A Vulkan fence that can be exported as a platform specific file descriptor. More...

#include <external_fence_vk.h>

Public Member Functions
	ExternalFenceVK (const std::shared_ptr< Context > &context)
	Create a new un-signaled fence that can be exported as a sync file descriptor. More...

	~ExternalFenceVK ()

	ExternalFenceVK (const ExternalFenceVK &)=delete

ExternalFenceVK &	operator= (const ExternalFenceVK &)=delete

bool	IsValid () const
	If a valid fence could be created. More...

fml::UniqueFD	CreateFD () const
	Create a new sync file descriptor for the underlying fence. The fence must already be signaled or have a signal operation pending in a queue. There are no checks for this in the implementation and only Vulkan validation will catch such a misuse and undefined behavior. More...

const vk::Fence &	GetHandle () const

const SharedHandleVK< vk::Fence > &	GetSharedHandle () const

Detailed Description

A Vulkan fence that can be exported as a platform specific file descriptor.

The fences are exported as sync file descriptors.

Warning: Only fences that have been signaled or have a single operation pending can be exported. Make sure to submit a fence signalling operation to a queue before attempted to obtain a file descriptor for the fence. See VUID-VkFenceGetFdInfoKHR-handleType-01454 for additional details on the implementation.

Definition at line 28 of file external_fence_vk.h.

Constructor & Destructor Documentation

◆ ExternalFenceVK() [1/2]

impeller::ExternalFenceVK::ExternalFenceVK ( const std::shared_ptr< Context > & context )

explicit

Create a new un-signaled fence that can be exported as a sync file descriptor.

Parameters

[in] context The device context.

Definition at line 12 of file external_fence_vk.cc.

                                                                       {
   if (!context) {
     return;
   }
   vk::StructureChain<vk::FenceCreateInfo, vk::ExportFenceCreateInfoKHR> info;
  
   info.get<vk::ExportFenceCreateInfoKHR>().handleTypes =
       vk::ExternalFenceHandleTypeFlagBits::eSyncFd;
  
   const auto& context_vk = ContextVK::Cast(*context);
   auto [result, fence] = context_vk.GetDevice().createFenceUnique(info.get());
   if (result != vk::Result::eSuccess) {
     VALIDATION_LOG << "Could not create external fence: "
                    << vk::to_string(result);
     return;
   }
  
   context_vk.SetDebugName(fence.get(), "ExternalFenceSyncFD");
  
   fence_ = MakeSharedVK(std::move(fence));
 }

References impeller::BackendCast< ContextVK, Context >::Cast(), impeller::MakeSharedVK(), and VALIDATION_LOG.

◆ ~ExternalFenceVK()

impeller::ExternalFenceVK::~ExternalFenceVK ( )

default

◆ ExternalFenceVK() [2/2]

impeller::ExternalFenceVK::ExternalFenceVK ( const ExternalFenceVK & )

delete

Member Function Documentation

◆ CreateFD()

fml::UniqueFD impeller::ExternalFenceVK::CreateFD ( ) const

Create a new sync file descriptor for the underlying fence. The fence must already be signaled or have a signal operation pending in a queue. There are no checks for this in the implementation and only Vulkan validation will catch such a misuse and undefined behavior.

Warning: Implementations are also allowed to return invalid file descriptors in case a fence has already been signaled. So it is not necessary an error to obtain an invalid descriptor from this call. For APIs that are meant to consume such descriptors, pass -1 as the file handle.

Since this call can return an invalid FD even in case of success, make sure to make the IsValid check before attempting to export a FD.

Returns: A (potentially invalid even in case of success) file descriptor.

Definition at line 40 of file external_fence_vk.cc.

                                             {
   if (!IsValid()) {
     return {};
   }
   vk::FenceGetFdInfoKHR info;
   info.fence = fence_->Get();
   info.handleType = vk::ExternalFenceHandleTypeFlagBits::eSyncFd;
   auto [result, fd] = fence_->GetUniqueWrapper().getOwner().getFenceFdKHR(info);
   if (result != vk::Result::eSuccess) {
     VALIDATION_LOG << "Could not export external fence FD: "
                    << vk::to_string(result);
     return {};
   }
   return fml::UniqueFD{fd};
 }

References IsValid(), and VALIDATION_LOG.

◆ GetHandle()

const vk::Fence & impeller::ExternalFenceVK::GetHandle ( ) const

Definition at line 56 of file external_fence_vk.cc.

                                                 {
   return fence_->Get();
 }

◆ GetSharedHandle()

const SharedHandleVK< vk::Fence > & impeller::ExternalFenceVK::GetSharedHandle ( ) const

Definition at line 60 of file external_fence_vk.cc.

                                                                       {
   return fence_;
 }

◆ IsValid()

bool impeller::ExternalFenceVK::IsValid ( ) const

If a valid fence could be created.

Returns: True if valid, False otherwise.

Definition at line 36 of file external_fence_vk.cc.

                                     {
   return !!fence_;
 }

Referenced by CreateFD().

◆ operator=()

ExternalFenceVK& impeller::ExternalFenceVK::operator= ( const ExternalFenceVK & )