Fix a race that kept the locale picker from working under heavy CPU load.

The locale picker and the activity transition would both change the
configuration, and depending upon the timing, the activity transition
would undo what the locale picker had just done.  Usually it worked right,
but would often fail if the user changed locales just after a data wipe,
when the media scanner was working hard in the background to index
the contents of the SD card.

http://b/issue?id=2216298

diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java
index ad1926e..56270f4 100644 (file)
--- a/services/java/com/android/server/am/ActivityManagerService.java
+++ b/services/java/com/android/server/am/ActivityManagerService.java
@@ -2705,13 +2705,31 @@ public final class ActivityManagerService extends ActivityManagerNative implemen
 
             // Have the window manager re-evaluate the orientation of
             // the screen based on the new activity order.
-            Configuration config = mWindowManager.updateOrientationFromAppTokens(
-                    mConfiguration,
-                    next.mayFreezeScreenLocked(next.app) ? next : null);
-            if (config != null) {
-                next.frozenBeforeDestroy = true;
-            }
-            if (!updateConfigurationLocked(config, next)) {
+            boolean updated;
+            synchronized (this) {
+                Configuration config = mWindowManager.updateOrientationFromAppTokens(
+                        mConfiguration,
+                        next.mayFreezeScreenLocked(next.app) ? next : null);
+                if (config != null) {
+                    /*
+                     * Explicitly restore the locale to the one from the
+                     * old configuration, since the one that comes back from
+                     * the window manager has the default (boot) locale.
+                     *
+                     * It looks like previously the locale picker only worked
+                     * by coincidence: usually it would do its setting of
+                     * the locale after the activity transition, so it didn't
+                     * matter that this lost it.  With the synchronized
+                     * block now keeping them from happening at the same time,
+                     * this one always would happen second and undo what the
+                     * locale picker had just done.
+                     */
+                    config.locale = mConfiguration.locale;
+                    next.frozenBeforeDestroy = true;
+                }
+                updated = updateConfigurationLocked(config, next);
+            }
+            if (!updated) {
                 // The configuration update wasn't able to keep the existing
                 // instance of the activity, and instead started a new one.
                 // We should be all done, but let's just make sure our activity