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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 <vector>
#include "mongo/base/status_with.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/db/clientcursor.h"
#include "mongo/db/namespace_string.h"
#include "mongo/rpc/op_msg.h"
#include "mongo/rpc/reply_builder_interface.h"
namespace mongo {
/**
* Builds the cursor field for a reply to a cursor-generating command in-place.
*/
class CursorResponseBuilder {
CursorResponseBuilder(const CursorResponseBuilder&) = delete;
CursorResponseBuilder& operator=(const CursorResponseBuilder&) = delete;
public:
/**
* Structure used to configure the CursorResponseBuilder.
*
* If we selected atClusterTime or received it from the client, transmit it back to the client
* in the cursor reply document by setting it here.
*/
struct Options {
bool isInitialResponse = false;
boost::optional<LogicalTime> atClusterTime = boost::none;
};
/**
* Once constructed, you may not use the passed-in ReplyBuilderInterface until you call either
* done()
* or abandon(), or this object goes out of scope. This is the same as the rule when using a
* BSONObjBuilder to build a sub-object with subobjStart().
*
* If the builder goes out of scope without a call to done(), the ReplyBuilderInterface will be
* reset.
*/
CursorResponseBuilder(rpc::ReplyBuilderInterface* replyBuilder, Options options);
~CursorResponseBuilder() {
if (_active)
abandon();
}
size_t bytesUsed() const {
invariant(_active);
return _batch->len();
}
void append(const BSONObj& obj) {
invariant(_active);
_batch->append(obj);
_numDocs++;
}
void setPostBatchResumeToken(BSONObj token) {
_postBatchResumeToken = token.getOwned();
}
void setPartialResultsReturned(bool partialResults) {
_partialResultsReturned = partialResults;
}
void setInvalidated() {
_invalidated = true;
}
long long numDocs() const {
return _numDocs;
}
void reserveReplyBuffer(size_t bytes) {
if (_replyBuilder != nullptr) {
_replyBuilder->reserveBytes(bytes);
}
}
/**
* Call this after successfully appending all fields that will be part of this response.
* After calling, you may not call any more methods on this object.
*/
void done(CursorId cursorId, StringData cursorNamespace);
/**
* Call this if the response should not contain cursor information. It will completely remove
* the cursor field from the commandResponse, as if the CursorResponseBuilder was never used.
* After calling, you may not call any more methods on this object.
*/
void abandon();
private:
const Options _options;
rpc::ReplyBuilderInterface* const _replyBuilder;
// Order here is important to ensure destruction in the correct order.
boost::optional<BSONObjBuilder> _bodyBuilder;
boost::optional<BSONObjBuilder> _cursorObject;
boost::optional<BSONArrayBuilder> _batch;
bool _active = true;
long long _numDocs = 0;
BSONObj _postBatchResumeToken;
bool _partialResultsReturned = false;
bool _invalidated = false;
};
/**
* Builds a cursor response object from the provided cursor identifiers and "firstBatch",
* and appends the response object to the provided builder under the field name "cursor".
*
* The response object has the following format:
* { id: <NumberLong>, ns: <String>, firstBatch: <Array> , type: <String>}.
*
* The type field is optional, but can be used to differentiate cursors if multiple are returned
* at once.
*
* This function is deprecated. Prefer CursorResponseBuilder or CursorResponse::toBSON() instead.
*/
void appendCursorResponseObject(long long cursorId,
StringData cursorNamespace,
BSONArray firstBatch,
boost::optional<StringData> cursorType,
BSONObjBuilder* builder);
/**
* Builds a getMore response object from the provided cursor identifiers and "nextBatch",
* and appends the response object to the provided builder under the field name "cursor".
*
* The response object has the following format:
* { id: <NumberLong>, ns: <String>, nextBatch: <Array> }.
*
* This function is deprecated. Prefer CursorResponseBuilder or CursorResponse::toBSON() instead.
*/
void appendGetMoreResponseObject(long long cursorId,
StringData cursorNamespace,
BSONArray nextBatch,
BSONObjBuilder* builder);
class CursorResponse {
public:
enum class ResponseType {
InitialResponse,
SubsequentResponse,
};
/**
* Constructs a vector of CursorResponses from a command BSON response that represents one or
* more cursors.
*/
static std::vector<StatusWith<CursorResponse>> parseFromBSONMany(const BSONObj& cmdResponse);
/**
* Constructs a CursorResponse from the command BSON response. If 'cmdResponse' is not owned,
* the second argument should be the object that owns the response.
*/
static StatusWith<CursorResponse> parseFromBSON(const BSONObj& cmdResponse,
const BSONObj* ownedObj = nullptr);
/**
* A throwing version of 'parseFromBSON'.
*/
static CursorResponse parseFromBSONThrowing(const BSONObj& cmdResponse) {
return uassertStatusOK(parseFromBSON(cmdResponse));
}
/**
* Constructs an empty cursor response.
*/
CursorResponse() = default;
/**
* Constructs from values for each of the fields.
*/
CursorResponse(NamespaceString nss,
CursorId cursorId,
std::vector<BSONObj> batch,
boost::optional<Timestamp> atClusterTime = boost::none,
boost::optional<BSONObj> postBatchResumeToken = boost::none,
boost::optional<BSONObj> writeConcernError = boost::none,
boost::optional<BSONObj> varsField = boost::none,
boost::optional<std::string> cursorType = boost::none,
bool partialResultsReturned = false,
bool invalidated = false);
CursorResponse(CursorResponse&& other) = default;
CursorResponse& operator=(CursorResponse&& other) = default;
//
// Accessors.
//
const NamespaceString& getNSS() const {
return _nss;
}
CursorId getCursorId() const {
return _cursorId;
}
const std::vector<BSONObj>& getBatch() const {
return _batch;
}
std::vector<BSONObj> releaseBatch() {
return std::move(_batch);
}
boost::optional<BSONObj> getPostBatchResumeToken() const {
return _postBatchResumeToken;
}
boost::optional<BSONObj> getWriteConcernError() const {
return _writeConcernError;
}
boost::optional<Timestamp> getAtClusterTime() const {
return _atClusterTime;
}
boost::optional<BSONObj> getVarsField() const {
return _varsField;
}
auto getCursorType() const {
return _cursorType;
}
bool getPartialResultsReturned() const {
return _partialResultsReturned;
}
bool getInvalidated() const {
return _invalidated;
}
/**
* Converts this response to its raw BSON representation.
*/
BSONObj toBSON(ResponseType responseType) const;
void addToBSON(ResponseType responseType, BSONObjBuilder* builder) const;
BSONObj toBSONAsInitialResponse() const {
return toBSON(ResponseType::InitialResponse);
}
private:
NamespaceString _nss;
CursorId _cursorId;
std::vector<BSONObj> _batch;
boost::optional<Timestamp> _atClusterTime;
boost::optional<BSONObj> _postBatchResumeToken;
boost::optional<BSONObj> _writeConcernError;
boost::optional<BSONObj> _varsField;
boost::optional<std::string> _cursorType;
bool _partialResultsReturned = false;
bool _invalidated = false;
};
} // namespace mongo
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