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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 <memory>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/status.h"
#include "mongo/rpc/protocol.h"
namespace mongo {
class BSONObj;
class Message;
namespace rpc {
class DocumentRange;
/**
* Constructs an RPC Reply.
*/
class ReplyBuilderInterface {
MONGO_DISALLOW_COPYING(ReplyBuilderInterface);
public:
/**
* Reply builders must have their fields set in order as they are immediately written into
* the underlying message buffer. This enum represents the next field that can be written
* into the builder. Note that when the builder is in state 'kInputDocs', multiple input
* docs can be added. After the builder's done() method is called it is in state 'kDone',
* and no further methods can be called.
*/
enum class State { kMetadata, kCommandReply, kOutputDocs, kDone };
virtual ~ReplyBuilderInterface() = default;
virtual ReplyBuilderInterface& setMetadata(const BSONObj& metadata) = 0;
/**
* Sets the raw command reply. This should probably not be used in favor of the
* variants that accept a Status or StatusWith.
*/
virtual ReplyBuilderInterface& setRawCommandReply(const BSONObj& reply) = 0;
/**
* Sets the reply for this command. If an engaged StatusWith<BSONObj> is passed, the command
* reply will be set to the contained BSONObj, augmented with the element {ok, 1.0} if it
* does not already have an "ok" field. If a disengaged StatusWith<BSONObj> is passed, the
* command reply will be set to {ok: 0.0, code: <code of status>,
* errmsg: <reason of status>}
*/
ReplyBuilderInterface& setCommandReply(StatusWith<BSONObj> commandReply);
/**
* Sets the reply for this command. The status parameter must be non-OK. The reply for
* this command will be set to an object containing all the fields in extraErrorInfo,
* augmented with {ok: 0.0} , {code: <code of status>}, and {errmsg: <reason of status>}.
* If any of the fields "ok", "code", or "errmsg" already exist in extraErrorInfo, they
* will be left as-is in the command reply. This use of this form is intended for
* interfacing with legacy code that adds additional data to a failed command reply and
* its use is discouraged in new code.
*/
ReplyBuilderInterface& setCommandReply(Status nonOKStatus, const BSONObj& extraErrorInfo);
/**
* Add a range of output documents to the reply. This method can be called multiple times
* before calling done(). A non OK status indicates that the message does not have
* enough space to store ouput documents.
*/
virtual Status addOutputDocs(DocumentRange outputDocs) = 0;
/**
* Add a single output document to the reply. This method can be called multiple times
* before calling done(). A non OK status indicates that the message does not have
* enough space to store ouput documents.
*/
virtual Status addOutputDoc(const BSONObj& outputDoc) = 0;
/**
* Gets the state of the builder. As the builder will simply crash the process if it is ever
* put in an invalid state, it isn't neccessary to call this method for correctness. Rather
* it may be helpful to explicitly assert that the builder is in a certain state to make
* code that manipulates the builder more readable.
*/
virtual State getState() const = 0;
/**
* Gets the protocol used to serialize this reply. This should be used for validity checks
* only - runtime behavior changes should be implemented with polymorphism.
*/
virtual Protocol getProtocol() const = 0;
/**
* Resets the state of the builder to kMetadata and clears any data that was previously
* written.
*/
virtual void reset() = 0;
/**
* Returns available space in bytes, should be used to verify that the message have enough
* space for ouput documents.
*/
virtual std::size_t availableBytes() const = 0;
/**
* Writes data then transfers ownership of the message to the caller. The behavior of
* calling any methods on the builder is subsequently undefined.
*/
virtual std::unique_ptr<Message> done() = 0;
protected:
ReplyBuilderInterface() = default;
};
} // namespace rpc
} // namespace mongo
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