[Impeller] Compute in Vulkan

impeller/renderer/backend/vulkan/command_buffer_vk.cc

@@ -48,12 +48,15 @@ const std::shared_ptr<CommandEncoderVK>& CommandBufferVK::GetEncoder() const {
 }
 
 bool CommandBufferVK::OnSubmitCommands(CompletionCallback callback) {
-  const auto submit = encoder_->Submit();
-  if (callback) {
-    callback(submit ? CommandBuffer::Status::kCompleted
-                    : CommandBuffer::Status::kError);
+  if (!callback) {
+    return encoder_->Submit();
   }
-  return submit;
+  return encoder_->Submit([callback](bool submit) {
+    if (!submit) {
+      callback(CommandBuffer::Status::kError);
+    }
+    callback(CommandBuffer::Status::kCompleted);
+  });
 }
 
 void CommandBufferVK::OnWaitUntilScheduled() {}

impeller/renderer/backend/vulkan/command_encoder_vk.cc

@@ -124,13 +124,23 @@ bool CommandEncoderVK::IsValid() const {
   return is_valid_;
 }
 
-bool CommandEncoderVK::Submit() {
+bool CommandEncoderVK::Submit(SubmitCallback callback) {
+  // Make sure to call callback with `false` if anything returns early.
+  bool fail_callback = !!callback;
   if (!IsValid()) {
+    if (fail_callback) {
+      callback(false);
+    }
     return false;
   }
 
   // Success or failure, you only get to submit once.
-  fml::ScopedCleanupClosure reset([&]() { Reset(); });
+  fml::ScopedCleanupClosure reset([&]() {
+    if (fail_callback) {
+      callback(false);
+    }
+    Reset();
+  });
 
   InsertDebugMarker("QueueSubmit");
 
@@ -155,10 +165,16 @@ bool CommandEncoderVK::Submit() {
     return false;
   }
 
+  // Submit will proceed, call callback with true when it is done and do not
+  // call when `reset` is collected.
+  fail_callback = false;
+
   return fence_waiter_->AddFence(
-      std::move(fence), [tracked_objects = std::move(tracked_objects_)] {
-        // Nothing to do, we just drop the tracked
-        // objects on the floor.
+      std::move(fence),
+      [callback, tracked_objects = std::move(tracked_objects_)] {
+        if (callback) {
+          callback(true);
+        }
       });
 }
 

impeller/renderer/backend/vulkan/command_encoder_vk.h

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <functional>
 #include <optional>
 #include <set>
 
@@ -32,11 +33,13 @@ class FenceWaiterVK;
 
 class CommandEncoderVK {
  public:
+  using SubmitCallback = std::function<void(bool)>;
+
   ~CommandEncoderVK();
 
   bool IsValid() const;
 
-  bool Submit();
+  bool Submit(SubmitCallback callback = {});
 
   bool Track(std::shared_ptr<SharedObjectVK> object);