DfsPackFile: Abstract the bitmap loading to support other backends

Current code reads the bitmap index from the pack extension and loads
all bitmaps into memory, with its IO and memory cost. We could
consider to store the bitmaps on e.g. a database and load them on
demand.

Abstract the loading of the PackBitmapIndex in an interface that can
be implemented with other backends.

Change-Id: Ib5f64d05954708ea5325feea7088a8df229b36a5

1 files changed, 41 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackFileTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackFileTest.java
index 77e5b7cb14..44694acc8d 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackFileTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackFileTest.java
@@ -14,6 +14,8 @@ import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_MIN_BYTES_OBJ_SIZE
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_PACK_SECTION;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 import java.io.ByteArrayOutputStream;
@@ -24,14 +26,18 @@ import java.util.zip.Deflater;
 
 import org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource;
 import org.eclipse.jgit.internal.storage.dfs.DfsReader.PackLoadListener;
+import org.eclipse.jgit.internal.storage.file.PackBitmapIndex;
 import org.eclipse.jgit.internal.storage.pack.PackExt;
 import org.eclipse.jgit.internal.storage.pack.PackOutputStream;
 import org.eclipse.jgit.internal.storage.pack.PackWriter;
 import org.eclipse.jgit.junit.JGitTestUtil;
 import org.eclipse.jgit.junit.TestRng;
+import org.eclipse.jgit.lib.BatchRefUpdate;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.NullProgressMonitor;
 import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.transport.ReceiveCommand;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -123,6 +129,41 @@ public class DfsPackFileTest {
 	}
 
 	@Test
+	public void testGetBitmapIndex() throws IOException {
+		bypassCache = false;
+		clearCache = true;
+		ObjectId objectId = setupPack(512, 800);
+
+		// Add a ref for GC
+		BatchRefUpdate batchRefUpdate = db.getRefDatabase().newBatchUpdate();
+		batchRefUpdate.addCommand(new ReceiveCommand(ObjectId.zeroId(),
+				objectId, "refs/heads/master"));
+		try (RevWalk rw = new RevWalk(db)) {
+			batchRefUpdate.execute(rw, NullProgressMonitor.INSTANCE);
+		}
+		DfsGarbageCollector gc = new DfsGarbageCollector(db);
+		gc.pack(NullProgressMonitor.INSTANCE);
+
+		DfsReader reader = db.getObjectDatabase().newReader();
+		PackBitmapIndex bitmapIndex = db.getObjectDatabase().getPacks()[0]
+				.getBitmapIndex(reader);
+		assertNotNull(bitmapIndex);
+		assertEquals(1, bitmapIndex.getObjectCount());
+	}
+
+	@Test
+	public void testGetBitmapIndex_noBitmaps() throws IOException {
+		bypassCache = false;
+		clearCache = true;
+		setupPack(512, 800);
+
+		DfsReader reader = db.getObjectDatabase().newReader();
+		PackBitmapIndex bitmapIndex = db.getObjectDatabase().getPacks()[0]
+				.getBitmapIndex(reader);
+		assertNull(bitmapIndex);
+	}
+
+	@Test
 	public void testLoadObjectSizeIndex_noIndex() throws IOException {
 		bypassCache = false;
 		clearCache = true;