DfsReader#getObjectSize: use size index if possible

getObjectSize reads the size from the first bytes of the object in the
pack, using IO. For blobs and depending on the configuration, the size
could be available in the object size index.

Try to get the size from the object size index if available. Read from
the pack otherwise.

Note that GC uses #getObjectSize from the existing pack to write the
next object size index.

Change-Id: Ia999290c06d061cb53aa8c0a2b28b1a9761567ef

1 files changed, 16 insertions, 33 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 c722c06e9c..a342796cbe 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
@@ -503,30 +503,28 @@ public class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 	public long getObjectSize(AnyObjectId objectId, int typeHint)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException {
-		if (last != null && !skipGarbagePack(last)) {
-			long sz = last.getObjectSize(this, objectId);
-			if (0 <= sz) {
-				return sz;
+		DfsPackFile pack = findPackWithObject(objectId);
+		if (pack == null) {
+			if (typeHint == OBJ_ANY) {
+				throw new MissingObjectException(objectId.copy(),
+						JGitText.get().unknownObjectType2);
 			}
+			throw new MissingObjectException(objectId.copy(), typeHint);
 		}
 
-		PackList packList = db.getPackList();
-		long sz = getObjectSizeImpl(packList, objectId);
-		if (0 <= sz) {
-			return sz;
-		}
-		if (packList.dirty()) {
-			sz = getObjectSizeImpl(packList, objectId);
-			if (0 <= sz) {
-				return sz;
-			}
+		if (typeHint != Constants.OBJ_BLOB || !pack.hasObjectSizeIndex(this)) {
+			return pack.getObjectSize(this, objectId);
 		}
 
-		if (typeHint == OBJ_ANY) {
-			throw new MissingObjectException(objectId.copy(),
-					JGitText.get().unknownObjectType2);
+		long sz = pack.getIndexedObjectSize(this, objectId);
+		if (sz >= 0) {
+			stats.objectSizeIndexHit += 1;
+			return sz;
 		}
-		throw new MissingObjectException(objectId.copy(), typeHint);
+
+		// Object wasn't in the index
+		stats.objectSizeIndexMiss += 1;
+		return pack.getObjectSize(this, objectId);
 	}
 
 
@@ -582,21 +580,6 @@ public class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 		return null;
 	}
 
-	private long getObjectSizeImpl(PackList packList, AnyObjectId objectId)
-			throws IOException {
-		for (DfsPackFile pack : packList.packs) {
-			if (pack == last || skipGarbagePack(pack)) {
-				continue;
-			}
-			long sz = pack.getObjectSize(this, objectId);
-			if (0 <= sz) {
-				last = pack;
-				return sz;
-			}
-		}
-		return -1;
-	}
-
 	@Override
 	public DfsObjectToPack newObjectToPack(AnyObjectId objectId, int type) {
 		return new DfsObjectToPack(objectId, type);