68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
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/*
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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 with LLVM Exceptions
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* https://llvm.org/LICENSE.txt
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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 <unifex/tag_invoke.hpp>
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#include <unifex/type_traits.hpp>
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#include <unifex/detail/prologue.hpp>
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namespace unifex {
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enum class blocking_kind {
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// No guarantees about the timing and context on which the receiver will
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// be called.
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maybe,
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// Always completes asynchronously.
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// Guarantees that the receiver will not be called on the current thread
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// before .start() returns. The receiver may be called on another thread
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// before .start() returns, however, or may be called on the current thread
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// some time after .start() returns.
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never,
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// Guarantees that the receiver will be called strongly-happens-before
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// .start() returns. Does not guarantee the call to the receiver happens
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// on the same thread that called .start(), however.
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always,
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// Caller guarantees that the receiver will be called inline on the
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// current thread that called .start() before .start() returns.
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always_inline
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};
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namespace _blocking {
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inline const struct _fn {
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template(typename Sender)
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(requires tag_invocable<_fn, const Sender&>)
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constexpr auto operator()(const Sender& s) const
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noexcept(is_nothrow_tag_invocable_v<_fn, const Sender&>)
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-> tag_invoke_result_t<_fn, const Sender&> {
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return tag_invoke(_fn{}, s);
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}
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template(typename Sender)
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(requires (!tag_invocable<_fn, const Sender&>))
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constexpr blocking_kind operator()(const Sender&) const noexcept {
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return blocking_kind::maybe;
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}
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} blocking{};
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} // namespace _blocking
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using _blocking::blocking;
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} // namespace unifex
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#include <unifex/detail/epilogue.hpp>
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