[390808] Integrate CDO with EMF Compare

https://bugs.eclipse.org/bugs/show_bug.cgi?id=390808

10 files changed, 765 insertions, 44 deletions

diff --git a/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CDOCompareUtil.java b/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CDOCompareUtil.java
index 736e8e8e1e..3fcffc08db 100644
--- a/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CDOCompareUtil.java
+++ b/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CDOCompareUtil.java
@@ -10,7 +10,38 @@
  */
 package org.eclipse.emf.cdo.compare;
 
+import org.eclipse.emf.cdo.CDOObject;
+import org.eclipse.emf.cdo.common.branch.CDOBranchPoint;
+import org.eclipse.emf.cdo.common.id.CDOID;
+import org.eclipse.emf.cdo.common.id.CDOIDUtil;
+import org.eclipse.emf.cdo.session.CDOSession;
+import org.eclipse.emf.cdo.spi.common.branch.CDOBranchUtil;
+import org.eclipse.emf.cdo.util.CDOUtil;
+import org.eclipse.emf.cdo.view.CDOView;
+
+import org.eclipse.net4j.util.lifecycle.ILifecycle;
+import org.eclipse.net4j.util.lifecycle.LifecycleEventAdapter;
+import org.eclipse.net4j.util.lifecycle.LifecycleUtil;
+
+import org.eclipse.emf.common.notify.Notifier;
+import org.eclipse.emf.compare.Comparison;
+import org.eclipse.emf.compare.EMFCompare;
+import org.eclipse.emf.compare.match.eobject.IEObjectMatcher;
+import org.eclipse.emf.compare.match.eobject.IdentifierEObjectMatcher;
+import org.eclipse.emf.compare.scope.AbstractComparisonScope;
+import org.eclipse.emf.compare.scope.IComparisonScope;
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.resource.Resource;
+import org.eclipse.emf.ecore.resource.ResourceSet;
+
+import com.google.common.base.Function;
+import com.google.common.collect.Iterators;
+
+import java.util.Iterator;
+
 /**
+ * Various static methods that may help EMF Compare in a CDO scope.
+ *
  * @author Eike Stepper
  */
 public final class CDOCompareUtil
@@ -19,13 +50,242 @@ public final class CDOCompareUtil
   {
   }
 
-  public static void getMatch()
+  public static CDOComparison compare(CDOView leftView, CDOBranchPoint right)
   {
-    // Function<EObject, String> cdoidFunction = new Function<EObject, String>()
+    return compare(leftView, right, true);
+  }
+
+  public static CDOComparison compare(CDOView leftView, CDOBranchPoint right, boolean threeWay)
+  {
+    CDOSession session = leftView.getSession();
+
+    CDOView rightView;
+    if (right instanceof CDOView)
+    {
+      rightView = (CDOView)right;
+      if (rightView.getSession() != session)
+      {
+        throw new IllegalArgumentException("Sessions are different");
+      }
+    }
+    else
+    {
+      rightView = session.openView(right);
+    }
+
+    CDOObject leftObject = leftView.getRootResource();
+    Notifier rightObject = rightView.getRootResource();
+
+    CDOView originView = null;
+    Notifier originObject = null;
+    if (threeWay)
+    {
+      CDOBranchPoint ancestor = CDOBranchUtil.getAncestor(leftView, rightView);
+      if (!ancestor.equals(leftView) && !ancestor.equals(rightView))
+      {
+        originView = session.openView(ancestor);
+        originObject = originView.getRootResource();
+      }
+    }
+
+    // Set<CDOID> ids;
+    // if (originView != null)
+    // {
+    // MergeData mergeData = ((InternalCDOSession)session).getMergeData(leftView, rightView, null);
+    // ids = mergeData.getIDs();
+    // }
+    // else
     // {
-    // };
-    //
-    // IdentifierEObjectMatcher eObjectMatcher = new
-    // IdentifierEObjectMatcher.Builder().idFunction(cdoidFunction).build();
+    // CDOChangeSetData changeSetData = leftView.compareRevisions(right);
+    // ids = changeSetData.getChangeKinds().keySet();
+    // }
+
+    IComparisonScope scope = new CDOComparisonScope.AllContents(leftObject, rightObject, originObject);
+    return createComparison(scope, leftView, rightView, originView);
+  }
+
+  public static CDOComparison compare(EObject leftRoot, CDOBranchPoint right)
+  {
+    return compare(leftRoot, right, true);
+  }
+
+  public static CDOComparison compare(EObject leftRoot, CDOBranchPoint right, boolean threeWay)
+  {
+    CDOObject leftObject = CDOUtil.getCDOObject(leftRoot);
+    CDOView leftView = leftObject.cdoView();
+    CDOBranchPoint left = CDOBranchUtil.copyBranchPoint(leftView);
+    CDOSession session = leftView.getSession();
+
+    CDOView rightView;
+    if (right instanceof CDOView)
+    {
+      rightView = (CDOView)right;
+      if (rightView.getSession() != session)
+      {
+        throw new IllegalArgumentException("Sessions are different");
+      }
+    }
+    else
+    {
+      rightView = session.openView(right);
+    }
+
+    Notifier rightObject = rightView.getObject(leftObject);
+
+    CDOView originView = null;
+    Notifier originObject = null;
+    if (threeWay)
+    {
+      CDOBranchPoint ancestor = CDOBranchUtil.getAncestor(left, right);
+      if (!ancestor.equals(left) && !ancestor.equals(right))
+      {
+        originView = session.openView(ancestor);
+        originObject = originView.getObject(leftObject);
+      }
+    }
+
+    IComparisonScope scope = new CDOComparisonScope.AllContents(leftObject, rightObject, originObject);
+    return createComparison(scope, leftView, rightView, originView);
+  }
+
+  private static EMFCompare createComparator(IComparisonScope scope)
+  {
+    Function<EObject, String> idFunction = new CDOIDFunction();
+    IEObjectMatcher matcher = new IdentifierEObjectMatcher.Builder().idFunction(idFunction).build();
+
+    EMFCompare comparator = EMFCompare.newComparator(scope);
+    comparator.setEObjectMatcher(matcher);
+    return comparator;
+  }
+
+  private static CDOComparison createComparison(IComparisonScope scope, CDOView leftView, CDOView rightView,
+      CDOView originView)
+  {
+    EMFCompare comparator = createComparator(scope);
+    Comparison comparison = comparator.compare();
+    return new CDOComparison(comparison, leftView, rightView, originView);
+  }
+
+  /**
+   * @author Eike Stepper
+   */
+  public static class CDOComparison extends DelegatingComparison implements CloseableComparison
+  {
+    private CDOView leftView;
+
+    private CDOView rightView;
+
+    private CDOView originView;
+
+    public CDOComparison(Comparison delegate, CDOView leftView, CDOView rightView, CDOView originView)
+    {
+      super(delegate);
+      this.leftView = leftView;
+      this.rightView = rightView;
+      this.originView = originView;
+
+      leftView.addListener(new LifecycleEventAdapter()
+      {
+        @Override
+        protected void onDeactivated(ILifecycle lifecycle)
+        {
+          close();
+        }
+      });
+    }
+
+    public CDOView getLeftView()
+    {
+      return leftView;
+    }
+
+    public CDOView getRightView()
+    {
+      return rightView;
+    }
+
+    public CDOView getOriginView()
+    {
+      return originView;
+    }
+
+    public void close()
+    {
+      close(false);
+    }
+
+    public void close(boolean closeLeftView)
+    {
+      if (closeLeftView)
+      {
+        LifecycleUtil.deactivate(leftView);
+      }
+
+      LifecycleUtil.deactivate(rightView);
+      LifecycleUtil.deactivate(originView);
+
+      leftView = null;
+      rightView = null;
+      originView = null;
+      delegate = null;
+    }
+
+    public boolean isClosed()
+    {
+      return delegate == null;
+    }
+  }
+
+  /**
+   * @author Eike Stepper
+   */
+  public static abstract class CDOComparisonScope extends AbstractComparisonScope
+  {
+    public CDOComparisonScope(Notifier left, Notifier right, Notifier origin)
+    {
+      super(left, right, origin);
+    }
+
+    public Iterator<? extends Resource> getCoveredResources(ResourceSet resourceSet)
+    {
+      return Iterators.emptyIterator();
+    }
+
+    public Iterator<? extends EObject> getCoveredEObjects(Resource resource)
+    {
+      return Iterators.emptyIterator();
+    }
+
+    /**
+     * @author Eike Stepper
+     */
+    public static class AllContents extends CDOComparisonScope
+    {
+      public AllContents(Notifier left, Notifier right, Notifier origin)
+      {
+        super(left, right, origin);
+      }
+
+      public Iterator<? extends EObject> getChildren(EObject eObject)
+      {
+        return eObject.eAllContents();
+      }
+    }
+  }
+
+  /**
+   * @author Eike Stepper
+   */
+  public static class CDOIDFunction implements Function<EObject, String>
+  {
+    public String apply(EObject o)
+    {
+      CDOObject object = CDOUtil.getCDOObject(o);
+      CDOID id = object.cdoID();
+
+      StringBuilder builder = new StringBuilder();
+      CDOIDUtil.write(builder, id);
+      return builder.toString();
+    }
   }
 }
diff --git a/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CloseableComparison.java b/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CloseableComparison.java
new file mode 100644
index 0000000000..9c002782ae
--- /dev/null
+++ b/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/CloseableComparison.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2004 - 2012 Eike Stepper (Berlin, Germany) and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Contributors:
+ *    Eike Stepper - initial API and implementation
+ */
+package org.eclipse.emf.cdo.compare;
+
+import org.eclipse.net4j.util.collection.Closeable;
+
+import org.eclipse.emf.compare.Comparison;
+
+/**
+ * @author Eike Stepper
+ */
+public interface CloseableComparison extends Comparison, Closeable
+{
+}
\ No newline at end of file
diff --git a/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/DelegatingComparison.java b/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/DelegatingComparison.java
new file mode 100644
index 0000000000..6880a713ff
--- /dev/null
+++ b/plugins/org.eclipse.emf.cdo.compare/src/org/eclipse/emf/cdo/compare/DelegatingComparison.java
@@ -0,0 +1,194 @@
+/*
+ * Copyright (c) 2004 - 2012 Eike Stepper (Berlin, Germany) and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Eike Stepper - initial API and implementation
+ */
+package org.eclipse.emf.cdo.compare;
+
+import org.eclipse.emf.common.notify.Adapter;
+import org.eclipse.emf.common.notify.Notification;
+import org.eclipse.emf.common.util.EList;
+import org.eclipse.emf.common.util.TreeIterator;
+import org.eclipse.emf.compare.Comparison;
+import org.eclipse.emf.compare.Conflict;
+import org.eclipse.emf.compare.Diff;
+import org.eclipse.emf.compare.EMFCompareConfiguration;
+import org.eclipse.emf.compare.Equivalence;
+import org.eclipse.emf.compare.Match;
+import org.eclipse.emf.compare.MatchResource;
+import org.eclipse.emf.ecore.EClass;
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.EOperation;
+import org.eclipse.emf.ecore.EReference;
+import org.eclipse.emf.ecore.EStructuralFeature;
+import org.eclipse.emf.ecore.resource.Resource;
+
+import java.lang.reflect.InvocationTargetException;
+
+/**
+ * @author Eike Stepper
+ */
+public class DelegatingComparison implements Comparison
+{
+  protected Comparison delegate;
+
+  public DelegatingComparison(Comparison delegate)
+  {
+    this.delegate = delegate;
+  }
+
+  public Comparison getDelegate()
+  {
+    return delegate;
+  }
+
+  public EList<Adapter> eAdapters()
+  {
+    return delegate.eAdapters();
+  }
+
+  public boolean eDeliver()
+  {
+    return delegate.eDeliver();
+  }
+
+  public void eSetDeliver(boolean deliver)
+  {
+    delegate.eSetDeliver(deliver);
+  }
+
+  public void eNotify(Notification notification)
+  {
+    delegate.eNotify(notification);
+  }
+
+  public EList<MatchResource> getMatchedResources()
+  {
+    return delegate.getMatchedResources();
+  }
+
+  public EList<Match> getMatches()
+  {
+    return delegate.getMatches();
+  }
+
+  public EClass eClass()
+  {
+    return delegate.eClass();
+  }
+
+  public EList<Conflict> getConflicts()
+  {
+    return delegate.getConflicts();
+  }
+
+  public Resource eResource()
+  {
+    return delegate.eResource();
+  }
+
+  public EList<Equivalence> getEquivalences()
+  {
+    return delegate.getEquivalences();
+  }
+
+  public EObject eContainer()
+  {
+    return delegate.eContainer();
+  }
+
+  public EMFCompareConfiguration getConfiguration()
+  {
+    return delegate.getConfiguration();
+  }
+
+  public EList<Diff> getDifferences()
+  {
+    return delegate.getDifferences();
+  }
+
+  public EStructuralFeature eContainingFeature()
+  {
+    return delegate.eContainingFeature();
+  }
+
+  public EList<Diff> getDifferences(EObject element)
+  {
+    return delegate.getDifferences(element);
+  }
+
+  public Match getMatch(EObject element)
+  {
+    return delegate.getMatch(element);
+  }
+
+  public EReference eContainmentFeature()
+  {
+    return delegate.eContainmentFeature();
+  }
+
+  public boolean isThreeWay()
+  {
+    return delegate.isThreeWay();
+  }
+
+  public void setThreeWay(boolean value)
+  {
+    delegate.setThreeWay(value);
+  }
+
+  public EList<EObject> eContents()
+  {
+    return delegate.eContents();
+  }
+
+  public TreeIterator<EObject> eAllContents()
+  {
+    return delegate.eAllContents();
+  }
+
+  public boolean eIsProxy()
+  {
+    return delegate.eIsProxy();
+  }
+
+  public EList<EObject> eCrossReferences()
+  {
+    return delegate.eCrossReferences();
+  }
+
+  public Object eGet(EStructuralFeature feature)
+  {
+    return delegate.eGet(feature);
+  }
+
+  public Object eGet(EStructuralFeature feature, boolean resolve)
+  {
+    return delegate.eGet(feature, resolve);
+  }
+
+  public void eSet(EStructuralFeature feature, Object newValue)
+  {
+    delegate.eSet(feature, newValue);
+  }
+
+  public boolean eIsSet(EStructuralFeature feature)
+  {
+    return delegate.eIsSet(feature);
+  }
+
+  public void eUnset(EStructuralFeature feature)
+  {
+    delegate.eUnset(feature);
+  }
+
+  public Object eInvoke(EOperation operation, EList<?> arguments) throws InvocationTargetException
+  {
+    return delegate.eInvoke(operation, arguments);
+  }
+}
diff --git a/plugins/org.eclipse.emf.cdo.server/src/org/eclipse/emf/cdo/internal/server/ServerCDOView.java b/plugins/org.eclipse.emf.cdo.server/src/org/eclipse/emf/cdo/internal/server/ServerCDOView.java
index 7c6bb4aa0e..9c3ed2af22 100644
--- a/plugins/org.eclipse.emf.cdo.server/src/org/eclipse/emf/cdo/internal/server/ServerCDOView.java
+++ b/plugins/org.eclipse.emf.cdo.server/src/org/eclipse/emf/cdo/internal/server/ServerCDOView.java
@@ -967,14 +967,21 @@ public class ServerCDOView extends AbstractCDOView implements org.eclipse.emf.cd
       throw new UnsupportedOperationException();
     }
 
+    @Deprecated
     public CDORevisionAvailabilityInfo createRevisionAvailabilityInfo(CDOBranchPoint branchPoint)
     {
       throw new UnsupportedOperationException();
     }
 
+    @Deprecated
     public void cacheRevisions(CDORevisionAvailabilityInfo info)
     {
       throw new UnsupportedOperationException();
     }
+
+    public MergeData getMergeData(CDOBranchPoint target, CDOBranchPoint source, CDOBranchPoint sourceBase)
+    {
+      throw new UnsupportedOperationException();
+    }
   }
 }
diff --git a/plugins/org.eclipse.emf.cdo.tests/META-INF/MANIFEST.MF b/plugins/org.eclipse.emf.cdo.tests/META-INF/MANIFEST.MF
index 0681f00b5d..4bed8e9286 100644
--- a/plugins/org.eclipse.emf.cdo.tests/META-INF/MANIFEST.MF
+++ b/plugins/org.eclipse.emf.cdo.tests/META-INF/MANIFEST.MF
@@ -18,6 +18,7 @@ Require-Bundle: org.eclipse.net4j.tests;bundle-version="[4.0.0,5.0.0)";visibilit
  org.eclipse.emf.transaction;bundle-version="[1.4.0,1.5.0)";visibility:=reexport,
  org.eclipse.emf.cdo.common;bundle-version="[4.0.0,5.0.0)";visibility:=reexport,
  org.eclipse.emf.cdo.common.db;bundle-version="[3.0.0,4.0.0)";visibility:=reexport,
+ org.eclipse.emf.cdo.compare;bundle-version="[4.2.0,5.0.0)";visibility:=reexport,
  org.eclipse.emf.cdo;bundle-version="[4.0.0,5.0.0)";visibility:=reexport,
  org.eclipse.emf.cdo.net4j;bundle-version="[4.0.0,5.0.0)";visibility:=reexport,
  org.eclipse.emf.cdo.server;bundle-version="[4.0.0,5.0.0)";visibility:=reexport,
diff --git a/plugins/org.eclipse.emf.cdo.tests/src/org/eclipse/emf/cdo/tests/AllConfigs.java b/plugins/org.eclipse.emf.cdo.tests/src/org/eclipse/emf/cdo/tests/AllConfigs.java
index b196f1aab4..e78a3e9050 100644
--- a/plugins/org.eclipse.emf.cdo.tests/src/org/eclipse/emf/cdo/tests/AllConfigs.java
+++ b/plugins/org.eclipse.emf.cdo.tests/src/org/eclipse/emf/cdo/tests/AllConfigs.java
@@ -98,6 +98,7 @@ public abstract class AllConfigs extends ConfigTestSuite
     testClasses.add(XRefTest.class);
     testClasses.add(StickyViewsTest.class);
     testClasses.add(LobTest.class);
+    testClasses.add(EMFCompareTest.class);
     testClasses.add(OCLQueryTest.class);
     testClasses.add(ViewProviderTest.class);
     testClasses.add(WorkspaceTest.class);
diff --git a/plugins/org.eclipse.emf.cdo.tests/src/org/eclipse/emf/cdo/tests/EMFCompareTest.java b/plugins/org.eclipse.emf.cdo.tests/src/org/eclipse/emf/cdo/tests/EMFCompareTest.java
new file mode 100644
index 0000000000..3edee66546
--- /dev/null
+++ b/plugins/org.eclipse.emf.cdo.tests/src/org/eclipse/emf/cdo/tests/EMFCompareTest.java
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2004 - 2012 Eike Stepper (Berlin, Germany) and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Eike Stepper - initial API and implementation
+ */
+package org.eclipse.emf.cdo.tests;
+
+import org.eclipse.emf.cdo.CDOObject;
+import org.eclipse.emf.cdo.common.commit.CDOCommitInfo;
+import org.eclipse.emf.cdo.compare.CDOCompareUtil;
+import org.eclipse.emf.cdo.compare.CDOCompareUtil.CDOComparison;
+import org.eclipse.emf.cdo.eresource.CDOResource;
+import org.eclipse.emf.cdo.session.CDOSession;
+import org.eclipse.emf.cdo.tests.config.IRepositoryConfig;
+import org.eclipse.emf.cdo.tests.config.impl.ConfigTest.Requires;
+import org.eclipse.emf.cdo.tests.model1.Company;
+import org.eclipse.emf.cdo.transaction.CDOTransaction;
+import org.eclipse.emf.cdo.util.CDOUtil;
+
+import org.eclipse.emf.common.util.EList;
+import org.eclipse.emf.compare.Diff;
+import org.eclipse.emf.compare.Match;
+import org.eclipse.emf.ecore.EObject;
+
+/**
+ * @author Eike Stepper
+ */
+@Requires(IRepositoryConfig.CAPABILITY_AUDITING)
+public class EMFCompareTest extends AbstractCDOTest
+{
+  @SuppressWarnings("unused")
+  public void testNewAudit() throws Exception
+  {
+    CDOSession session = openSession();
+    CDOTransaction transaction = session.openTransaction();
+    CDOResource resource = transaction.createResource(getResourcePath("/res1"));
+
+    Company company = getModel1Factory().createCompany();
+    company.setName("ESC");
+    resource.getContents().add(company);
+    CDOCommitInfo commit1 = transaction.commit();
+
+    company.setName("Sympedia");
+    CDOCommitInfo commit2 = transaction.commit();
+
+    company.setName("Eclipse");
+    CDOCommitInfo commit3 = transaction.commit();
+
+    // CloseableComparison comparison = CDOCompareUtil.compare(session.openView(commit2).getObject(company), commit3);
+    CDOComparison comparison = CDOCompareUtil.compare(company, commit2);
+    dump(comparison.getMatches(), "");
+    comparison.close();
+  }
+
+  private static void dump(EList<Match> matches, String indent)
+  {
+    for (Match match : matches)
+    {
+      System.out.println(indent + "Match:");
+      System.out.println(indent + "   Left:   " + toString(match.getLeft()));
+      System.out.println(indent + "   Right:  " + toString(match.getRight()));
+      String origin = toString(match.getOrigin());
+      if (origin != null)
+      {
+        System.out.println(indent + "   Origin: " + origin);
+      }
+
+      System.out.println(indent + "   Differences:");
+      for (Diff diff : match.getDifferences())
+      {
+        System.out.println(indent + "      " + diff);
+      }
+
+      dump(match.getSubmatches(), indent + "   ");
+    }
+  }
+
+  private static String toString(EObject object)
+  {
+    if (object == null)
+    {
+      return null;
+    }
+
+    CDOObject cdoObject = CDOUtil.getCDOObject(object);
+    if (cdoObject != null)
+    {
+      return cdoObject.cdoRevision().toString();
+    }
+
+    return object.toString();
+  }
+}
diff --git a/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/session/CDOSessionImpl.java b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/session/CDOSessionImpl.java
index 35b1ad839a..c5e1a44656 100644
--- a/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/session/CDOSessionImpl.java
+++ b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/session/CDOSessionImpl.java
@@ -20,6 +20,7 @@ import org.eclipse.emf.cdo.common.branch.CDOBranch;
 import org.eclipse.emf.cdo.common.branch.CDOBranchPoint;
 import org.eclipse.emf.cdo.common.branch.CDOBranchVersion;
 import org.eclipse.emf.cdo.common.commit.CDOChangeKind;
+import org.eclipse.emf.cdo.common.commit.CDOChangeSet;
 import org.eclipse.emf.cdo.common.commit.CDOChangeSetData;
 import org.eclipse.emf.cdo.common.commit.CDOCommitInfo;
 import org.eclipse.emf.cdo.common.commit.CDOCommitInfoManager;
@@ -1247,19 +1248,56 @@ public abstract class CDOSessionImpl extends CDOTransactionContainerImpl impleme
       source = source.getBranch().getPoint(now);
     }
 
-    CDORevisionAvailabilityInfo targetInfo = createRevisionAvailabilityInfo(target);
-    CDORevisionAvailabilityInfo sourceInfo = createRevisionAvailabilityInfo(source);
+    CDORevisionAvailabilityInfo targetInfo = createRevisionAvailabilityInfo2(target);
+    CDORevisionAvailabilityInfo sourceInfo = createRevisionAvailabilityInfo2(source);
 
     Set<CDOID> ids = sessionProtocol.loadMergeData(targetInfo, sourceInfo, null, null);
 
-    cacheRevisions(targetInfo);
-    cacheRevisions(sourceInfo);
+    cacheRevisions2(targetInfo);
+    cacheRevisions2(sourceInfo);
 
     return CDORevisionUtil.createChangeSetData(ids, sourceInfo, targetInfo);
   }
 
+  public MergeData getMergeData(CDOBranchPoint target, CDOBranchPoint source, CDOBranchPoint sourceBase)
+  {
+    CDOBranchPoint ancestor = CDOBranchUtil.getAncestor(target, source);
+
+    CDORevisionAvailabilityInfo ancestorInfo = createRevisionAvailabilityInfo2(ancestor);
+    CDORevisionAvailabilityInfo targetInfo = createRevisionAvailabilityInfo2(target);
+    CDORevisionAvailabilityInfo sourceInfo = createRevisionAvailabilityInfo2(source);
+    CDORevisionAvailabilityInfo baseInfo = sourceBase != null ? createRevisionAvailabilityInfo2(sourceBase) : null;
+
+    Set<CDOID> ids = sessionProtocol.loadMergeData(targetInfo, sourceInfo, ancestorInfo, baseInfo);
+
+    cacheRevisions2(targetInfo);
+    cacheRevisions2(sourceInfo);
+    cacheRevisions2(ancestorInfo);
+
+    if (baseInfo != null)
+    {
+      cacheRevisions2(baseInfo);
+    }
+    else
+    {
+      baseInfo = ancestorInfo;
+    }
+
+    CDOChangeSet targetChanges = createChangeSet(ids, ancestorInfo, targetInfo);
+    CDOChangeSet sourceChanges = createChangeSet(ids, baseInfo, sourceInfo);
+
+    return new MergeData(target, source, sourceBase, ancestor, targetInfo, sourceInfo, baseInfo, ancestorInfo, ids,
+        targetChanges, sourceChanges);
+  }
+
+  @Deprecated
   public CDORevisionAvailabilityInfo createRevisionAvailabilityInfo(CDOBranchPoint branchPoint)
   {
+    throw new UnsupportedOperationException();
+  }
+
+  private CDORevisionAvailabilityInfo createRevisionAvailabilityInfo2(CDOBranchPoint branchPoint)
+  {
     CDORevisionAvailabilityInfo info = new CDORevisionAvailabilityInfo(branchPoint);
 
     InternalCDORevisionManager revisionManager = getRevisionManager();
@@ -1292,8 +1330,14 @@ public abstract class CDOSessionImpl extends CDOTransactionContainerImpl impleme
     return info;
   }
 
+  @Deprecated
   public void cacheRevisions(CDORevisionAvailabilityInfo info)
   {
+    throw new UnsupportedOperationException();
+  }
+
+  private void cacheRevisions2(CDORevisionAvailabilityInfo info)
+  {
     InternalCDORevisionManager revisionManager = getRevisionManager();
     CDOBranch branch = info.getBranchPoint().getBranch();
     for (CDORevisionKey key : info.getAvailableRevisions().values())
@@ -1317,6 +1361,13 @@ public abstract class CDOSessionImpl extends CDOTransactionContainerImpl impleme
     }
   }
 
+  private CDOChangeSet createChangeSet(Set<CDOID> ids, CDORevisionAvailabilityInfo startInfo,
+      CDORevisionAvailabilityInfo endInfo)
+  {
+    CDOChangeSetData data = CDORevisionUtil.createChangeSetData(ids, startInfo, endInfo);
+    return CDORevisionUtil.createChangeSet(startInfo.getBranchPoint(), endInfo.getBranchPoint(), data);
+  }
+
   @Override
   protected void doActivate() throws Exception
   {
diff --git a/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/transaction/CDOTransactionImpl.java b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/transaction/CDOTransactionImpl.java
index 8ee3561726..900ccea9a7 100644
--- a/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/transaction/CDOTransactionImpl.java
+++ b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/transaction/CDOTransactionImpl.java
@@ -153,6 +153,7 @@ import org.eclipse.emf.spi.cdo.FSMUtil;
 import org.eclipse.emf.spi.cdo.InternalCDOObject;
 import org.eclipse.emf.spi.cdo.InternalCDOSavepoint;
 import org.eclipse.emf.spi.cdo.InternalCDOSession;
+import org.eclipse.emf.spi.cdo.InternalCDOSession.MergeData;
 import org.eclipse.emf.spi.cdo.InternalCDOTransaction;
 import org.eclipse.emf.spi.cdo.InternalCDOViewSet;
 
@@ -468,48 +469,21 @@ public class CDOTransactionImpl extends CDOViewImpl implements InternalCDOTransa
       throw new IllegalArgumentException("Source base is not contained in " + source);
     }
 
-    CDOBranchPoint ancestor = CDOBranchUtil.getAncestor(target, source);
-
     InternalCDOSession session = getSession();
-    CDORevisionAvailabilityInfo ancestorInfo = session.createRevisionAvailabilityInfo(ancestor);
-    CDORevisionAvailabilityInfo targetInfo = session.createRevisionAvailabilityInfo(target);
-    CDORevisionAvailabilityInfo sourceInfo = session.createRevisionAvailabilityInfo(source);
-    CDORevisionAvailabilityInfo baseInfo = sourceBase != null ? session.createRevisionAvailabilityInfo(sourceBase)
-        : null;
-
-    CDOSessionProtocol sessionProtocol = session.getSessionProtocol();
-    Set<CDOID> ids = sessionProtocol.loadMergeData(targetInfo, sourceInfo, ancestorInfo, baseInfo);
-
-    session.cacheRevisions(targetInfo);
-    session.cacheRevisions(sourceInfo);
-    session.cacheRevisions(ancestorInfo);
-
-    if (baseInfo != null)
-    {
-      session.cacheRevisions(baseInfo);
-    }
-    else
-    {
-      baseInfo = ancestorInfo;
-    }
-
-    CDOChangeSet targetChanges = createChangeSet(ids, ancestorInfo, targetInfo);
-    CDOChangeSet sourceChanges = createChangeSet(ids, baseInfo, sourceInfo);
+    MergeData mergeData = session.getMergeData(target, source, sourceBase);
 
+    CDOChangeSet targetChanges = mergeData.getTargetChanges();
+    CDOChangeSet sourceChanges = mergeData.getSourceChanges();
     CDOChangeSetData result = merger.merge(targetChanges, sourceChanges);
     if (result == null)
     {
       return null;
     }
 
-    return applyChangeSet(result, ancestorInfo, targetInfo, source, false).getChangeSetData();
-  }
-
-  private CDOChangeSet createChangeSet(Set<CDOID> ids, CDORevisionAvailabilityInfo startInfo,
-      CDORevisionAvailabilityInfo endInfo)
-  {
-    CDOChangeSetData data = CDORevisionUtil.createChangeSetData(ids, startInfo, endInfo);
-    return CDORevisionUtil.createChangeSet(startInfo.getBranchPoint(), endInfo.getBranchPoint(), data);
+    CDORevisionAvailabilityInfo ancestorInfo = mergeData.getAncestorInfo();
+    CDORevisionAvailabilityInfo targetInfo = mergeData.getTargetInfo();
+    ApplyChangeSetResult changeSet = applyChangeSet(result, ancestorInfo, targetInfo, source, false);
+    return changeSet.getChangeSetData();
   }
 
   @Deprecated
diff --git a/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/spi/cdo/InternalCDOSession.java b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/spi/cdo/InternalCDOSession.java
index 8894ccb72f..c6a693cf8f 100644
--- a/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/spi/cdo/InternalCDOSession.java
+++ b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/spi/cdo/InternalCDOSession.java
@@ -13,6 +13,7 @@ package org.eclipse.emf.spi.cdo;
 import org.eclipse.emf.cdo.common.CDOCommonRepository;
 import org.eclipse.emf.cdo.common.branch.CDOBranch;
 import org.eclipse.emf.cdo.common.branch.CDOBranchPoint;
+import org.eclipse.emf.cdo.common.commit.CDOChangeSet;
 import org.eclipse.emf.cdo.common.commit.CDOCommitInfo;
 import org.eclipse.emf.cdo.common.id.CDOID;
 import org.eclipse.emf.cdo.common.id.CDOIDGenerator;
@@ -41,6 +42,7 @@ import org.eclipse.emf.spi.cdo.CDOSessionProtocol.RefreshSessionResult;
 
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * If the meaning of this type isn't clear, there really should be more of a description here...
@@ -239,11 +241,122 @@ public interface InternalCDOSession extends CDOSession, PackageProcessor, Packag
 
   /**
    * @since 4.0
+   * @deprecated As of 4.2 not used anymore.
    */
+  @Deprecated
   public CDORevisionAvailabilityInfo createRevisionAvailabilityInfo(CDOBranchPoint branchPoint);
 
   /**
    * @since 4.0
+   * @deprecated As of 4.2 not used anymore.
    */
+  @Deprecated
   public void cacheRevisions(CDORevisionAvailabilityInfo info);
+
+  /**
+   * @since 4.2
+   */
+  public MergeData getMergeData(CDOBranchPoint target, CDOBranchPoint source, CDOBranchPoint sourceBase);
+
+  /**
+   * @author Eike Stepper
+   * @since 4.2
+   */
+  public static final class MergeData
+  {
+    private final CDOBranchPoint target;
+
+    private final CDOBranchPoint source;
+
+    private final CDOBranchPoint sourceBase;
+
+    private final CDOBranchPoint ancestor;
+
+    private final CDORevisionAvailabilityInfo targetInfo;
+
+    private final CDORevisionAvailabilityInfo sourceInfo;
+
+    private final CDORevisionAvailabilityInfo baseInfo;
+
+    private final CDORevisionAvailabilityInfo ancestorInfo;
+
+    private final Set<CDOID> ids;
+
+    private final CDOChangeSet targetChanges;
+
+    private final CDOChangeSet sourceChanges;
+
+    public MergeData(CDOBranchPoint target, CDOBranchPoint source, CDOBranchPoint sourceBase, CDOBranchPoint ancestor,
+        CDORevisionAvailabilityInfo targetInfo, CDORevisionAvailabilityInfo sourceInfo,
+        CDORevisionAvailabilityInfo baseInfo, CDORevisionAvailabilityInfo ancestorInfo, Set<CDOID> ids,
+        CDOChangeSet targetChanges, CDOChangeSet sourceChanges)
+    {
+      this.target = target;
+      this.source = source;
+      this.sourceBase = sourceBase;
+      this.ancestor = ancestor;
+      this.targetInfo = targetInfo;
+      this.sourceInfo = sourceInfo;
+      this.baseInfo = baseInfo;
+      this.ancestorInfo = ancestorInfo;
+      this.ids = ids;
+      this.targetChanges = targetChanges;
+      this.sourceChanges = sourceChanges;
+    }
+
+    public CDOBranchPoint getTarget()
+    {
+      return target;
+    }
+
+    public CDOBranchPoint getSource()
+    {
+      return source;
+    }
+
+    public CDOBranchPoint getSourceBase()
+    {
+      return sourceBase;
+    }
+
+    public CDOBranchPoint getAncestor()
+    {
+      return ancestor;
+    }
+
+    public CDORevisionAvailabilityInfo getTargetInfo()
+    {
+      return targetInfo;
+    }
+
+    public CDORevisionAvailabilityInfo getSourceInfo()
+    {
+      return sourceInfo;
+    }
+
+    public CDORevisionAvailabilityInfo getBaseInfo()
+    {
+      return baseInfo;
+    }
+
+    public CDORevisionAvailabilityInfo getAncestorInfo()
+    {
+      return ancestorInfo;
+    }
+
+    public Set<CDOID> getIDs()
+    {
+      return ids;
+    }
+
+    public CDOChangeSet getTargetChanges()
+    {
+      return targetChanges;
+    }
+
+    public CDOChangeSet getSourceChanges()
+    {
+      return sourceChanges;
+    }
+  }
 }