119 lines
3.2 KiB
C++
119 lines
3.2 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/fibers/Baton.h>
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namespace folly {
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namespace fibers {
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template <class T, class BatonT>
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Promise<T, BatonT>::Promise(folly::Try<T>& value, BatonT& baton)
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: value_(&value), baton_(&baton) {}
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template <class T, class BatonT>
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Promise<T, BatonT>::Promise(Promise&& other) noexcept
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: value_(other.value_), baton_(other.baton_) {
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other.value_ = nullptr;
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other.baton_ = nullptr;
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}
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template <class T, class BatonT>
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Promise<T, BatonT>& Promise<T, BatonT>::operator=(Promise&& other) {
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std::swap(value_, other.value_);
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std::swap(baton_, other.baton_);
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return *this;
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}
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template <class T, class BatonT>
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void Promise<T, BatonT>::throwIfFulfilled() const {
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if (!value_) {
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throw std::logic_error("promise already fulfilled");
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}
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}
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template <class T, class BatonT>
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Promise<T, BatonT>::~Promise() {
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if (value_) {
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setException(folly::make_exception_wrapper<std::logic_error>(
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"promise not fulfilled"));
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}
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}
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template <class T, class BatonT>
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void Promise<T, BatonT>::setException(folly::exception_wrapper e) {
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setTry(folly::Try<T>(e));
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}
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template <class T, class BatonT>
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void Promise<T, BatonT>::setTry(folly::Try<T>&& t) {
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throwIfFulfilled();
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*value_ = std::move(t);
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value_ = nullptr;
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// Baton::post has to be the last step here, since if Promise is not owned by
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// the posting thread, it may be destroyed right after Baton::post is called.
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baton_->post();
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}
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template <class T, class BatonT>
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template <class M>
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void Promise<T, BatonT>::setValue(M&& v) {
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static_assert(!std::is_same<T, void>::value, "Use setValue() instead");
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setTry(folly::Try<T>(std::forward<M>(v)));
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}
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template <class T, class BatonT>
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void Promise<T, BatonT>::setValue() {
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static_assert(std::is_same<T, void>::value, "Use setValue(value) instead");
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setTry(folly::Try<void>());
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}
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template <class T, class BatonT>
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template <class F>
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void Promise<T, BatonT>::setWith(F&& func) {
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setTry(makeTryWith(std::forward<F>(func)));
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}
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template <class T, class BatonT>
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template <class F>
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typename Promise<T, BatonT>::value_type Promise<T, BatonT>::await_async(
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F&& func) {
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folly::Try<value_type> result;
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std::exception_ptr funcException;
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BatonT baton;
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baton.wait([&func, &result, &baton, &funcException]() mutable {
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try {
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func(Promise<value_type, BatonT>(result, baton));
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} catch (...) {
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// Save the exception, but still wait for baton to be posted by user code
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// or promise destructor.
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funcException = std::current_exception();
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}
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});
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if (UNLIKELY(funcException != nullptr)) {
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std::rethrow_exception(funcException);
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}
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return std::move(result).value();
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}
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} // namespace fibers
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} // namespace folly
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