Fix DEBUG_THREADS in the Android port

* java/org/gnu/emacs/EmacsService.java (EmacsService): New field
`mainThread'.
(onCreate): Set `mainThread' to the thread where the service's
looper executes.
(checkEmacsThread): Compare against SERVICE.mainThread.

1 files changed, 12 insertions, 1 deletions

diff --git a/java/org/gnu/emacs/EmacsService.java b/java/org/gnu/emacs/EmacsService.java
index 93e34e6e694..b65b10b9528 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -136,6 +136,10 @@ public final class EmacsService extends Service
      been created yet.  */
   private EmacsSafThread storageThread;
 
+  /* The Thread object representing the Android user interface
+     thread.  */
+  private Thread mainThread;
+
   static
   {
     servicingQuery = new AtomicInteger ();
@@ -236,6 +240,7 @@ public final class EmacsService extends Service
                           / metrics.density)
                          * pixelDensityX);
     resolver = getContentResolver ();
+    mainThread = Thread.currentThread ();
 
     /* If the density used to compute the text size is lesser than
        160, there's likely a bug with display density computation.
@@ -384,7 +389,13 @@ public final class EmacsService extends Service
   {
     if (DEBUG_THREADS)
       {
-        if (Thread.currentThread () instanceof EmacsThread)
+        /* When SERVICE is NULL, Emacs is being executed non-interactively.  */
+        if (SERVICE == null
+            /* It was previously assumed that only instances of
+               `EmacsThread' were valid for graphics calls, but this is
+               no longer true now that Lisp threads can be attached to
+               the JVM.  */
+            || (Thread.currentThread () != SERVICE.mainThread))
           return;
 
         throw new RuntimeException ("Emacs thread function"