124 lines
3.8 KiB
C++
124 lines
3.8 KiB
C++
#ifndef OSMIUM_THREAD_FUNCTION_WRAPPER_HPP
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#define OSMIUM_THREAD_FUNCTION_WRAPPER_HPP
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/*
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This file is part of Osmium (http://osmcode.org/libosmium).
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Copyright 2013-2016 Jochen Topf <jochen@topf.org> and others (see README).
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Boost Software License - Version 1.0 - August 17th, 2003
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Permission is hereby granted, free of charge, to any person or organization
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obtaining a copy of the software and accompanying documentation covered by
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this license (the "Software") to use, reproduce, display, distribute,
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execute, and transmit the Software, and to prepare derivative works of the
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Software, and to permit third-parties to whom the Software is furnished to
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do so, all subject to the following:
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The copyright notices in the Software and this entire statement, including
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the above license grant, this restriction and the following disclaimer,
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must be included in all copies of the Software, in whole or in part, and
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all derivative works of the Software, unless such copies or derivative
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works are solely in the form of machine-executable object code generated by
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a source language processor.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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DEALINGS IN THE SOFTWARE.
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*/
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#include <algorithm>
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#include <memory>
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namespace osmium {
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namespace thread {
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/**
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* This function wrapper can collect move-only functions unlike
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* std::function which needs copyable functions.
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* Taken from the book "C++ Concurrency in Action".
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*/
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class function_wrapper {
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struct impl_base {
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virtual ~impl_base() = default;
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virtual bool call() {
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return true;
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}
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}; // struct impl_base
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std::unique_ptr<impl_base> impl;
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template <typename F>
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struct impl_type : impl_base {
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F m_functor;
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explicit impl_type(F&& functor) :
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m_functor(std::forward<F>(functor)) {
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}
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bool call() override {
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m_functor();
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return false;
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}
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}; // struct impl_type
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public:
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// Constructor must not be "explicit" for wrapper
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// to work seemlessly.
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template <typename TFunction>
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function_wrapper(TFunction&& f) :
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impl(new impl_type<TFunction>(std::forward<TFunction>(f))) {
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}
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// The integer parameter is only used to signal that we want
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// the special function wrapper that makes the worker thread
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// shut down.
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function_wrapper(int) :
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impl(new impl_base()) {
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}
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bool operator()() {
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return impl->call();
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}
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function_wrapper() = default;
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function_wrapper(function_wrapper&& other) :
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impl(std::move(other.impl)) {
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}
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function_wrapper& operator=(function_wrapper&& other) {
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impl = std::move(other.impl);
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return *this;
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}
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function_wrapper(const function_wrapper&) = delete;
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function_wrapper& operator=(const function_wrapper&) = delete;
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~function_wrapper() = default;
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explicit operator bool() const {
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return static_cast<bool>(impl);
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}
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}; // class function_wrapper
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} // namespace thread
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} // namespace osmium
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#endif // OSMIUM_THREAD_FUNCTION_WRAPPER_HPP
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