From ac5c3e77c39d9726ec6c91d60ba1fae73283e11e Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Fri, 17 Jun 2022 11:26:59 -0700
Subject: [PATCH] jonahs feedback - faster smaller messages

---
 .../window/platform_message_response_dart.cc  | 40 ++++++++++---------
 .../tonic/typed_data/dart_byte_data.cc        | 10 ++---
 third_party/tonic/typed_data/dart_byte_data.h |  1 +
 3 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/lib/ui/window/platform_message_response_dart.cc b/lib/ui/window/platform_message_response_dart.cc
index a6b19d04e9efd..c1551cd1ef0b9 100644
--- a/lib/ui/window/platform_message_response_dart.cc
+++ b/lib/ui/window/platform_message_response_dart.cc
@@ -69,26 +69,28 @@ PlatformMessageResponseDart::~PlatformMessageResponseDart() {
 }
 
 void PlatformMessageResponseDart::Complete(std::unique_ptr<fml::Mapping> data) {
-  PostCompletion(std::move(callback_), ui_task_runner_, &is_complete_, channel_,
-                 [data = std::move(data)]() mutable {
-                   void* mapping = data->GetMutableMapping();
-                   Dart_Handle byte_buffer;
-                   if (mapping) {
-                     size_t data_size = data->GetSize();
-                     byte_buffer = Dart_NewExternalTypedDataWithFinalizer(
-                         /*type=*/Dart_TypedData_kByteData,
-                         /*data=*/mapping,
-                         /*length=*/data_size,
-                         /*peer=*/data.release(),
-                         /*external_allocation_size=*/data_size,
-                         /*callback=*/MappingFinalizer);
+  PostCompletion(
+      std::move(callback_), ui_task_runner_, &is_complete_, channel_,
+      [data = std::move(data)]() mutable {
+        void* mapping = data->GetMutableMapping();
+        Dart_Handle byte_buffer;
+        size_t data_size = data->GetSize();
+        if (mapping &&
+            data_size >= tonic::DartByteData::kExternalSizeThreshold) {
+          byte_buffer = Dart_NewExternalTypedDataWithFinalizer(
+              /*type=*/Dart_TypedData_kByteData,
+              /*data=*/mapping,
+              /*length=*/data_size,
+              /*peer=*/data.release(),
+              /*external_allocation_size=*/data_size,
+              /*callback=*/MappingFinalizer);
 
-                   } else {
-                     byte_buffer = tonic::DartByteData::Create(
-                         data->GetMapping(), data->GetSize());
-                   }
-                   return byte_buffer;
-                 });
+        } else {
+          byte_buffer =
+              tonic::DartByteData::Create(data->GetMapping(), data->GetSize());
+        }
+        return byte_buffer;
+      });
 }
 
 void PlatformMessageResponseDart::CompleteEmpty() {
diff --git a/third_party/tonic/typed_data/dart_byte_data.cc b/third_party/tonic/typed_data/dart_byte_data.cc
index cab038d14f85d..f4a557f17e946 100644
--- a/third_party/tonic/typed_data/dart_byte_data.cc
+++ b/third_party/tonic/typed_data/dart_byte_data.cc
@@ -11,17 +11,15 @@
 namespace tonic {
 
 namespace {
-
-// For large objects it is more efficient to use an external typed data object
-// with a buffer allocated outside the Dart heap.
-const int kExternalSizeThreshold = 1000;
-
 void FreeFinalizer(void* isolate_callback_data, void* peer) {
   free(peer);
 }
-
 }  // anonymous namespace
 
+// For large objects it is more efficient to use an external typed data object
+// with a buffer allocated outside the Dart heap.
+const size_t DartByteData::kExternalSizeThreshold = 1000;
+
 Dart_Handle DartByteData::Create(const void* data, size_t length) {
   if (length < kExternalSizeThreshold) {
     auto handle = DartByteData{data, length}.dart_handle();
diff --git a/third_party/tonic/typed_data/dart_byte_data.h b/third_party/tonic/typed_data/dart_byte_data.h
index 9e14bc969fb8e..911d0d5da0d7e 100644
--- a/third_party/tonic/typed_data/dart_byte_data.h
+++ b/third_party/tonic/typed_data/dart_byte_data.h
@@ -14,6 +14,7 @@ namespace tonic {
 
 class DartByteData {
  public:
+  static const size_t kExternalSizeThreshold;
   static Dart_Handle Create(const void* data, size_t length);
 
   explicit DartByteData(Dart_Handle list);