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https://gitlab.freedesktop.org/mesa/vulkan-wsi-layer.git
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9b698b4a2f
This commit adds the initial sources for the vulkan-wsi-layer project: a Vulkan layer which implements some of the Vulkan window system integration extensions such as VK_KHR_swapchain. The layer is designed to be GPU vendor agnostic when used as part of the Vulkan ICD/loader architecture. The project currently implements support for VK_EXT_headless_surface and its dependencies. We hope to extend support for further platforms such as Wayland and direct-to-display rendering in the future. This initial commit collects contributions from different individuals employed by Arm. More information on the project (building instructions, how to contribute, etc.) can be found on the README.md file at the top of the project tree. Signed-off-by: Matteo Franchin <matteo.franchin@arm.com>
115 lines
3.5 KiB
C++
115 lines
3.5 KiB
C++
/*
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* Copyright (c) 2017, 2019 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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{
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#include <pthread.h>
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}
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#include <vulkan/vulkan.h>
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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
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{
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public:
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/* copying not implemented */
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timed_semaphore &operator=(const timed_semaphore &) = delete;
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timed_semaphore(const timed_semaphore &) = delete;
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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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