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/**
* Copyright (C) 2021-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/bson/bsonobjbuilder.h"
#include "mongo/db/client.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/session/logical_session_id.h"
namespace mongo::load_balancer_support {
/**
* Gets the load balancer port, if we are configured to enable one.
*/
boost::optional<int> getLoadBalancerPort();
/**
* Helper for handling the `hello` command on mongos.
* `helloHasLoadBalancedOption` must be true if the hello command had the
* `loadBalanced` option present and set to `true`.
*
* For only the initial `hello` command, we respond to a `loadBalanced: true`
* option by including the `serviceId` of this mongos in the hello reply.
*
* A connection marked as having come in through a load balancer must confirm
* that it is using a load-balancer-aware driver by setting the `loadBalanced:
* true` option in its first `hello` command. Otherwise, this function will
* throw with `ErrorCodes::LoadBalancerSupportMismatch`.
*/
void handleHello(OperationContext* opCtx, BSONObjBuilder* result, bool helloHasLoadBalancedOption);
bool isFromLoadBalancer(Client* client);
/**
* Returns whether the feature flag for load balancer support is enabled.
*/
bool isEnabled();
/**
* Returns the LSID of the session most recently used by the given Client as part of a
* multi-statement transaction
*/
LogicalSessionId getMruSession(Client* client);
void setMruSession(Client* client, LogicalSessionId id);
} // namespace mongo::load_balancer_support
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