DfsReader: give subclasses visiblity over the pack bitmap index

Subclasses intercept many methods in DfsReader to capture metrics, but
they cannot record stats from PackBitmapIndex, as it is wrapped inside
a BitmapIndex.

Move the creation of the BitmapIndex to a protected method. Subclasses
can override it to e.g. read metrics from the index or set listeners to
the BitmapIndex.

Change-Id: I86c13b3ef88663d7faf59f2ec77df0a36b1627ed

1 files changed, 14 insertions, 1 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java
index 3f0adcba1a..c722c06e9c 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java
@@ -28,6 +28,7 @@ import java.util.Set;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
 
+import org.eclipse.jgit.annotations.NonNull;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.StoredObjectRepresentationNotAvailableException;
@@ -120,11 +121,23 @@ public class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 		for (DfsPackFile pack : db.getPacks()) {
 			PackBitmapIndex bitmapIndex = pack.getBitmapIndex(this);
 			if (bitmapIndex != null)
-				return new BitmapIndexImpl(bitmapIndex);
+				return createBitmapIndex(bitmapIndex);
 		}
 		return null;
 	}
 
+	/**
+	 * Give subclasses a chance to record pack index stats
+	 *
+	 * @param packBitmapIndex
+	 *            packBitmapIndex found in a pack (never null)
+	 * @return an instance of BitmapIndex
+	 */
+	protected BitmapIndex createBitmapIndex(
+			@NonNull PackBitmapIndex packBitmapIndex) {
+		return new BitmapIndexImpl(packBitmapIndex);
+	}
+
 	@Override
 	public Optional<CommitGraph> getCommitGraph() throws IOException {
 		for (DfsPackFile pack : db.getPacks()) {