vulkan: Add a pipeline cache

Make the display handle the cache, because we only need one.

We store the cache in
  $CACHE_DIR/gtk-4.0/vulkan-pipeline-cache/$UUID.$VERSION
so we regenerate caches for each different device (different UUID) and
each different driver version.

We also keep track of the etag of the cache file, so if 2 different
applications update the cache, we can detect that.
Vulkan allows merging caches, so the 2nd app reloads the new cache file
and merges it into its cache before saving.

gdk/gdkdisplayprivate.h

@@ -100,6 +100,10 @@ struct _GdkDisplay
   VkDevice vk_device;
   VkQueue vk_queue;
   uint32_t vk_queue_family_index;
+  VkPipelineCache vk_pipeline_cache;
+  gsize vk_pipeline_cache_size;
+  char *vk_pipeline_cache_etag;
+  guint vk_save_pipeline_cache_source;
 
   guint vulkan_refcount;
 #endif /* GDK_RENDERING_VULKAN */

gdk/gdkvulkancontext.c

@@ -931,6 +931,216 @@ gdk_vulkan_context_get_queue_family_index (GdkVulkanContext *context)
   return gdk_draw_context_get_display (GDK_DRAW_CONTEXT (context))->vk_queue_family_index;
 }
 
+static char *
+gdk_vulkan_get_pipeline_cache_dirname (void)
+{
+  return g_build_filename (g_get_user_cache_dir (), "gtk-4.0", "vulkan-pipeline-cache", NULL);
+}
+
+static GFile *
+gdk_vulkan_get_pipeline_cache_file (GdkDisplay *display)
+{
+  VkPhysicalDeviceProperties props;
+  char *dirname, *basename, *path;
+  GFile *result;
+
+  vkGetPhysicalDeviceProperties (display->vk_physical_device, &props);
+
+  dirname = gdk_vulkan_get_pipeline_cache_dirname ();
+  basename = g_strdup_printf ("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x"
+                              "-%02x%02x%02x%02x%02x%02x.%u",
+                              props.pipelineCacheUUID[0], props.pipelineCacheUUID[1],
+                              props.pipelineCacheUUID[2], props.pipelineCacheUUID[3],
+                              props.pipelineCacheUUID[4], props.pipelineCacheUUID[5],
+                              props.pipelineCacheUUID[6], props.pipelineCacheUUID[7],
+                              props.pipelineCacheUUID[8], props.pipelineCacheUUID[9],
+                              props.pipelineCacheUUID[10], props.pipelineCacheUUID[11],
+                              props.pipelineCacheUUID[12], props.pipelineCacheUUID[13],
+                              props.pipelineCacheUUID[14], props.pipelineCacheUUID[15],
+                              props.driverVersion);
+
+  path = g_build_filename (dirname, basename, NULL);
+  result = g_file_new_for_path (path);
+
+  g_free (path);
+  g_free (basename);
+  g_free (dirname);
+
+  return result;
+}
+
+static VkPipelineCache
+gdk_display_load_pipeline_cache (GdkDisplay *display)
+{
+  GError *error = NULL;
+  VkPipelineCache result;
+  GFile *cache_file;
+  char *etag, *data;
+  gsize size;
+
+  cache_file = gdk_vulkan_get_pipeline_cache_file (display);
+  if (!g_file_load_contents (cache_file, NULL, &data, &size, &etag, &error))
+    {
+      GDK_DEBUG (VULKAN, "failed to load Vulkan pipeline cache file '%s': %s\n",
+                 g_file_peek_path (cache_file), error->message);
+      g_object_unref (cache_file);
+      g_clear_error (&error);
+      return VK_NULL_HANDLE;
+    }
+
+  if (GDK_VK_CHECK (vkCreatePipelineCache, display->vk_device,
+                                           &(VkPipelineCacheCreateInfo) {
+                                             .sType = VK_STRUCTURE_TYPE_PIPELINE_CACHE_CREATE_INFO,
+                                             .initialDataSize = size,
+                                             .pInitialData = data,
+                                           },
+                                           NULL,
+                                           &result) != VK_SUCCESS)
+    result = VK_NULL_HANDLE;
+
+  g_free (data);
+  g_free (display->vk_pipeline_cache_etag);
+  display->vk_pipeline_cache_etag = etag;
+  display->vk_pipeline_cache_size = size;
+
+  return result;
+}
+
+static gboolean
+gdk_vulkan_save_pipeline_cache (GdkDisplay *display)
+{
+  GError *error = NULL;
+  VkDevice device;
+  VkPipelineCache cache;
+  GFile *file;
+  char *path;
+  size_t size;
+  char *data, *etag;
+
+  device = display->vk_device;
+  cache = display->vk_pipeline_cache;
+
+  GDK_VK_CHECK (vkGetPipelineCacheData, device, cache, &size, NULL);
+  if (size == 0)
+    return TRUE;
+  
+  if (size == display->vk_pipeline_cache_size)
+    {
+      GDK_DEBUG (VULKAN, "pipeline cache size (%zu bytes) unchanged, skipping save", size);
+      return TRUE;
+    }
+
+
+  data = g_malloc (size);
+  if (GDK_VK_CHECK (vkGetPipelineCacheData, device, cache, &size, data) != VK_SUCCESS)
+    {
+      g_free (data);
+      return FALSE;
+    }
+
+  path = gdk_vulkan_get_pipeline_cache_dirname ();
+  if (g_mkdir_with_parents (path, 0755) != 0)
+    {
+      g_warning_once ("Failed to create pipeline cache directory");
+      g_free (path);
+      return FALSE;
+    }
+  g_free (path);
+
+  file = gdk_vulkan_get_pipeline_cache_file (display);
+
+  GDK_DEBUG (VULKAN, "Saving pipeline cache to %s", g_file_peek_path (file));
+
+  if (!g_file_replace_contents (file,
+                                data,
+                                size,
+                                display->vk_pipeline_cache_etag,
+                                FALSE,
+                                0,
+                                &etag,
+                                NULL,
+                                &error))
+    {
+      if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_WRONG_ETAG))
+        {
+          VkPipelineCache new_cache;
+          
+          GDK_DEBUG (VULKAN, "Pipeline cache file modified, merging into current");
+          new_cache = gdk_display_load_pipeline_cache (display);
+          if (new_cache)
+            {
+              GDK_VK_CHECK (vkMergePipelineCaches, device, cache, 1, &new_cache);
+              vkDestroyPipelineCache (device, new_cache, NULL);
+            }
+          else
+            {
+              g_clear_pointer (&display->vk_pipeline_cache_etag, g_free);
+            }
+          g_clear_error (&error);
+          g_object_unref (file);
+
+          /* try again */
+          return gdk_vulkan_save_pipeline_cache (display);
+        }
+
+      g_warning ("Failed to save pipeline cache: %s", error->message);
+      g_clear_error (&error);
+      g_object_unref (file);
+      return FALSE;
+    }
+
+  g_object_unref (file);
+  g_free (display->vk_pipeline_cache_etag);
+  display->vk_pipeline_cache_etag = etag;
+
+  return TRUE;
+}
+
+static gboolean
+gdk_vulkan_save_pipeline_cache_cb (gpointer data)
+{
+  GdkDisplay *display = data;
+
+  gdk_vulkan_save_pipeline_cache (display);
+
+  display->vk_save_pipeline_cache_source = 0;
+  return G_SOURCE_REMOVE;
+}
+
+void
+gdk_vulkan_context_pipeline_cache_updated (GdkVulkanContext *self)
+{
+  GdkDisplay *display = gdk_draw_context_get_display (GDK_DRAW_CONTEXT (self));
+
+  g_clear_handle_id (&display->vk_save_pipeline_cache_source, g_source_remove);
+  display->vk_save_pipeline_cache_source = g_timeout_add_seconds_full (G_PRIORITY_DEFAULT_IDLE - 10,
+                                                                       10, /* random choice that is not now */
+                                                                       gdk_vulkan_save_pipeline_cache_cb,
+                                                                       display,
+                                                                       NULL);
+}
+
+static void
+gdk_display_create_pipeline_cache (GdkDisplay *display)
+{
+  display->vk_pipeline_cache = gdk_display_load_pipeline_cache (display);
+
+  GDK_VK_CHECK (vkCreatePipelineCache, display->vk_device,
+                                       &(VkPipelineCacheCreateInfo) {
+                                         .sType = VK_STRUCTURE_TYPE_PIPELINE_CACHE_CREATE_INFO,
+                                       },
+                                       NULL,
+                                       &display->vk_pipeline_cache);
+}
+
+VkPipelineCache
+gdk_vulkan_context_get_pipeline_cache (GdkVulkanContext *self)
+{
+  g_return_val_if_fail (GDK_IS_VULKAN_CONTEXT (self), NULL);
+
+  return gdk_draw_context_get_display (GDK_DRAW_CONTEXT (self))->vk_pipeline_cache;
+}
+
 /**
  * gdk_vulkan_context_get_image_format:
  * @context: a `GdkVulkanContext`
@@ -1381,6 +1591,8 @@ gdk_display_create_vulkan_instance (GdkDisplay  *display,
       return FALSE;
     }
 
+  gdk_display_create_pipeline_cache (display);
+
   return TRUE;
 }
 
@@ -1409,6 +1621,16 @@ gdk_display_unref_vulkan (GdkDisplay *display)
   if (display->vulkan_refcount > 0)
     return;
 
+  if (display->vk_save_pipeline_cache_source)
+    {
+      gdk_vulkan_save_pipeline_cache_cb (display);
+      g_assert (display->vk_save_pipeline_cache_source == 0);
+    }
+  vkDestroyPipelineCache (display->vk_device, display->vk_pipeline_cache, NULL);
+  display->vk_device = VK_NULL_HANDLE;
+  g_clear_pointer (&display->vk_pipeline_cache_etag, g_free);
+  display->vk_pipeline_cache_size = 0;
+
   vkDestroyDevice (display->vk_device, NULL);
   display->vk_device = VK_NULL_HANDLE;
   if (display->vk_debug_callback != VK_NULL_HANDLE)

gdk/gdkvulkancontextprivate.h

@@ -73,6 +73,9 @@ gboolean                gdk_display_ref_vulkan                          (GdkDisp
                                                                          GError               **error);
 void                    gdk_display_unref_vulkan                        (GdkDisplay            *display);
 
+VkPipelineCache         gdk_vulkan_context_get_pipeline_cache           (GdkVulkanContext      *self);
+void                    gdk_vulkan_context_pipeline_cache_updated       (GdkVulkanContext      *self);
+
 GdkMemoryFormat         gdk_vulkan_context_get_offscreen_format         (GdkVulkanContext      *context,
                                                                          GdkMemoryDepth         depth);
 

gsk/vulkan/gskvulkanpipeline.c

@@ -5,6 +5,8 @@
 #include "gskvulkanpushconstantsprivate.h"
 #include "gskvulkanshaderprivate.h"
 
+#include "gdk/gdkvulkancontextprivate.h"
+
 #include <graphene.h>
 
 typedef struct _GskVulkanPipelinePrivate GskVulkanPipelinePrivate;
@@ -87,7 +89,7 @@ gsk_vulkan_pipeline_new (GType             pipeline_type,
   priv->vertex_stride = vertex_input_state->pVertexBindingDescriptions[0].stride;
 
   GSK_VK_CHECK (vkCreateGraphicsPipelines, device,
-                                           VK_NULL_HANDLE,
+                                           gdk_vulkan_context_get_pipeline_cache (context),
                                            1,
                                            &(VkGraphicsPipelineCreateInfo) {
                                                .sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO,
@@ -160,6 +162,8 @@ gsk_vulkan_pipeline_new (GType             pipeline_type,
                                            NULL,
                                            &priv->pipeline);
 
+  gdk_vulkan_context_pipeline_cache_updated (context);
+
   return self;
 }