From 2caec7ba30b63785d5d5ee5d1341bd11f373aa12 Mon Sep 17 00:00:00 2001
From: Louis Chang <louischang@google.com>
Date: Mon, 10 Aug 2020 13:17:22 +0800
Subject: [PATCH] Avoid adjusting top focused root task while clear task

Top focused root task was updated while clear task for reuse, which
isn't necessary. This was happening after 046523c merged.

Also avoid resuming the top activity in next focused
root task to prevent additional top-resumed-activity state changes.

Bug: 160613519
Test: asit/perf/junit/jank_systemui_test

Change-Id: I8ddbfc3b0a62ddb29833d324e42812ed0dc096db
---
 .../com/android/server/wm/ActivityRecord.java |  4 +++-
 .../android/server/wm/ActivityStarter.java    |  2 --
 .../core/java/com/android/server/wm/Task.java | 19 +++++++++++++++----
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/services/core/java/com/android/server/wm/ActivityRecord.java b/services/core/java/com/android/server/wm/ActivityRecord.java
index e573d362fef42..c877b75c6208a 100644
--- a/services/core/java/com/android/server/wm/ActivityRecord.java
+++ b/services/core/java/com/android/server/wm/ActivityRecord.java
@@ -2549,7 +2549,9 @@ final class ActivityRecord extends WindowToken implements WindowManagerService.A
 
         final Task stack = getRootTask();
         final boolean mayAdjustTop = (isState(RESUMED) || stack.mResumedActivity == null)
-                && stack.isFocusedStackOnDisplay();
+                && stack.isFocusedStackOnDisplay()
+                // Do not adjust focus task because the task will be reused to launch new activity.
+                && !task.isClearingToReuseTask();
         final boolean shouldAdjustGlobalFocus = mayAdjustTop
                 // It must be checked before {@link #makeFinishingLocked} is called, because a stack
                 // is not visible if it only contains finishing activities.
diff --git a/services/core/java/com/android/server/wm/ActivityStarter.java b/services/core/java/com/android/server/wm/ActivityStarter.java
index f7cb0146ea523..15e88fc447465 100644
--- a/services/core/java/com/android/server/wm/ActivityStarter.java
+++ b/services/core/java/com/android/server/wm/ActivityStarter.java
@@ -2023,8 +2023,6 @@ class ActivityStarter {
             // of history or if it is finished immediately), thus disassociating the task. Also note
             // that mReuseTask is reset as a result of {@link Task#performClearTaskLocked}
             // launching another activity.
-            // TODO(b/36119896):  We shouldn't trigger activity launches in this path since we are
-            // already launching one.
             targetTask.performClearTaskLocked();
             targetTask.setIntent(mStartActivity);
             mAddingToTask = true;
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index be0815b060515..36711119b979b 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -1836,14 +1836,25 @@ class Task extends WindowContainer<WindowContainer> {
      */
     void performClearTaskLocked() {
         mReuseTask = true;
-        performClearTask("clear-task-all");
-        mReuseTask = false;
+        mStackSupervisor.beginDeferResume();
+        try {
+            performClearTask("clear-task-all");
+        } finally {
+            mStackSupervisor.endDeferResume();
+            mReuseTask = false;
+        }
     }
 
     ActivityRecord performClearTaskForReuseLocked(ActivityRecord newR, int launchFlags) {
         mReuseTask = true;
-        final ActivityRecord result = performClearTaskLocked(newR, launchFlags);
-        mReuseTask = false;
+        mStackSupervisor.beginDeferResume();
+        final ActivityRecord result;
+        try {
+            result = performClearTaskLocked(newR, launchFlags);
+        } finally {
+            mStackSupervisor.endDeferResume();
+            mReuseTask = false;
+        }
         return result;
     }