Clear image caches in reaction to system VM warnings

* java/org/gnu/emacs/EmacsNative.java (onLowMemory):

* java/org/gnu/emacs/EmacsService.java (onLowMemory): New
function.

* src/android.c (android_on_low_memory, onLowMemory): New
functions called when a VM caution is registered.  Clear
the image cache and run garbage collection.

2 files changed, 15 insertions, 0 deletions

diff --git a/java/org/gnu/emacs/EmacsNative.java b/java/org/gnu/emacs/EmacsNative.java
index 946a38f7f84..78176dd0e47 100644
--- a/java/org/gnu/emacs/EmacsNative.java
+++ b/java/org/gnu/emacs/EmacsNative.java
@@ -96,6 +96,9 @@ public final class EmacsNative
      thread, then return.  */
   public static native void shutDownEmacs ();
 
+  /* Garbage collect and clear each frame's image cache.  */
+  public static native void onLowMemory ();
+
   /* Abort and generate a native core dump.  */
   public static native void emacsAbort ();
 
diff --git a/java/org/gnu/emacs/EmacsService.java b/java/org/gnu/emacs/EmacsService.java
index ab6d57b9c4f..1aac1a6c4dd 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -321,6 +321,10 @@ public final class EmacsService extends Service
       }
   }
 
+  /* The native functions the subsequent two functions call do nothing
+     in the infrequent case the Emacs thread is awaiting a response
+     for the main thread.  Caveat emptor! */
+
   @Override
   public void
   onDestroy ()
@@ -333,6 +337,14 @@ public final class EmacsService extends Service
     super.onDestroy ();
   }
 
+  @Override
+  public void
+  onLowMemory ()
+  {
+    EmacsNative.onLowMemory ();
+    super.onLowMemory ();
+  }
+
 
 
   /* Functions from here on must only be called from the Emacs