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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 <functional>
#include <memory>
#include <vector>
#include "mongo/bson/bsonobj.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/pipeline/aggregate_command_gen.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
#include "mongo/db/read_concern_support_result.h"
namespace mongo {
/**
* A semi-parsed version of a Pipeline, parsed just enough to determine information like what
* foreign collections are involved.
*/
class LiteParsedPipeline {
public:
/**
* Constructs a LiteParsedPipeline from the raw BSON stages given in 'request'.
*
* May throw a AssertionException if there is an invalid stage specification, although full
* validation happens later, during Pipeline construction.
*/
LiteParsedPipeline(const AggregateCommandRequest& request)
: LiteParsedPipeline(request.getNamespace(), request.getPipeline()) {}
LiteParsedPipeline(const NamespaceString& nss, const std::vector<BSONObj>& pipelineStages) {
_stageSpecs.reserve(pipelineStages.size());
for (auto&& rawStage : pipelineStages) {
_stageSpecs.push_back(LiteParsedDocumentSource::parse(nss, rawStage));
}
}
/**
* Returns all foreign namespaces referenced by stages within this pipeline, if any.
*/
stdx::unordered_set<NamespaceString> getInvolvedNamespaces() const {
stdx::unordered_set<NamespaceString> involvedNamespaces;
for (auto&& spec : _stageSpecs) {
auto stagesInvolvedNamespaces = spec->getInvolvedNamespaces();
involvedNamespaces.insert(stagesInvolvedNamespaces.begin(),
stagesInvolvedNamespaces.end());
}
return involvedNamespaces;
}
/**
* Returns a vector of the foreign collections(s) referenced by this stage that potentially will
* be involved in query execution, if any. For example, consider the pipeline:
*
* [{$lookup: {from: "bar", localField: "a", foreignField: "b", as: "output"}},
* {$unionWith: {coll: "foo", pipeline: [...]}}].
*
* Here, "foo" is not considered a foreign execution namespace because "$unionWith" cannot be
* pushed down into the execution subsystem underneath the leading cursor stage, while "bar"
* is considered one because "$lookup" can be pushed down in certain cases.
*/
std::vector<NamespaceStringOrUUID> getForeignExecutionNamespaces() const {
stdx::unordered_set<NamespaceString> nssSet;
for (auto&& spec : _stageSpecs) {
spec->getForeignExecutionNamespaces(nssSet);
}
return {nssSet.begin(), nssSet.end()};
}
/**
* Returns a list of the priviliges required for this pipeline.
*/
PrivilegeVector requiredPrivileges(bool isMongos, bool bypassDocumentValidation) const {
PrivilegeVector requiredPrivileges;
for (auto&& spec : _stageSpecs) {
Privilege::addPrivilegesToPrivilegeVector(
&requiredPrivileges, spec->requiredPrivileges(isMongos, bypassDocumentValidation));
}
return requiredPrivileges;
}
/**
* Returns true if the pipeline begins with a $collStats stage.
*/
bool startsWithCollStats() const {
return !_stageSpecs.empty() && _stageSpecs.front()->isCollStats();
}
/**
* Returns true if the pipeline begins with a $indexStats stage.
*/
bool startsWithIndexStats() const {
return !_stageSpecs.empty() && _stageSpecs.front()->isIndexStats();
}
/**
* Returns true if the pipeline begins with a $documents stage.
*/
bool startsWithDocuments() const {
return !_stageSpecs.empty() && _stageSpecs.front()->isDocuments();
}
/**
* Returns true if the pipeline has a $changeStream stage.
*/
bool hasChangeStream() const {
return std::any_of(_stageSpecs.begin(), _stageSpecs.end(), [](auto&& spec) {
return spec->isChangeStream();
});
}
/**
* Returns false if the pipeline has any stages which cannot be passed through to the shards.
*/
bool allowedToPassthroughFromMongos() const {
return std::all_of(_stageSpecs.cbegin(), _stageSpecs.cend(), [](const auto& spec) {
return spec->allowedToPassthroughFromMongos();
});
}
/**
* Returns false if at least one of the stages does not allow the involved namespace 'nss' to be
* sharded.
*/
bool allowShardedForeignCollection(NamespaceString nss, bool isMultiDocumentTransaction) const {
return std::all_of(_stageSpecs.begin(),
_stageSpecs.end(),
[&nss, isMultiDocumentTransaction](auto&& spec) {
return spec->allowShardedForeignCollection(
nss, isMultiDocumentTransaction);
});
}
/**
* Verifies that this pipeline is allowed to run with the specified read concern level.
*/
ReadConcernSupportResult supportsReadConcern(repl::ReadConcernLevel level,
bool isImplicitDefault,
boost::optional<ExplainOptions::Verbosity> explain,
bool enableMajorityReadConcern) const;
/**
* Checks that all of the stages in this pipeline are allowed to run with the specified read
* concern level. Does not do any pipeline global checks.
*/
ReadConcernSupportResult sourcesSupportReadConcern(repl::ReadConcernLevel level,
bool isImplicitDefault) const;
/**
* Verifies that this pipeline is allowed to run in a multi-document transaction. This ensures
* that each stage is compatible, and throws a UserException if not. This should only be called
* if the caller has determined the current operation is part of a transaction.
*/
void assertSupportsMultiDocumentTransaction(
boost::optional<ExplainOptions::Verbosity> explain) const;
/**
* Verifies that this pipeline is allowed to run with the read concern from the provided opCtx.
* Used only when asserting is the desired behavior, otherwise use supportsReadConcern instead.
*/
void assertSupportsReadConcern(OperationContext* opCtx,
boost::optional<ExplainOptions::Verbosity> explain) const;
/**
* Perform checks that verify that the LitePipe is valid. Note that this function must be called
* before forwarding an aggregation command on an unsharded collection, in order to verify that
* the involved namespaces are allowed to be sharded.
*/
void verifyIsSupported(OperationContext* opCtx,
std::function<bool(OperationContext*, const NamespaceString&)> isSharded,
boost::optional<ExplainOptions::Verbosity> explain,
bool enableMajorityReadConcern) const;
/**
* Returns true if the first stage in the pipeline does not require an input source.
*/
bool startsWithInitialSource() const {
return !_stageSpecs.empty() && _stageSpecs.front()->isInitialSource();
}
/**
* Increments global stage counters corresponding to the stages in this lite parsed pipeline.
*/
void tickGlobalStageCounters() const;
/**
* Verifies that the pipeline contains valid stages. Optionally calls
* 'validatePipelineStagesforAPIVersion' with 'opCtx'.
*/
void validate(const OperationContext* opCtx, bool performApiVersionChecks = true) const;
private:
std::vector<std::unique_ptr<LiteParsedDocumentSource>> _stageSpecs;
};
} // namespace mongo
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