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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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kQuery
#include "mongo/platform/basic.h"
#include <iterator>
#include "mongo/db/commands/test_commands_enabled.h"
#include "mongo/db/pipeline/document_source_match.h"
#include "mongo/db/pipeline/document_source_single_document_transformation.h"
#include "mongo/db/pipeline/document_source_union_with.h"
#include "mongo/db/pipeline/document_source_union_with_gen.h"
#include "mongo/util/log.h"
namespace mongo {
REGISTER_DOCUMENT_SOURCE(unionWith,
DocumentSourceUnionWith::LiteParsed::parse,
DocumentSourceUnionWith::createFromBson);
namespace {
std::unique_ptr<Pipeline, PipelineDeleter> buildPipelineFromViewDefinition(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
ExpressionContext::ResolvedNamespace resolvedNs,
std::vector<BSONObj> currentPipeline) {
// Copy the ExpressionContext of the base aggregation, using the inner namespace instead.
auto unionExpCtx = expCtx->copyForSubPipeline(resolvedNs.ns);
if (resolvedNs.pipeline.empty()) {
return uassertStatusOK(Pipeline::parse(std::move(currentPipeline), unionExpCtx));
}
auto resolvedPipeline = std::move(resolvedNs.pipeline);
resolvedPipeline.reserve(currentPipeline.size() + resolvedPipeline.size());
resolvedPipeline.insert(resolvedPipeline.end(),
std::make_move_iterator(currentPipeline.begin()),
std::make_move_iterator(currentPipeline.end()));
return uassertStatusOK(Pipeline::parse(std::move(resolvedPipeline), unionExpCtx));
}
} // namespace
std::unique_ptr<DocumentSourceUnionWith::LiteParsed> DocumentSourceUnionWith::LiteParsed::parse(
const NamespaceString& nss, const BSONElement& spec) {
uassert(ErrorCodes::FailedToParse,
str::stream()
<< "the $unionWith stage specification must be an object or string, but found "
<< typeName(spec.type()),
spec.type() == BSONType::Object || spec.type() == BSONType::String);
NamespaceString unionNss;
boost::optional<LiteParsedPipeline> liteParsedPipeline;
if (spec.type() == BSONType::String) {
unionNss = NamespaceString(nss.db(), spec.valueStringData());
} else {
auto unionWithSpec =
UnionWithSpec::parse(IDLParserErrorContext(kStageName), spec.embeddedObject());
unionNss = NamespaceString(nss.db(), unionWithSpec.getColl());
// Recursively lite parse the nested pipeline, if one exists.
if (unionWithSpec.getPipeline()) {
liteParsedPipeline = LiteParsedPipeline(unionNss, *unionWithSpec.getPipeline());
}
}
return std::make_unique<DocumentSourceUnionWith::LiteParsed>(std::move(unionNss),
std::move(liteParsedPipeline));
}
PrivilegeVector DocumentSourceUnionWith::LiteParsed::requiredPrivileges(
bool isMongos, bool bypassDocumentValidation) const {
PrivilegeVector requiredPrivileges;
invariant(_pipelines.size() <= 1);
invariant(_foreignNss);
// If no pipeline is specified, then assume that we're reading directly from the collection.
// Otherwise check whether the pipeline starts with an "initial source" indicating that we don't
// require the "find" privilege.
if (_pipelines.empty() || !_pipelines[0].startsWithInitialSource()) {
Privilege::addPrivilegeToPrivilegeVector(
&requiredPrivileges,
Privilege(ResourcePattern::forExactNamespace(*_foreignNss), ActionType::find));
}
// Add the sub-pipeline privileges, if one was specified.
if (!_pipelines.empty()) {
const LiteParsedPipeline& pipeline = _pipelines[0];
Privilege::addPrivilegesToPrivilegeVector(
&requiredPrivileges,
std::move(pipeline.requiredPrivileges(isMongos, bypassDocumentValidation)));
}
return requiredPrivileges;
}
boost::intrusive_ptr<DocumentSource> DocumentSourceUnionWith::createFromBson(
BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& expCtx) {
uassert(ErrorCodes::FailedToParse,
str::stream()
<< "the $unionWith stage specification must be an object or string, but found "
<< typeName(elem.type()),
elem.type() == BSONType::Object || elem.type() == BSONType::String);
NamespaceString unionNss;
std::vector<BSONObj> pipeline;
if (elem.type() == BSONType::String) {
unionNss = NamespaceString(expCtx->ns.db().toString(), elem.valueStringData());
} else {
auto unionWithSpec =
UnionWithSpec::parse(IDLParserErrorContext(kStageName), elem.embeddedObject());
unionNss = NamespaceString(expCtx->ns.db().toString(), unionWithSpec.getColl());
pipeline = unionWithSpec.getPipeline().value_or(std::vector<BSONObj>{});
}
return make_intrusive<DocumentSourceUnionWith>(
expCtx,
buildPipelineFromViewDefinition(
expCtx, expCtx->getResolvedNamespace(std::move(unionNss)), std::move(pipeline)));
}
DocumentSource::GetNextResult DocumentSourceUnionWith::doGetNext() {
if (!_sourceExhausted) {
auto nextInput = pSource->getNext();
if (!nextInput.isEOF()) {
return nextInput;
}
_sourceExhausted = true;
// All documents from the base collection have been returned, switch to iterating the sub-
// pipeline by falling through below.
}
if (!_cursorAttached) {
auto ctx = _pipeline->getContext();
_pipeline =
pExpCtx->mongoProcessInterface->attachCursorSourceToPipeline(ctx, _pipeline.release());
_cursorAttached = true;
LOG(3) << "$unionWith attached cursor to pipeline";
}
if (auto res = _pipeline->getNext())
return std::move(*res);
return GetNextResult::makeEOF();
}
Pipeline::SourceContainer::iterator DocumentSourceUnionWith::doOptimizeAt(
Pipeline::SourceContainer::iterator itr, Pipeline::SourceContainer* container) {
auto duplicateAcrossUnion = [&](auto&& nextStage) {
_pipeline->addFinalSource(nextStage->clone());
auto newStageItr = container->insert(itr, std::move(nextStage));
container->erase(std::next(itr));
return newStageItr == container->begin() ? newStageItr : std::prev(newStageItr);
};
if (std::next(itr) != container->end()) {
if (auto nextMatch = dynamic_cast<DocumentSourceMatch*>((*std::next(itr)).get()))
return duplicateAcrossUnion(nextMatch);
else if (auto nextProject = dynamic_cast<DocumentSourceSingleDocumentTransformation*>(
(*std::next(itr)).get()))
return duplicateAcrossUnion(nextProject);
}
return std::next(itr);
};
void DocumentSourceUnionWith::doDispose() {
if (_pipeline) {
_pipeline->dispose(pExpCtx->opCtx);
_pipeline.reset();
}
}
void DocumentSourceUnionWith::serializeToArray(
std::vector<Value>& array, boost::optional<ExplainOptions::Verbosity> explain) const {
BSONArrayBuilder bab;
for (auto&& stage : _pipeline->serialize())
bab << stage;
Document doc = DOC(getSourceName() << DOC("coll" << _pipeline->getContext()->ns.coll()
<< "pipeline" << bab.arr()));
array.push_back(Value(doc));
}
DepsTracker::State DocumentSourceUnionWith::getDependencies(DepsTracker* deps) const {
// Since the $unionWith stage is a simple passthrough, we *could* report SEE_NEXT here in an
// attempt to get a covered plan for the base collection. The ideal solution would involve
// pushing down any dependencies to the inner pipeline as well.
return DepsTracker::State::NOT_SUPPORTED;
}
void DocumentSourceUnionWith::detachFromOperationContext() {
// We have a pipeline we're going to be executing across multiple calls to getNext(), so we
// use Pipeline::detachFromOperationContext() to take care of updating the Pipeline's
// ExpressionContext.
if (_pipeline) {
_pipeline->detachFromOperationContext();
}
}
void DocumentSourceUnionWith::reattachToOperationContext(OperationContext* opCtx) {
// We have a pipeline we're going to be executing across multiple calls to getNext(), so we
// use Pipeline::reattachToOperationContext() to take care of updating the Pipeline's
// ExpressionContext.
if (_pipeline) {
_pipeline->reattachToOperationContext(opCtx);
}
}
void DocumentSourceUnionWith::addInvolvedCollections(
stdx::unordered_set<NamespaceString>* collectionNames) const {
collectionNames->insert(_pipeline->getContext()->ns);
collectionNames->merge(_pipeline->getInvolvedCollections());
}
} // namespace mongo
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