org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackCompactor.java - sop/jgit - Git at Google

 /*
  * Copyright (C) 2011, Google Inc.
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
  * under the terms of the Eclipse Distribution License v1.0 which
  * accompanies this distribution, is reproduced below, and is
  * available at http://www.eclipse.org/org/documents/edl-v10.php
  *
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or
  * without modification, are permitted provided that the following
  * conditions are met:
  *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  *
  * - Redistributions in binary form must reproduce the above
  *   copyright notice, this list of conditions and the following
  *   disclaimer in the documentation and/or other materials provided
  *   with the distribution.
  *
  * - Neither the name of the Eclipse Foundation, Inc. nor the
  *   names of its contributors may be used to endorse or promote
  *   products derived from this software without specific prior
  *   written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 package org.eclipse.jgit.internal.storage.dfs;

 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.COMPACT;
 import static org.eclipse.jgit.internal.storage.pack.PackExt.INDEX;
 import static org.eclipse.jgit.internal.storage.pack.PackExt.PACK;
 import static org.eclipse.jgit.internal.storage.pack.StoredObjectRepresentation.PACK_DELTA;

 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;

 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.internal.storage.file.PackIndex;
 import org.eclipse.jgit.internal.storage.file.PackReverseIndex;
 import org.eclipse.jgit.internal.storage.pack.PackWriter;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.NullProgressMonitor;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectIdSet;
 import org.eclipse.jgit.lib.ProgressMonitor;
 import org.eclipse.jgit.revwalk.RevFlag;
 import org.eclipse.jgit.revwalk.RevObject;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.storage.pack.PackConfig;
 import org.eclipse.jgit.storage.pack.PackStatistics;
 import org.eclipse.jgit.util.BlockList;
 import org.eclipse.jgit.util.io.CountingOutputStream;

 /**
  * Combine several pack files into one pack.
  * <p>
  * The compactor combines several pack files together by including all objects
  * contained in each pack file into the same output pack. If an object appears
  * multiple times, it is only included once in the result. Because the new pack
  * is constructed by enumerating the indexes of the source packs, it is quicker
  * than doing a full repack of the repository, however the result is not nearly
  * as space efficient as new delta compression is disabled.
  * <p>
  * This method is suitable for quickly combining several packs together after
  * receiving a number of small fetch or push operations into a repository,
  * allowing the system to maintain reasonable read performance without expending
  * a lot of time repacking the entire repository.
  */
 public class DfsPackCompactor {
 	private final DfsRepository repo;

 	private final List<DfsPackFile> srcPacks;

 	private final List<ObjectIdSet> exclude;

 	private final List<DfsPackDescription> newPacks;

 	private final List<PackStatistics> newStats;

 	private int autoAddSize;

 	private RevWalk rw;
 	private RevFlag added;
 	private RevFlag isBase;

 	/**
 	 * Initialize a pack compactor.
 	 *
 	 * @param repository
 	 *            repository objects to be packed will be read from.
 	 */
 	public DfsPackCompactor(DfsRepository repository) {
 		repo = repository;
 		autoAddSize = 5 * 1024 * 1024; // 5 MiB
 		srcPacks = new ArrayList<>();
 		exclude = new ArrayList<>(4);
 		newPacks = new ArrayList<>(1);
 		newStats = new ArrayList<>(1);
 	}

 	/**
 	 * Add a pack to be compacted.
 	 * <p>
 	 * All of the objects in this pack will be copied into the resulting pack.
 	 * The resulting pack will order objects according to the source pack's own
 	 * description ordering (which is based on creation date), and then by the
 	 * order the objects appear in the source pack.
 	 *
 	 * @param pack
 	 *            a pack to combine into the resulting pack.
 	 * @return {@code this}
 	 */
 	public DfsPackCompactor add(DfsPackFile pack) {
 		srcPacks.add(pack);
 		return this;
 	}

 	/**
 	 * Automatically select packs to be included, and add them.
 	 * <p>
 	 * Packs are selected based on size, smaller packs get included while bigger
 	 * ones are omitted.
 	 *
 	 * @return {@code this}
 	 * @throws IOException
 	 *             existing packs cannot be read.
 	 */
 	public DfsPackCompactor autoAdd() throws IOException {
 		DfsObjDatabase objdb = repo.getObjectDatabase();
 		for (DfsPackFile pack : objdb.getPacks()) {
 			DfsPackDescription d = pack.getPackDescription();
 			if (d.getFileSize(PACK) < autoAddSize)
 				add(pack);
 			else
 				exclude(pack);
 		}
 		return this;
 	}

 	/**
 	 * Exclude objects from the compacted pack.
 	 *
 	 * @param set
 	 *            objects to not include.
 	 * @return {@code this}.
 	 */
 	public DfsPackCompactor exclude(ObjectIdSet set) {
 		exclude.add(set);
 		return this;
 	}

 	/**
 	 * Exclude objects from the compacted pack.
 	 *
 	 * @param pack
 	 *            objects to not include.
 	 * @return {@code this}.
 	 * @throws IOException
 	 *             pack index cannot be loaded.
 	 */
 	public DfsPackCompactor exclude(DfsPackFile pack) throws IOException {
 		final PackIndex idx;
 		try (DfsReader ctx = (DfsReader) repo.newObjectReader()) {
 			idx = pack.getPackIndex(ctx);
 		}
 		return exclude(idx);
 	}

 	/**
 	 * Compact the pack files together.
 	 *
 	 * @param pm
 	 *            progress monitor to receive updates on as packing may take a
 	 *            while, depending on the size of the repository.
 	 * @throws IOException
 	 *             the packs cannot be compacted.
 	 */
 	public void compact(ProgressMonitor pm) throws IOException {
 		if (pm == null)
 			pm = NullProgressMonitor.INSTANCE;

 		DfsObjDatabase objdb = repo.getObjectDatabase();
 		try (DfsReader ctx = objdb.newReader()) {
 			PackConfig pc = new PackConfig(repo);
 			pc.setIndexVersion(2);
 			pc.setDeltaCompress(false);
 			pc.setReuseDeltas(true);
 			pc.setReuseObjects(true);

 			PackWriter pw = new PackWriter(pc, ctx);
 			try {
 				pw.setDeltaBaseAsOffset(true);
 				pw.setReuseDeltaCommits(false);

 				addObjectsToPack(pw, ctx, pm);
 				if (pw.getObjectCount() == 0) {
 					List<DfsPackDescription> remove = toPrune();
 					if (remove.size() > 0)
 						objdb.commitPack(
 								Collections.<DfsPackDescription>emptyList(),
 								remove);
 					return;
 				}

 				boolean rollback = true;
 				DfsPackDescription pack = objdb.newPack(COMPACT,
 						estimatePackSize());
 				try {
 					writePack(objdb, pack, pw, pm);
 					writeIndex(objdb, pack, pw);

 					PackStatistics stats = pw.getStatistics();
 					pw.close();
 					pw = null;

 					pack.setPackStats(stats);
 					objdb.commitPack(Collections.singletonList(pack), toPrune());
 					newPacks.add(pack);
 					newStats.add(stats);
 					rollback = false;
 				} finally {
 					if (rollback)
 						objdb.rollbackPack(Collections.singletonList(pack));
 				}
 			} finally {
 				if (pw != null)
 					pw.close();
 			}
 		} finally {
 			rw = null;
 		}
 	}

 	private long estimatePackSize() {
 		// Every pack file contains 12 bytes of header and 20 bytes of trailer.
 		// Include the final pack file header and trailer size here and ignore
 		// the same from individual pack files.
 		long size = 32;
 		for (DfsPackFile pack : srcPacks) {
 			size += pack.getPackDescription().getFileSize(PACK) - 32;
 		}
 		return size;
 	}

 	/** @return all of the source packs that fed into this compaction. */
 	public List<DfsPackDescription> getSourcePacks() {
 		return toPrune();
 	}

 	/** @return new packs created by this compaction. */
 	public List<DfsPackDescription> getNewPacks() {
 		return newPacks;
 	}

 	/** @return statistics corresponding to the {@link #getNewPacks()}. */
 	public List<PackStatistics> getNewPackStatistics() {
 		return newStats;
 	}

 	private List<DfsPackDescription> toPrune() {
 		int cnt = srcPacks.size();
 		List<DfsPackDescription> all = new ArrayList<>(cnt);
 		for (DfsPackFile pack : srcPacks)
 			all.add(pack.getPackDescription());
 		return all;
 	}

 	private void addObjectsToPack(PackWriter pw, DfsReader ctx,
 			ProgressMonitor pm) throws IOException,
 			IncorrectObjectTypeException {
 		// Sort packs by description ordering, this places newer packs before
 		// older packs, allowing the PackWriter to be handed newer objects
 		// first and older objects last.
 		Collections.sort(srcPacks, new Comparator<DfsPackFile>() {
 			@Override
 			public int compare(DfsPackFile a, DfsPackFile b) {
 				return a.getPackDescription().compareTo(b.getPackDescription());
 			}
 		});

 		rw = new RevWalk(ctx);
 		added = rw.newFlag("ADDED"); //$NON-NLS-1$
 		isBase = rw.newFlag("IS_BASE"); //$NON-NLS-1$
 		List<RevObject> baseObjects = new BlockList<>();

 		pm.beginTask(JGitText.get().countingObjects, ProgressMonitor.UNKNOWN);
 		for (DfsPackFile src : srcPacks) {
 			List<ObjectIdWithOffset> want = toInclude(src, ctx);
 			if (want.isEmpty())
 				continue;

 			PackReverseIndex rev = src.getReverseIdx(ctx);
 			DfsObjectRepresentation rep = new DfsObjectRepresentation(src);
 			for (ObjectIdWithOffset id : want) {
 				int type = src.getObjectType(ctx, id.offset);
 				RevObject obj = rw.lookupAny(id, type);
 				if (obj.has(added))
 					continue;

 				pm.update(1);
 				pw.addObject(obj);
 				obj.add(added);

 				src.representation(rep, id.offset, ctx, rev);
 				if (rep.getFormat() != PACK_DELTA)
 					continue;

 				RevObject base = rw.lookupAny(rep.getDeltaBase(), type);
 				if (!base.has(added) && !base.has(isBase)) {
 					baseObjects.add(base);
 					base.add(isBase);
 				}
 			}
 		}
 		for (RevObject obj : baseObjects) {
 			if (!obj.has(added)) {
 				pm.update(1);
 				pw.addObject(obj);
 				obj.add(added);
 			}
 		}
 		pm.endTask();
 	}

 	private List<ObjectIdWithOffset> toInclude(DfsPackFile src, DfsReader ctx)
 			throws IOException {
 		PackIndex srcIdx = src.getPackIndex(ctx);
 		List<ObjectIdWithOffset> want = new BlockList<>(
 				(int) srcIdx.getObjectCount());
 		SCAN: for (PackIndex.MutableEntry ent : srcIdx) {
 			ObjectId id = ent.toObjectId();
 			RevObject obj = rw.lookupOrNull(id);
 			if (obj != null && (obj.has(added) || obj.has(isBase)))
 				continue;
 			for (ObjectIdSet e : exclude)
 				if (e.contains(id))
 					continue SCAN;
 			want.add(new ObjectIdWithOffset(id, ent.getOffset()));
 		}
 		Collections.sort(want, new Comparator<ObjectIdWithOffset>() {
 			@Override
 			public int compare(ObjectIdWithOffset a, ObjectIdWithOffset b) {
 				return Long.signum(a.offset - b.offset);
 			}
 		});
 		return want;
 	}

 	private static void writePack(DfsObjDatabase objdb,
 			DfsPackDescription pack,
 			PackWriter pw, ProgressMonitor pm) throws IOException {
 		try (DfsOutputStream out = objdb.writeFile(pack, PACK)) {
 			pw.writePack(pm, pm, out);
 			pack.addFileExt(PACK);
 			pack.setBlockSize(PACK, out.blockSize());
 		}
 	}

 	private static void writeIndex(DfsObjDatabase objdb,
 			DfsPackDescription pack,
 			PackWriter pw) throws IOException {
 		try (DfsOutputStream out = objdb.writeFile(pack, INDEX)) {
 			CountingOutputStream cnt = new CountingOutputStream(out);
 			pw.writeIndex(cnt);
 			pack.addFileExt(INDEX);
 			pack.setFileSize(INDEX, cnt.getCount());
 			pack.setBlockSize(INDEX, out.blockSize());
 			pack.setIndexVersion(pw.getIndexVersion());
 		}
 	}

 	private static class ObjectIdWithOffset extends ObjectId {
 		final long offset;

 		ObjectIdWithOffset(AnyObjectId id, long ofs) {
 			super(id);
 			offset = ofs;
 		}
 	}
 }
	/*
	* Copyright (C) 2011, Google Inc.
	* and other copyright owners as documented in the project's IP log.
	*
	* This program and the accompanying materials are made available
	* under the terms of the Eclipse Distribution License v1.0 which
	* accompanies this distribution, is reproduced below, and is
	* available at http://www.eclipse.org/org/documents/edl-v10.php
	*
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or
	* without modification, are permitted provided that the following
	* conditions are met:
	*
	* - Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* - Redistributions in binary form must reproduce the above
	* copyright notice, this list of conditions and the following
	* disclaimer in the documentation and/or other materials provided
	* with the distribution.
	*
	* - Neither the name of the Eclipse Foundation, Inc. nor the
	* names of its contributors may be used to endorse or promote
	* products derived from this software without specific prior
	* written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
	* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	package org.eclipse.jgit.internal.storage.dfs;

	import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.COMPACT;
	import static org.eclipse.jgit.internal.storage.pack.PackExt.INDEX;
	import static org.eclipse.jgit.internal.storage.pack.PackExt.PACK;
	import static org.eclipse.jgit.internal.storage.pack.StoredObjectRepresentation.PACK_DELTA;

	import java.io.IOException;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.List;

	import org.eclipse.jgit.errors.IncorrectObjectTypeException;
	import org.eclipse.jgit.internal.JGitText;
	import org.eclipse.jgit.internal.storage.file.PackIndex;
	import org.eclipse.jgit.internal.storage.file.PackReverseIndex;
	import org.eclipse.jgit.internal.storage.pack.PackWriter;
	import org.eclipse.jgit.lib.AnyObjectId;
	import org.eclipse.jgit.lib.NullProgressMonitor;
	import org.eclipse.jgit.lib.ObjectId;
	import org.eclipse.jgit.lib.ObjectIdSet;
	import org.eclipse.jgit.lib.ProgressMonitor;
	import org.eclipse.jgit.revwalk.RevFlag;
	import org.eclipse.jgit.revwalk.RevObject;
	import org.eclipse.jgit.revwalk.RevWalk;
	import org.eclipse.jgit.storage.pack.PackConfig;
	import org.eclipse.jgit.storage.pack.PackStatistics;
	import org.eclipse.jgit.util.BlockList;
	import org.eclipse.jgit.util.io.CountingOutputStream;

	/**
	* Combine several pack files into one pack.
	* <p>
	* The compactor combines several pack files together by including all objects
	* contained in each pack file into the same output pack. If an object appears
	* multiple times, it is only included once in the result. Because the new pack
	* is constructed by enumerating the indexes of the source packs, it is quicker
	* than doing a full repack of the repository, however the result is not nearly
	* as space efficient as new delta compression is disabled.
	* <p>
	* This method is suitable for quickly combining several packs together after
	* receiving a number of small fetch or push operations into a repository,
	* allowing the system to maintain reasonable read performance without expending
	* a lot of time repacking the entire repository.
	*/
	public class DfsPackCompactor {
	private final DfsRepository repo;

	private final List<DfsPackFile> srcPacks;

	private final List<ObjectIdSet> exclude;

	private final List<DfsPackDescription> newPacks;

	private final List<PackStatistics> newStats;

	private int autoAddSize;

	private RevWalk rw;
	private RevFlag added;
	private RevFlag isBase;

	/**
	* Initialize a pack compactor.
	*
	* @param repository
	* repository objects to be packed will be read from.
	*/
	public DfsPackCompactor(DfsRepository repository) {
	repo = repository;
	autoAddSize = 5 * 1024 * 1024; // 5 MiB
	srcPacks = new ArrayList<>();
	exclude = new ArrayList<>(4);
	newPacks = new ArrayList<>(1);
	newStats = new ArrayList<>(1);
	}

	/**
	* Add a pack to be compacted.
	* <p>
	* All of the objects in this pack will be copied into the resulting pack.
	* The resulting pack will order objects according to the source pack's own
	* description ordering (which is based on creation date), and then by the
	* order the objects appear in the source pack.
	*
	* @param pack
	* a pack to combine into the resulting pack.
	* @return {@code this}
	*/
	public DfsPackCompactor add(DfsPackFile pack) {
	srcPacks.add(pack);
	return this;
	}

	/**
	* Automatically select packs to be included, and add them.
	* <p>
	* Packs are selected based on size, smaller packs get included while bigger
	* ones are omitted.
	*
	* @return {@code this}
	* @throws IOException
	* existing packs cannot be read.
	*/
	public DfsPackCompactor autoAdd() throws IOException {
	DfsObjDatabase objdb = repo.getObjectDatabase();
	for (DfsPackFile pack : objdb.getPacks()) {
	DfsPackDescription d = pack.getPackDescription();
	if (d.getFileSize(PACK) < autoAddSize)
	add(pack);
	else
	exclude(pack);
	}
	return this;
	}

	/**
	* Exclude objects from the compacted pack.
	*
	* @param set
	* objects to not include.
	* @return {@code this}.
	*/
	public DfsPackCompactor exclude(ObjectIdSet set) {
	exclude.add(set);
	return this;
	}

	/**
	* Exclude objects from the compacted pack.
	*
	* @param pack
	* objects to not include.
	* @return {@code this}.
	* @throws IOException
	* pack index cannot be loaded.
	*/
	public DfsPackCompactor exclude(DfsPackFile pack) throws IOException {
	final PackIndex idx;
	try (DfsReader ctx = (DfsReader) repo.newObjectReader()) {
	idx = pack.getPackIndex(ctx);
	}
	return exclude(idx);
	}

	/**
	* Compact the pack files together.
	*
	* @param pm
	* progress monitor to receive updates on as packing may take a
	* while, depending on the size of the repository.
	* @throws IOException
	* the packs cannot be compacted.
	*/
	public void compact(ProgressMonitor pm) throws IOException {
	if (pm == null)
	pm = NullProgressMonitor.INSTANCE;

	DfsObjDatabase objdb = repo.getObjectDatabase();
	try (DfsReader ctx = objdb.newReader()) {
	PackConfig pc = new PackConfig(repo);
	pc.setIndexVersion(2);
	pc.setDeltaCompress(false);
	pc.setReuseDeltas(true);
	pc.setReuseObjects(true);

	PackWriter pw = new PackWriter(pc, ctx);
	try {
	pw.setDeltaBaseAsOffset(true);
	pw.setReuseDeltaCommits(false);

	addObjectsToPack(pw, ctx, pm);
	if (pw.getObjectCount() == 0) {
	List<DfsPackDescription> remove = toPrune();
	if (remove.size() > 0)
	objdb.commitPack(
	Collections.<DfsPackDescription>emptyList(),
	remove);
	return;
	}

	boolean rollback = true;
	DfsPackDescription pack = objdb.newPack(COMPACT,
	estimatePackSize());
	try {
	writePack(objdb, pack, pw, pm);
	writeIndex(objdb, pack, pw);

	PackStatistics stats = pw.getStatistics();
	pw.close();
	pw = null;

	pack.setPackStats(stats);
	objdb.commitPack(Collections.singletonList(pack), toPrune());
	newPacks.add(pack);
	newStats.add(stats);
	rollback = false;
	} finally {
	if (rollback)
	objdb.rollbackPack(Collections.singletonList(pack));
	}
	} finally {
	if (pw != null)
	pw.close();
	}
	} finally {
	rw = null;
	}
	}

	private long estimatePackSize() {
	// Every pack file contains 12 bytes of header and 20 bytes of trailer.
	// Include the final pack file header and trailer size here and ignore
	// the same from individual pack files.
	long size = 32;
	for (DfsPackFile pack : srcPacks) {
	size += pack.getPackDescription().getFileSize(PACK) - 32;
	}
	return size;
	}

	/** @return all of the source packs that fed into this compaction. */
	public List<DfsPackDescription> getSourcePacks() {
	return toPrune();
	}

	/** @return new packs created by this compaction. */
	public List<DfsPackDescription> getNewPacks() {
	return newPacks;
	}

	/** @return statistics corresponding to the {@link #getNewPacks()}. */
	public List<PackStatistics> getNewPackStatistics() {
	return newStats;
	}

	private List<DfsPackDescription> toPrune() {
	int cnt = srcPacks.size();
	List<DfsPackDescription> all = new ArrayList<>(cnt);
	for (DfsPackFile pack : srcPacks)
	all.add(pack.getPackDescription());
	return all;
	}

	private void addObjectsToPack(PackWriter pw, DfsReader ctx,
	ProgressMonitor pm) throws IOException,
	IncorrectObjectTypeException {
	// Sort packs by description ordering, this places newer packs before
	// older packs, allowing the PackWriter to be handed newer objects
	// first and older objects last.
	Collections.sort(srcPacks, new Comparator<DfsPackFile>() {
	@Override
	public int compare(DfsPackFile a, DfsPackFile b) {
	return a.getPackDescription().compareTo(b.getPackDescription());
	}
	});

	rw = new RevWalk(ctx);
	added = rw.newFlag("ADDED"); //$NON-NLS-1$
	isBase = rw.newFlag("IS_BASE"); //$NON-NLS-1$
	List<RevObject> baseObjects = new BlockList<>();

	pm.beginTask(JGitText.get().countingObjects, ProgressMonitor.UNKNOWN);
	for (DfsPackFile src : srcPacks) {
	List<ObjectIdWithOffset> want = toInclude(src, ctx);
	if (want.isEmpty())
	continue;

	PackReverseIndex rev = src.getReverseIdx(ctx);
	DfsObjectRepresentation rep = new DfsObjectRepresentation(src);
	for (ObjectIdWithOffset id : want) {
	int type = src.getObjectType(ctx, id.offset);
	RevObject obj = rw.lookupAny(id, type);
	if (obj.has(added))
	continue;

	pm.update(1);
	pw.addObject(obj);
	obj.add(added);

	src.representation(rep, id.offset, ctx, rev);
	if (rep.getFormat() != PACK_DELTA)
	continue;

	RevObject base = rw.lookupAny(rep.getDeltaBase(), type);
	if (!base.has(added) && !base.has(isBase)) {
	baseObjects.add(base);
	base.add(isBase);
	}
	}
	}
	for (RevObject obj : baseObjects) {
	if (!obj.has(added)) {
	pm.update(1);
	pw.addObject(obj);
	obj.add(added);
	}
	}
	pm.endTask();
	}

	private List<ObjectIdWithOffset> toInclude(DfsPackFile src, DfsReader ctx)
	throws IOException {
	PackIndex srcIdx = src.getPackIndex(ctx);
	List<ObjectIdWithOffset> want = new BlockList<>(
	(int) srcIdx.getObjectCount());
	SCAN: for (PackIndex.MutableEntry ent : srcIdx) {
	ObjectId id = ent.toObjectId();
	RevObject obj = rw.lookupOrNull(id);
	if (obj != null && (obj.has(added) \|\| obj.has(isBase)))
	continue;
	for (ObjectIdSet e : exclude)
	if (e.contains(id))
	continue SCAN;
	want.add(new ObjectIdWithOffset(id, ent.getOffset()));
	}
	Collections.sort(want, new Comparator<ObjectIdWithOffset>() {
	@Override
	public int compare(ObjectIdWithOffset a, ObjectIdWithOffset b) {
	return Long.signum(a.offset - b.offset);
	}
	});
	return want;
	}

	private static void writePack(DfsObjDatabase objdb,
	DfsPackDescription pack,
	PackWriter pw, ProgressMonitor pm) throws IOException {
	try (DfsOutputStream out = objdb.writeFile(pack, PACK)) {
	pw.writePack(pm, pm, out);
	pack.addFileExt(PACK);
	pack.setBlockSize(PACK, out.blockSize());
	}
	}

	private static void writeIndex(DfsObjDatabase objdb,
	DfsPackDescription pack,
	PackWriter pw) throws IOException {
	try (DfsOutputStream out = objdb.writeFile(pack, INDEX)) {
	CountingOutputStream cnt = new CountingOutputStream(out);
	pw.writeIndex(cnt);
	pack.addFileExt(INDEX);
	pack.setFileSize(INDEX, cnt.getCount());
	pack.setBlockSize(INDEX, out.blockSize());
	pack.setIndexVersion(pw.getIndexVersion());
	}
	}

	private static class ObjectIdWithOffset extends ObjectId {
	final long offset;

	ObjectIdWithOffset(AnyObjectId id, long ofs) {
	super(id);
	offset = ofs;
	}
	}
	}