Make sure the UI won't try to compute the LCS for huge lists

Change-Id: If5c456fb90063919d927edfd9f07012ee5bbb55c

2 files changed, 6 insertions, 15 deletions

diff --git a/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/property/PropertyDescriptorItem.java b/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/property/PropertyDescriptorItem.java
index d66cf7479..9a397a597 100644
--- a/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/property/PropertyDescriptorItem.java
+++ b/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/property/PropertyDescriptorItem.java
@@ -31,6 +31,7 @@ import org.eclipse.emf.compare.DifferenceSource;
 import org.eclipse.emf.compare.Match;
 import org.eclipse.emf.compare.ide.ui.internal.configuration.EMFCompareConfiguration;
 import org.eclipse.emf.compare.internal.utils.DiffUtil;
+import org.eclipse.emf.compare.rcp.ui.internal.EMFCompareConstants;
 import org.eclipse.emf.compare.rcp.ui.internal.util.MergeViewerUtil;
 import org.eclipse.emf.compare.rcp.ui.mergeviewer.IMergeViewer.MergeViewerSide;
 import org.eclipse.emf.compare.rcp.ui.mergeviewer.item.IMergeViewerItem;
@@ -119,7 +120,7 @@ class PropertyDescriptorItem extends PropertyItem {
 					getSide()));
 		}
 
-		if (haveDiffs()) {
+		if (haveDiffs() && listValue.size() < EMFCompareConstants.LIST_SIZE_INSERTION_POINT_THRESHOLD) {
 			createPlaceholders(propertyItems);
 		}
 	}
@@ -154,7 +155,7 @@ class PropertyDescriptorItem extends PropertyItem {
 							final int count = size(filter(subList, IMergeViewerItem.IS_INSERTION_POINT));
 							index = Math.min(insertionIndex + count, propertyItems.size());
 						} else {
-						    index = 0;
+							index = 0;
 						}
 
 						// Create the placeholder and insert it at the appropriate
diff --git a/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/tree/provider/TreeMergeViewerItemContentProvider.java b/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/tree/provider/TreeMergeViewerItemContentProvider.java
index 2ddb4b231..ad9de1fbe 100644
--- a/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/tree/provider/TreeMergeViewerItemContentProvider.java
+++ b/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/contentmergeviewer/tree/provider/TreeMergeViewerItemContentProvider.java
@@ -54,6 +54,7 @@ import org.eclipse.emf.compare.ResourceAttachmentChange;
 import org.eclipse.emf.compare.graph.IGraphView;
 import org.eclipse.emf.compare.internal.utils.DiffUtil;
 import org.eclipse.emf.compare.match.impl.NotLoadedFragmentMatch;
+import org.eclipse.emf.compare.rcp.ui.internal.EMFCompareConstants;
 import org.eclipse.emf.compare.rcp.ui.internal.mergeviewer.item.impl.MergeViewerItem;
 import org.eclipse.emf.compare.rcp.ui.internal.mergeviewer.item.impl.ResourceAttachmentChangeMergeViewerItem;
 import org.eclipse.emf.compare.rcp.ui.internal.util.MergeViewerUtil;
@@ -81,17 +82,6 @@ import org.eclipse.emf.edit.provider.ITreeItemContentProvider;
 public class TreeMergeViewerItemContentProvider implements IMergeViewerItemContentProvider {
 
 	/**
-	 * If the list on any one of the sides contains more elements than the given threshold, don't try and
-	 * compute the insertion index for differences merging. On the one hand, showing insertion points in lists
-	 * with so many elements wouldn't reallybe human readable, on the other hand, trying to compute insertion
-	 * indices for too large lists will easily result in OutOfMemoryErrors. For example, if the left and right
-	 * sides contain 60000 elements, we'll end up trying to instantiate an array with the following signature:
-	 * "int[60000][60000]" to compute the LCS (see DiffUtils). Such an array would cost 13GB of memory as a
-	 * conservative estimate.
-	 */
-	private static final short LIST_SIZE_INSERTION_POINT_THRESHOLD = 10000;
-
-	/**
 	 * {@inheritDoc}
 	 */
 	public boolean canHandle(Object object) {
@@ -311,8 +301,8 @@ public class TreeMergeViewerItemContentProvider implements IMergeViewerItemConte
 		List<Object> ancestorContent = getChildrenFromContentProvider(
 				getSideValue(parent, MergeViewerSide.ANCESTOR), adapterFactory);
 
-		if (sideContent.size() > LIST_SIZE_INSERTION_POINT_THRESHOLD
-				&& oppositeContent.size() > LIST_SIZE_INSERTION_POINT_THRESHOLD) {
+		if (sideContent.size() > EMFCompareConstants.LIST_SIZE_INSERTION_POINT_THRESHOLD
+				&& oppositeContent.size() > EMFCompareConstants.LIST_SIZE_INSERTION_POINT_THRESHOLD) {
 			return new ArrayList<IMergeViewerItem>(values);
 		}