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>

3 files changed, 119 insertions, 65 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/CheckoutCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/CheckoutCommand.java
index f3a2e53602..8caff06292 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/CheckoutCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/CheckoutCommand.java
@@ -66,6 +66,7 @@ import org.eclipse.jgit.errors.CheckoutConflictException;
 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 class CheckoutCommand extends GitCommand<Ref> {
 			}
 
 			File workTree = repo.getWorkTree();
-			for (String file : files)
-				DirCacheCheckout.checkoutEntry(repo, new File(workTree, file),
-						dc.getEntry(file));
+			ObjectReader r = repo.getObjectDatabase().newReader();
+			try {
+				for (String file : files)
+					DirCacheCheckout.checkoutEntry(repo, new File(workTree,
+							file), dc.getEntry(file), r);
+			} finally {
+				r.release();
+			}
 		} finally {
 			dc.unlock();
 			revWalk.release();
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheCheckout.java b/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheCheckout.java
index 79f2297b26..8559483292 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheCheckout.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheCheckout.java
@@ -60,6 +60,7 @@ import org.eclipse.jgit.errors.MissingObjectException;
 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;
@@ -386,64 +387,68 @@ public class DirCacheCheckout {
 			MissingObjectException, IncorrectObjectTypeException,
 			CheckoutConflictException, IndexWriteException {
 		toBeDeleted.clear();
-		if (headCommitTree != null)
-			preScanTwoTrees();
-		else
-			prescanOneTree();
 
-		if (!conflicts.isEmpty()) {
-			if (failOnConflict) {
-				dc.unlock();
-				throw new CheckoutConflictException(conflicts.toArray(new String[conflicts.size()]));
-			} else
-				cleanUpConflicts();
-		}
+		ObjectReader objectReader = repo.getObjectDatabase().newReader();
+		try {
+			if (headCommitTree != null)
+				preScanTwoTrees();
+			else
+				prescanOneTree();
 
-		// update our index
-		builder.finish();
-
-		File file=null;
-		String last = "";
-		// when deleting files process them in the opposite order as they have
-		// been reported. This ensures the files are deleted before we delete
-		// their parent folders
-		for (int i = removed.size() - 1; i >= 0; i--) {
-			String r = removed.get(i);
-			file = new File(repo.getWorkTree(), r);
-			if (!file.delete() && file.exists())
-					toBeDeleted.add(r);
-			else {
-				if (!isSamePrefix(r, last))
-					removeEmptyParents(new File(repo.getWorkTree(), last));
-				last = r;
+			if (!conflicts.isEmpty()) {
+				if (failOnConflict) {
+					dc.unlock();
+					throw new CheckoutConflictException(conflicts.toArray(new String[conflicts.size()]));
+				} else
+					cleanUpConflicts();
 			}
-		}
-		if (file != null)
-			removeEmptyParents(file);
 
-		for (String path : updated.keySet()) {
-			// ... create/overwrite this file ...
-			file = new File(repo.getWorkTree(), path);
-			if (!file.getParentFile().mkdirs()) {
-				// ignore
+			// update our index
+			builder.finish();
+
+			File file = null;
+			String last = "";
+			// when deleting files process them in the opposite order as they have
+			// been reported. This ensures the files are deleted before we delete
+			// their parent folders
+			for (int i = removed.size() - 1; i >= 0; i--) {
+				String r = removed.get(i);
+				file = new File(repo.getWorkTree(), r);
+				if (!file.delete() && file.exists())
+					toBeDeleted.add(r);
+				else {
+					if (!isSamePrefix(r, last))
+						removeEmptyParents(new File(repo.getWorkTree(), last));
+					last = r;
+				}
 			}
+			if (file != null)
+				removeEmptyParents(file);
+
+			for (String path : updated.keySet()) {
+				// ... create/overwrite this file ...
+				file = new File(repo.getWorkTree(), path);
+				if (!file.getParentFile().mkdirs()) {
+					// ignore
+				}
 
-			DirCacheEntry entry = dc.getEntry(path);
-
-			// submodules are handled with separate operations
-			if (FileMode.GITLINK.equals(entry.getRawMode()))
-				continue;
+				DirCacheEntry entry = dc.getEntry(path);
 
-			checkoutEntry(repo, file, entry);
-		}
+				// submodules are handled with separate operations
+				if (FileMode.GITLINK.equals(entry.getRawMode()))
+					continue;
 
+				checkoutEntry(repo, file, entry, objectReader);
+			}
 
-		// commit the index builder - a new index is persisted
-		if (!builder.commit()) {
-			dc.unlock();
-			throw new IndexWriteException();
+			// commit the index builder - a new index is persisted
+			if (!builder.commit()) {
+				dc.unlock();
+				throw new IndexWriteException();
+			}
+		} finally {
+			objectReader.release();
 		}
-
 		return toBeDeleted.size() == 0;
 	}
 
@@ -848,22 +853,61 @@ public class DirCacheCheckout {
 	 * 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. 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
+	 * </p>
+	 *
+	 * @param repository
+	 * @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
+	 * @throws IOException
+	 */
+	public static void checkoutEntry(final Repository repository, File f,
+			DirCacheEntry entry) throws IOException {
+		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) throws IOException {
-		ObjectLoader ol = repo.open(entry.getObjectId());
+			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);
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java b/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java
index d347b59a0b..b763568951 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java
@@ -238,19 +238,23 @@ public class ResolveMerger extends ThreeWayMerger {
 	}
 
 	private void checkout() throws NoWorkTreeException, IOException {
-		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,
-						f,
-						entry.getValue());
-			} else {
-				if (!f.delete())
-					failingPaths.put(entry.getKey(),
-							MergeFailureReason.COULD_NOT_DELETE);
+		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, f, entry.getValue(), r);
+				} else {
+					if (!f.delete())
+						failingPaths.put(entry.getKey(),
+								MergeFailureReason.COULD_NOT_DELETE);
+				}
+				modifiedFiles.add(entry.getKey());
 			}
-			modifiedFiles.add(entry.getKey());
+		} finally {
+			r.release();
 		}
 	}