Defensively protect present semaphores

per spec interpretation in
KhronosGroup/Vulkan-Docs#1150

src/HelloTriangle.cpp

@@ -379,7 +379,7 @@ int helloTriangle() try{
  vector<VkCommandBuffer> commandBuffers;
 
  vector<VkSemaphore> imageReadySs;
- VkSemaphore renderDoneS = VK_NULL_HANDLE; // has to be NULL for the case the app ends before even first swapchain
+ vector<VkSemaphore> renderDoneSs;
 
  // workaround for validation layer "memory leak" + might also help the driver to cleanup old resources
  // this should not be needed for a real-word app, because they are likely to use fences naturaly (e.g. responding to user input )
@@ -393,6 +393,9 @@ int helloTriangle() try{
  // swapchain recreation -- will be done before the first frame too;
  TODO( "This may be triggered from many sources (e.g. WM_SIZE event, and VK_ERROR_OUT_OF_DATE_KHR too). Should prevent duplicate swapchain recreation." )
 
+ const VkSwapchainKHR oldSwapchain = swapchain;
+ swapchain = VK_NULL_HANDLE;
+
  VkSurfaceCapabilitiesKHR capabilities = getSurfaceCapabilities( physicalDevice, surface );
 
  if( capabilities.currentExtent.width == UINT32_MAX && capabilities.currentExtent.height == UINT32_MAX ){
@@ -410,16 +413,18 @@ int helloTriangle() try{
  && surfaceSize.height > 0
  };
 
+
  // cleanup old
- if( swapchain ){
+ vector<VkSemaphore> oldImageReadySs = imageReadySs; imageReadySs.clear();
+ if( oldSwapchain ){
  {VkResult errorCode = vkDeviceWaitIdle( device ); RESULT_HANDLER( errorCode, "vkDeviceWaitIdle" );}
 
  // fences might be in unsignaled state, so kill them too to get fresh signaled
  killFences( device, submissionFences );
 
  // semaphores might be in signaled state, so kill them too to get fresh unsignaled
- killSemaphore( device, renderDoneS );
- killSemaphores( device, imageReadySs );
+ killSemaphores( device, renderDoneSs );
+ // kill imageReadySs later when oldSwapchain is destroyed
 
  // only reset + later reuse already allocated and create new only if needed
  {VkResult errorCode = vkResetCommandPool( device, commandPool, 0 ); RESULT_HANDLER( errorCode, "vkResetCommandPool" );}
@@ -428,18 +433,13 @@ int helloTriangle() try{
  killFramebuffers( device, framebuffers );
  killSwapchainImageViews( device, swapchainImageViews );
 
- if( !swapchainCreatable ){
- // we need to wait for size that is compatible with swapchain
- // so just destroy swapchain to conserve resources in the meantime
- killSwapchain( device, swapchain );
- swapchain = VK_NULL_HANDLE;
- }
+ // kill oldSwapchain later, after it is potentially used by vkCreateSwapchainKHR
  }
 
  // creating new
  if( swapchainCreatable ){
  // reuses & destroys the oldSwapchain
- swapchain = initSwapchain( physicalDevice, device, surface, surfaceFormat, capabilities, graphicsQueueFamily, presentQueueFamily, swapchain );
+ swapchain = initSwapchain( physicalDevice, device, surface, surfaceFormat, capabilities, graphicsQueueFamily, presentQueueFamily, oldSwapchain );
 
  vector<VkImage> swapchainImages = enumerate<VkImage>( device, swapchain );
  swapchainImageViews = initSwapchainImageViews( device, swapchainImages, surfaceFormat.format );
@@ -471,12 +471,21 @@ int helloTriangle() try{
  }
 
  imageReadySs = initSemaphores( device, maxInflightSubmissions );
- renderDoneS = initSemaphore( device );
+ // per https://github.com/KhronosGroup/Vulkan-Docs/issues/1150 need upto swapchain-image count
+ renderDoneSs = initSemaphores( device, swapchainImages.size());
 
  submissionFences = initFences( device, maxInflightSubmissions, VK_FENCE_CREATE_SIGNALED_BIT ); // signaled fence means previous execution finished, so we start rendering presignaled
  submissionNr = 0;
  }
 
+ if( oldSwapchain ){
+ killSwapchain( device, oldSwapchain );
+
+ // per current spec, we can't really be sure these are not used :/ at least kill them after the swapchain
+ // https://github.com/KhronosGroup/Vulkan-Docs/issues/152
+ killSemaphores( device, oldImageReadySs );
+ }
+
  return swapchain != VK_NULL_HANDLE;
  };
 
@@ -498,16 +507,16 @@ int helloTriangle() try{
  uint32_t nextSwapchainImageIndex = getNextImageIndex( device, swapchain, imageReadySs[submissionNr] );
  unsafeSemaphore = false;
 
- if( presentQueueFamily != graphicsQueueFamily ) vkQueueWaitIdle( presentQueue ); // in the obscure case of separate present queue, make sure the renderDoneS can be reused; not really worried about perf for this obscure case
- submitToQueue( graphicsQueue, commandBuffers[nextSwapchainImageIndex], imageReadySs[submissionNr], renderDoneS, submissionFences[submissionNr] );
- present( presentQueue, swapchain, nextSwapchainImageIndex, renderDoneS );
+ submitToQueue( graphicsQueue, commandBuffers[nextSwapchainImageIndex], imageReadySs[submissionNr], renderDoneSs[nextSwapchainImageIndex], submissionFences[submissionNr] );
+ present( presentQueue, swapchain, nextSwapchainImageIndex, renderDoneSs[nextSwapchainImageIndex] );
 
  submissionNr = (submissionNr + 1) % maxInflightSubmissions;
  }
  catch( VulkanResultException ex ){
  if( ex.result == VK_SUBOPTIMAL_KHR || ex.result == VK_ERROR_OUT_OF_DATE_KHR ){
  if( unsafeSemaphore && ex.result == VK_SUBOPTIMAL_KHR ){
  cleanupUnsafeSemaphore( graphicsQueue, imageReadySs[submissionNr] );
+ // no way to sanitize vkQueuePresentKHR semaphores, really
  }
  recreateSwapchain();
 
@@ -533,8 +542,8 @@ int helloTriangle() try{
 
 
  // kill swapchain
- killSemaphore( device, renderDoneS );
- killSemaphores( device, imageReadySs );
+ killSemaphores( device, renderDoneSs );
+ // imageReadySs killed after the swapchain
 
  // command buffers killed with pool
 
@@ -545,6 +554,10 @@ int helloTriangle() try{
  killSwapchainImageViews( device, swapchainImageViews );
  killSwapchain( device, swapchain );
 
+ // per current spec, we can't really be sure these are not used :/ at least kill them after the swapchain
+ // https://github.com/KhronosGroup/Vulkan-Docs/issues/152
+ killSemaphores( device, imageReadySs );
+
 
  // kill vulkan
  killFences( device, submissionFences );
@@ -1248,8 +1261,6 @@ VkSwapchainKHR initSwapchain(
  VkSwapchainKHR swapchain;
  VkResult errorCode = vkCreateSwapchainKHR( device, &swapchainInfo, nullptr, &swapchain ); RESULT_HANDLER( errorCode, "vkCreateSwapchainKHR" );
 
- killSwapchain( device, oldSwapchain );
-
  return swapchain;
 }