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/**
* Copyright (C) 2015 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 <tuple>
#include "mongo/base/status_with.h"
#include "mongo/stdx/functional.h"
namespace mongo {
class BSONObj;
class BSONObjBuilder;
class OperationContext;
/**
* Utilities for converting metadata between the legacy OP_QUERY format and the new
* OP_COMMAND format.
*
* Metadata consists of information independent of any particular command such as:
*
* Request/Reply/Both | (legacy) OP_QUERY format | OP_COMMAND format
*__________________________________________________________________________________________________
* Request | the slaveOk bit | $secondaryOk on metadata obj
* Request | $readPreference field of command | $readPreference on metadata obj
* Request | $impersonatedUsers on command obj| $impersonatedUsers on metadata obj
* Request | $impersonatedRoles on command obj| $impersonatedRoles on metadata obj
* Request | maxTimeMS on command obj | $maxTimeMS on metadata obj
* Reply | $gleStats field on command reply | $gleStats on metadata obj
*
* TODO: currently only $secondaryOk (request only) is handled. SERVER-18236 will cover the rest.
*/
namespace rpc {
/**
* Returns an empty metadata object.
*/
BSONObj makeEmptyMetadata();
/**
* Reads metadata from a metadata object and sets it on this OperationContext.
*/
Status readRequestMetadata(OperationContext* txn, const BSONObj& metadataObj);
/**
* Writes metadata from an OperationContext to a metadata object.
*/
Status writeRequestMetadata(OperationContext* txn, BSONObjBuilder* metadataBob);
/**
* A command object and a corresponding metadata object.
*/
using CommandAndMetadata = std::tuple<BSONObj, BSONObj>;
/**
* A legacy command object and a corresponding query flags bitfield. The legacy command object
* may contain metadata fields, so it cannot safely be passed to a command's run method.
*/
using LegacyCommandAndFlags = std::tuple<BSONObj, int>;
/**
* Given a legacy command object and a query flags bitfield, attempts to parse and remove
* the metadata from the command object and construct a corresponding metadata object.
*/
StatusWith<CommandAndMetadata> upconvertRequestMetadata(BSONObj legacyCmdObj, int queryFlags);
/**
* Given a command object and a metadata object, attempts to construct a legacy command
* object and query flags bitfield augmented with the given metadata.
*/
StatusWith<LegacyCommandAndFlags> downconvertRequestMetadata(BSONObj cmdObj, BSONObj metadata);
/**
* A command reply and associated metadata object.
*/
using CommandReplyWithMetadata = std::tuple<BSONObj, BSONObj>;
/**
* Given a legacy command reply, attempts to strip the metadata from the reply and construct
* a metadata object.
*/
StatusWith<CommandReplyWithMetadata> upconvertReplyMetadata(BSONObj legacyReply);
/**
* Given a command reply object and an associated metadata object,
* attempts to construct a legacy command object.
*/
StatusWith<BSONObj> downconvertReplyMetadata(BSONObj commandReply, BSONObj replyMetadata);
/**
* A function type for writing request metadata. The function takes a pointer to a
* BSONObjBuilder used to construct the metadata object and returns a Status indicating
* if the metadata was written successfully.
*/
using RequestMetadataWriter = stdx::function<Status(BSONObjBuilder*)>;
/**
* A function type for reading reply metadata. The function takes a a reference to a
* metadata object received in a command reply and a string containing the server address of the
* host that executed the command and returns a Status indicating if the
* metadata was read successfully.
*
* TODO: would it be a layering violation if this hook took an OperationContext* ?
*/
using ReplyMetadataReader = stdx::function<Status(const BSONObj&, StringData)>;
} // namespace rpc
} // namespace mongo
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