From 78aef38bfa6865b409b30ce143c50635f93b3cc3 Mon Sep 17 00:00:00 2001
From: Andrew Clark <acdlite@fb.com>
Date: Fri, 28 Oct 2016 11:44:52 -0700
Subject: [PATCH] Add config to enable sync scheduling by default

I'll turn this on in ReactDOMFiber once I figure out batchedUpdates.
---
 src/renderers/shared/fiber/ReactFiberReconciler.js | 3 ++-
 src/renderers/shared/fiber/ReactFiberScheduler.js  | 5 ++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/renderers/shared/fiber/ReactFiberReconciler.js b/src/renderers/shared/fiber/ReactFiberReconciler.js
index d5995a3c65..d86c4946d4 100644
--- a/src/renderers/shared/fiber/ReactFiberReconciler.js
+++ b/src/renderers/shared/fiber/ReactFiberReconciler.js
@@ -56,8 +56,9 @@ export type HostConfig<T, P, I, TI, C> = {
   removeChild(parentInstance : I, child : I | TI) : void,
 
   scheduleAnimationCallback(callback : () => void) : void,
-  scheduleDeferredCallback(callback : (deadline : Deadline) => void) : void
+  scheduleDeferredCallback(callback : (deadline : Deadline) => void) : void,
 
+  useSyncScheduling ?: boolean,
 };
 
 type OpaqueNode = Fiber;
diff --git a/src/renderers/shared/fiber/ReactFiberScheduler.js b/src/renderers/shared/fiber/ReactFiberScheduler.js
index ab83161fde..139fe9d8bf 100644
--- a/src/renderers/shared/fiber/ReactFiberScheduler.js
+++ b/src/renderers/shared/fiber/ReactFiberScheduler.js
@@ -62,11 +62,14 @@ module.exports = function<T, P, I, TI, C>(config : HostConfig<T, P, I, TI, C>) {
 
   const scheduleAnimationCallback = config.scheduleAnimationCallback;
   const scheduleDeferredCallback = config.scheduleDeferredCallback;
+  const useSyncScheduling = config.useSyncScheduling;
 
   // The priority level to use when scheduling an update.
   let priorityContext : (PriorityLevel | null) = null;
   // The priority level to use if there is no priority context.
-  let defaultPriorityContext : PriorityLevel = LowPriority;
+  let defaultPriorityContext : PriorityLevel = useSyncScheduling ?
+    SynchronousPriority :
+    LowPriority;
 
   // The next work in progress fiber that we're currently working on.
   let nextUnitOfWork : ?Fiber = null;