Add runtime scheduler priorities

Summary:
Changelog: [internal]

Add runtime scheduler priorities

Reviewed By: JoshuaGross

Differential Revision: D27618305

fbshipit-source-id: 95e4e02f3473acb41bca0c22df7b271a8d710f34

ReactCommon/react/renderer/runtimescheduler/RuntimeSchedulerBinding.cpp

@@ -6,6 +6,7 @@
  */
 
 #include "RuntimeSchedulerBinding.h"
+#include "SchedulerPriority.h"
 
 #include <memory>
 
@@ -37,8 +38,29 @@ RuntimeSchedulerBinding::createAndInstallIfNeeded(jsi::Runtime &runtime) {
 jsi::Value RuntimeSchedulerBinding::get(
     jsi::Runtime &runtime,
     jsi::PropNameID const &name) {
-  (void)runtime;
-  (void)name;
+  auto propertyName = name.utf8(runtime);
+
+  if (propertyName == "unstable_ImmediatePriority") {
+    return jsi::Value(runtime, serialize(SchedulerPriority::ImmediatePriority));
+  }
+
+  if (propertyName == "unstable_UserBlockingPriority") {
+    return jsi::Value(
+        runtime, serialize(SchedulerPriority::UserBlockingPriority));
+  }
+
+  if (propertyName == "unstable_NormalPriority") {
+    return jsi::Value(runtime, serialize(SchedulerPriority::NormalPriority));
+  }
+
+  if (propertyName == "unstable_LowPriority") {
+    return jsi::Value(runtime, serialize(SchedulerPriority::LowPriority));
+  }
+
+  if (propertyName == "unstable_IdlePriority") {
+    return jsi::Value(runtime, serialize(SchedulerPriority::IdlePriority));
+  }
+
   return jsi::Value::undefined();
 }
 

ReactCommon/react/renderer/runtimescheduler/SchedulerPriority.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+namespace facebook::react {
+
+enum class SchedulerPriority : int {
+  ImmediatePriority = 1,
+  UserBlockingPriority = 2,
+  NormalPriority = 3,
+  LowPriority = 4,
+  IdlePriority = 5,
+};
+
+static constexpr std::underlying_type<SchedulerPriority>::type serialize(
+    SchedulerPriority schedulerPriority) {
+  return static_cast<std::underlying_type<SchedulerPriority>::type>(
+      schedulerPriority);
+}
+
+} // namespace facebook::react