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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 <boost/intrusive_ptr.hpp>
#include <boost/optional.hpp>
#include <memory>
#include <string>
#include <vector>
#include "mongo/bson/bsonobj.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/pipeline/aggregation_request.h"
#include "mongo/db/pipeline/document_comparator.h"
#include "mongo/db/pipeline/mongo_process_interface.h"
#include "mongo/db/pipeline/value_comparator.h"
#include "mongo/db/pipeline/variables.h"
#include "mongo/db/query/collation/collator_interface.h"
#include "mongo/db/query/datetime/date_time_support.h"
#include "mongo/db/query/explain_options.h"
#include "mongo/db/query/tailable_mode.h"
#include "mongo/db/server_options.h"
#include "mongo/util/intrusive_counter.h"
#include "mongo/util/string_map.h"
#include "mongo/util/uuid.h"
namespace mongo {
class ExpressionContext : public RefCountable {
public:
struct ResolvedNamespace {
ResolvedNamespace() = default;
ResolvedNamespace(NamespaceString ns, std::vector<BSONObj> pipeline);
NamespaceString ns;
std::vector<BSONObj> pipeline;
};
/**
* An RAII type that will temporarily change the ExpressionContext's collator. Resets the
* collator to the previous value upon destruction.
*/
class CollatorStash {
public:
/**
* Resets the collator on '_expCtx' to the original collator present at the time this
* CollatorStash was constructed.
*/
~CollatorStash();
private:
/**
* Temporarily changes the collator on 'expCtx' to be 'newCollator'. The collator will be
* set back to the original value when this CollatorStash is deleted.
*
* This constructor is private, all CollatorStashes should be created by calling
* ExpressionContext::temporarilyChangeCollator().
*/
CollatorStash(const boost::intrusive_ptr<ExpressionContext>& expCtx,
std::unique_ptr<CollatorInterface> newCollator);
friend class ExpressionContext;
boost::intrusive_ptr<ExpressionContext> _expCtx;
BSONObj _originalCollation;
std::unique_ptr<CollatorInterface> _originalCollatorOwned;
const CollatorInterface* _originalCollatorUnowned{nullptr};
};
/**
* Constructs an ExpressionContext to be used for Pipeline parsing and evaluation.
* 'resolvedNamespaces' maps collection names (not full namespaces) to ResolvedNamespaces.
*/
ExpressionContext(OperationContext* opCtx,
const AggregationRequest& request,
std::unique_ptr<CollatorInterface> collator,
std::shared_ptr<MongoProcessInterface> mongoProcessInterface,
StringMap<ExpressionContext::ResolvedNamespace> resolvedNamespaces,
boost::optional<UUID> collUUID);
/**
* Constructs an ExpressionContext to be used for MatchExpression parsing outside of the context
* of aggregation.
*/
ExpressionContext(OperationContext* opCtx, const CollatorInterface* collator);
/**
* Used by a pipeline to check for interrupts so that killOp() works. Throws a UserAssertion if
* this aggregation pipeline has been interrupted.
*/
void checkForInterrupt();
/**
* Returns true if this is a collectionless aggregation on the specified database.
*/
bool isDBAggregation(StringData dbName) const {
return ns.db() == dbName && ns.isCollectionlessAggregateNS();
}
/**
* Returns true if this is a collectionless aggregation on the 'admin' database.
*/
bool isClusterAggregation() const {
return ns.isAdminDB() && ns.isCollectionlessAggregateNS();
}
/**
* Returns true if this aggregation is running on a single, specific namespace.
*/
bool isSingleNamespaceAggregation() const {
return !ns.isCollectionlessAggregateNS();
}
const CollatorInterface* getCollator() const {
return _collator;
}
void setCollator(const CollatorInterface* collator);
const DocumentComparator& getDocumentComparator() const {
return _documentComparator;
}
const ValueComparator& getValueComparator() const {
return _valueComparator;
}
/**
* Temporarily resets the collator to be 'newCollator'. Returns a CollatorStash which will reset
* the collator back to the old value upon destruction.
*/
std::unique_ptr<CollatorStash> temporarilyChangeCollator(
std::unique_ptr<CollatorInterface> newCollator);
/**
* Returns an ExpressionContext that is identical to 'this' that can be used to execute a
* separate aggregation pipeline on 'ns' with the optional 'uuid'.
*/
boost::intrusive_ptr<ExpressionContext> copyWith(
NamespaceString ns,
boost::optional<UUID> uuid = boost::none,
boost::optional<std::unique_ptr<CollatorInterface>> collator = boost::none) const;
/**
* Returns the ResolvedNamespace corresponding to 'nss'. It is an error to call this method on a
* namespace not involved in the pipeline.
*/
const ResolvedNamespace& getResolvedNamespace(const NamespaceString& nss) const {
auto it = _resolvedNamespaces.find(nss.coll());
invariant(it != _resolvedNamespaces.end());
return it->second;
};
/**
* Convenience call that returns true if the tailableMode indicates a tailable and awaitData
* query.
*/
bool isTailableAwaitData() const {
return tailableMode == TailableModeEnum::kTailableAndAwaitData;
}
/**
* Sets the resolved definition for an involved namespace.
*/
void setResolvedNamespace_forTest(const NamespaceString& nss,
ResolvedNamespace resolvedNamespace) {
_resolvedNamespaces[nss.coll()] = std::move(resolvedNamespace);
}
// The explain verbosity requested by the user, or boost::none if no explain was requested.
boost::optional<ExplainOptions::Verbosity> explain;
// The comment provided by the user, or the empty string if no comment was provided.
std::string comment;
bool fromMongos = false;
bool needsMerge = false;
bool mergeByPBRT = false;
bool inMongos = false;
bool allowDiskUse = false;
bool bypassDocumentValidation = false;
bool inMultiDocumentTransaction = false;
NamespaceString ns;
// If known, the UUID of the execution namespace for this aggregation command.
boost::optional<UUID> uuid;
std::string tempDir; // Defaults to empty to prevent external sorting in mongos.
OperationContext* opCtx;
// An interface for accessing information or performing operations that have different
// implementations on mongod and mongos, or that only make sense on one of the two.
// Additionally, putting some of this functionality behind an interface prevents aggregation
// libraries from having large numbers of dependencies. This pointer is always non-null.
std::shared_ptr<MongoProcessInterface> mongoProcessInterface;
const TimeZoneDatabase* timeZoneDatabase;
// Collation requested by the user for this pipeline. Empty if the user did not request a
// collation.
BSONObj collation;
Variables variables;
VariablesParseState variablesParseState;
TailableModeEnum tailableMode = TailableModeEnum::kNormal;
// For a changeStream aggregation, this is the starting postBatchResumeToken. Empty otherwise.
BSONObj initialPostBatchResumeToken;
// Tracks the depth of nested aggregation sub-pipelines. Used to enforce depth limits.
size_t subPipelineDepth = 0;
// If set, this will disallow use of features introduced in versions above the provided version.
boost::optional<ServerGlobalParams::FeatureCompatibility::Version>
maxFeatureCompatibilityVersion;
protected:
static const int kInterruptCheckPeriod = 128;
ExpressionContext(NamespaceString nss,
std::shared_ptr<MongoProcessInterface>,
const TimeZoneDatabase* tzDb);
/**
* Sets '_ownedCollator' and resets '_collator', 'documentComparator' and 'valueComparator'.
*
* Use with caution - '_ownedCollator' is used in the context of a Pipeline, and it is illegal
* to change the collation once a Pipeline has been parsed with this ExpressionContext.
*/
void setCollator(std::unique_ptr<CollatorInterface> collator) {
_ownedCollator = std::move(collator);
setCollator(_ownedCollator.get());
}
friend class CollatorStash;
// Collator used for comparisons. This is owned in the context of a Pipeline.
// TODO SERVER-31294: Move ownership of an aggregation's collator elsewhere.
std::unique_ptr<CollatorInterface> _ownedCollator;
// Collator used for comparisons. If '_ownedCollator' is non-null, then this must point to the
// same collator object.
const CollatorInterface* _collator = nullptr;
// Used for all comparisons of Document/Value during execution of the aggregation operation.
// Must not be changed after parsing a Pipeline with this ExpressionContext.
DocumentComparator _documentComparator;
ValueComparator _valueComparator;
// A map from namespace to the resolved namespace, in case any views are involved.
StringMap<ResolvedNamespace> _resolvedNamespaces;
int _interruptCounter = kInterruptCheckPeriod;
};
} // namespace mongo
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