DEV: a shared resource utility added
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include/utl/utility/shared.h
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include/utl/utility/shared.h
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/*!
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* \file utility/shared.h
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* \brief
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* A CRTP base class to provide acquire/release functionality for shared resources
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* without handle pointers.
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*
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* \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
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*
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* <dl class=\"section copyright\"><dt>License</dt><dd>
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* The MIT License (MIT)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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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 AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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* </dd></dl>
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*/
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#ifndef utl_utility_shared_h__
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#define utl_utility_shared_h__
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#include <utl/core/impl.h>
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#include <utility>
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namespace utl {
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/*!
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* A CRTP base class to provide acquire/release functionality for shared resources
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* without handle pointers.
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*
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* \example
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* \code
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* class GPIOClock : public shared<GPIOClock> {
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* friend shared<GPIOClock>;
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* void acquire_impl() { // HAL enable gpio clock }
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* void release_impl() { // HAL disable gpio clock }
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* };
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* GPIOClock clk;
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* class Pin {
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* Pin() {
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* clk.acquire();
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* // init pin
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* }
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* ~Pin() {
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* // de-init pin
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* clk.release();
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* }
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* };
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* \endcode
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*
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* \tparam Impl_t The derived class type
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*/
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template <typename Impl_t>
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class shared {
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_CRTP_IMPL(Impl_t);
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int count {}; //!< acquisition counter
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protected:
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shared() noexcept = default;
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shared(const shared&) = delete; //!< No copies
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shared operator=(const shared&) = delete; //!< No copies
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public:
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/*!
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* Acquires the recourse. If it is the first call to acquire the resource we actually acquire it.
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* Otherwise we just keep track of how many acquisition have made.
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*
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* \tparam Ts The types of possible arguments
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* \param args Possible arguments to pass to acquire_impl() of derived class
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*/
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template <typename ...Ts>
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void acquire (Ts&&... args) {
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if (!count++) impl().acquire_impl(std::forward<Ts>(args)...);
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}
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/*!
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* Release the recourse. On every call we decrease the count of acquisitions. If we reach zero
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* we actually release the resource.
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*
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* \tparam Ts The types of possible arguments
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* \param args Possible arguments to pass to release_impl() of derived class
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*/
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template <typename ...Ts>
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void release (Ts&&... args) noexcept {
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if (--count <= 0) {
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impl().release_impl(std::forward<Ts>(args)...);
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count =0;
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}
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}
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};
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} // namespace utl;
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#endif /* utl_utility_shared_h__ */
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