master ba96c4ec56a 1/2: Port restart-emacs to Android 4.3 and earlier

[Po Lu]

branch: master
commit ba96c4ec56a9978fce155c0af34a0412aee817b2
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Port restart-emacs to Android 4.3 and earlier
    
    * java/org/gnu/emacs/EmacsService.java (restartEmacs): Run Emacs
    from an alarm if required.
---
 java/org/gnu/emacs/EmacsService.java | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/java/org/gnu/emacs/EmacsService.java 
b/java/org/gnu/emacs/EmacsService.java
index 07bfb525be9..4e863c750d3 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -46,9 +46,11 @@ import android.view.KeyEvent;
 import android.view.inputmethod.CursorAnchorInfo;
 import android.view.inputmethod.ExtractedText;
 
+import android.app.AlarmManager;
 import android.app.Notification;
-import android.app.NotificationManager;
 import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
 import android.app.Service;
 
 import android.content.ClipboardManager;
@@ -724,11 +726,29 @@ public final class EmacsService extends Service
   restartEmacs ()
   {
     Intent intent;
+    PendingIntent pending;
+    AlarmManager manager;
 
     intent = new Intent (this, EmacsActivity.class);
     intent.addFlags (Intent.FLAG_ACTIVITY_NEW_TASK
                     | Intent.FLAG_ACTIVITY_CLEAR_TASK);
-    startActivity (intent);
+
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT)
+      startActivity (intent);
+    else
+      {
+       /* Experimentation has established that Android 4.3 and earlier
+          versions do not attempt to recreate a process when it crashes
+          immediately after requesting that an intent for itself be
+          started.  Schedule an intent to start some time after Emacs
+          exits instead.  */
+
+       pending = PendingIntent.getActivity (this, 0, intent, 0);
+       manager = (AlarmManager) getSystemService (Context.ALARM_SERVICE);
+       manager.set (AlarmManager.RTC, System.currentTimeMillis () + 100,
+                    pending);
+      }
+
     System.exit (0);
   }