From a431c22fdaefb8d6ce81e929c0074da71fd941ae Mon Sep 17 00:00:00 2001
From: Riddle Hsu <riddlehsu@google.com>
Date: Thu, 20 Aug 2020 16:47:22 +0800
Subject: [PATCH] Make the removal in finish-package-activities deterministic

Sometimes the removal of activity may be deferred by animating.
And it is possible that the deferred record is removed with
another finishing activity (finishIfPossible ->
performSurfacePlacement -> handleCompleteDeferredRemoval) that
causes index of bounds in forAllActivities (next index is
size-1, but the size becomes size-2).

Now the activities to finish are collected to an independent list
so it won't be affected by any changes of hierarchy containers.

The checking for home activity can also be removed because if
home is restarted, it won't appear in the collected list.

Bug: 160752989
Test: ActivityStackTests# \
      testFinishDisabledPackageActivities_FinishAliveActivities
      testFinishDisabledPackageActivities_RemoveNonAliveActivities

Change-Id: I2fcbac35fb23295cfe54856c5f08eae97fa6b87f
---
 .../server/wm/RootWindowContainer.java        | 53 +++++++++----------
 1 file changed, 26 insertions(+), 27 deletions(-)

diff --git a/services/core/java/com/android/server/wm/RootWindowContainer.java b/services/core/java/com/android/server/wm/RootWindowContainer.java
index aeaffd98f8200..78836b49351b7 100644
--- a/services/core/java/com/android/server/wm/RootWindowContainer.java
+++ b/services/core/java/com/android/server/wm/RootWindowContainer.java
@@ -3124,7 +3124,6 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
     FinishDisabledPackageActivitiesHelper mFinishDisabledPackageActivitiesHelper =
             new FinishDisabledPackageActivitiesHelper();
     class FinishDisabledPackageActivitiesHelper {
-        private boolean mDidSomething;
         private String mPackageName;
         private Set<String> mFilterByClasses;
         private boolean mDoit;
@@ -3132,11 +3131,10 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
         private int mUserId;
         private boolean mOnlyRemoveNoProcess;
         private Task mLastTask;
-        private ComponentName mHomeActivity;
+        private final ArrayList<ActivityRecord> mCollectedActivities = new ArrayList<>();
 
         private void reset(String packageName, Set<String> filterByClasses,
                 boolean doit, boolean evenPersistent, int userId, boolean onlyRemoveNoProcess) {
-            mDidSomething = false;
             mPackageName = packageName;
             mFilterByClasses = filterByClasses;
             mDoit = doit;
@@ -3144,7 +3142,6 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
             mUserId = userId;
             mOnlyRemoveNoProcess = onlyRemoveNoProcess;
             mLastTask = null;
-            mHomeActivity = null;
         }
 
         boolean process(String packageName, Set<String> filterByClasses,
@@ -3152,14 +3149,35 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
             reset(packageName, filterByClasses, doit, evenPersistent, userId, onlyRemoveNoProcess);
 
             final PooledFunction f = PooledLambda.obtainFunction(
-                    FinishDisabledPackageActivitiesHelper::processActivity, this,
+                    FinishDisabledPackageActivitiesHelper::collectActivity, this,
                     PooledLambda.__(ActivityRecord.class));
             forAllActivities(f);
             f.recycle();
-            return mDidSomething;
+
+            boolean didSomething = false;
+            final int size = mCollectedActivities.size();
+            // Keep the finishing order from top to bottom.
+            for (int i = 0; i < size; i++) {
+                final ActivityRecord r = mCollectedActivities.get(i);
+                if (mOnlyRemoveNoProcess) {
+                    if (!r.hasProcess()) {
+                        didSomething = true;
+                        Slog.i(TAG, "  Force removing " + r);
+                        r.cleanUp(false /* cleanServices */, false /* setState */);
+                        r.removeFromHistory("force-stop");
+                    }
+                } else {
+                    didSomething = true;
+                    Slog.i(TAG, "  Force finishing " + r);
+                    r.finishIfPossible("force-stop", true /* oomAdj */);
+                }
+            }
+            mCollectedActivities.clear();
+
+            return didSomething;
         }
 
-        private boolean processActivity(ActivityRecord r) {
+        private boolean collectActivity(ActivityRecord r) {
             final boolean sameComponent =
                     (r.packageName.equals(mPackageName) && (mFilterByClasses == null
                             || mFilterByClasses.contains(r.mActivityComponent.getClassName())))
@@ -3176,26 +3194,7 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
                     }
                     return true;
                 }
-                if (r.isActivityTypeHome()) {
-                    if (mHomeActivity != null && mHomeActivity.equals(r.mActivityComponent)) {
-                        Slog.i(TAG, "Skip force-stop again " + r);
-                        return false;
-                    } else {
-                        mHomeActivity = r.mActivityComponent;
-                    }
-                }
-                if (mOnlyRemoveNoProcess) {
-                    if (noProcess) {
-                        mDidSomething = true;
-                        Slog.i(TAG, "  Force removing " + r);
-                        r.cleanUp(false /* cleanServices */, false /* setState */);
-                        r.removeFromHistory("force-stop");
-                    }
-                } else {
-                    mDidSomething = true;
-                    Slog.i(TAG, "  Force finishing " + r);
-                    r.finishIfPossible("force-stop", true /* oomAdj */);
-                }
+                mCollectedActivities.add(r);
                 mLastTask = r.getTask();
             }