Reuse ObjectReader for all objects touched during checkout

Bug: 349361
Change-Id: I61ffcb7694eb8b99ebaf4d0d0acd63e0ee91bcb3
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/CheckoutCommand.java

@@ -66,6 +66,7 @@
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.RefUpdate;
 import org.eclipse.jgit.lib.RefUpdate.Result;
@@ -266,9 +267,14 @@ public void apply(DirCacheEntry ent) {
 			}
 
 			File workTree = repo.getWorkTree();
+			ObjectReader r = repo.getObjectDatabase().newReader();
+			try {
 				for (String file : files)
-				DirCacheCheckout.checkoutEntry(repo, new File(workTree, file),
+					DirCacheCheckout.checkoutEntry(repo, new File(workTree,
-						dc.getEntry(file));
+							file), dc.getEntry(file), r);
+			} finally {
+				r.release();
+			}
 		} finally {
 			dc.unlock();
 			revWalk.release();

org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheCheckout.java

@@ -60,6 +60,7 @@
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.treewalk.AbstractTreeIterator;
 import org.eclipse.jgit.treewalk.CanonicalTreeParser;
@@ -386,6 +387,9 @@ private boolean doCheckout() throws CorruptObjectException, IOException,
 			MissingObjectException, IncorrectObjectTypeException,
 			CheckoutConflictException, IndexWriteException {
 		toBeDeleted.clear();
+
+		ObjectReader objectReader = repo.getObjectDatabase().newReader();
+		try {
 			if (headCommitTree != null)
 				preScanTwoTrees();
 			else
@@ -434,16 +438,17 @@ private boolean doCheckout() throws CorruptObjectException, IOException,
 				if (FileMode.GITLINK.equals(entry.getRawMode()))
 					continue;
 
-			checkoutEntry(repo, file, entry);
+				checkoutEntry(repo, file, entry, objectReader);
 			}
 
-
 			// commit the index builder - a new index is persisted
 			if (!builder.commit()) {
 				dc.unlock();
 				throw new IndexWriteException();
 			}
-
+		} finally {
+			objectReader.release();
+		}
 		return toBeDeleted.size() == 0;
 	}
 
@@ -848,12 +853,19 @@ private boolean isModified(String path) throws CorruptObjectException, IOExcepti
 	 * Updates the file in the working tree with content and mode from an entry
 	 * in the index. The new content is first written to a new temporary file in
 	 * the same directory as the real file. Then that new file is renamed to the
-	 * final filename.
+	 * final filename. Use this method only for checkout of a single entry.
+	 * Otherwise use
+	 * {@code checkoutEntry(Repository, File f, DirCacheEntry, ObjectReader)}
+	 * instead which allows to reuse one {@code ObjectReader} for multiple
+	 * entries.
 	 *
+	 * <p>
 	 * TODO: this method works directly on File IO, we may need another
 	 * abstraction (like WorkingTreeIterator). This way we could tell e.g.
 	 * Eclipse that Files in the workspace got changed
-	 * @param repo
+	 * </p>
+	 *
+	 * @param repository
 	 * @param f
 	 *            the file to be modified. The parent directory for this file
 	 *            has to exist already
@@ -861,9 +873,41 @@ private boolean isModified(String path) throws CorruptObjectException, IOExcepti
 	 *            the entry containing new mode and content
 	 * @throws IOException
 	 */
-	public static void checkoutEntry(final Repository repo, File f,
+	public static void checkoutEntry(final Repository repository, File f,
 			DirCacheEntry entry) throws IOException {
-		ObjectLoader ol = repo.open(entry.getObjectId());
+		ObjectReader or = repository.newObjectReader();
+		try {
+			checkoutEntry(repository, f, entry, repository.newObjectReader());
+		} finally {
+			or.release();
+		}
+	}
+
+	/**
+	 * Updates the file in the working tree with content and mode from an entry
+	 * in the index. The new content is first written to a new temporary file in
+	 * the same directory as the real file. Then that new file is renamed to the
+	 * final filename.
+	 *
+	 * <p>
+	 * TODO: this method works directly on File IO, we may need another
+	 * abstraction (like WorkingTreeIterator). This way we could tell e.g.
+	 * Eclipse that Files in the workspace got changed
+	 * </p>
+	 *
+	 * @param repo
+	 * @param f
+	 *            the file to be modified. The parent directory for this file
+	 *            has to exist already
+	 * @param entry
+	 *            the entry containing new mode and content
+	 * @param or
+	 *            object reader to use for checkout
+	 * @throws IOException
+	 */
+	public static void checkoutEntry(final Repository repo, File f,
+			DirCacheEntry entry, ObjectReader or) throws IOException {
+		ObjectLoader ol = or.open(entry.getObjectId());
 		File parentDir = f.getParentFile();
 		File tmpFile = File.createTempFile("._" + f.getName(), null, parentDir);
 		FileOutputStream channel = new FileOutputStream(tmpFile);

org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java

@@ -238,13 +238,14 @@ protected boolean mergeImpl() throws IOException {
 	}
 
 	private void checkout() throws NoWorkTreeException, IOException {
-		for (Map.Entry<String, DirCacheEntry> entry : toBeCheckedOut.entrySet()) {
+		ObjectReader r = db.getObjectDatabase().newReader();
+		try {
+			for (Map.Entry<String, DirCacheEntry> entry : toBeCheckedOut
+					.entrySet()) {
 				File f = new File(db.getWorkTree(), entry.getKey());
 				if (entry.getValue() != null) {
 					createDir(f.getParentFile());
-				DirCacheCheckout.checkoutEntry(db,
+					DirCacheCheckout.checkoutEntry(db, f, entry.getValue(), r);
-						f,
-						entry.getValue());
 				} else {
 					if (!f.delete())
 						failingPaths.put(entry.getKey(),
@@ -252,6 +253,9 @@ private void checkout() throws NoWorkTreeException, IOException {
 				}
 				modifiedFiles.add(entry.getKey());
 			}
+		} finally {
+			r.release();
+		}
 	}
 
 	private void createDir(File f) throws IOException {