Ensure RevWalk is released when done

Update a number of calling sites of RevWalk to ensure the walker's
internal ObjectReader is released after the walk is no longer used.
Because the ObjectReader is likely to hold onto a native resource
like an Inflater, we don't want to leak them outside of their
useful scope.

Where possible we also try to share ObjectReaders across several
walk pools, or between a walker and a PackWriter.  This permits
the ObjectReader to actually do some caching if it felt inclined
to do so.

Not everything was updated, we'll probably need to come back and
update even more call sites, but these are some of the biggest
offenders.  Test cases in particular aren't updated.  My plan is to
move most storage-agnostic tests onto some purely in-memory storage
solution that doesn't do compression.

Change-Id: I04087ec79faeea208b19848939898ad7172b6672
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit.http.server/src/org/eclipse/jgit/http/server/InfoRefsServlet.java

@@ -74,13 +74,15 @@ class InfoRefsServlet extends HttpServlet {
 
 		final Repository db = getRepository(req);
 		final RevWalk walk = new RevWalk(db);
+		try {
 			final RevFlag ADVERTISED = walk.newFlag("ADVERTISED");
 
 			final OutputStreamWriter out = new OutputStreamWriter(
 					new SmartOutputStream(req, rsp), Constants.CHARSET);
 			final RefAdvertiser adv = new RefAdvertiser() {
 				@Override
-			protected void writeOne(final CharSequence line) throws IOException {
+				protected void writeOne(final CharSequence line)
+						throws IOException {
 					// Whoever decided that info/refs should use a different
 					// delimiter than the native git:// protocol shouldn't
 					// be allowed to design this sort of stuff. :-(
@@ -99,5 +101,8 @@ class InfoRefsServlet extends HttpServlet {
 			refs.remove(Constants.HEAD);
 			adv.send(refs);
 			out.close();
+		} finally {
+			walk.release();
+		}
 	}
 }

org.eclipse.jgit.http.server/src/org/eclipse/jgit/http/server/ReceivePackServlet.java

@@ -83,7 +83,12 @@ class ReceivePackServlet extends HttpServlet {
 		protected void advertise(HttpServletRequest req, Repository db,
 				PacketLineOutRefAdvertiser pck) throws IOException,
 				ServiceNotEnabledException, ServiceNotAuthorizedException {
-			receivePackFactory.create(req, db).sendAdvertisedRefs(pck);
+			ReceivePack rp = receivePackFactory.create(req, db);
+			try {
+				rp.sendAdvertisedRefs(pck);
+			} finally {
+				rp.getRevWalk().release();
+			}
 		}
 	}
 

org.eclipse.jgit.http.server/src/org/eclipse/jgit/http/server/UploadPackServlet.java

@@ -83,7 +83,12 @@ class UploadPackServlet extends HttpServlet {
 		protected void advertise(HttpServletRequest req, Repository db,
 				PacketLineOutRefAdvertiser pck) throws IOException,
 				ServiceNotEnabledException, ServiceNotAuthorizedException {
-			uploadPackFactory.create(req, db).sendAdvertisedRefs(pck);
+			UploadPack up = uploadPackFactory.create(req, db);
+			try {
+				up.sendAdvertisedRefs(pck);
+			} finally {
+				up.getRevWalk().release();
+			}
 		}
 	}
 

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/RebuildCommitGraph.java

@@ -297,6 +297,7 @@ class RebuildCommitGraph extends TextBuiltin {
 						name, id));
 			}
 		} finally {
+			rw.release();
 			br.close();
 		}
 		return refs;

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

@@ -160,8 +160,9 @@ public class CommitCommand extends GitCommand<RevCommit> {
 							.format(commit));
 					odi.flush();
 
-					RevCommit revCommit = new RevWalk(repo)
+					RevWalk revWalk = new RevWalk(repo);
-							.parseCommit(commitId);
+					try {
+						RevCommit revCommit = revWalk.parseCommit(commitId);
 						RefUpdate ru = repo.updateRef(Constants.HEAD);
 						ru.setNewObjectId(commitId);
 						ru.setRefLogMessage("commit : "
@@ -185,13 +186,16 @@ public class CommitCommand extends GitCommand<RevCommit> {
 						}
 						case REJECTED:
 						case LOCK_FAILURE:
-						throw new ConcurrentRefUpdateException(
+							throw new ConcurrentRefUpdateException(JGitText
-								JGitText.get().couldNotLockHEAD, ru.getRef(),
+									.get().couldNotLockHEAD, ru.getRef(), rc);
-								rc);
 						default:
-						throw new JGitInternalException(MessageFormat.format(
+							throw new JGitInternalException(MessageFormat
-								JGitText.get().updatingRefFailed,
+									.format(JGitText.get().updatingRefFailed,
-								Constants.HEAD, commitId.toString(), rc));
+											Constants.HEAD,
+											commitId.toString(), rc));
+						}
+					} finally {
+						revWalk.release();
 					}
 				} finally {
 					odi.release();

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

@@ -119,6 +119,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 
 			// Check for FAST_FORWARD, ALREADY_UP_TO_DATE
 			RevWalk revWalk = new RevWalk(repo);
+			try {
 				RevCommit headCommit = revWalk.lookupCommit(head.getObjectId());
 
 				Ref ref = commits.get(0);
@@ -151,6 +152,9 @@ public class MergeCommand extends GitCommand<MergeResult> {
 							mergeStrategy,
 							JGitText.get().onlyAlreadyUpToDateAndFastForwardMergesAreAvailable);
 				}
+			} finally {
+				revWalk.release();
+			}
 		} catch (IOException e) {
 			throw new JGitInternalException(
 					MessageFormat.format(

org.eclipse.jgit/src/org/eclipse/jgit/lib/RefUpdate.java

@@ -440,7 +440,12 @@ public abstract class RefUpdate {
 	 *             an unexpected IO error occurred while writing changes.
 	 */
 	public Result update() throws IOException {
-		return update(new RevWalk(getRepository()));
+		RevWalk rw = new RevWalk(getRepository());
+		try {
+			return update(rw);
+		} finally {
+			rw.release();
+		}
 	}
 
 	/**
@@ -485,7 +490,12 @@ public abstract class RefUpdate {
 	 * @throws IOException
 	 */
 	public Result delete() throws IOException {
-		return delete(new RevWalk(getRepository()));
+		RevWalk rw = new RevWalk(getRepository());
+		try {
+			return delete(rw);
+		} finally {
+			rw.release();
+		}
 	}
 
 	/**

org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java

@@ -484,9 +484,17 @@ public abstract class Repository {
 	 *             on serious errors
 	 */
 	public ObjectId resolve(final String revstr) throws IOException {
+		RevWalk rw = new RevWalk(this);
+		try {
+			return resolve(rw, revstr);
+		} finally {
+			rw.release();
+		}
+	}
+
+	private ObjectId resolve(final RevWalk rw, final String revstr) throws IOException {
 		char[] rev = revstr.toCharArray();
 		RevObject ref = null;
-		RevWalk rw = new RevWalk(this);
 		for (int i = 0; i < rev.length; ++i) {
 			switch (rev[i]) {
 			case '^':

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/RefDirectory.java

@@ -74,6 +74,7 @@ import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.eclipse.jgit.JGitText;
+import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.ObjectWritingException;
 import org.eclipse.jgit.events.RefsChangedEvent;
 import org.eclipse.jgit.lib.Constants;
@@ -418,16 +419,7 @@ public class RefDirectory extends RefDatabase {
 		if (leaf.isPeeled() || leaf.getObjectId() == null)
 			return ref;
 
-		RevWalk rw = new RevWalk(getRepository());
+		ObjectIdRef newLeaf = doPeel(leaf);
-		RevObject obj = rw.parseAny(leaf.getObjectId());
-		ObjectIdRef newLeaf;
-		if (obj instanceof RevTag) {
-			newLeaf = new ObjectIdRef.PeeledTag(leaf.getStorage(), leaf
-					.getName(), leaf.getObjectId(), rw.peel(obj).copy());
-		} else {
-			newLeaf = new ObjectIdRef.PeeledNonTag(leaf.getStorage(), leaf
-					.getName(), leaf.getObjectId());
-		}
 
 		// Try to remember this peeling in the cache, so we don't have to do
 		// it again in the future, but only if the reference is unchanged.
@@ -444,6 +436,23 @@ public class RefDirectory extends RefDatabase {
 		return recreate(ref, newLeaf);
 	}
 
+	private ObjectIdRef doPeel(final Ref leaf) throws MissingObjectException,
+			IOException {
+		RevWalk rw = new RevWalk(getRepository());
+		try {
+			RevObject obj = rw.parseAny(leaf.getObjectId());
+			if (obj instanceof RevTag) {
+				return new ObjectIdRef.PeeledTag(leaf.getStorage(), leaf
+						.getName(), leaf.getObjectId(), rw.peel(obj).copy());
+			} else {
+				return new ObjectIdRef.PeeledNonTag(leaf.getStorage(), leaf
+						.getName(), leaf.getObjectId());
+			}
+		} finally {
+			rw.release();
+		}
+	}
+
 	private static Ref recreate(final Ref old, final ObjectIdRef leaf) {
 		if (old.isSymbolic()) {
 			Ref dst = recreate(old.getTarget(), leaf);

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/RefDirectoryRename.java

@@ -92,10 +92,10 @@ class RefDirectoryRename extends RefRename {
 		if (source.getRef().isSymbolic())
 			return Result.IO_FAILURE; // not supported
 
-		final RevWalk rw = new RevWalk(refdb.getRepository());
 		objId = source.getOldObjectId();
 		updateHEAD = needToUpdateHEAD();
 		tmp = refdb.newTemporaryUpdate();
+		final RevWalk rw = new RevWalk(refdb.getRepository());
 		try {
 			// First backup the source so its never unreachable.
 			tmp.setNewObjectId(objId);
@@ -177,6 +177,7 @@ class RefDirectoryRename extends RefRename {
 			} catch (IOException err) {
 				refdb.fileFor(tmp.getName()).delete();
 			}
+			rw.release();
 		}
 	}
 

org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java

@@ -63,6 +63,7 @@ import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.StoredObjectRepresentationNotAvailableException;
 import org.eclipse.jgit.lib.AnyObjectId;
+import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.CoreConfig;
 import org.eclipse.jgit.lib.NullProgressMonitor;
@@ -181,8 +182,6 @@ public class PackWriter {
 	// edge objects for thin packs
 	private final ObjectIdSubclassMap<ObjectId> edgeObjects = new ObjectIdSubclassMap<ObjectId>();
 
-	private final Repository db;
-
 	private final Deflater deflater;
 
 	private final ObjectReader reader;
@@ -218,19 +217,51 @@ public class PackWriter {
 	 *            repository where objects are stored.
 	 */
 	public PackWriter(final Repository repo) {
-		this.db = repo;
+		this(repo, repo.newObjectReader());
+	}
 
-		reader = db.newObjectReader();
+	/**
+	 * Create a writer to load objects from the specified reader.
+	 * <p>
+	 * Objects for packing are specified in {@link #preparePack(Iterator)} or
+	 * {@link #preparePack(ProgressMonitor, Collection, Collection)}.
+	 *
+	 * @param reader
+	 *            reader to read from the repository with.
+	 */
+	public PackWriter(final ObjectReader reader) {
+		this(null, reader);
+	}
+
+	/**
+	 * Create writer for specified repository.
+	 * <p>
+	 * Objects for packing are specified in {@link #preparePack(Iterator)} or
+	 * {@link #preparePack(ProgressMonitor, Collection, Collection)}.
+	 *
+	 * @param repo
+	 *            repository where objects are stored.
+	 * @param reader
+	 *            reader to read from the repository with.
+	 */
+	public PackWriter(final Repository repo, final ObjectReader reader) {
+		this.reader = reader;
 		if (reader instanceof ObjectReuseAsIs)
 			reuseSupport = ((ObjectReuseAsIs) reader);
 		else
 			reuseSupport = null;
 
-		final CoreConfig coreConfig = db.getConfig().get(CoreConfig.KEY);
+		final CoreConfig coreConfig = configOf(repo).get(CoreConfig.KEY);
-		this.deflater = new Deflater(coreConfig.getCompression());
+		deflater = new Deflater(coreConfig.getCompression());
 		outputVersion = coreConfig.getPackIndexVersion();
 	}
 
+	private static Config configOf(final Repository repo) {
+		if (repo == null)
+			return new Config();
+		return repo.getConfig();
+	}
+
 	/**
 	 * Check whether object is configured to reuse deltas existing in
 	 * repository.

org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackFetchConnection.java

@@ -270,6 +270,12 @@ abstract class BasePackFetchConnection extends BasePackConnection implements
 		}
 	}
 
+	@Override
+	public void close() {
+		walk.release();
+		super.close();
+	}
+
 	private int maxTimeWanted(final Collection<Ref> wants) {
 		int maxTime = 0;
 		for (final Ref r : wants) {

org.eclipse.jgit/src/org/eclipse/jgit/transport/BundleFetchConnection.java

@@ -213,6 +213,7 @@ class BundleFetchConnection extends BaseFetchConnection {
 			return;
 
 		final RevWalk rw = new RevWalk(transport.local);
+		try {
 			final RevFlag PREREQ = rw.newFlag("PREREQ");
 			final RevFlag SEEN = rw.newFlag("SEEN");
 
@@ -229,12 +230,14 @@ class BundleFetchConnection extends BaseFetchConnection {
 				} catch (MissingObjectException notFound) {
 					missing.put(p, e.getValue());
 				} catch (IOException err) {
-				throw new TransportException(transport.uri
+					throw new TransportException(transport.uri, MessageFormat
-						, MessageFormat.format(JGitText.get().cannotReadCommit, p.name()), err);
+							.format(JGitText.get().cannotReadCommit, p.name()),
+							err);
 				}
 			}
 			if (!missing.isEmpty())
-			throw new MissingBundlePrerequisiteException(transport.uri, missing);
+				throw new MissingBundlePrerequisiteException(transport.uri,
+						missing);
 
 			for (final Ref r : transport.local.getAllRefs().values()) {
 				try {
@@ -255,7 +258,8 @@ class BundleFetchConnection extends BaseFetchConnection {
 					}
 				}
 			} catch (IOException err) {
-			throw new TransportException(transport.uri, JGitText.get().cannotReadObject, err);
+				throw new TransportException(transport.uri,
+						JGitText.get().cannotReadObject, err);
 			}
 
 			if (remaining > 0) {
@@ -263,7 +267,11 @@ class BundleFetchConnection extends BaseFetchConnection {
 					if (!o.has(SEEN))
 						missing.put(o, prereqs.get(o));
 				}
-			throw new MissingBundlePrerequisiteException(transport.uri, missing);
+				throw new MissingBundlePrerequisiteException(transport.uri,
+						missing);
+			}
+		} finally {
+			rw.release();
 		}
 	}
 

org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchProcess.java

@@ -176,6 +176,7 @@ class FetchProcess {
 		}
 
 		final RevWalk walk = new RevWalk(transport.local);
+		try {
 			if (transport.isRemoveDeletedRefs())
 				deleteStaleTrackingRefs(result, walk);
 			for (TrackingRefUpdate u : localUpdates) {
@@ -183,10 +184,14 @@ class FetchProcess {
 					u.update(walk);
 					result.add(u);
 				} catch (IOException err) {
-				throw new TransportException(MessageFormat.format(
+					throw new TransportException(MessageFormat.format(JGitText
-						JGitText.get().failureUpdatingTrackingRef, u.getLocalName(), err.getMessage()), err);
+							.get().failureUpdatingTrackingRef,
+							u.getLocalName(), err.getMessage()), err);
 				}
 			}
+		} finally {
+			walk.release();
+		}
 
 		if (!fetchHeadUpdates.isEmpty()) {
 			try {
@@ -296,11 +301,15 @@ class FetchProcess {
 	private boolean askForIsComplete() throws TransportException {
 		try {
 			final ObjectWalk ow = new ObjectWalk(transport.local);
+			try {
 				for (final ObjectId want : askFor.keySet())
 					ow.markStart(ow.parseAny(want));
 				for (final Ref ref : transport.local.getAllRefs().values())
 					ow.markUninteresting(ow.parseAny(ref.getObjectId()));
 				ow.checkConnectivity();
+			} finally {
+				ow.release();
+			}
 			return true;
 		} catch (MissingObjectException e) {
 			return false;

org.eclipse.jgit/src/org/eclipse/jgit/transport/PushProcess.java

@@ -122,12 +122,15 @@ class PushProcess {
 	 */
 	PushResult execute(final ProgressMonitor monitor)
 			throws NotSupportedException, TransportException {
-		monitor.beginTask(PROGRESS_OPENING_CONNECTION, ProgressMonitor.UNKNOWN);
+		try {
+			monitor.beginTask(PROGRESS_OPENING_CONNECTION,
+					ProgressMonitor.UNKNOWN);
 
 			final PushResult res = new PushResult();
 			connection = transport.openPush();
 			try {
-			res.setAdvertisedRefs(transport.getURI(), connection.getRefsMap());
+				res.setAdvertisedRefs(transport.getURI(), connection
+						.getRefsMap());
 				res.setRemoteUpdates(toPush);
 				monitor.endTask();
 
@@ -148,6 +151,9 @@ class PushProcess {
 					res.add(tru);
 			}
 			return res;
+		} finally {
+			walker.release();
+		}
 	}
 
 	private Map<String, RemoteRefUpdate> prepareRemoteUpdates()

org.eclipse.jgit/src/org/eclipse/jgit/transport/ReceivePack.java

@@ -574,6 +574,7 @@ public class ReceivePack {
 
 			service();
 		} finally {
+			walk.release();
 			try {
 				if (pckOut != null)
 					pckOut.flush();

org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java

@@ -296,6 +296,7 @@ public class UploadPack {
 			pckOut = new PacketLineOut(rawOut);
 			service();
 		} finally {
+			walk.release();
 			if (timer != null) {
 				try {
 					timer.terminate();
@@ -567,7 +568,7 @@ public class UploadPack {
 						SideBandOutputStream.CH_PROGRESS, bufsz, rawOut));
 		}
 
-		final PackWriter pw = new PackWriter(db);
+		final PackWriter pw = new PackWriter(db, walk.getObjectReader());
 		try {
 			pw.setDeltaBaseAsOffset(options.contains(OPTION_OFS_DELTA));
 			pw.setThin(thin);