later during
// serialization.
if (expCtx->explain >= ExplainOptions::Verbosity::kExecStats) {
_cachedPipeline = _pipeline->getSources();
}
}
DocumentSourceUnionWith(const DocumentSourceUnionWith& original,
const boost::intrusive_ptr<ExpressionContext>& newExpCtx)
: DocumentSource(kStageName, newExpCtx), _pipeline(original._pipeline->clone()) {
_pipeline->getContext()->inUnionWith = true;
}
~DocumentSourceUnionWith();
const char* getSourceName() const final {
return kStageName.rawData();
}
GetModPathsReturn getModifiedPaths() const final {
// Since we might have a document arrive from the foreign pipeline with the same path as a
// document in the main pipeline. Without introspecting the sub-pipeline, we must report
// that all paths have been modified.
return {GetModPathsReturn::Type::kAllPaths, {}, {}};
}
StageConstraints constraints(Pipeline::SplitState) const final {
StageConstraints unionConstraints(
StreamType::kStreaming,
PositionRequirement::kNone,
HostTypeRequirement::kAnyShard,
DiskUseRequirement::kNoDiskUse,
FacetRequirement::kAllowed,
TransactionRequirement::kNotAllowed,
// The check to disallow $unionWith on a sharded collection within $lookup happens
// outside of the constraints as long as the involved namespaces are reported correctly.
LookupRequirement::kAllowed,
UnionRequirement::kAllowed);
if (_pipeline) {
// The constraints of the sub-pipeline determine the constraints of the $unionWith
// stage. We want to forward the strictest requirements of the stages in the
// sub-pipeline.
unionConstraints = StageConstraints::getStrictestConstraints(_pipeline->getSources(),
unionConstraints);
}
// DocumentSourceUnionWith cannot directly swap with match but it contains custom logic in
// the doOptimizeAt() member function to allow itself to duplicate any match ahead in the
// current pipeline and place one copy inside its sub-pipeline and one copy behind in the
// current pipeline.
unionConstraints.canSwapWithMatch = false;
return unionConstraints;
}
DepsTracker::State getDependencies(DepsTracker* deps) const final;
void addVariableRefs(std::set<Variables::Id>* refs) const final;
boost::optional<DistributedPlanLogic> distributedPlanLogic() final {
// {shardsStage, mergingStage, sortPattern}
return DistributedPlanLogic{nullptr, this, boost::none};
}
void addInvolvedCollections(stdx::unordered_set<NamespaceString>* collectionNames) const final;
void detachFromOperationContext() final;
void reattachToOperationContext(OperationContext* opCtx) final;
bool validateOperationContext(const OperationContext* opCtx) const final;
bool usedDisk() final;
const SpecificStats* getSpecificStats() const final {
return &_stats;
}
const Pipeline& getPipeline() const {
return *_pipeline;
}
boost::intrusive_ptr<DocumentSource> clone(
const boost::intrusive_ptr<ExpressionContext>& newExpCtx) const final;
const Pipeline::SourceContainer* getSubPipeline() const final {
if (_pipeline) {
return &_pipeline->getSources();
}
return nullptr;
}
protected:
GetNextResult doGetNext() final;
Pipeline::SourceContainer::iterator doOptimizeAt(Pipeline::SourceContainer::iterator itr,
Pipeline::SourceContainer* container) final;
boost::intrusive_ptr<DocumentSource> optimize() final {
_pipeline->optimizePipeline();
return this;
}
void doDispose() final;
private:
enum ExecutionProgress {
// We haven't yet iterated 'pSource' to completion.
kIteratingSource,
// We finished iterating 'pSource', but haven't started on the sub pipeline and need to do
// some setup first.
kStartingSubPipeline,
// We finished iterating 'pSource' and are now iterating '_pipeline', but haven't finished
// yet.
kIteratingSubPipeline,
// There are no more results.
kFinished
};
Value serialize(boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final;
Value serialize(SerializationOptions opts) const final override {
MONGO_UNIMPLEMENTED;
}
void addViewDefinition(NamespaceString nss, std::vector<BSONObj> viewPipeline);
void logStartingSubPipeline(const std::vector<BSONObj>& serializedPipeline);
void logShardedViewFound(
const ExceptionFor<ErrorCodes::CommandOnShardedViewNotSupportedOnMongod>& e);
std::unique_ptr<Pipeline, PipelineDeleter> _pipeline;
Pipeline::SourceContainer _cachedPipeline;
ExecutionProgress _executionState = ExecutionProgress::kIteratingSource;
UnionWithStats _stats;
};
} // namespace mongo
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