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// Copyright 2018 The SwiftShader Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef VK_SEMAPHORE_HPP_
#define VK_SEMAPHORE_HPP_
#include "VkConfig.hpp"
#include "VkObject.hpp"
#include "marl/event.h"
#include "marl/mutex.h"
#include "marl/tsa.h"
#if VK_USE_PLATFORM_FUCHSIA
# include <zircon/types.h>
#endif
namespace vk {
class Semaphore : public Object<Semaphore, VkSemaphore>
{
public:
Semaphore(const VkSemaphoreCreateInfo *pCreateInfo, void *mem, const VkAllocationCallbacks *pAllocator);
void destroy(const VkAllocationCallbacks *pAllocator);
static size_t ComputeRequiredAllocationSize(const VkSemaphoreCreateInfo *pCreateInfo);
void wait();
void wait(const VkPipelineStageFlags &flag)
{
// NOTE: not sure what else to do here?
wait();
}
void signal();
#if SWIFTSHADER_EXTERNAL_SEMAPHORE_OPAQUE_FD
VkResult importFd(int fd, bool temporaryImport);
VkResult exportFd(int *pFd);
#endif
#if VK_USE_PLATFORM_FUCHSIA
VkResult importHandle(zx_handle_t handle, bool temporaryImport);
VkResult exportHandle(zx_handle_t *pHandle);
#endif
class External;
private:
// Small technical note on how semaphores are imported/exported with Vulkan:
//
// - A Vulkan Semaphore objects has a "payload", corresponding to a
// simple atomic boolean flag.
//
// - A Vulkan Semaphore object can be "exported": this creates a
// platform-specific handle / descriptor (which can be passed to other
// processes), and is linked in some way to the original semaphore's
// payload.
//
// - Similarly, said handle / descriptor can be "imported" into a Vulkan
// Semaphore object. By default, that semaphore loses its payload, and
// instead uses the one referenced / shared through the descriptor.
//
// Hence if semaphore A exports its payload through a descriptor that
// is later imported into semaphore B, then both A and B will use/share
// the same payload (i.e. signal flag), making cross-process
// synchronization possible.
//
// - There are also "temporary imports", where the target semaphore's
// payload is not lost, but is simply hidden/stashed. But the next wait()
// operation on the same semaphore should remove the temporary import,
// and restore the previous payload.
//
// - There are many handle / descriptor types, which are listed through
// the VkExternalSemaphoreHandleTypeFlagBits. A given Vulkan
// implementation might support onle one or several at the same time
// (e.g. on Linux or Android, it could support both OPAQUE_FD_BIT and
// SYNC_FD_BIT, while on Windows, it would be OPAQUE_WIN32_BIT +
// OPAQUE_WIN32_KMT_BIT + D3D12_FENCE_BIT).
//
// - To be able to export a semaphore, VkCreateSemaphore() must be called
// with a VkSemaphoreCreateInfo that lists the types of all possible
// platform-specific handles the semaphore could be exported to
// (e.g. on Linux, it is possible to specify that a semaphore might be
// exported as an opaque FD, or as a Linux Sync FD).
//
// However, which exact type is however only determined later by the
// export operation itself (e.g. vkGetSemaphoreFdKHR() could be called to export
// either a VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT or a
// VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT).
//
// Once a semaphore has been exported as one type, it is not possible
// to export the same payload with a different type (though the spec
// doesn't seem to be explicit about this, it's simply impossible in
// general).
//
// This leads to the following design:
//
// - |internal| is a simple marl::Event that represents the semaphore's
// payload when it is not exported, or imported non-temporarily.
//
// - |external| points to an external semaphore payload. It is created
// on demand if the semaphore is exported or imported non-temporarily.
// Note that once |external| is created, |internal| is ignored.
//
// - |tempExternal| points to a linked-list of temporary external
// semaphore payloads. The list head corresponds to the most recent
// temporary import.
//
// Internal template to allocate a new External implementation.
template<class EXTERNAL>
External *allocateExternal();
void deallocateExternal(External *ext);
// Used internally to import an external payload.
// |temporaryImport| is true iff the import is temporary.
// |alloc_func| is callable that allocates a new External instance of the
// appropriate type.
// |import_func| is callable that takes a single parameter, which
// corresponds to the external handle/descriptor, and returns a VkResult
// values.
template<typename ALLOC_FUNC, typename IMPORT_FUNC>
VkResult importPayload(bool temporaryImport,
ALLOC_FUNC alloc_func,
IMPORT_FUNC import_func);
// Used internally to export a given payload.
// |alloc_func| is a callable that allocates a new External instance of
// the appropriate type.
// |export_func| is a callable that takes a pointer to an External instance,
// and a pointer to a handle/descriptor, and returns a VkResult.
template<typename ALLOC_FUNC, typename EXPORT_FUNC>
VkResult exportPayload(ALLOC_FUNC alloc_func, EXPORT_FUNC export_func);
const VkAllocationCallbacks *allocator = nullptr;
VkExternalSemaphoreHandleTypeFlags exportableHandleTypes = (VkExternalSemaphoreHandleTypeFlags)0;
marl::Event internal;
marl::mutex mutex;
External *external GUARDED_BY(mutex) = nullptr;
External *tempExternal GUARDED_BY(mutex) = nullptr;
};
static inline Semaphore *Cast(VkSemaphore object)
{
return Semaphore::Cast(object);
}
} // namespace vk
#endif // VK_SEMAPHORE_HPP_