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/**
* Copyright (C) 2010-2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <atomic>
#include "mongo/client/connection_string.h"
#include "mongo/db/query/explain_options.h"
#include "mongo/s/client/shard.h"
namespace mongo {
class DbMessage;
class NamespaceString;
class OperationContext;
class QueryRequest;
namespace rpc {
class ServerSelectionMetadata;
} // namespace rpc
/**
* Legacy interface for processing client read/write/cmd requests.
*/
class Strategy {
public:
/**
* Handles a legacy-style opQuery request and sends the response back on success or throws on
* error.
*
* Must not be called with legacy '.$cmd' commands.
*/
static void queryOp(OperationContext* opCtx, const NamespaceString& nss, DbMessage* dbm);
/**
* Handles a legacy-style getMore request and sends the response back on success (or cursor not
* found) or throws on error.
*/
static void getMore(OperationContext* opCtx, const NamespaceString& nss, DbMessage* dbm);
/**
* Handles a legacy-style killCursors request. Doesn't send any response on success or throws on
* error.
*/
static void killCursors(OperationContext* opCtx, DbMessage* dbm);
/**
* Handles a legacy-style write operation request and updates the last error state on the client
* with the result from the operation. Doesn't send any response back and does not throw on
* errors.
*/
static void writeOp(OperationContext* opCtx, DbMessage* dbm);
/**
* Executes a legacy-style ($cmd namespace) command. Does not throw and returns the response
* regardless of success or error.
*
* Catches StaleConfigException errors and retries the command automatically after refreshing
* the metadata for the failing namespace.
*/
static void clientCommandOp(OperationContext* opCtx,
const NamespaceString& nss,
DbMessage* dbm);
/**
* Helper to run an explain of a find operation on the shards. Fills 'out' with the result of
* the of the explain command on success. On failure, returns a non-OK status and does not
* modify 'out'.
*
* Used both if mongos receives an explain command and if it receives an OP_QUERY find with the
* $explain modifier.
*/
static Status explainFind(OperationContext* opCtx,
const BSONObj& findCommand,
const QueryRequest& qr,
ExplainOptions::Verbosity verbosity,
const rpc::ServerSelectionMetadata& serverSelectionMetadata,
BSONObjBuilder* out);
struct CommandResult {
ShardId shardTargetId;
ConnectionString target;
BSONObj result;
};
/**
* Executes a command against a particular database, and targets the command based on a
* collection in that database, according to 'targetingQuery' and 'targetingCollation'. If
* 'targetingCollation' is empty, the collection default collation is used for targeting.
*
* This version should be used by internal commands when possible.
*
* TODO: Replace these methods and all other methods of command dispatch with a more general
* command op framework.
*/
static void commandOp(OperationContext* opCtx,
const std::string& db,
const BSONObj& command,
int options,
const std::string& versionedNS,
const BSONObj& targetingQuery,
const BSONObj& targetingCollation,
std::vector<CommandResult>* results);
};
} // namespace mongo
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