7171163: [macosx] Shortcomings in the design of the secondary native event...

7171163: [macosx] Shortcomings in the design of the secondary native event loop made JavaFX DnD deadlock
Reviewed-by: anthony, art

src/macosx/classes/sun/lwawt/macosx/CToolkitThreadBlockedHandler.java

@@ -41,10 +41,11 @@ final class CToolkitThreadBlockedHandler implements ToolkitThreadBlockedHandler
     }
 
     public void enter() {
-        toolkit.startNativeNestedEventLoop();
+        // Execute the next AppKit event while we are waiting for system to
+        // finish our request - this will save us from biting our own tail
+        toolkit.executeNextAppKitEvent();
     }
 
     public void exit() {
-        toolkit.stopNativeNestedEventLoop();
     }
 }

src/macosx/classes/sun/lwawt/macosx/LWCToolkit.java

@@ -63,9 +63,7 @@ public class LWCToolkit extends LWToolkit {
 
     private static native void initIDs();
 
-    static native void startNativeNestedEventLoop();
-
-    static native void stopNativeNestedEventLoop();
+    static native void executeNextAppKitEvent();
 
     private static CInputMethodDescriptor sInputMethodDescriptor;
 

src/macosx/native/sun/awt/LWCToolkit.m

@@ -42,7 +42,6 @@ jint* gButtonDownMasks;
 @implementation AWTToolkit
 
 static long eventCount;
-static bool shouldKeepRunningNestedLoop = NO;
 
 + (long) getEventCount{
     return eventCount;
@@ -460,33 +459,18 @@ Java_sun_font_FontManager_populateFontFileNameMap
 
 /*
  * Class:     sun_lwawt_macosx_LWCToolkit
- * Method:    startNativeNestedEventLoop
+ * Method:    executeNextAppKitEvent
  * Signature: ()V
  */
-JNIEXPORT void JNICALL Java_sun_lwawt_macosx_LWCToolkit_startNativeNestedEventLoop
+JNIEXPORT void JNICALL Java_sun_lwawt_macosx_LWCToolkit_executeNextAppKitEvent
 (JNIEnv *env, jclass cls)
 {
-    if(!shouldKeepRunningNestedLoop) {
-        NSRunLoop *theRL = [NSRunLoop currentRunLoop];
-        NSApplication * app = [NSApplication sharedApplication];
-        shouldKeepRunningNestedLoop = YES;
-        while (shouldKeepRunningNestedLoop && [theRL runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]])
-        {
-            NSEvent * event = [app nextEventMatchingMask: 0xFFFFFFFF untilDate:nil inMode:NSDefaultRunLoopMode dequeue:YES];
-            if (event != nil) {
-                [app sendEvent: event];
-            }
-        }
+    // Simply get the next event in native loop and pass it to execution
+    // We'll be called repeatedly so there's no need to block here
+    NSRunLoop *theRL = [NSRunLoop currentRunLoop];
+    NSApplication * app = [NSApplication sharedApplication];
+    NSEvent * event = [app nextEventMatchingMask: 0xFFFFFFFF untilDate:nil inMode:NSDefaultRunLoopMode dequeue:YES];
+    if (event != nil) {
+        [app sendEvent: event];
     }
 }
-
-/*
- * Class:     sun_lwawt_macosx_LWCToolkit
- * Method:    stopNativeNestedEventLoop
- * Signature: ()V
- */
-JNIEXPORT void JNICALL Java_sun_lwawt_macosx_LWCToolkit_stopNativeNestedEventLoop
-(JNIEnv *env, jclass cls)
-{
-    shouldKeepRunningNestedLoop = NO;
-}

src/share/classes/sun/awt/dnd/SunDropTargetContextPeer.java

@@ -498,7 +498,7 @@ public abstract class SunDropTargetContextPeer implements DropTargetContextPeer,
         postDropTargetEvent(component, x, y, dropAction, actions,
                             formats, nativeCtxt,
                             SunDropTargetEvent.MOUSE_DROPPED,
-                            !SunDropTargetContextPeer.DISPATCH_SYNC);
+                            SunDropTargetContextPeer.DISPATCH_SYNC);
     }
 
     /**