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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 <set>
#include <string>
#include "mongo/client/query.h"
#include "mongo/client/query_spec.h"
#include "mongo/db/namespace_string.h"
#include "mongo/s/client/shard.h"
#include "mongo/s/stale_exception.h"
namespace mongo {
class ChunkManager;
class DBClientCursor;
class DBClientCursorHolder;
class OperationContext;
struct ParallelConnectionMetadata;
struct ParallelConnectionState;
struct CommandInfo {
CommandInfo() = default;
CommandInfo(const std::string& vns, const BSONObj& filter, const BSONObj& collation)
: versionedNS(vns), cmdFilter(filter), cmdCollation(collation) {}
bool isEmpty() const {
return versionedNS.empty();
}
std::string toString() const {
return str::stream() << "CInfo "
<< BSON("v_ns" << versionedNS << "filter" << cmdFilter << "collation"
<< cmdCollation);
}
std::string versionedNS;
BSONObj cmdFilter;
BSONObj cmdCollation;
};
/**
* Runs a query in parallel across N servers, enforcing compatible chunk versions for queries
* across all shards.
*
* If CommandInfo is provided, the ParallelCursor does not use the direct .$cmd namespace in the
* query spec, but instead enforces versions across another namespace specified by CommandInfo.
* This is to support commands like:
* db.runCommand({ fileMD5 : "<coll name>" })
*
* There is a deprecated legacy mode as well which effectively does a merge-sort across a number
* of servers, but does not correctly enforce versioning (used only in mapreduce).
*/
class ParallelSortClusteredCursor {
public:
ParallelSortClusteredCursor(const QuerySpec& qSpec, const CommandInfo& cInfo);
// DEPRECATED legacy constructor for pure mergesort functionality - do not use
ParallelSortClusteredCursor(const std::set<std::string>& servers,
const std::string& ns,
const Query& q,
int options = 0,
const BSONObj& fields = BSONObj());
~ParallelSortClusteredCursor();
void init(OperationContext* opCtx);
bool more();
BSONObj next();
/**
* Returns the set of shards with open cursors.
*/
void getQueryShardIds(std::set<ShardId>& shardIds) const;
std::shared_ptr<DBClientCursor> getShardCursor(const ShardId& shardId) const;
private:
using ShardCursorsMap = std::map<ShardId, ParallelConnectionMetadata>;
void fullInit(OperationContext* opCtx);
void startInit(OperationContext* opCtx);
void finishInit(OperationContext* opCtx);
bool isCommand() {
return NamespaceString(_qSpec.ns()).isCommand();
}
void _finishCons();
void _markStaleNS(const NamespaceString& staleNS, const StaleConfigException& e);
bool _didInit;
bool _done;
QuerySpec _qSpec;
CommandInfo _cInfo;
// Count round-trips req'd for namespaces and total
std::map<std::string, int> _staleNSMap;
int _totalTries;
ShardCursorsMap _cursorMap;
// LEGACY BELOW
int _numServers;
int _lastFrom;
std::set<std::string> _servers;
BSONObj _sortKey;
DBClientCursorHolder* _cursors;
int _needToSkip;
/**
* Setups the shard version of the connection. When using a replica
* set connection and the primary cannot be reached, the version
* will not be set if the slaveOk flag is set.
*/
void setupVersionAndHandleSlaveOk(OperationContext* opCtx,
std::shared_ptr<ParallelConnectionState> state /* in & out */,
const ShardId& shardId,
std::shared_ptr<Shard> primary /* in */,
const NamespaceString& ns,
const std::string& vinfo,
std::shared_ptr<ChunkManager> manager /* in */);
// LEGACY init - Needed for map reduce
void _oldInit(OperationContext* opCtx);
// LEGACY - Needed ONLY for _oldInit
std::string _ns;
BSONObj _query;
int _options;
BSONObj _fields;
int _batchSize;
};
/**
* Throws a StaleConfigException wrapping the stale error document in this cursor when the
* ShardConfigStale flag is set or a command returns a ErrorCodes::StaleConfig error code.
*/
void throwCursorStale(DBClientCursor* cursor);
} // namespace mongo
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