commit f46779fe014ba78478d0a0a88b3fd654d635f18b
author Sunny Goyal <sunnygoyal@google.com> Thu May 31 14:04:59 2018 -0700
committer Sunny Goyal <sunnygoyal@google.com> Thu May 31 14:12:52 2018 -0700
tree fd8686335fd9beb61be3c8c814021b6822af7971
parent f4392dbf5aa43140a84f357537f0b22decd42946

Do not run StateHandler code while holding the lock

Deadlock:
Main thread:
  InternalStateHandler.run() =>
  	 LauncherFrameDrawn =>
  	 Switch MotionEventQueue to Main thread =>
  	 Try to acquire MotionEventQueue lock while holding InternalStateHandler lock

Remote UI thread
  Recents Animation cancel on MotionEventQueue =>
     Cancel SwipeHandler =>
     Clear previously registered InternalStateHandler =>
     Try to acquire InternalStateHandler lock while holding MotionEventQueue lock

Bug: 80536505
Change-Id: I75e522edea2a76f8bc90e8abc2a174583cc709c4

src/com/android/launcher3/states/InternalStateHandler.java

diff --git a/src/com/android/launcher3/states/InternalStateHandler.java b/src/com/android/launcher3/states/InternalStateHandler.java
index cf7c6ba..c6370c5 100644
--- a/src/com/android/launcher3/states/InternalStateHandler.java
+++ b/src/com/android/launcher3/states/InternalStateHandler.java
@@ -96,10 +96,12 @@
         private WeakReference<InternalStateHandler> mPendingHandler = new WeakReference<>(null);
         private MainThreadExecutor mMainThreadExecutor;
 
-        public synchronized void schedule(InternalStateHandler handler) {
-            mPendingHandler = new WeakReference<>(handler);
-            if (mMainThreadExecutor == null) {
-                mMainThreadExecutor = new MainThreadExecutor();
+        public void schedule(InternalStateHandler handler) {
+            synchronized (this) {
+                mPendingHandler = new WeakReference<>(handler);
+                if (mMainThreadExecutor == null) {
+                    mMainThreadExecutor = new MainThreadExecutor();
+                }
             }
             mMainThreadExecutor.execute(this);
         }
@@ -118,23 +120,25 @@
             initIfPending(launcher, launcher.isStarted());
         }
 
-        public synchronized boolean initIfPending(Launcher launcher, boolean alreadyOnHome) {
+        public boolean initIfPending(Launcher launcher, boolean alreadyOnHome) {
             InternalStateHandler pendingHandler = mPendingHandler.get();
             if (pendingHandler != null) {
                 if (!pendingHandler.init(launcher, alreadyOnHome)) {
-                    mPendingHandler.clear();
+                    clearReference(pendingHandler);
                 }
                 return true;
             }
             return false;
         }
 
-        public synchronized boolean clearReference(InternalStateHandler handler) {
-            if (mPendingHandler.get() == handler) {
-                mPendingHandler.clear();
-                return true;
+        public boolean clearReference(InternalStateHandler handler) {
+            synchronized (this) {
+                if (mPendingHandler.get() == handler) {
+                    mPendingHandler.clear();
+                    return true;
+                }
+                return false;
             }
-            return false;
         }
 
         public boolean hasPending() {