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/**
* Copyright (C) 2022-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 "mongo/base/status.h"
#include "mongo/client/read_preference.h"
#include "mongo/db/auth/validated_tenancy_scope.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/server_options.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/cancellation.h"
#include "mongo/util/future.h"
#include "mongo/util/net/hostandport.h"
#include <vector>
namespace mongo {
namespace async_rpc {
class Targeter {
public:
Targeter() = default;
virtual ~Targeter() = default;
/*
* Returns a collection of possible Hosts on which the command may run based on the specific
* settings (ReadPreference, etc.) of the targeter. Note that if no targets can be found on
* which to run the command, the returned future should be set with an error - an empty vector
* should never be returned and is treated as a programmer error.
*/
virtual SemiFuture<std::vector<HostAndPort>> resolve(CancellationToken t) = 0;
/*
* Informs the Targeter that an error happened when trying to run a command on a
* HostAndPort. Allows the targeter to update its view of the cluster's topology if network
* or shutdown errors are received.
*/
virtual SemiFuture<void> onRemoteCommandError(HostAndPort h, Status s) = 0;
};
class LocalHostTargeter : public Targeter {
public:
LocalHostTargeter() = default;
SemiFuture<std::vector<HostAndPort>> resolve(CancellationToken t) override final {
HostAndPort h = HostAndPort("localhost", serverGlobalParams.port);
std::vector<HostAndPort> hostList{h};
return SemiFuture<std::vector<HostAndPort>>::makeReady(hostList);
}
SemiFuture<void> onRemoteCommandError(HostAndPort h, Status s) override final {
return SemiFuture<void>::makeReady();
}
};
/**
* Basic Targeter that wraps a single HostAndPort. Use when you need to make a call
* to the sendCommand function but already know what HostAndPort to target.
*/
class FixedTargeter : public Targeter {
public:
FixedTargeter(HostAndPort host) : _host(host){};
SemiFuture<std::vector<HostAndPort>> resolve(CancellationToken t) override final {
std::vector<HostAndPort> hostList{_host};
return SemiFuture<std::vector<HostAndPort>>::makeReady(hostList);
}
SemiFuture<void> onRemoteCommandError(HostAndPort h, Status s) override final {
return SemiFuture<void>::makeReady();
}
private:
HostAndPort _host;
};
} // namespace async_rpc
} // namespace mongo
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