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https://gitlab.freedesktop.org/mesa/vulkan-wsi-layer.git
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4423a52816
Signed-off-by: Dennis Tsiang <dennis.tsiang@arm.com> Change-Id: I76f87648a8ddaeddb6774123d263957b845d10a1
111 lines
3.4 KiB
C++
111 lines
3.4 KiB
C++
/*
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* Copyright (c) 2017, 2019, 2024 Arm Limited.
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*
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* SPDX-License-Identifier: 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
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell 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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*/
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/**
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* @file timed_semaphore.hpp
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*
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* @brief Contains the class definition for a semaphore with a relative timedwait
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*
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* sem_timedwait takes an absolute time, based on CLOCK_REALTIME. Simply
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* taking the current time and adding on a relative timeout is not correct,
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* as the system time may change, resulting in an incorrect timeout period
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* (potentially by a significant amount).
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*
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* We therefore have to re-engineer semaphores using condition variables.
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*
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* This code does not use the C++ standard library to avoid exceptions.
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*/
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#pragma once
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extern "C" {
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#include <pthread.h>
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}
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#include <vulkan/vulkan.h>
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#include "helpers.hpp"
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namespace util
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{
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/**
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* brief semaphore with a safe relative timed wait
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*
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* sem_timedwait takes an absolute time, based on CLOCK_REALTIME. Simply
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* taking the current time and adding on a relative timeout is not correct,
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* as the system time may change, resulting in an incorrect timeout period
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* (potentially by a significant amount).
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*
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* We therefore have to re-engineer semaphores using condition variables.
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*
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* This code does not use the C++ standard library to avoid exceptions.
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*/
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class timed_semaphore : private noncopyable
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{
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public:
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~timed_semaphore();
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timed_semaphore()
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: initialized(false){};
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/**
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* @brief initializes the semaphore
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*
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* @param count initial value of the semaphore
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* @retval VK_ERROR_OUT_OF_HOST_MEMORY out of memory condition from pthread calls
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* @retval VK_SUCCESS on success
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*/
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VkResult init(unsigned count);
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/**
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* @brief decrement semaphore, waiting (with timeout) if the value is 0
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*
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* @param timeout time to wait (ns). 0 doesn't block, UINT64_MAX waits indefinately.
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* @retval VK_TIMEOUT timeout was non-zero and reached the timeout
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* @retval VK_NOT_READY timeout was zero and count is 0
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* @retval VK_SUCCESS on success
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*/
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VkResult wait(uint64_t timeout);
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/**
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* @brief increment semaphore, potentially unblocking a waiting thread
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*/
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void post();
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private:
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/**
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* @brief true if the semaphore has been initialized
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*
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* Determines if the destructor should cleanup the mutex and cond.
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*/
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bool initialized;
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/**
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* @brief semaphore value
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*/
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unsigned m_count;
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pthread_mutex_t m_mutex;
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pthread_cond_t m_cond;
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};
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} /* namespace util */
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