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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/api_parameters.h"
#include "mongo/db/auth/authorization_checks.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/commands.h"
#include "mongo/db/query/cursor_response.h"
#include "mongo/db/query/getmore_command_gen.h"
#include "mongo/db/stats/counters.h"
#include "mongo/s/query/cluster_cursor_manager.h"
#include "mongo/s/query/cluster_find.h"
namespace mongo {
namespace {
// getMore can run with any readConcern, because cursor-creating commands like find can run with any
// readConcern. However, since getMore automatically uses the readConcern of the command that
// created the cursor, it is not appropriate to apply the default readConcern (just as
// client-specified readConcern isn't appropriate).
static const ReadConcernSupportResult kSupportsReadConcernResult{
Status::OK(),
{{ErrorCodes::InvalidOptions,
"default read concern not permitted (getMore uses the cursor's read concern)"}}};
/**
* Implements the getMore command on mongos. Retrieves more from an existing mongos cursor
* corresponding to the cursor id passed from the application. In order to generate these results,
* may issue getMore commands to remote nodes in one or more shards.
*/
class ClusterGetMoreCmd final : public Command {
public:
ClusterGetMoreCmd() : Command("getMore") {}
// Do not currently use apiVersions because clients are prohibited from calling
// getMore with apiVersion.
const std::set<std::string>& apiVersions() const {
return kApiVersions1;
}
std::unique_ptr<CommandInvocation> parse(OperationContext* opCtx,
const OpMsgRequest& opMsgRequest) override {
return std::make_unique<Invocation>(this, opMsgRequest);
}
class Invocation final : public CommandInvocation {
public:
Invocation(Command* cmd, const OpMsgRequest& request)
: CommandInvocation(cmd),
_cmd(GetMoreCommandRequest::parse({"getMore"}, request.body)) {
APIParameters::uassertNoApiParameters(request.body);
}
private:
NamespaceString ns() const override {
return NamespaceString(_cmd.getDbName(), _cmd.getCollection());
}
bool supportsWriteConcern() const override {
return false;
}
ReadConcernSupportResult supportsReadConcern(repl::ReadConcernLevel level) const override {
return kSupportsReadConcernResult;
}
void doCheckAuthorization(OperationContext* opCtx) const override {
uassertStatusOK(auth::checkAuthForGetMore(AuthorizationSession::get(opCtx->getClient()),
ns(),
_cmd.getCommandParameter(),
_cmd.getTerm().is_initialized()));
}
void run(OperationContext* opCtx, rpc::ReplyBuilderInterface* reply) override {
// Counted as a getMore, not as a command.
globalOpCounters.gotGetMore();
auto bob = reply->getBodyBuilder();
auto response = uassertStatusOK(ClusterFind::runGetMore(opCtx, _cmd));
response.addToBSON(CursorResponse::ResponseType::SubsequentResponse, &bob);
if (getTestCommandsEnabled()) {
validateResult(bob.asTempObj());
}
}
void validateResult(const BSONObj& replyObj) {
CursorGetMoreReply::parse({"CursorGetMoreReply"}, replyObj.removeField("ok"));
}
const GetMoreCommandRequest _cmd;
};
AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
return AllowedOnSecondary::kAlways;
}
bool maintenanceOk() const override {
return false;
}
bool adminOnly() const override {
return false;
}
/**
* A getMore command increments the getMore counter, not the command counter.
*/
bool shouldAffectCommandCounter() const override {
return false;
}
std::string help() const override {
return "retrieve more documents for a cursor id";
}
LogicalOp getLogicalOp() const override {
return LogicalOp::opGetMore;
}
} cmdGetMoreCluster;
} // namespace
} // namespace mongo
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