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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 <memory>
#include <vector>
#include "mongo/executor/remote_command_response.h"
#include "mongo/executor/task_executor.h"
#include "mongo/platform/mutex.h"
#include "mongo/util/net/hostandport.h"
namespace mongo {
namespace executor {
/**
* An async harness for scatter/gathering a command across an arbitrary number of specific hosts
*/
class AsyncMulticaster {
public:
using Reply = std::tuple<HostAndPort, executor::RemoteCommandResponse>;
static constexpr size_t kMaxConcurrency = 100;
struct Options {
// maxConcurrency controls the maximum number of inflight operations. I.e. limiting it
// prevents the fan out from overwhelming the host, if the number of servers to multicast
// to is very high.
size_t maxConcurrency = kMaxConcurrency;
};
AsyncMulticaster(std::shared_ptr<executor::TaskExecutor> executor, Options options);
/**
* Sends the cmd out to all passed servers (via the executor), observing the multicaster's
* maxConcurrency.
*
* The timeout value on multicast is per operation. The overall timeout will be:
* timeoutMillis - if max concurrency is greater than servers.size()
* or
* timeoutMillis * (servers.size() / maxConcurrency) - if not
*/
std::vector<Reply> multicast(const std::vector<HostAndPort> servers,
const std::string& theDbName,
const BSONObj& theCmdObj,
OperationContext* opCtx,
Milliseconds timeoutMillis);
private:
Options _options;
std::shared_ptr<executor::TaskExecutor> _executor;
};
} // namespace executor
} // namespace mongo
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