From 2d15d4e65ad3f7b796e22e38a9a930128b284ab9 Mon Sep 17 00:00:00 2001
From: Sebastian Zarnekow <Sebastian.Zarnekow@itemis.de>
Date: Mon, 11 Feb 2013 11:50:28 +0100
Subject: [PATCH] [xbase][typesystem] Guard against concurrent resolution

Should prevent dead locks and other surprises.
---
 .../SynchronizedXtextResourceSet.java         | 26 ++++++++++++++++++-
 .../eclipse/xtext/resource/XtextResource.java | 14 ++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/SynchronizedXtextResourceSet.java b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/SynchronizedXtextResourceSet.java
index 5aedec70f..81c581696 100644
--- a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/SynchronizedXtextResourceSet.java
+++ b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/SynchronizedXtextResourceSet.java
@@ -10,11 +10,14 @@ import org.eclipse.emf.common.util.AbstractEList;
 import org.eclipse.emf.common.util.EList;
 import org.eclipse.emf.common.util.URI;
 import org.eclipse.emf.ecore.resource.Resource;
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.xtext.util.concurrent.IUnitOfWork;
 
 /**
  * @author Sebastian Zarnekow - Initial contribution and API
  */
-public class SynchronizedXtextResourceSet extends XtextResourceSet {
+public class SynchronizedXtextResourceSet extends XtextResourceSet implements ISynchronizable<SynchronizedXtextResourceSet> {
 	private final Object lock = new Object();
 
 	@Override
@@ -36,6 +39,27 @@ public class SynchronizedXtextResourceSet extends XtextResourceSet {
 	public EList<Resource> getResources() {
 		return super.getResources();
 	}
+	
+	/**
+	 * Returns a synchronization lock that works for the complete resource set.
+	 * @since 2.4
+	 */
+	@NonNull
+	public Object getLock() {
+		return lock;
+	}
+	
+	/**
+	 * {@inheritDoc}
+	 * 
+	 * @since 2.4
+	 */
+	@NonNullByDefault
+	public <Result> Result execute(IUnitOfWork<Result, ? super SynchronizedXtextResourceSet> unit) throws Exception {
+		synchronized (getLock()) {
+			return unit.exec(this);
+		}
+	}
 
 	/**
 	 * @since 2.4
diff --git a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/XtextResource.java b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/XtextResource.java
index 2608a9b6f..a30a24e91 100644
--- a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/XtextResource.java
+++ b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/XtextResource.java
@@ -23,6 +23,7 @@ import org.eclipse.emf.common.util.TreeIterator;
 import org.eclipse.emf.common.util.URI;
 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.emf.ecore.resource.impl.ResourceImpl;
+import org.eclipse.jdt.annotation.NonNull;
 import org.eclipse.jdt.annotation.Nullable;
 import org.eclipse.xtext.Constants;
 import org.eclipse.xtext.diagnostics.Severity;
@@ -285,6 +286,19 @@ public class XtextResource extends ResourceImpl {
 
 	@Override
 	public EObject getEObject(String uriFragment) {
+		return basicGetEObject(uriFragment);
+	}
+
+	/**
+	 * Resolves a fragment to an {@link EObject}. The returned object is not necessarily
+	 * contained in this resource. It may resolve to a different one, instead.
+	 * The result may be <code>null</code>.
+	 * 
+	 * @see ResourceImpl#getEObject(String)
+	 * @see IFragmentProvider
+	 * @since 2.4
+	 */
+	protected EObject basicGetEObject(@NonNull String uriFragment) {
 		if (fragmentProvider != null) {
 			EObject result = fragmentProvider.getEObject(this, uriFragment, fragmentProviderFallback);
 			return result;