From c8525ecbe3863f8d6dc17a688dbb9668597c4a8a Mon Sep 17 00:00:00 2001
From: Robert Snoeberger <snoeberger@google.com>
Date: Mon, 20 Jul 2020 14:18:08 -0400
Subject: [PATCH] Prevent NotificationSwipeHelper from retaining notification

It has been observed that NotificationSwipeHelper can retain an
ExpandableNotificationRow in memory after the notification has been
dismissed. To prevent this, this change breaks the reference chain
between the NotificationSwipeHelper and the NotificationMenuRow. A weak
reference is used to refer to the NotificationMenuRow in the
NotificationSwipeHelper.

Fixes: 157506961
Bug: 161119435
Test: manual - Swipe to dismiss notifiation. Take heap dump. Verify that
NotificationMenuRow isn't retained view NotificationSwipeHelper.

Change-Id: Ibe445c31494b592f657b5ae94e4a7ee478a40070
---
 .../stack/NotificationSwipeHelper.java        | 34 +++++++++++++------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationSwipeHelper.java b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationSwipeHelper.java
index d7d09e05c2386..d3b8a8cd20932 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationSwipeHelper.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationSwipeHelper.java
@@ -34,6 +34,8 @@ import com.android.systemui.plugins.statusbar.NotificationSwipeActionHelper;
 import com.android.systemui.statusbar.notification.row.ExpandableNotificationRow;
 import com.android.systemui.statusbar.notification.row.ExpandableView;
 
+import java.lang.ref.WeakReference;
+
 class NotificationSwipeHelper extends SwipeHelper implements NotificationSwipeActionHelper {
 
     @VisibleForTesting
@@ -47,7 +49,11 @@ class NotificationSwipeHelper extends SwipeHelper implements NotificationSwipeAc
 
     private static final long SWIPE_MENU_TIMING = 200;
 
-    private NotificationMenuRowPlugin mCurrMenuRow;
+    // Hold a weak ref to the menu row so that it isn't accidentally retained in memory. The
+    // lifetime of the row should be the same as the ActivatableView, which is owned by the
+    // NotificationStackScrollLayout. If the notification isn't in the notification shade, then it
+    // isn't possible to swipe it and, so, this class doesn't need to "help."
+    private WeakReference<NotificationMenuRowPlugin> mCurrMenuRowRef;
     private boolean mIsExpanded;
     private boolean mPulsing;
 
@@ -82,11 +88,17 @@ class NotificationSwipeHelper extends SwipeHelper implements NotificationSwipeAc
         return mMenuExposedView;
     }
 
-    public void setCurrentMenuRow(NotificationMenuRowPlugin menuRow) {
-        mCurrMenuRow = menuRow;
+    @VisibleForTesting
+    void setCurrentMenuRow(NotificationMenuRowPlugin menuRow) {
+        mCurrMenuRowRef = menuRow != null ? new WeakReference(menuRow) : null;
     }
 
-    public NotificationMenuRowPlugin getCurrentMenuRow() {  return mCurrMenuRow; }
+    public NotificationMenuRowPlugin getCurrentMenuRow() {
+        if (mCurrMenuRowRef == null) {
+            return null;
+        }
+        return mCurrMenuRowRef.get();
+    }
 
     @VisibleForTesting
     protected Handler getHandler() { return mHandler; }
@@ -102,8 +114,9 @@ class NotificationSwipeHelper extends SwipeHelper implements NotificationSwipeAc
 
     @Override
     protected void onChildSnappedBack(View animView, float targetLeft) {
-        if (mCurrMenuRow != null && targetLeft == 0) {
-            mCurrMenuRow.resetMenu();
+        final NotificationMenuRowPlugin menuRow = getCurrentMenuRow();
+        if (menuRow != null && targetLeft == 0) {
+            menuRow.resetMenu();
             clearCurrentMenuRow();
         }
     }
@@ -129,10 +142,11 @@ class NotificationSwipeHelper extends SwipeHelper implements NotificationSwipeAc
     @VisibleForTesting
     protected void initializeRow(SwipeableView row) {
         if (row.hasFinishedInitialization()) {
-            mCurrMenuRow = row.createMenu();
-            if (mCurrMenuRow != null) {
-                mCurrMenuRow.setMenuClickListener(mMenuListener);
-                mCurrMenuRow.onTouchStart();
+            final NotificationMenuRowPlugin menuRow = row.createMenu();
+            setCurrentMenuRow(menuRow);
+            if (menuRow != null) {
+                menuRow.setMenuClickListener(mMenuListener);
+                menuRow.onTouchStart();
             }
         }
     }