163 lines
4.0 KiB
C++
163 lines
4.0 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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#pragma once
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#include <atomic>
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#include <thread>
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#include <utility>
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#include <folly/executors/InlineExecutor.h>
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#include <folly/futures/detail/Core.h>
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#include <folly/lang/Pretty.h>
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namespace folly {
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namespace futures {
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namespace detail {
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template <typename T>
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void coreDetachPromiseMaybeWithResult(Core<T>& core) {
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if (!core.hasResult()) {
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core.setResult(Try<T>(exception_wrapper(BrokenPromise(pretty_name<T>()))));
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}
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core.detachPromise();
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}
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template <typename T>
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void setTry(Promise<T>& p, Executor::KeepAlive<>&& ka, Try<T>&& t) {
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p.setTry(std::move(ka), std::move(t));
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}
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} // namespace detail
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} // namespace futures
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template <class T>
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Promise<T> Promise<T>::makeEmpty() noexcept {
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return Promise<T>(futures::detail::EmptyConstruct{});
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}
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template <class T>
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Promise<T>::Promise() : retrieved_(false), core_(Core::make()) {}
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template <class T>
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Promise<T>::Promise(Promise<T>&& other) noexcept
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: retrieved_(std::exchange(other.retrieved_, false)),
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core_(std::exchange(other.core_, nullptr)) {}
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template <class T>
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Promise<T>& Promise<T>::operator=(Promise<T>&& other) noexcept {
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detach();
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retrieved_ = std::exchange(other.retrieved_, false);
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core_ = std::exchange(other.core_, nullptr);
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return *this;
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}
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template <class T>
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void Promise<T>::throwIfFulfilled() const {
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if (getCore().hasResult()) {
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throw_exception<PromiseAlreadySatisfied>();
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}
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}
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template <class T>
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Promise<T>::Promise(futures::detail::EmptyConstruct) noexcept
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: retrieved_(false), core_(nullptr) {}
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template <class T>
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Promise<T>::~Promise() {
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detach();
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}
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template <class T>
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void Promise<T>::detach() {
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if (core_) {
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if (!retrieved_) {
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core_->detachFuture();
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}
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futures::detail::coreDetachPromiseMaybeWithResult(*core_);
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core_ = nullptr;
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}
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}
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template <class T>
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SemiFuture<T> Promise<T>::getSemiFuture() {
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if (retrieved_) {
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throw_exception<FutureAlreadyRetrieved>();
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}
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retrieved_ = true;
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return SemiFuture<T>(&getCore());
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}
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template <class T>
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Future<T> Promise<T>::getFuture() {
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// An InlineExecutor approximates the old behaviour of continuations
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// running inine on setting the value of the promise.
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return getSemiFuture().via(&InlineExecutor::instance());
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}
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template <class T>
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template <class E>
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typename std::enable_if<std::is_base_of<std::exception, E>::value>::type
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Promise<T>::setException(E const& e) {
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setException(make_exception_wrapper<E>(e));
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}
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template <class T>
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void Promise<T>::setException(exception_wrapper ew) {
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setTry(Try<T>(std::move(ew)));
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}
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template <class T>
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template <typename F>
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void Promise<T>::setInterruptHandler(F&& fn) {
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getCore().setInterruptHandler(std::forward<F>(fn));
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}
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template <class T>
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void Promise<T>::setTry(Try<T>&& t) {
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throwIfFulfilled();
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core_->setResult(std::move(t));
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}
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template <class T>
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void Promise<T>::setTry(Executor::KeepAlive<>&& ka, Try<T>&& t) {
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throwIfFulfilled();
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core_->setResult(std::move(ka), std::move(t));
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}
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template <class T>
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template <class M>
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void Promise<T>::setValue(M&& v) {
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static_assert(!std::is_same<T, void>::value, "Use setValue() instead");
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setTry(Try<T>(std::forward<M>(v)));
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}
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template <class T>
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template <class F>
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void Promise<T>::setWith(F&& func) {
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throwIfFulfilled();
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setTry(makeTryWith(std::forward<F>(func)));
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}
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template <class T>
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bool Promise<T>::isFulfilled() const noexcept {
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if (core_) {
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return core_->hasResult();
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}
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return true;
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}
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} // namespace folly
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