Reduce memory held and speed up DfsGarbageCollector.

getObjectList() returns a list of ObjectToPack. These can hold on to a
lot of memory. Furthermore, binary searching for objects in a sorted
array can be slow. Improve the speed and reduce the memory by creating a
copy of the ObjectId and inserting it into an ObjectIdOwnerMap.

Change-Id: Ib5aa5b7447e05938b47fa55812a87b9872c20ea7

org.eclipse.jgit/src/org/eclipse/jgit/storage/dfs/DfsGarbageCollector.java

@@ -61,6 +61,7 @@ import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.NullProgressMonitor;
 import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectIdOwnerMap;
 import org.eclipse.jgit.lib.ProgressMonitor;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.revwalk.RevWalk;
@@ -332,10 +333,11 @@ public class DfsGarbageCollector {
 			out.close();
 		}
 
-		final List<ObjectId> packedObjs = pw.getObjectList();
+		final ObjectIdOwnerMap<ObjectIdOwnerMap.Entry> packedObjs = pw
+				.getObjectSet();
 		newPackObj.add(new PackWriter.ObjectIdSet() {
 			public boolean contains(AnyObjectId objectId) {
-				return 0 <= Collections.binarySearch(packedObjs, objectId);
+				return packedObjs.contains(objectId);
 			}
 		});
 

org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java

@@ -519,8 +519,7 @@ public class PackWriter {
 	}
 
 	/**
-	 * Returns the object ids in the pack file that was created by this writer,
-	 * sorted by name.
+	 * Returns the object ids in the pack file that was created by this writer.
 	 *
 	 * This method can only be invoked after
 	 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)} has
@@ -530,13 +529,23 @@ public class PackWriter {
 	 * @throws IOException
 	 *             a cached pack cannot supply its object ids.
 	 */
-	public List<ObjectId> getObjectList() throws IOException {
+	public ObjectIdOwnerMap<ObjectIdOwnerMap.Entry> getObjectSet()
+			throws IOException {
 		if (!cachedPacks.isEmpty())
 			throw new IOException(
 					JGitText.get().cachedPacksPreventsListingObjects);
 
-		return Collections.unmodifiableList(
-				(List<? extends ObjectId>) sortByName());
+		ObjectIdOwnerMap<ObjectIdOwnerMap.Entry> objs = new ObjectIdOwnerMap<
+				ObjectIdOwnerMap.Entry>();
+		for (BlockList<ObjectToPack> objList : objectsLists) {
+			if (objList != null) {
+				for (ObjectToPack otp : objList)
+					objs.add(new ObjectIdOwnerMap.Entry(otp) {
+						// A new entry that copies the ObjectId
+					});
+			}
+		}
+		return objs;
 	}
 
 	/**