From 142a8ecfaa7f64bf921b55821bfc996383254b49 Mon Sep 17 00:00:00 2001
From: Pablo Baxter <pablobaxter@msn.com>
Date: Thu, 1 Sep 2022 21:33:38 -0700
Subject: [PATCH] Ensure `awaitFrame()` only awaits a single frame when used
 from the main thread

---
 ui/kotlinx-coroutines-android/src/HandlerDispatcher.kt   | 9 ++++++---
 .../test/HandlerDispatcherTest.kt                        | 6 +++---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/ui/kotlinx-coroutines-android/src/HandlerDispatcher.kt b/ui/kotlinx-coroutines-android/src/HandlerDispatcher.kt
index 5e33169dd1..91cd2abe98 100644
--- a/ui/kotlinx-coroutines-android/src/HandlerDispatcher.kt
+++ b/ui/kotlinx-coroutines-android/src/HandlerDispatcher.kt
@@ -190,11 +190,14 @@ public suspend fun awaitFrame(): Long {
             postFrameCallback(choreographer, cont)
         }
     }
-    // post into looper thread to figure it out
     return suspendCancellableCoroutine { cont ->
-        Dispatchers.Main.dispatch(EmptyCoroutineContext, Runnable {
+        if (Looper.myLooper() === Looper.getMainLooper()) { // Check if we are already in the main looper thread
             updateChoreographerAndPostFrameCallback(cont)
-        })
+        } else { // post into looper thread to figure it out
+            Dispatchers.Main.dispatch(EmptyCoroutineContext, Runnable {
+                updateChoreographerAndPostFrameCallback(cont)
+            })
+        }
     }
 }
 
diff --git a/ui/kotlinx-coroutines-android/test/HandlerDispatcherTest.kt b/ui/kotlinx-coroutines-android/test/HandlerDispatcherTest.kt
index fe97ae8d27..c016f35533 100644
--- a/ui/kotlinx-coroutines-android/test/HandlerDispatcherTest.kt
+++ b/ui/kotlinx-coroutines-android/test/HandlerDispatcherTest.kt
@@ -109,14 +109,14 @@ class HandlerDispatcherTest : TestBase() {
         launch(Dispatchers.Main, start = CoroutineStart.UNDISPATCHED) {
             expect(1)
             awaitFrame()
-            expect(5)
+            expect(3)
         }
         expect(2)
         // Run choreographer detection
         mainLooper.runOneTask()
-        expect(3)
-        mainLooper.scheduler.advanceBy(50, TimeUnit.MILLISECONDS)
         expect(4)
+        mainLooper.scheduler.advanceBy(50, TimeUnit.MILLISECONDS)
+        expect(5)
         mainLooper.scheduler.advanceBy(51, TimeUnit.MILLISECONDS)
         finish(6)
     }