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-rw-r--r-- | src/seastar/include/seastar/core/with_timeout.hh | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/src/seastar/include/seastar/core/with_timeout.hh b/src/seastar/include/seastar/core/with_timeout.hh new file mode 100644 index 000000000..cbe4758dd --- /dev/null +++ b/src/seastar/include/seastar/core/with_timeout.hh @@ -0,0 +1,73 @@ +/* + * 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 |