From bd441b3c5e2909130f710a60c52a79cd48f2c5a1 Mon Sep 17 00:00:00 2001
From: jonahwilliams <jonahwilliams@google.com>
Date: Fri, 28 Jul 2023 15:24:30 -0700
Subject: [PATCH 1/2] [Impeller] revert removal of wait until scheduled.

---
 .../renderer/backend/metal/surface_mtl.mm     | 32 ++++---------------
 1 file changed, 7 insertions(+), 25 deletions(-)

diff --git a/impeller/renderer/backend/metal/surface_mtl.mm b/impeller/renderer/backend/metal/surface_mtl.mm
index 450302d89da98..80b973d7ef6e1 100644
--- a/impeller/renderer/backend/metal/surface_mtl.mm
+++ b/impeller/renderer/backend/metal/surface_mtl.mm
@@ -218,20 +218,6 @@
   return IRect::MakeSize(resolve_texture_->GetSize());
 }
 
-static bool ShouldWaitForCommandBuffer() {
-#if ((FML_OS_MACOSX && !FML_OS_IOS) || FML_OS_IOS_SIMULATOR)
-  // If a transaction is present, `presentDrawable` will present too early. And
-  // so we wait on an empty command buffer to get scheduled instead, which
-  // forces us to also wait for all of the previous command buffers in the queue
-  // to get scheduled.
-  return true;
-#else
-  // On Physical iOS devices we still need to wait if we're taking a frame
-  // capture.
-  return [[MTLCaptureManager sharedCaptureManager] isCapturing];
-#endif  // ((FML_OS_MACOSX && !FML_OS_IOS) || FML_OS_IOS_SIMULATOR)
-}
-
 // |Surface|
 bool SurfaceMTL::Present() const {
   auto context = context_.lock();
@@ -262,17 +248,13 @@ static bool ShouldWaitForCommandBuffer() {
   }
 
   if (drawable_) {
-    // In certain situations, we need to wait until the command queue has been
-    // flushed before presenting to the onscreen texture. See the comments in
-    // `ShouldWaitForCommandBuffer` for more details.
-    if (ShouldWaitForCommandBuffer()) {
-      id<MTLCommandBuffer> command_buffer =
-          ContextMTL::Cast(context.get())
-              ->CreateMTLCommandBuffer("Present Waiter Command Buffer");
-      [command_buffer commit];
-      [command_buffer waitUntilScheduled];
-    }
-    [drawable_ present];
+    TRACE_EVENT0("flutter", "waitUntilScheduled");
+    id<MTLCommandBuffer> command_buffer =
+        ContextMTL::Cast(context.get())
+            ->CreateMTLCommandBuffer("Present Waiter Command Buffer");
+    [command_buffer presentDrawable:drawable_];
+
+    [command_buffer commit];
   }
 
   return true;

From ca65e8d2ff336faa4b20d885d568336b9ea49308 Mon Sep 17 00:00:00 2001
From: jonahwilliams <jonahwilliams@google.com>
Date: Fri, 28 Jul 2023 15:25:32 -0700
Subject: [PATCH 2/2] ++

---
 impeller/renderer/backend/metal/surface_mtl.mm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/impeller/renderer/backend/metal/surface_mtl.mm b/impeller/renderer/backend/metal/surface_mtl.mm
index 80b973d7ef6e1..526e66f4c5ff5 100644
--- a/impeller/renderer/backend/metal/surface_mtl.mm
+++ b/impeller/renderer/backend/metal/surface_mtl.mm
@@ -252,9 +252,9 @@
     id<MTLCommandBuffer> command_buffer =
         ContextMTL::Cast(context.get())
             ->CreateMTLCommandBuffer("Present Waiter Command Buffer");
-    [command_buffer presentDrawable:drawable_];
-
     [command_buffer commit];
+    [command_buffer waitUntilScheduled];
+    [drawable_ present];
   }
 
   return true;