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/*
* This file is open source software, licensed to you under the terms
* of the Apache License, Version 2.0 (the "License"). See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. You may not use this file except in compliance with the License.
*
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/*
* Copyright (C) 2020 ScyllaDB.
*/
#pragma once
#include <chrono>
#include <seastar/core/future.hh>
#include <seastar/core/timed_out_error.hh>
#include <seastar/core/timer.hh>
namespace seastar {
/// \addtogroup future-util
/// @{
/// \brief Wait for either a future, or a timeout, whichever comes first
///
/// When timeout is reached the returned future resolves with an exception
/// produced by ExceptionFactory::timeout(). By default it is \ref timed_out_error exception.
///
/// Note that timing out doesn't cancel any tasks associated with the original future.
/// It also doesn't cancel the callback registerred on it.
///
/// \param f future to wait for
/// \param timeout time point after which the returned future should be failed
///
/// \return a future which will be either resolved with f or a timeout exception
template<typename ExceptionFactory = default_timeout_exception_factory, typename Clock, typename Duration, typename... T>
future<T...> with_timeout(std::chrono::time_point<Clock, Duration> timeout, future<T...> f) {
if (f.available()) {
return f;
}
auto pr = std::make_unique<promise<T...>>();
auto result = pr->get_future();
timer<Clock> timer([&pr = *pr] {
pr.set_exception(std::make_exception_ptr(ExceptionFactory::timeout()));
});
timer.arm(timeout);
// Future is returned indirectly.
(void)f.then_wrapped([pr = std::move(pr), timer = std::move(timer)] (auto&& f) mutable {
if (timer.cancel()) {
f.forward_to(std::move(*pr));
} else {
f.ignore_ready_future();
}
});
return result;
}
/// @}
} // namespace seastar
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