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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 "mongo/base/disallow_copying.h"
#include "mongo/util/future.h"
#include "mongo/util/net/hostandport.h"
#include "mongo/util/time_support.h"
namespace mongo {
class ConnectionString;
class OperationContext;
struct ReadPreferenceSetting;
struct HostAndPort;
template <typename T>
class StatusWith;
/**
* Interface encapsulating the targeting logic for a given replica set or a standalone host.
*/
class RemoteCommandTargeter {
MONGO_DISALLOW_COPYING(RemoteCommandTargeter);
public:
virtual ~RemoteCommandTargeter() = default;
/**
* Retrieves the full connection string for the replica set or standalone host which are
* represented by this targeter. This value is always constant for a standalone host and may
* vary for replica sets as hosts are added, discovered and removed during the lifetime of the
* set.
*/
virtual ConnectionString connectionString() = 0;
/**
* Finds a host matching readPref blocking up to 20 seconds or until the given operation is
* interrupted or its deadline expires.
*
* TODO(schwerin): Once operation max-time behavior is more uniformly integrated into sharding,
* remove the 20-second ceiling on wait time.
*/
virtual StatusWith<HostAndPort> findHost(OperationContext* opCtx,
const ReadPreferenceSetting& readPref) = 0;
/**
* Finds a host that matches the read preference specified by readPref, blocking for up to
* specified maxWait milliseconds, if a match cannot be found immediately.
*
* DEPRECATED. Prefer findHost(OperationContext*, const ReadPreferenceSetting&), whenever
* an OperationContext is available.
*/
virtual Future<HostAndPort> findHostWithMaxWait(const ReadPreferenceSetting& readPref,
Milliseconds maxWait) = 0;
/**
* Finds a host matching the given read preference, giving up if a match is not found promptly.
*
* This method may still engage in blocking networking calls, but will attempt contact every
* member of the replica set at most one time.
*
* TODO(schwerin): Change this implementation to not perform any networking, once existing
* callers have been shown to be safe with this behavior or changed to call findHost.
*/
StatusWith<HostAndPort> findHostNoWait(const ReadPreferenceSetting& readPref) {
return findHostWithMaxWait(readPref, Milliseconds::zero()).getNoThrow();
}
/**
* Reports to the targeter that a 'status' indicating a not master error was received when
* communicating with 'host', and so it should update its bookkeeping to avoid giving out the
* host again on a subsequent request for the primary.
*/
virtual void markHostNotMaster(const HostAndPort& host, const Status& status) = 0;
/**
* Reports to the targeter that a 'status' indicating a network error was received when trying
* to communicate with 'host', and so it should update its bookkeeping to avoid giving out the
* host again on a subsequent request for the primary.
*/
virtual void markHostUnreachable(const HostAndPort& host, const Status& status) = 0;
protected:
RemoteCommandTargeter() = default;
};
} // namespace mongo
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