Fix: Suppress NPE in XtextDocument, added pointers to some "unexpected" code

2 files changed, 6 insertions, 3 deletions

diff --git a/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocument.java b/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocument.java
index 1721128..db9103b 100644
--- a/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocument.java
+++ b/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocument.java
@@ -100,8 +100,9 @@ public class XtextDocument extends Document implements IXtextDocument {
 		resource.setValidationDisabled(file == null);
 	}
 
+	// XXX why is this one not called inside an readOnly action???
 	public boolean isReferenced(IResource anIResource) {
-		if (!(anIResource instanceof IFile))
+		if (!(anIResource instanceof IFile) || resource == null || resource.getResourceSet() == null)
 			return false;
 		EList<Resource> resources = resource.getResourceSet().getResources();
 		final Map<String, Resource> uriToRes = new HashMap<String, Resource>();
diff --git a/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocumentProvider.java b/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocumentProvider.java
index 1f9d229..1c67ee9 100644
--- a/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocumentProvider.java
+++ b/plugins/org.eclipse.xtext.ui.core/src/org/eclipse/xtext/ui/core/editor/model/XtextDocumentProvider.java
@@ -57,6 +57,8 @@ public class XtextDocumentProvider extends FileDocumentProvider {
 			this.document = document;
 		}
 
+		// XXX: Is this a potential dead lock? A UoW tries to spawn another one for
+		// another document. This one may try to lock the first one ...
 		public void resourceChanged(final IResourceChangeEvent event) {
 
 			final ResourceDeltaVisitor visitor = new ResourceDeltaVisitor(document);
@@ -116,7 +118,7 @@ public class XtextDocumentProvider extends FileDocumentProvider {
 						}
 					});
 					return Status.OK_STATUS;
-				}}.schedule();
+				}}.schedule(); // do we need to lock the workspace?
 			}
 		}
 	}
@@ -140,7 +142,7 @@ public class XtextDocumentProvider extends FileDocumentProvider {
 			int flags = delta.getFlags();
 			if ((kind == IResourceDelta.REMOVED ||
 					(kind == IResourceDelta.CHANGED && ((IResourceDelta.CONTENT & flags) != 0)))
-					&& document.isReferenced(res)) {
+					&& document.isReferenced(res)) { // this should be a UoW as we access the resource
 				deltas.add(delta);
 			}
 			return true;