/*
 * Copyright (C) 2008-2010, Google Inc.
 * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
 * 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.pack;

import static java.util.Objects.requireNonNull;
import static org.eclipse.jgit.internal.storage.pack.StoredObjectRepresentation.PACK_DELTA;
import static org.eclipse.jgit.internal.storage.pack.StoredObjectRepresentation.PACK_WHOLE;
import static org.eclipse.jgit.lib.Constants.OBJECT_ID_LENGTH;
import static org.eclipse.jgit.lib.Constants.OBJ_BLOB;
import static org.eclipse.jgit.lib.Constants.OBJ_COMMIT;
import static org.eclipse.jgit.lib.Constants.OBJ_TAG;
import static org.eclipse.jgit.lib.Constants.OBJ_TREE;

import java.io.IOException;
import java.io.OutputStream;
import java.lang.ref.WeakReference;
import java.security.MessageDigest;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.zip.CRC32;
import java.util.zip.CheckedOutputStream;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;

import org.eclipse.jgit.annotations.NonNull;
import org.eclipse.jgit.annotations.Nullable;
import org.eclipse.jgit.errors.CorruptObjectException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.LargeObjectException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.errors.StoredObjectRepresentationNotAvailableException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.internal.storage.file.PackBitmapIndexBuilder;
import org.eclipse.jgit.internal.storage.file.PackBitmapIndexWriterV1;
import org.eclipse.jgit.internal.storage.file.PackIndexWriter;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.AsyncObjectSizeQueue;
import org.eclipse.jgit.lib.BatchingProgressMonitor;
import org.eclipse.jgit.lib.BitmapIndex;
import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
import org.eclipse.jgit.lib.BitmapObject;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.NullProgressMonitor;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectIdOwnerMap;
import org.eclipse.jgit.lib.ObjectIdSet;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.lib.ThreadSafeProgressMonitor;
import org.eclipse.jgit.revwalk.AsyncRevObjectQueue;
import org.eclipse.jgit.revwalk.BitmapWalker;
import org.eclipse.jgit.revwalk.DepthWalk;
import org.eclipse.jgit.revwalk.ObjectWalk;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevFlag;
import org.eclipse.jgit.revwalk.RevObject;
import org.eclipse.jgit.revwalk.RevSort;
import org.eclipse.jgit.revwalk.RevTag;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.storage.pack.PackConfig;
import org.eclipse.jgit.storage.pack.PackStatistics;
import org.eclipse.jgit.transport.FilterSpec;
import org.eclipse.jgit.transport.ObjectCountCallback;
import org.eclipse.jgit.transport.PacketLineOut;
import org.eclipse.jgit.transport.WriteAbortedException;
import org.eclipse.jgit.util.BlockList;
import org.eclipse.jgit.util.TemporaryBuffer;


PackWriter class is responsible for generating pack files from specified set
of objects from repository. This implementation produce pack files in format
version 2.


Source of objects may be specified in two ways:

(usually) by providing sets of interesting and uninteresting objects in
repository - all interesting objects and their ancestors except uninteresting
objects and their ancestors will be included in pack, or
by providing iterator of RevObject specifying exact list and order of objects in pack

 Typical usage consists of creating an instance, configuring options, preparing the list of objects by calling preparePack(Iterator<RevObject>) or preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>), and streaming with writePack(ProgressMonitor, ProgressMonitor, OutputStream). If the pack is being stored as a file the matching index can be written out after writing the pack by writeIndex(OutputStream). An optional bitmap index can be made by calling prepareBitmapIndex(ProgressMonitor) followed by writeBitmapIndex(OutputStream). 
 Class provide set of configurable options and ProgressMonitor support, as operations may take a long time for big repositories. Deltas searching algorithm is NOT
IMPLEMENTED yet - this implementation relies only on deltas and objects
reuse.


This class is not thread safe. It is intended to be used in one thread as a
single pass to produce one pack. Invoking methods multiple times or out of
order is not supported as internal data structures are destroyed during
certain phases to save memory when packing large repositories.

/**
 * <p>
 * PackWriter class is responsible for generating pack files from specified set
 * of objects from repository. This implementation produce pack files in format
 * version 2.
 * </p>
 * <p>
 * Source of objects may be specified in two ways:
 * <ul>
 * <li>(usually) by providing sets of interesting and uninteresting objects in
 * repository - all interesting objects and their ancestors except uninteresting
 * objects and their ancestors will be included in pack, or</li>
 * <li>by providing iterator of {@link org.eclipse.jgit.revwalk.RevObject}
 * specifying exact list and order of objects in pack</li>
 * </ul>
 * <p>
 * Typical usage consists of creating an instance, configuring options,
 * preparing the list of objects by calling {@link #preparePack(Iterator)} or
 * {@link #preparePack(ProgressMonitor, Set, Set)}, and streaming with
 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)}. If the
 * pack is being stored as a file the matching index can be written out after
 * writing the pack by {@link #writeIndex(OutputStream)}. An optional bitmap
 * index can be made by calling {@link #prepareBitmapIndex(ProgressMonitor)}
 * followed by {@link #writeBitmapIndex(OutputStream)}.
 * </p>
 * <p>
 * Class provide set of configurable options and
 * {@link org.eclipse.jgit.lib.ProgressMonitor} support, as operations may take
 * a long time for big repositories. Deltas searching algorithm is <b>NOT
 * IMPLEMENTED</b> yet - this implementation relies only on deltas and objects
 * reuse.
 * </p>
 * <p>
 * This class is not thread safe. It is intended to be used in one thread as a
 * single pass to produce one pack. Invoking methods multiple times or out of
 * order is not supported as internal data structures are destroyed during
 * certain phases to save memory when packing large repositories.
 * </p>
 */
public class PackWriter implements AutoCloseable {
	private static final int PACK_VERSION_GENERATED = 2;

	
Empty set of objects for preparePack(). /** Empty set of objects for {@code preparePack()}. */
	public static final Set<ObjectId> NONE = Collections.emptySet();

	private static final Map<WeakReference<PackWriter>, Boolean> instances =
			new ConcurrentHashMap<>();

	private static final Iterable<PackWriter> instancesIterable = new Iterable<PackWriter>() {
		@Override
		public Iterator<PackWriter> iterator() {
			return new Iterator<PackWriter>() {
				private final Iterator<WeakReference<PackWriter>> it =
						instances.keySet().iterator();
				private PackWriter next;

				@Override
				public boolean hasNext() {
					if (next != null)
						return true;
					while (it.hasNext()) {
						WeakReference<PackWriter> ref = it.next();
						next = ref.get();
						if (next != null)
							return true;
						it.remove();
					}
					return false;
				}

				@Override
				public PackWriter next() {
					if (hasNext()) {
						PackWriter result = next;
						next = null;
						return result;
					}
					throw new NoSuchElementException();
				}

				@Override
				public void remove() {
					throw new UnsupportedOperationException();
				}
			};
		}
	};

	
Get all allocated, non-released PackWriters instances.
Returns:
all allocated, non-released PackWriters instances./**
	 * Get all allocated, non-released PackWriters instances.
	 *
	 * @return all allocated, non-released PackWriters instances.
	 */
	public static Iterable<PackWriter> getInstances() {
		return instancesIterable;
	}

	@SuppressWarnings("unchecked")
	BlockList<ObjectToPack> objectsLists[] = new BlockList[OBJ_TAG + 1];
	{
		objectsLists[OBJ_COMMIT] = new BlockList<>();
		objectsLists[OBJ_TREE] = new BlockList<>();
		objectsLists[OBJ_BLOB] = new BlockList<>();
		objectsLists[OBJ_TAG] = new BlockList<>();
	}

	private ObjectIdOwnerMap<ObjectToPack> objectsMap = new ObjectIdOwnerMap<>();

	// edge objects for thin packs
	private List<ObjectToPack> edgeObjects = new BlockList<>();

	// Objects the client is known to have already.
	private BitmapBuilder haveObjects;

	private List<CachedPack> cachedPacks = new ArrayList<>(2);

	private Set<ObjectId> tagTargets = NONE;

	private Set<? extends ObjectId> excludeFromBitmapSelection = NONE;

	private ObjectIdSet[] excludeInPacks;

	private ObjectIdSet excludeInPackLast;

	private Deflater myDeflater;

	private final ObjectReader reader;

	
reader recast to the reuse interface, if it supports it. /** {@link #reader} recast to the reuse interface, if it supports it. */
	private final ObjectReuseAsIs reuseSupport;

	final PackConfig config;

	private final PackStatistics.Accumulator stats;

	private final MutableState state;

	private final WeakReference<PackWriter> selfRef;

	private PackStatistics.ObjectType.Accumulator typeStats;

	private List<ObjectToPack> sortedByName;

	private byte packcsum[];

	private boolean deltaBaseAsOffset;

	private boolean reuseDeltas;

	private boolean reuseDeltaCommits;

	private boolean reuseValidate;

	private boolean thin;

	private boolean useCachedPacks;

	private boolean useBitmaps;

	private boolean ignoreMissingUninteresting = true;

	private boolean pruneCurrentObjectList;

	private boolean shallowPack;

	private boolean canBuildBitmaps;

	private boolean indexDisabled;

	private int depth;

	private Collection<? extends ObjectId> unshallowObjects;

	private PackBitmapIndexBuilder writeBitmaps;

	private CRC32 crc32;

	private ObjectCountCallback callback;

	private FilterSpec filterSpec = FilterSpec.NO_FILTER;

	private PackfileUriConfig packfileUriConfig;

	
Create writer for specified repository.
 Objects for packing are specified in preparePack(Iterator<RevObject>) or preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>). 
Params:
repo – 
           repository where objects are stored./**
	 * Create writer for specified repository.
	 * <p>
	 * Objects for packing are specified in {@link #preparePack(Iterator)} or
	 * {@link #preparePack(ProgressMonitor, Set, Set)}.
	 *
	 * @param repo
	 *            repository where objects are stored.
	 */
	public PackWriter(Repository repo) {
		this(repo, repo.newObjectReader());
	}

	
Create a writer to load objects from the specified reader.
 Objects for packing are specified in preparePack(Iterator<RevObject>) or preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>). 
Params:
reader – 
           reader to read from the repository with./**
	 * Create a writer to load objects from the specified reader.
	 * <p>
	 * Objects for packing are specified in {@link #preparePack(Iterator)} or
	 * {@link #preparePack(ProgressMonitor, Set, Set)}.
	 *
	 * @param reader
	 *            reader to read from the repository with.
	 */
	public PackWriter(ObjectReader reader) {
		this(new PackConfig(), reader);
	}

	
Create writer for specified repository.
 Objects for packing are specified in preparePack(Iterator<RevObject>) or preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>). 
Params:
repo – 
           repository where objects are stored.
reader – 
           reader to read from the repository with./**
	 * Create writer for specified repository.
	 * <p>
	 * Objects for packing are specified in {@link #preparePack(Iterator)} or
	 * {@link #preparePack(ProgressMonitor, Set, Set)}.
	 *
	 * @param repo
	 *            repository where objects are stored.
	 * @param reader
	 *            reader to read from the repository with.
	 */
	public PackWriter(Repository repo, ObjectReader reader) {
		this(new PackConfig(repo), reader);
	}

	
Create writer with a specified configuration.
 Objects for packing are specified in preparePack(Iterator<RevObject>) or preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>). 
Params:
config – 
           configuration for the pack writer.
reader – 
           reader to read from the repository with./**
	 * Create writer with a specified configuration.
	 * <p>
	 * Objects for packing are specified in {@link #preparePack(Iterator)} or
	 * {@link #preparePack(ProgressMonitor, Set, Set)}.
	 *
	 * @param config
	 *            configuration for the pack writer.
	 * @param reader
	 *            reader to read from the repository with.
	 */
	public PackWriter(PackConfig config, ObjectReader reader) {
		this(config, reader, null);
	}

	
Create writer with a specified configuration.
 Objects for packing are specified in preparePack(Iterator<RevObject>) or preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>). 
Params:
config – 
           configuration for the pack writer.
reader – 
           reader to read from the repository with.
statsAccumulator – 
           accumulator for statics/**
	 * Create writer with a specified configuration.
	 * <p>
	 * Objects for packing are specified in {@link #preparePack(Iterator)} or
	 * {@link #preparePack(ProgressMonitor, Set, Set)}.
	 *
	 * @param config
	 *            configuration for the pack writer.
	 * @param reader
	 *            reader to read from the repository with.
	 * @param statsAccumulator
	 *            accumulator for statics
	 */
	public PackWriter(PackConfig config, final ObjectReader reader,
			@Nullable PackStatistics.Accumulator statsAccumulator) {
		this.config = config;
		this.reader = reader;
		if (reader instanceof ObjectReuseAsIs)
			reuseSupport = ((ObjectReuseAsIs) reader);
		else
			reuseSupport = null;

		deltaBaseAsOffset = config.isDeltaBaseAsOffset();
		reuseDeltas = config.isReuseDeltas();
		reuseValidate = true; // be paranoid by default
		stats = statsAccumulator != null ? statsAccumulator
				: new PackStatistics.Accumulator();
		state = new MutableState();
		selfRef = new WeakReference<>(this);
		instances.put(selfRef, Boolean.TRUE);
	}

	
Set the ObjectCountCallback. 
 It should be set before calling writePack(ProgressMonitor, ProgressMonitor, OutputStream). 
Params:
callback – 
           the callback to set
Returns:
this object for chaining./**
	 * Set the {@code ObjectCountCallback}.
	 * <p>
	 * It should be set before calling
	 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)}.
	 *
	 * @param callback
	 *            the callback to set
	 * @return this object for chaining.
	 */
	public PackWriter setObjectCountCallback(ObjectCountCallback callback) {
		this.callback = callback;
		return this;
	}

	
Records the set of shallow commits in the client.
Params:
clientShallowCommits – 
           the shallow commits in the client/**
	 * Records the set of shallow commits in the client.
	 *
	 * @param clientShallowCommits
	 *            the shallow commits in the client
	 */
	public void setClientShallowCommits(Set<ObjectId> clientShallowCommits) {
		stats.clientShallowCommits = Collections
				.unmodifiableSet(new HashSet<>(clientShallowCommits));
	}

	
Check whether writer can store delta base as an offset (new style reducing pack size) or should store it as an object id (legacy style, compatible with old readers). Default setting: false 
Returns:
true if delta base is stored as an offset; false if it is stored
        as an object id./**
	 * Check whether writer can store delta base as an offset (new style
	 * reducing pack size) or should store it as an object id (legacy style,
	 * compatible with old readers).
	 *
	 * Default setting: {@value PackConfig#DEFAULT_DELTA_BASE_AS_OFFSET}
	 *
	 * @return true if delta base is stored as an offset; false if it is stored
	 *         as an object id.
	 */
	public boolean isDeltaBaseAsOffset() {
		return deltaBaseAsOffset;
	}

	
Set writer delta base format. Delta base can be written as an offset in a pack file (new approach reducing file size) or as an object id (legacy approach, compatible with old readers). Default setting: false 
Params:
deltaBaseAsOffset – 
           boolean indicating whether delta base can be stored as an
           offset./**
	 * Set writer delta base format. Delta base can be written as an offset in a
	 * pack file (new approach reducing file size) or as an object id (legacy
	 * approach, compatible with old readers).
	 *
	 * Default setting: {@value PackConfig#DEFAULT_DELTA_BASE_AS_OFFSET}
	 *
	 * @param deltaBaseAsOffset
	 *            boolean indicating whether delta base can be stored as an
	 *            offset.
	 */
	public void setDeltaBaseAsOffset(boolean deltaBaseAsOffset) {
		this.deltaBaseAsOffset = deltaBaseAsOffset;
	}

	
Check if the writer will reuse commits that are already stored as deltas.
Returns:
true if the writer would reuse commits stored as deltas, assuming
        delta reuse is already enabled./**
	 * Check if the writer will reuse commits that are already stored as deltas.
	 *
	 * @return true if the writer would reuse commits stored as deltas, assuming
	 *         delta reuse is already enabled.
	 */
	public boolean isReuseDeltaCommits() {
		return reuseDeltaCommits;
	}

	
Set the writer to reuse existing delta versions of commits.
Params:
reuse – 
           if true, the writer will reuse any commits stored as deltas.
           By default the writer does not reuse delta commits./**
	 * Set the writer to reuse existing delta versions of commits.
	 *
	 * @param reuse
	 *            if true, the writer will reuse any commits stored as deltas.
	 *            By default the writer does not reuse delta commits.
	 */
	public void setReuseDeltaCommits(boolean reuse) {
		reuseDeltaCommits = reuse;
	}

	
Check if the writer validates objects before copying them.
Returns:
true if validation is enabled; false if the reader will handle
        object validation as a side-effect of it consuming the output./**
	 * Check if the writer validates objects before copying them.
	 *
	 * @return true if validation is enabled; false if the reader will handle
	 *         object validation as a side-effect of it consuming the output.
	 */
	public boolean isReuseValidatingObjects() {
		return reuseValidate;
	}

	
Enable (or disable) object validation during packing.
Params:
validate – 
           if true the pack writer will validate an object before it is
           put into the output. This additional validation work may be
           necessary to avoid propagating corruption from one local pack
           file to another local pack file./**
	 * Enable (or disable) object validation during packing.
	 *
	 * @param validate
	 *            if true the pack writer will validate an object before it is
	 *            put into the output. This additional validation work may be
	 *            necessary to avoid propagating corruption from one local pack
	 *            file to another local pack file.
	 */
	public void setReuseValidatingObjects(boolean validate) {
		reuseValidate = validate;
	}

	
Whether this writer is producing a thin pack.
Returns:
true if this writer is producing a thin pack./**
	 * Whether this writer is producing a thin pack.
	 *
	 * @return true if this writer is producing a thin pack.
	 */
	public boolean isThin() {
		return thin;
	}

	
Whether writer may pack objects with delta base object not within set of
objects to pack
Params:
packthin – 
           a boolean indicating whether writer may pack objects with
           delta base object not within set of objects to pack, but
           belonging to party repository (uninteresting/boundary) as
           determined by set; this kind of pack is used only for
           transport; true - to produce thin pack, false - otherwise./**
	 * Whether writer may pack objects with delta base object not within set of
	 * objects to pack
	 *
	 * @param packthin
	 *            a boolean indicating whether writer may pack objects with
	 *            delta base object not within set of objects to pack, but
	 *            belonging to party repository (uninteresting/boundary) as
	 *            determined by set; this kind of pack is used only for
	 *            transport; true - to produce thin pack, false - otherwise.
	 */
	public void setThin(boolean packthin) {
		thin = packthin;
	}

	
Whether to reuse cached packs.
Returns:
true to reuse cached packs. If true index creation isn't available./**
	 * Whether to reuse cached packs.
	 *
	 * @return {@code true} to reuse cached packs. If true index creation isn't
	 *         available.
	 */
	public boolean isUseCachedPacks() {
		return useCachedPacks;
	}

	
Whether to use cached packs
Params:
useCached –  if set to true and a cached pack is present, it will be appended onto the end of a thin-pack, reducing the amount of working set space and CPU used by PackWriter. Enabling this feature prevents PackWriter from creating an index for the newly created pack, so its only suitable for writing to a network client, where the client will make the index./**
	 * Whether to use cached packs
	 *
	 * @param useCached
	 *            if set to {@code true} and a cached pack is present, it will
	 *            be appended onto the end of a thin-pack, reducing the amount
	 *            of working set space and CPU used by PackWriter. Enabling this
	 *            feature prevents PackWriter from creating an index for the
	 *            newly created pack, so its only suitable for writing to a
	 *            network client, where the client will make the index.
	 */
	public void setUseCachedPacks(boolean useCached) {
		useCachedPacks = useCached;
	}

	
Whether to use bitmaps
Returns:
true to use bitmaps for ObjectWalks, if available./**
	 * Whether to use bitmaps
	 *
	 * @return {@code true} to use bitmaps for ObjectWalks, if available.
	 */
	public boolean isUseBitmaps() {
		return useBitmaps;
	}

	
Whether to use bitmaps
Params:
useBitmaps – 
           if set to true, bitmaps will be used when preparing a pack./**
	 * Whether to use bitmaps
	 *
	 * @param useBitmaps
	 *            if set to true, bitmaps will be used when preparing a pack.
	 */
	public void setUseBitmaps(boolean useBitmaps) {
		this.useBitmaps = useBitmaps;
	}

	
Whether the index file cannot be created by this PackWriter.
Returns:
true if the index file cannot be created by this PackWriter./**
	 * Whether the index file cannot be created by this PackWriter.
	 *
	 * @return {@code true} if the index file cannot be created by this
	 *         PackWriter.
	 */
	public boolean isIndexDisabled() {
		return indexDisabled || !cachedPacks.isEmpty();
	}

	
Whether to disable creation of the index file.
Params:
noIndex –  true to disable creation of the index file./**
	 * Whether to disable creation of the index file.
	 *
	 * @param noIndex
	 *            {@code true} to disable creation of the index file.
	 */
	public void setIndexDisabled(boolean noIndex) {
		this.indexDisabled = noIndex;
	}

	
Whether to ignore missing uninteresting objects
Returns:
true to ignore objects that are uninteresting and also not found on local disk; false to throw a MissingObjectException out of preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>) if an uninteresting object is not in the source repository. By default, true, permitting gracefully ignoring of uninteresting objects./**
	 * Whether to ignore missing uninteresting objects
	 *
	 * @return {@code true} to ignore objects that are uninteresting and also
	 *         not found on local disk; false to throw a
	 *         {@link org.eclipse.jgit.errors.MissingObjectException} out of
	 *         {@link #preparePack(ProgressMonitor, Set, Set)} if an
	 *         uninteresting object is not in the source repository. By default,
	 *         true, permitting gracefully ignoring of uninteresting objects.
	 */
	public boolean isIgnoreMissingUninteresting() {
		return ignoreMissingUninteresting;
	}

	
Whether writer should ignore non existing uninteresting objects
Params:
ignore –  true if writer should ignore non existing uninteresting objects during construction set of objects to pack; false otherwise - non existing uninteresting objects may cause MissingObjectException/**
	 * Whether writer should ignore non existing uninteresting objects
	 *
	 * @param ignore
	 *            {@code true} if writer should ignore non existing
	 *            uninteresting objects during construction set of objects to
	 *            pack; false otherwise - non existing uninteresting objects may
	 *            cause {@link org.eclipse.jgit.errors.MissingObjectException}
	 */
	public void setIgnoreMissingUninteresting(boolean ignore) {
		ignoreMissingUninteresting = ignore;
	}

	
Set the tag targets that should be hoisted earlier during packing.

Callers may put objects into this set before invoking any of the
preparePack methods to influence where an annotated tag's target is
stored within the resulting pack. Typically these will be clustered
together, and hoisted earlier in the file even if they are ancient
revisions, allowing readers to find tag targets with better locality.
Params:
objects – 
           objects that annotated tags point at./**
	 * Set the tag targets that should be hoisted earlier during packing.
	 * <p>
	 * Callers may put objects into this set before invoking any of the
	 * preparePack methods to influence where an annotated tag's target is
	 * stored within the resulting pack. Typically these will be clustered
	 * together, and hoisted earlier in the file even if they are ancient
	 * revisions, allowing readers to find tag targets with better locality.
	 *
	 * @param objects
	 *            objects that annotated tags point at.
	 */
	public void setTagTargets(Set<ObjectId> objects) {
		tagTargets = objects;
	}

	
Configure this pack for a shallow clone.
Params:
depth – 
           maximum depth of history to return. 1 means return only the
           "wants".
unshallow – 
           objects which used to be shallow on the client, but are being
           extended as part of this fetch/**
	 * Configure this pack for a shallow clone.
	 *
	 * @param depth
	 *            maximum depth of history to return. 1 means return only the
	 *            "wants".
	 * @param unshallow
	 *            objects which used to be shallow on the client, but are being
	 *            extended as part of this fetch
	 */
	public void setShallowPack(int depth,
			Collection<? extends ObjectId> unshallow) {
		this.shallowPack = true;
		this.depth = depth;
		this.unshallowObjects = unshallow;
	}

	
Params:
filter – the filter which indicates what and what not this writer
           should include/**
	 * @param filter the filter which indicates what and what not this writer
	 *            should include
	 */
	public void setFilterSpec(@NonNull FilterSpec filter) {
		filterSpec = requireNonNull(filter);
	}

	
Params:
config – configuration related to packfile URIs
Since:
5.5/**
	 * @param config configuration related to packfile URIs
	 * @since 5.5
	 */
	public void setPackfileUriConfig(PackfileUriConfig config) {
		packfileUriConfig = config;
	}

	
Returns objects number in a pack file that was created by this writer.
Throws:
IOException – 
            a cached pack cannot supply its object count.
Returns:
number of objects in pack./**
	 * Returns objects number in a pack file that was created by this writer.
	 *
	 * @return number of objects in pack.
	 * @throws java.io.IOException
	 *             a cached pack cannot supply its object count.
	 */
	public long getObjectCount() throws IOException {
		if (stats.totalObjects == 0) {
			long objCnt = 0;

			objCnt += objectsLists[OBJ_COMMIT].size();
			objCnt += objectsLists[OBJ_TREE].size();
			objCnt += objectsLists[OBJ_BLOB].size();
			objCnt += objectsLists[OBJ_TAG].size();

			for (CachedPack pack : cachedPacks)
				objCnt += pack.getObjectCount();
			return objCnt;
		}
		return stats.totalObjects;
	}

	private long getUnoffloadedObjectCount() throws IOException {
		long objCnt = 0;

		objCnt += objectsLists[OBJ_COMMIT].size();
		objCnt += objectsLists[OBJ_TREE].size();
		objCnt += objectsLists[OBJ_BLOB].size();
		objCnt += objectsLists[OBJ_TAG].size();

		for (CachedPack pack : cachedPacks) {
			CachedPackUriProvider.PackInfo packInfo =
				packfileUriConfig.cachedPackUriProvider.getInfo(
					pack, packfileUriConfig.protocolsSupported);
			if (packInfo == null) {
				objCnt += pack.getObjectCount();
			}
		}

		return objCnt;
	}

	
Returns the object ids in the pack file that was created by this writer.
 This method can only be invoked after writePack(ProgressMonitor, ProgressMonitor, OutputStream) has been invoked and completed successfully. 
Throws:
IOException – 
            a cached pack cannot supply its object ids.
Returns:
set of objects in pack./**
	 * Returns the object ids in the pack file that was created by this writer.
	 * <p>
	 * This method can only be invoked after
	 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)} has
	 * been invoked and completed successfully.
	 *
	 * @return set of objects in pack.
	 * @throws java.io.IOException
	 *             a cached pack cannot supply its object ids.
	 */
	public ObjectIdOwnerMap<ObjectIdOwnerMap.Entry> getObjectSet()
			throws IOException {
		if (!cachedPacks.isEmpty())
			throw new IOException(
					JGitText.get().cachedPacksPreventsListingObjects);

		if (writeBitmaps != null) {
			return writeBitmaps.getObjectSet();
		}

		ObjectIdOwnerMap<ObjectIdOwnerMap.Entry> r = new ObjectIdOwnerMap<>();
		for (BlockList<ObjectToPack> objList : objectsLists) {
			if (objList != null) {
				for (ObjectToPack otp : objList)
					r.add(new ObjectIdOwnerMap.Entry(otp) {
						// A new entry that copies the ObjectId
					});
			}
		}
		return r;
	}

	
Add a pack index whose contents should be excluded from the result.
Params:
idx – 
           objects in this index will not be in the output pack./**
	 * Add a pack index whose contents should be excluded from the result.
	 *
	 * @param idx
	 *            objects in this index will not be in the output pack.
	 */
	public void excludeObjects(ObjectIdSet idx) {
		if (excludeInPacks == null) {
			excludeInPacks = new ObjectIdSet[] { idx };
			excludeInPackLast = idx;
		} else {
			int cnt = excludeInPacks.length;
			ObjectIdSet[] newList = new ObjectIdSet[cnt + 1];
			System.arraycopy(excludeInPacks, 0, newList, 0, cnt);
			newList[cnt] = idx;
			excludeInPacks = newList;
		}
	}

	
Prepare the list of objects to be written to the pack stream.

Iterator exactly determines which objects are included in a pack
and order they appear in pack (except that objects order by type is not
needed at input). This order should conform general rules of ordering
objects in git - by recency and path (type and delta-base first is
internally secured) and responsibility for guaranteeing this order is on
a caller side. Iterator must return each id of object to write exactly
once.

Params:
objectsSource –  iterator of object to store in a pack; order of objects within each type is important, ordering by type is not needed; allowed types for objects are Constants.OBJ_COMMIT, Constants.OBJ_TREE, Constants.OBJ_BLOB and Constants.OBJ_TAG; objects returned by iterator may be later reused by caller as object id and type are internally copied in each iteration.
Throws:
IOException – 
            when some I/O problem occur during reading objects./**
	 * Prepare the list of objects to be written to the pack stream.
	 * <p>
	 * Iterator <b>exactly</b> determines which objects are included in a pack
	 * and order they appear in pack (except that objects order by type is not
	 * needed at input). This order should conform general rules of ordering
	 * objects in git - by recency and path (type and delta-base first is
	 * internally secured) and responsibility for guaranteeing this order is on
	 * a caller side. Iterator must return each id of object to write exactly
	 * once.
	 * </p>
	 *
	 * @param objectsSource
	 *            iterator of object to store in a pack; order of objects within
	 *            each type is important, ordering by type is not needed;
	 *            allowed types for objects are
	 *            {@link org.eclipse.jgit.lib.Constants#OBJ_COMMIT},
	 *            {@link org.eclipse.jgit.lib.Constants#OBJ_TREE},
	 *            {@link org.eclipse.jgit.lib.Constants#OBJ_BLOB} and
	 *            {@link org.eclipse.jgit.lib.Constants#OBJ_TAG}; objects
	 *            returned by iterator may be later reused by caller as object
	 *            id and type are internally copied in each iteration.
	 * @throws java.io.IOException
	 *             when some I/O problem occur during reading objects.
	 */
	public void preparePack(@NonNull Iterator<RevObject> objectsSource)
			throws IOException {
		while (objectsSource.hasNext()) {
			addObject(objectsSource.next());
		}
	}

	
Prepare the list of objects to be written to the pack stream.
 Basing on these 2 sets, another set of objects to put in a pack file is created: this set consists of all objects reachable (ancestors) from interesting objects, except uninteresting objects and their ancestors. This method uses class ObjectWalk extensively to find out that appropriate set of output objects and their optimal order in output pack. Order is consistent with general git in-pack rules: sort by object type, recency, path and delta-base first. 
Params:
countingMonitor – 
           progress during object enumeration.
want –  collection of objects to be marked as interesting (start points of graph traversal). Must not be null.
have –  collection of objects to be marked as uninteresting (end points of graph traversal). Pass NONE if all objects reachable from want are desired, such as when serving a clone.
Throws:
IOException – 
            when some I/O problem occur during reading objects./**
	 * Prepare the list of objects to be written to the pack stream.
	 * <p>
	 * Basing on these 2 sets, another set of objects to put in a pack file is
	 * created: this set consists of all objects reachable (ancestors) from
	 * interesting objects, except uninteresting objects and their ancestors.
	 * This method uses class {@link org.eclipse.jgit.revwalk.ObjectWalk}
	 * extensively to find out that appropriate set of output objects and their
	 * optimal order in output pack. Order is consistent with general git
	 * in-pack rules: sort by object type, recency, path and delta-base first.
	 * </p>
	 *
	 * @param countingMonitor
	 *            progress during object enumeration.
	 * @param want
	 *            collection of objects to be marked as interesting (start
	 *            points of graph traversal). Must not be {@code null}.
	 * @param have
	 *            collection of objects to be marked as uninteresting (end
	 *            points of graph traversal). Pass {@link #NONE} if all objects
	 *            reachable from {@code want} are desired, such as when serving
	 *            a clone.
	 * @throws java.io.IOException
	 *             when some I/O problem occur during reading objects.
	 */
	public void preparePack(ProgressMonitor countingMonitor,
			@NonNull Set<? extends ObjectId> want,
			@NonNull Set<? extends ObjectId> have) throws IOException {
		preparePack(countingMonitor, want, have, NONE, NONE);
	}

	
Prepare the list of objects to be written to the pack stream.
 Like preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>) but also allows specifying commits that should not be walked past ("shallow" commits). The caller is responsible for filtering out commits that should not be shallow any more ("unshallow" commits as in setShallowPack) from the shallow set. 
Params:
countingMonitor – 
           progress during object enumeration.
want –  objects of interest, ancestors of which will be included in the pack. Must not be null.
have –  objects whose ancestors (up to and including shallow commits) do not need to be included in the pack because they are already available from elsewhere. Must not be null.
shallow –  commits indicating the boundary of the history marked with have. Shallow commits have parents but those parents are considered not to be already available. Parents of shallow commits and earlier generations will be included in the pack if requested by want. Must not be null.
Throws:
IOException – 
            an I/O problem occurred while reading objects./**
	 * Prepare the list of objects to be written to the pack stream.
	 * <p>
	 * Like {@link #preparePack(ProgressMonitor, Set, Set)} but also allows
	 * specifying commits that should not be walked past ("shallow" commits).
	 * The caller is responsible for filtering out commits that should not be
	 * shallow any more ("unshallow" commits as in {@link #setShallowPack}) from
	 * the shallow set.
	 *
	 * @param countingMonitor
	 *            progress during object enumeration.
	 * @param want
	 *            objects of interest, ancestors of which will be included in
	 *            the pack. Must not be {@code null}.
	 * @param have
	 *            objects whose ancestors (up to and including {@code shallow}
	 *            commits) do not need to be included in the pack because they
	 *            are already available from elsewhere. Must not be
	 *            {@code null}.
	 * @param shallow
	 *            commits indicating the boundary of the history marked with
	 *            {@code have}. Shallow commits have parents but those parents
	 *            are considered not to be already available. Parents of
	 *            {@code shallow} commits and earlier generations will be
	 *            included in the pack if requested by {@code want}. Must not be
	 *            {@code null}.
	 * @throws java.io.IOException
	 *             an I/O problem occurred while reading objects.
	 */
	public void preparePack(ProgressMonitor countingMonitor,
			@NonNull Set<? extends ObjectId> want,
			@NonNull Set<? extends ObjectId> have,
			@NonNull Set<? extends ObjectId> shallow) throws IOException {
		preparePack(countingMonitor, want, have, shallow, NONE);
	}

	
Prepare the list of objects to be written to the pack stream.
 Like preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>) but also allows specifying commits that should not be walked past ("shallow" commits). The caller is responsible for filtering out commits that should not be shallow any more ("unshallow" commits as in setShallowPack) from the shallow set. 
Params:
countingMonitor – 
           progress during object enumeration.
want –  objects of interest, ancestors of which will be included in the pack. Must not be null.
have –  objects whose ancestors (up to and including shallow commits) do not need to be included in the pack because they are already available from elsewhere. Must not be null.
shallow –  commits indicating the boundary of the history marked with have. Shallow commits have parents but those parents are considered not to be already available. Parents of shallow commits and earlier generations will be included in the pack if requested by want. Must not be null.
noBitmaps – 
           collection of objects to be excluded from bitmap commit
           selection.
Throws:
IOException – 
            an I/O problem occurred while reading objects./**
	 * Prepare the list of objects to be written to the pack stream.
	 * <p>
	 * Like {@link #preparePack(ProgressMonitor, Set, Set)} but also allows
	 * specifying commits that should not be walked past ("shallow" commits).
	 * The caller is responsible for filtering out commits that should not be
	 * shallow any more ("unshallow" commits as in {@link #setShallowPack}) from
	 * the shallow set.
	 *
	 * @param countingMonitor
	 *            progress during object enumeration.
	 * @param want
	 *            objects of interest, ancestors of which will be included in
	 *            the pack. Must not be {@code null}.
	 * @param have
	 *            objects whose ancestors (up to and including {@code shallow}
	 *            commits) do not need to be included in the pack because they
	 *            are already available from elsewhere. Must not be
	 *            {@code null}.
	 * @param shallow
	 *            commits indicating the boundary of the history marked with
	 *            {@code have}. Shallow commits have parents but those parents
	 *            are considered not to be already available. Parents of
	 *            {@code shallow} commits and earlier generations will be
	 *            included in the pack if requested by {@code want}. Must not be
	 *            {@code null}.
	 * @param noBitmaps
	 *            collection of objects to be excluded from bitmap commit
	 *            selection.
	 * @throws java.io.IOException
	 *             an I/O problem occurred while reading objects.
	 */
	public void preparePack(ProgressMonitor countingMonitor,
			@NonNull Set<? extends ObjectId> want,
			@NonNull Set<? extends ObjectId> have,
			@NonNull Set<? extends ObjectId> shallow,
			@NonNull Set<? extends ObjectId> noBitmaps) throws IOException {
		try (ObjectWalk ow = getObjectWalk()) {
			ow.assumeShallow(shallow);
			preparePack(countingMonitor, ow, want, have, noBitmaps);
		}
	}

	private ObjectWalk getObjectWalk() {
		return shallowPack ? new DepthWalk.ObjectWalk(reader, depth - 1)
				: new ObjectWalk(reader);
	}

	
A visitation policy which uses the depth at which the object is seen to
decide if re-traversal is necessary. In particular, if the object has
already been visited at this depth or shallower, it is not necessary to
re-visit at this depth.
/**
	 * A visitation policy which uses the depth at which the object is seen to
	 * decide if re-traversal is necessary. In particular, if the object has
	 * already been visited at this depth or shallower, it is not necessary to
	 * re-visit at this depth.
	 */
	private static class DepthAwareVisitationPolicy
			implements ObjectWalk.VisitationPolicy {
		private final Map<ObjectId, Integer> lowestDepthVisited = new HashMap<>();

		private final ObjectWalk walk;

		DepthAwareVisitationPolicy(ObjectWalk walk) {
			this.walk = requireNonNull(walk);
		}

		@Override
		public boolean shouldVisit(RevObject o) {
			Integer lastDepth = lowestDepthVisited.get(o);
			if (lastDepth == null) {
				return true;
			}
			return walk.getTreeDepth() < lastDepth.intValue();
		}

		@Override
		public void visited(RevObject o) {
			lowestDepthVisited.put(o, Integer.valueOf(walk.getTreeDepth()));
		}
	}

	
Prepare the list of objects to be written to the pack stream.
 Basing on these 2 sets, another set of objects to put in a pack file is created: this set consists of all objects reachable (ancestors) from interesting objects, except uninteresting objects and their ancestors. This method uses class ObjectWalk extensively to find out that appropriate set of output objects and their optimal order in output pack. Order is consistent with general git in-pack rules: sort by object type, recency, path and delta-base first. 
Params:
countingMonitor – 
           progress during object enumeration.
walk – 
           ObjectWalk to perform enumeration.
interestingObjects –  collection of objects to be marked as interesting (start points of graph traversal). Must not be null.
uninterestingObjects –  collection of objects to be marked as uninteresting (end points of graph traversal). Pass NONE if all objects reachable from want are desired, such as when serving a clone.
noBitmaps – 
           collection of objects to be excluded from bitmap commit
           selection.
Throws:
IOException – 
            when some I/O problem occur during reading objects./**
	 * Prepare the list of objects to be written to the pack stream.
	 * <p>
	 * Basing on these 2 sets, another set of objects to put in a pack file is
	 * created: this set consists of all objects reachable (ancestors) from
	 * interesting objects, except uninteresting objects and their ancestors.
	 * This method uses class {@link org.eclipse.jgit.revwalk.ObjectWalk}
	 * extensively to find out that appropriate set of output objects and their
	 * optimal order in output pack. Order is consistent with general git
	 * in-pack rules: sort by object type, recency, path and delta-base first.
	 * </p>
	 *
	 * @param countingMonitor
	 *            progress during object enumeration.
	 * @param walk
	 *            ObjectWalk to perform enumeration.
	 * @param interestingObjects
	 *            collection of objects to be marked as interesting (start
	 *            points of graph traversal). Must not be {@code null}.
	 * @param uninterestingObjects
	 *            collection of objects to be marked as uninteresting (end
	 *            points of graph traversal). Pass {@link #NONE} if all objects
	 *            reachable from {@code want} are desired, such as when serving
	 *            a clone.
	 * @param noBitmaps
	 *            collection of objects to be excluded from bitmap commit
	 *            selection.
	 * @throws java.io.IOException
	 *             when some I/O problem occur during reading objects.
	 */
	public void preparePack(ProgressMonitor countingMonitor,
			@NonNull ObjectWalk walk,
			@NonNull Set<? extends ObjectId> interestingObjects,
			@NonNull Set<? extends ObjectId> uninterestingObjects,
			@NonNull Set<? extends ObjectId> noBitmaps)
			throws IOException {
		if (countingMonitor == null)
			countingMonitor = NullProgressMonitor.INSTANCE;
		if (shallowPack && !(walk instanceof DepthWalk.ObjectWalk))
			throw new IllegalArgumentException(
					JGitText.get().shallowPacksRequireDepthWalk);
		if (filterSpec.getTreeDepthLimit() >= 0) {
			walk.setVisitationPolicy(new DepthAwareVisitationPolicy(walk));
		}
		findObjectsToPack(countingMonitor, walk, interestingObjects,
				uninterestingObjects, noBitmaps);
	}

	
Determine if the pack file will contain the requested object.
Params:
id – 
           the object to test the existence of.
Throws:
IOException – 
            a cached pack cannot be examined.
Returns:
true if the object will appear in the output pack file./**
	 * Determine if the pack file will contain the requested object.
	 *
	 * @param id
	 *            the object to test the existence of.
	 * @return true if the object will appear in the output pack file.
	 * @throws java.io.IOException
	 *             a cached pack cannot be examined.
	 */
	public boolean willInclude(AnyObjectId id) throws IOException {
		ObjectToPack obj = objectsMap.get(id);
		return obj != null && !obj.isEdge();
	}

	
Lookup the ObjectToPack object for a given ObjectId.
Params:
id – 
           the object to find in the pack.
Returns:
the object we are packing, or null./**
	 * Lookup the ObjectToPack object for a given ObjectId.
	 *
	 * @param id
	 *            the object to find in the pack.
	 * @return the object we are packing, or null.
	 */
	public ObjectToPack get(AnyObjectId id) {
		ObjectToPack obj = objectsMap.get(id);
		return obj != null && !obj.isEdge() ? obj : null;
	}

	
Computes SHA-1 of lexicographically sorted objects ids written in this
pack, as used to name a pack file in repository.
Returns:
ObjectId representing SHA-1 name of a pack that was created./**
	 * Computes SHA-1 of lexicographically sorted objects ids written in this
	 * pack, as used to name a pack file in repository.
	 *
	 * @return ObjectId representing SHA-1 name of a pack that was created.
	 */
	public ObjectId computeName() {
		final byte[] buf = new byte[OBJECT_ID_LENGTH];
		final MessageDigest md = Constants.newMessageDigest();
		for (ObjectToPack otp : sortByName()) {
			otp.copyRawTo(buf, 0);
			md.update(buf, 0, OBJECT_ID_LENGTH);
		}
		return ObjectId.fromRaw(md.digest());
	}

	
Returns the index format version that will be written.
 This method can only be invoked after writePack(ProgressMonitor, ProgressMonitor, OutputStream) has been invoked and completed successfully. 
Returns:
the index format version./**
	 * Returns the index format version that will be written.
	 * <p>
	 * This method can only be invoked after
	 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)} has
	 * been invoked and completed successfully.
	 *
	 * @return the index format version.
	 */
	public int getIndexVersion() {
		int indexVersion = config.getIndexVersion();
		if (indexVersion <= 0) {
			for (BlockList<ObjectToPack> objs : objectsLists)
				indexVersion = Math.max(indexVersion,
						PackIndexWriter.oldestPossibleFormat(objs));
		}
		return indexVersion;
	}

	
Create an index file to match the pack file just written.
 Called after writePack(ProgressMonitor, ProgressMonitor, OutputStream). 

Writing an index is only required for local pack storage. Packs sent on
the network do not need to create an index.
Params:
indexStream – 
           output for the index data. Caller is responsible for closing
           this stream.
Throws:
IOException – 
            the index data could not be written to the supplied stream./**
	 * Create an index file to match the pack file just written.
	 * <p>
	 * Called after
	 * {@link #writePack(ProgressMonitor, ProgressMonitor, OutputStream)}.
	 * <p>
	 * Writing an index is only required for local pack storage. Packs sent on
	 * the network do not need to create an index.
	 *
	 * @param indexStream
	 *            output for the index data. Caller is responsible for closing
	 *            this stream.
	 * @throws java.io.IOException
	 *             the index data could not be written to the supplied stream.
	 */
	public void writeIndex(OutputStream indexStream) throws IOException {
		if (isIndexDisabled())
			throw new IOException(JGitText.get().cachedPacksPreventsIndexCreation);

		long writeStart = System.currentTimeMillis();
		final PackIndexWriter iw = PackIndexWriter.createVersion(
				indexStream, getIndexVersion());
		iw.write(sortByName(), packcsum);
		stats.timeWriting += System.currentTimeMillis() - writeStart;
	}

	
Create a bitmap index file to match the pack file just written.
 Called after prepareBitmapIndex(ProgressMonitor). 
Params:
bitmapIndexStream – 
           output for the bitmap index data. Caller is responsible for
           closing this stream.
Throws:
IOException – 
            the index data could not be written to the supplied stream./**
	 * Create a bitmap index file to match the pack file just written.
	 * <p>
	 * Called after {@link #prepareBitmapIndex(ProgressMonitor)}.
	 *
	 * @param bitmapIndexStream
	 *            output for the bitmap index data. Caller is responsible for
	 *            closing this stream.
	 * @throws java.io.IOException
	 *             the index data could not be written to the supplied stream.
	 */
	public void writeBitmapIndex(OutputStream bitmapIndexStream)
			throws IOException {
		if (writeBitmaps == null)
			throw new IOException(JGitText.get().bitmapsMustBePrepared);

		long writeStart = System.currentTimeMillis();
		final PackBitmapIndexWriterV1 iw = new PackBitmapIndexWriterV1(bitmapIndexStream);
		iw.write(writeBitmaps, packcsum);
		stats.timeWriting += System.currentTimeMillis() - writeStart;
	}

	private List<ObjectToPack> sortByName() {
		if (sortedByName == null) {
			int cnt = 0;
			cnt += objectsLists[OBJ_COMMIT].size();
			cnt += objectsLists[OBJ_TREE].size();
			cnt += objectsLists[OBJ_BLOB].size();
			cnt += objectsLists[OBJ_TAG].size();

			sortedByName = new BlockList<>(cnt);
			sortedByName.addAll(objectsLists[OBJ_COMMIT]);
			sortedByName.addAll(objectsLists[OBJ_TREE]);
			sortedByName.addAll(objectsLists[OBJ_BLOB]);
			sortedByName.addAll(objectsLists[OBJ_TAG]);
			Collections.sort(sortedByName);
		}
		return sortedByName;
	}

	private void beginPhase(PackingPhase phase, ProgressMonitor monitor,
			long cnt) {
		state.phase = phase;
		String task;
		switch (phase) {
		case COUNTING:
			task = JGitText.get().countingObjects;
			break;
		case GETTING_SIZES:
			task = JGitText.get().searchForSizes;
			break;
		case FINDING_SOURCES:
			task = JGitText.get().searchForReuse;
			break;
		case COMPRESSING:
			task = JGitText.get().compressingObjects;
			break;
		case WRITING:
			task = JGitText.get().writingObjects;
			break;
		case BUILDING_BITMAPS:
			task = JGitText.get().buildingBitmaps;
			break;
		default:
			throw new IllegalArgumentException(
					MessageFormat.format(JGitText.get().illegalPackingPhase, phase));
		}
		monitor.beginTask(task, (int) cnt);
	}

	private void endPhase(ProgressMonitor monitor) {
		monitor.endTask();
	}

	
Write the prepared pack to the supplied stream.
 Called after preparePack(ProgressMonitor, ObjectWalk, Set<? extends ObjectId>, Set<? extends ObjectId>, Set<? extends ObjectId>) or preparePack(ProgressMonitor, Set<? extends ObjectId>, Set<? extends ObjectId>). 

Performs delta search if enabled and writes the pack stream.

All reused objects data checksum (Adler32/CRC32) is computed and
validated against existing checksum.
Params:
compressMonitor – 
           progress monitor to report object compression work.
writeMonitor – 
           progress monitor to report the number of objects written.
packStream – 
           output stream of pack data. The stream should be buffered by
           the caller. The caller is responsible for closing the stream.
Throws:
IOException – 
            an error occurred reading a local object's data to include in
            the pack, or writing compressed object data to the output
            stream.
WriteAbortedException –  the write operation is aborted by ObjectCountCallback ./**
	 * Write the prepared pack to the supplied stream.
	 * <p>
	 * Called after
	 * {@link #preparePack(ProgressMonitor, ObjectWalk, Set, Set, Set)} or
	 * {@link #preparePack(ProgressMonitor, Set, Set)}.
	 * <p>
	 * Performs delta search if enabled and writes the pack stream.
	 * <p>
	 * All reused objects data checksum (Adler32/CRC32) is computed and
	 * validated against existing checksum.
	 *
	 * @param compressMonitor
	 *            progress monitor to report object compression work.
	 * @param writeMonitor
	 *            progress monitor to report the number of objects written.
	 * @param packStream
	 *            output stream of pack data. The stream should be buffered by
	 *            the caller. The caller is responsible for closing the stream.
	 * @throws java.io.IOException
	 *             an error occurred reading a local object's data to include in
	 *             the pack, or writing compressed object data to the output
	 *             stream.
	 * @throws WriteAbortedException
	 *             the write operation is aborted by
	 *             {@link org.eclipse.jgit.transport.ObjectCountCallback} .
	 */
	public void writePack(ProgressMonitor compressMonitor,
			ProgressMonitor writeMonitor, OutputStream packStream)
			throws IOException {
		if (compressMonitor == null)
			compressMonitor = NullProgressMonitor.INSTANCE;
		if (writeMonitor == null)
			writeMonitor = NullProgressMonitor.INSTANCE;

		excludeInPacks = null;
		excludeInPackLast = null;

		boolean needSearchForReuse = reuseSupport != null && (
				   reuseDeltas
				|| config.isReuseObjects()
				|| !cachedPacks.isEmpty());

		if (compressMonitor instanceof BatchingProgressMonitor) {
			long delay = 1000;
			if (needSearchForReuse && config.isDeltaCompress())
				delay = 500;
			((BatchingProgressMonitor) compressMonitor).setDelayStart(
					delay,
					TimeUnit.MILLISECONDS);
		}

		if (needSearchForReuse)
			searchForReuse(compressMonitor);
		if (config.isDeltaCompress())
			searchForDeltas(compressMonitor);

		crc32 = new CRC32();
		final PackOutputStream out = new PackOutputStream(
			writeMonitor,
			isIndexDisabled()
				? packStream
				: new CheckedOutputStream(packStream, crc32),
			this);

		long objCnt = packfileUriConfig == null ? getObjectCount() :
			getUnoffloadedObjectCount();
		stats.totalObjects = objCnt;
		if (callback != null)
			callback.setObjectCount(objCnt);
		beginPhase(PackingPhase.WRITING, writeMonitor, objCnt);
		long writeStart = System.currentTimeMillis();
		try {
			List<CachedPack> unwrittenCachedPacks;

			if (packfileUriConfig != null) {
				unwrittenCachedPacks = new ArrayList<>();
				CachedPackUriProvider p = packfileUriConfig.cachedPackUriProvider;
				PacketLineOut o = packfileUriConfig.pckOut;

				o.writeString("packfile-uris\n"); //$NON-NLS-1$
				for (CachedPack pack : cachedPacks) {
					CachedPackUriProvider.PackInfo packInfo = p.getInfo(
							pack, packfileUriConfig.protocolsSupported);
					if (packInfo != null) {
						o.writeString(packInfo.getHash() + ' ' +
								packInfo.getUri() + '\n');
					} else {
						unwrittenCachedPacks.add(pack);
					}
				}
				packfileUriConfig.pckOut.writeDelim();
				packfileUriConfig.pckOut.writeString("packfile\n"); //$NON-NLS-1$
			} else {
				unwrittenCachedPacks = cachedPacks;
			}

			out.writeFileHeader(PACK_VERSION_GENERATED, objCnt);
			out.flush();

			writeObjects(out);
			if (!edgeObjects.isEmpty() || !cachedPacks.isEmpty()) {
				for (PackStatistics.ObjectType.Accumulator typeStat : stats.objectTypes) {
					if (typeStat == null)
						continue;
					stats.thinPackBytes += typeStat.bytes;
				}
			}

			stats.reusedPacks = Collections.unmodifiableList(cachedPacks);
			for (CachedPack pack : unwrittenCachedPacks) {
				long deltaCnt = pack.getDeltaCount();
				stats.reusedObjects += pack.getObjectCount();
				stats.reusedDeltas += deltaCnt;
				stats.totalDeltas += deltaCnt;
				reuseSupport.copyPackAsIs(out, pack);
			}
			writeChecksum(out);
			out.flush();
		} finally {
			stats.timeWriting = System.currentTimeMillis() - writeStart;
			stats.depth = depth;

			for (PackStatistics.ObjectType.Accumulator typeStat : stats.objectTypes) {
				if (typeStat == null)
					continue;
				typeStat.cntDeltas += typeStat.reusedDeltas;
				stats.reusedObjects += typeStat.reusedObjects;
				stats.reusedDeltas += typeStat.reusedDeltas;
				stats.totalDeltas += typeStat.cntDeltas;
			}
		}

		stats.totalBytes = out.length();
		reader.close();
		endPhase(writeMonitor);
	}

	
Get statistics of what this PackWriter did in order to create the final
pack stream.
Returns:
description of what this PackWriter did in order to create the
        final pack stream. This should only be invoked after the calls to
        create the pack/index/bitmap have completed./**
	 * Get statistics of what this PackWriter did in order to create the final
	 * pack stream.
	 *
	 * @return description of what this PackWriter did in order to create the
	 *         final pack stream. This should only be invoked after the calls to
	 *         create the pack/index/bitmap have completed.
	 */
	public PackStatistics getStatistics() {
		return new PackStatistics(stats);
	}

	
Get snapshot of the current state of this PackWriter.
Returns:
snapshot of the current state of this PackWriter./**
	 * Get snapshot of the current state of this PackWriter.
	 *
	 * @return snapshot of the current state of this PackWriter.
	 */
	public State getState() {
		return state.snapshot();
	}

	
{@inheritDoc}

Release all resources used by this writer.
/**
	 * {@inheritDoc}
	 * <p>
	 * Release all resources used by this writer.
	 */
	@Override
	public void close() {
		reader.close();
		if (myDeflater != null) {
			myDeflater.end();
			myDeflater = null;
		}
		instances.remove(selfRef);
	}

	private void searchForReuse(ProgressMonitor monitor) throws IOException {
		long cnt = 0;
		cnt += objectsLists[OBJ_COMMIT].size();
		cnt += objectsLists[OBJ_TREE].size();
		cnt += objectsLists[OBJ_BLOB].size();
		cnt += objectsLists[OBJ_TAG].size();

		long start = System.currentTimeMillis();
		beginPhase(PackingPhase.FINDING_SOURCES, monitor, cnt);
		if (cnt <= 4096) {
			// For small object counts, do everything as one list.
			BlockList<ObjectToPack> tmp = new BlockList<>((int) cnt);
			tmp.addAll(objectsLists[OBJ_TAG]);
			tmp.addAll(objectsLists[OBJ_COMMIT]);
			tmp.addAll(objectsLists[OBJ_TREE]);
			tmp.addAll(objectsLists[OBJ_BLOB]);
			searchForReuse(monitor, tmp);
			if (pruneCurrentObjectList) {
				// If the list was pruned, we need to re-prune the main lists.
				pruneEdgesFromObjectList(objectsLists[OBJ_COMMIT]);
				pruneEdgesFromObjectList(objectsLists[OBJ_TREE]);
				pruneEdgesFromObjectList(objectsLists[OBJ_BLOB]);
				pruneEdgesFromObjectList(objectsLists[OBJ_TAG]);
			}
		} else {
			searchForReuse(monitor, objectsLists[OBJ_TAG]);
			searchForReuse(monitor, objectsLists[OBJ_COMMIT]);
			searchForReuse(monitor, objectsLists[OBJ_TREE]);
			searchForReuse(monitor, objectsLists[OBJ_BLOB]);
		}
		endPhase(monitor);
		stats.timeSearchingForReuse = System.currentTimeMillis() - start;

		if (config.isReuseDeltas() && config.getCutDeltaChains()) {
			cutDeltaChains(objectsLists[OBJ_TREE]);
			cutDeltaChains(objectsLists[OBJ_BLOB]);
		}
	}

	private void searchForReuse(ProgressMonitor monitor, List<ObjectToPack> list)
			throws IOException, MissingObjectException {
		pruneCurrentObjectList = false;
		reuseSupport.selectObjectRepresentation(this, monitor, list);
		if (pruneCurrentObjectList)
			pruneEdgesFromObjectList(list);
	}

	private void cutDeltaChains(BlockList<ObjectToPack> list)
			throws IOException {
		int max = config.getMaxDeltaDepth();
		for (int idx = list.size() - 1; idx >= 0; idx--) {
			int d = 0;
			ObjectToPack b = list.get(idx).getDeltaBase();
			while (b != null) {
				if (d < b.getChainLength())
					break;
				b.setChainLength(++d);
				if (d >= max && b.isDeltaRepresentation()) {
					reselectNonDelta(b);
					break;
				}
				b = b.getDeltaBase();
			}
		}
		if (config.isDeltaCompress()) {
			for (ObjectToPack otp : list)
				otp.clearChainLength();
		}
	}

	private void searchForDeltas(ProgressMonitor monitor)
			throws MissingObjectException, IncorrectObjectTypeException,
			IOException {
		// Commits and annotated tags tend to have too many differences to
		// really benefit from delta compression. Consequently just don't
		// bother examining those types here.
		//
		ObjectToPack[] list = new ObjectToPack[
				  objectsLists[OBJ_TREE].size()
				+ objectsLists[OBJ_BLOB].size()
				+ edgeObjects.size()];
		int cnt = 0;
		cnt = findObjectsNeedingDelta(list, cnt, OBJ_TREE);
		cnt = findObjectsNeedingDelta(list, cnt, OBJ_BLOB);
		if (cnt == 0)
			return;
		int nonEdgeCnt = cnt;

		// Queue up any edge objects that we might delta against.  We won't
		// be sending these as we assume the other side has them, but we need
		// them in the search phase below.
		//
		for (ObjectToPack eo : edgeObjects) {
			eo.setWeight(0);
			list[cnt++] = eo;
		}

		// Compute the sizes of the objects so we can do a proper sort.
		// We let the reader skip missing objects if it chooses. For
		// some readers this can be a huge win. We detect missing objects
		// by having set the weights above to 0 and allowing the delta
		// search code to discover the missing object and skip over it, or
		// abort with an exception if we actually had to have it.
		//
		final long sizingStart = System.currentTimeMillis();
		beginPhase(PackingPhase.GETTING_SIZES, monitor, cnt);
		AsyncObjectSizeQueue<ObjectToPack> sizeQueue = reader.getObjectSize(
				Arrays.<ObjectToPack> asList(list).subList(0, cnt), false);
		try {
			final long limit = Math.min(
					config.getBigFileThreshold(),
					Integer.MAX_VALUE);
			for (;;) {
				try {
					if (!sizeQueue.next())
						break;
				} catch (MissingObjectException notFound) {
					monitor.update(1);
					if (ignoreMissingUninteresting) {
						ObjectToPack otp = sizeQueue.getCurrent();
						if (otp != null && otp.isEdge()) {
							otp.setDoNotDelta();
							continue;
						}

						otp = objectsMap.get(notFound.getObjectId());
						if (otp != null && otp.isEdge()) {
							otp.setDoNotDelta();
							continue;
						}
					}
					throw notFound;
				}

				ObjectToPack otp = sizeQueue.getCurrent();
				if (otp == null)
					otp = objectsMap.get(sizeQueue.getObjectId());

				long sz = sizeQueue.getSize();
				if (DeltaIndex.BLKSZ < sz && sz < limit)
					otp.setWeight((int) sz);
				else
					otp.setDoNotDelta(); // too small, or too big
				monitor.update(1);
			}
		} finally {
			sizeQueue.release();
		}
		endPhase(monitor);
		stats.timeSearchingForSizes = System.currentTimeMillis() - sizingStart;

		// Sort the objects by path hash so like files are near each other,
		// and then by size descending so that bigger files are first. This
		// applies "Linus' Law" which states that newer files tend to be the
		// bigger ones, because source files grow and hardly ever shrink.
		//
		Arrays.sort(list, 0, cnt, (ObjectToPack a, ObjectToPack b) -> {
			int cmp = (a.isDoNotDelta() ? 1 : 0) - (b.isDoNotDelta() ? 1 : 0);
			if (cmp != 0) {
				return cmp;
			}

			cmp = a.getType() - b.getType();
			if (cmp != 0) {
				return cmp;
			}

			cmp = (a.getPathHash() >>> 1) - (b.getPathHash() >>> 1);
			if (cmp != 0) {
				return cmp;
			}

			cmp = (a.getPathHash() & 1) - (b.getPathHash() & 1);
			if (cmp != 0) {
				return cmp;
			}

			cmp = (a.isEdge() ? 0 : 1) - (b.isEdge() ? 0 : 1);
			if (cmp != 0) {
				return cmp;
			}

			return b.getWeight() - a.getWeight();
		});

		// Above we stored the objects we cannot delta onto the end.
		// Remove them from the list so we don't waste time on them.
		while (0 < cnt && list[cnt - 1].isDoNotDelta()) {
			if (!list[cnt - 1].isEdge())
				nonEdgeCnt--;
			cnt--;
		}
		if (cnt == 0)
			return;

		final long searchStart = System.currentTimeMillis();
		searchForDeltas(monitor, list, cnt);
		stats.deltaSearchNonEdgeObjects = nonEdgeCnt;
		stats.timeCompressing = System.currentTimeMillis() - searchStart;

		for (int i = 0; i < cnt; i++)
			if (!list[i].isEdge() && list[i].isDeltaRepresentation())
				stats.deltasFound++;
	}

	private int findObjectsNeedingDelta(ObjectToPack[] list, int cnt, int type) {
		for (ObjectToPack otp : objectsLists[type]) {
			if (otp.isDoNotDelta()) // delta is disabled for this path
				continue;
			if (otp.isDeltaRepresentation()) // already reusing a delta
				continue;
			otp.setWeight(0);
			list[cnt++] = otp;
		}
		return cnt;
	}

	private void reselectNonDelta(ObjectToPack otp) throws IOException {
		otp.clearDeltaBase();
		otp.clearReuseAsIs();
		boolean old = reuseDeltas;
		reuseDeltas = false;
		reuseSupport.selectObjectRepresentation(this,
				NullProgressMonitor.INSTANCE,
				Collections.singleton(otp));
		reuseDeltas = old;
	}

	private void searchForDeltas(final ProgressMonitor monitor,
			final ObjectToPack[] list, final int cnt)
			throws MissingObjectException, IncorrectObjectTypeException,
			LargeObjectException, IOException {
		int threads = config.getThreads();
		if (threads == 0)
			threads = Runtime.getRuntime().availableProcessors();
		if (threads <= 1 || cnt <= config.getDeltaSearchWindowSize())
			singleThreadDeltaSearch(monitor, list, cnt);
		else
			parallelDeltaSearch(monitor, list, cnt, threads);
	}

	private void singleThreadDeltaSearch(ProgressMonitor monitor,
			ObjectToPack[] list, int cnt) throws IOException {
		long totalWeight = 0;
		for (int i = 0; i < cnt; i++) {
			ObjectToPack o = list[i];
			totalWeight += DeltaTask.getAdjustedWeight(o);
		}

		long bytesPerUnit = 1;
		while (DeltaTask.MAX_METER <= (totalWeight / bytesPerUnit))
			bytesPerUnit <<= 10;
		int cost = (int) (totalWeight / bytesPerUnit);
		if (totalWeight % bytesPerUnit != 0)
			cost++;

		beginPhase(PackingPhase.COMPRESSING, monitor, cost);
		new DeltaWindow(config, new DeltaCache(config), reader,
				monitor, bytesPerUnit,
				list, 0, cnt).search();
		endPhase(monitor);
	}

	private void parallelDeltaSearch(ProgressMonitor monitor,
			ObjectToPack[] list, int cnt, int threads) throws IOException {
		DeltaCache dc = new ThreadSafeDeltaCache(config);
		ThreadSafeProgressMonitor pm = new ThreadSafeProgressMonitor(monitor);
		DeltaTask.Block taskBlock = new DeltaTask.Block(threads, config,
				reader, dc, pm,
				list, 0, cnt);
		taskBlock.partitionTasks();
		beginPhase(PackingPhase.COMPRESSING, monitor, taskBlock.cost());
		pm.startWorkers(taskBlock.tasks.size());

		Executor executor = config.getExecutor();
		final List<Throwable> errors =
				Collections.synchronizedList(new ArrayList<>(threads));
		if (executor instanceof ExecutorService) {
			// Caller supplied us a service, use it directly.
			runTasks((ExecutorService) executor, pm, taskBlock, errors);
		} else if (executor == null) {
			// Caller didn't give us a way to run the tasks, spawn up a
			// temporary thread pool and make sure it tears down cleanly.
			ExecutorService pool = Executors.newFixedThreadPool(threads);
			try {
				runTasks(pool, pm, taskBlock, errors);
			} finally {
				pool.shutdown();
				for (;;) {
					try {
						if (pool.awaitTermination(60, TimeUnit.SECONDS))
							break;
					} catch (InterruptedException e) {
						throw new IOException(
								JGitText.get().packingCancelledDuringObjectsWriting);
					}
				}
			}
		} else {
			// The caller gave us an executor, but it might not do
			// asynchronous execution.  Wrap everything and hope it
			// can schedule these for us.
			for (DeltaTask task : taskBlock.tasks) {
				executor.execute(() -> {
					try {
						task.call();
					} catch (Throwable failure) {
						errors.add(failure);
					}
				});
			}
			try {
				pm.waitForCompletion();
			} catch (InterruptedException ie) {
				// We can't abort the other tasks as we have no handle.
				// Cross our fingers and just break out anyway.
				//
				throw new IOException(
						JGitText.get().packingCancelledDuringObjectsWriting);
			}
		}

		// If any task threw an error, try to report it back as
		// though we weren't using a threaded search algorithm.
		//
		if (!errors.isEmpty()) {
			Throwable err = errors.get(0);
			if (err instanceof Error)
				throw (Error) err;
			if (err instanceof RuntimeException)
				throw (RuntimeException) err;
			if (err instanceof IOException)
				throw (IOException) err;

			throw new IOException(err.getMessage(), err);
		}
		endPhase(monitor);
	}

	private static void runTasks(ExecutorService pool,
			ThreadSafeProgressMonitor pm,
			DeltaTask.Block tb, List<Throwable> errors) throws IOException {
		List<Future<?>> futures = new ArrayList<>(tb.tasks.size());
		for (DeltaTask task : tb.tasks)
			futures.add(pool.submit(task));

		try {
			pm.waitForCompletion();
			for (Future<?> f : futures) {
				try {
					f.get();
				} catch (ExecutionException failed) {
					errors.add(failed.getCause());
				}
			}
		} catch (InterruptedException ie) {
			for (Future<?> f : futures)
				f.cancel(true);
			throw new IOException(
					JGitText.get().packingCancelledDuringObjectsWriting);
		}
	}

	private void writeObjects(PackOutputStream out) throws IOException {
		writeObjects(out, objectsLists[OBJ_COMMIT]);
		writeObjects(out, objectsLists[OBJ_TAG]);
		writeObjects(out, objectsLists[OBJ_TREE]);
		writeObjects(out, objectsLists[OBJ_BLOB]);
	}

	private void writeObjects(PackOutputStream out, List<ObjectToPack> list)
			throws IOException {
		if (list.isEmpty())
			return;

		typeStats = stats.objectTypes[list.get(0).getType()];
		long beginOffset = out.length();

		if (reuseSupport != null) {
			reuseSupport.writeObjects(out, list);
		} else {
			for (ObjectToPack otp : list)
				out.writeObject(otp);
		}

		typeStats.bytes += out.length() - beginOffset;
		typeStats.cntObjects = list.size();
	}

	void writeObject(PackOutputStream out, ObjectToPack otp) throws IOException {
		if (!otp.isWritten())
			writeObjectImpl(out, otp);
	}

	private void writeObjectImpl(PackOutputStream out, ObjectToPack otp)
			throws IOException {
		if (otp.wantWrite()) {
			// A cycle exists in this delta chain. This should only occur if a
			// selected object representation disappeared during writing
			// (for example due to a concurrent repack) and a different base
			// was chosen, forcing a cycle. Select something other than a
			// delta, and write this object.
			reselectNonDelta(otp);
		}
		otp.markWantWrite();

		while (otp.isReuseAsIs()) {
			writeBase(out, otp.getDeltaBase());
			if (otp.isWritten())
				return; // Delta chain cycle caused this to write already.

			crc32.reset();
			otp.setOffset(out.length());
			try {
				reuseSupport.copyObjectAsIs(out, otp, reuseValidate);
				out.endObject();
				otp.setCRC((int) crc32.getValue());
				typeStats.reusedObjects++;
				if (otp.isDeltaRepresentation()) {
					typeStats.reusedDeltas++;
					typeStats.deltaBytes += out.length() - otp.getOffset();
				}
				return;
			} catch (StoredObjectRepresentationNotAvailableException gone) {
				if (otp.getOffset() == out.length()) {
					otp.setOffset(0);
					otp.clearDeltaBase();
					otp.clearReuseAsIs();
					reuseSupport.selectObjectRepresentation(this,
							NullProgressMonitor.INSTANCE,
							Collections.singleton(otp));
					continue;
				} else {
					// Object writing already started, we cannot recover.
					//
					CorruptObjectException coe;
					coe = new CorruptObjectException(otp, ""); //$NON-NLS-1$
					coe.initCause(gone);
					throw coe;
				}
			}
		}

		// If we reached here, reuse wasn't possible.
		//
		if (otp.isDeltaRepresentation())
			writeDeltaObjectDeflate(out, otp);
		else
			writeWholeObjectDeflate(out, otp);
		out.endObject();
		otp.setCRC((int) crc32.getValue());
	}

	private void writeBase(PackOutputStream out, ObjectToPack base)
			throws IOException {
		if (base != null && !base.isWritten() && !base.isEdge())
			writeObjectImpl(out, base);
	}

	private void writeWholeObjectDeflate(PackOutputStream out,
			final ObjectToPack otp) throws IOException {
		final Deflater deflater = deflater();
		final ObjectLoader ldr = reader.open(otp, otp.getType());

		crc32.reset();
		otp.setOffset(out.length());
		out.writeHeader(otp, ldr.getSize());

		deflater.reset();
		DeflaterOutputStream dst = new DeflaterOutputStream(out, deflater);
		ldr.copyTo(dst);
		dst.finish();
	}

	private void writeDeltaObjectDeflate(PackOutputStream out,
			final ObjectToPack otp) throws IOException {
		writeBase(out, otp.getDeltaBase());

		crc32.reset();
		otp.setOffset(out.length());

		DeltaCache.Ref ref = otp.popCachedDelta();
		if (ref != null) {
			byte[] zbuf = ref.get();
			if (zbuf != null) {
				out.writeHeader(otp, otp.getCachedSize());
				out.write(zbuf);
				typeStats.cntDeltas++;
				typeStats.deltaBytes += out.length() - otp.getOffset();
				return;
			}
		}

		try (TemporaryBuffer.Heap delta = delta(otp)) {
			out.writeHeader(otp, delta.length());

			Deflater deflater = deflater();
			deflater.reset();
			DeflaterOutputStream dst = new DeflaterOutputStream(out, deflater);
			delta.writeTo(dst, null);
			dst.finish();
		}
		typeStats.cntDeltas++;
		typeStats.deltaBytes += out.length() - otp.getOffset();
	}

	private TemporaryBuffer.Heap delta(ObjectToPack otp)
			throws IOException {
		DeltaIndex index = new DeltaIndex(buffer(otp.getDeltaBaseId()));
		byte[] res = buffer(otp);

		// We never would have proposed this pair if the delta would be
		// larger than the unpacked version of the object. So using it
		// as our buffer limit is valid: we will never reach it.
		//
		TemporaryBuffer.Heap delta = new TemporaryBuffer.Heap(res.length);
		index.encode(delta, res);
		return delta;
	}

	private byte[] buffer(AnyObjectId objId) throws IOException {
		return buffer(config, reader, objId);
	}

	static byte[] buffer(PackConfig config, ObjectReader or, AnyObjectId objId)
			throws IOException {
		// PackWriter should have already pruned objects that
		// are above the big file threshold, so our chances of
		// the object being below it are very good. We really
		// shouldn't be here, unless the implementation is odd.

		return or.open(objId).getCachedBytes(config.getBigFileThreshold());
	}

	private Deflater deflater() {
		if (myDeflater == null)
			myDeflater = new Deflater(config.getCompressionLevel());
		return myDeflater;
	}

	private void writeChecksum(PackOutputStream out) throws IOException {
		packcsum = out.getDigest();
		out.write(packcsum);
	}

	private void findObjectsToPack(@NonNull ProgressMonitor countingMonitor,
			@NonNull ObjectWalk walker, @NonNull Set<? extends ObjectId> want,
			@NonNull Set<? extends ObjectId> have,
			@NonNull Set<? extends ObjectId> noBitmaps) throws IOException {
		final long countingStart = System.currentTimeMillis();
		beginPhase(PackingPhase.COUNTING, countingMonitor, ProgressMonitor.UNKNOWN);

		stats.interestingObjects = Collections.unmodifiableSet(new HashSet<ObjectId>(want));
		stats.uninterestingObjects = Collections.unmodifiableSet(new HashSet<ObjectId>(have));
		excludeFromBitmapSelection = noBitmaps;

		canBuildBitmaps = config.isBuildBitmaps()
				&& !shallowPack
				&& have.isEmpty()
				&& (excludeInPacks == null || excludeInPacks.length == 0);
		if (!shallowPack && useBitmaps) {
			BitmapIndex bitmapIndex = reader.getBitmapIndex();
			if (bitmapIndex != null) {
				BitmapWalker bitmapWalker = new BitmapWalker(
						walker, bitmapIndex, countingMonitor);
				findObjectsToPackUsingBitmaps(bitmapWalker, want, have);
				endPhase(countingMonitor);
				stats.timeCounting = System.currentTimeMillis() - countingStart;
				stats.bitmapIndexMisses = bitmapWalker.getCountOfBitmapIndexMisses();
				return;
			}
		}

		List<ObjectId> all = new ArrayList<>(want.size() + have.size());
		all.addAll(want);
		all.addAll(have);

		final RevFlag include = walker.newFlag("include"); //$NON-NLS-1$
		final RevFlag added = walker.newFlag("added"); //$NON-NLS-1$

		walker.carry(include);

		int haveEst = have.size();
		if (have.isEmpty()) {
			walker.sort(RevSort.COMMIT_TIME_DESC);
		} else {
			walker.sort(RevSort.TOPO);
			if (thin)
				walker.sort(RevSort.BOUNDARY, true);
		}

		List<RevObject> wantObjs = new ArrayList<>(want.size());
		List<RevObject> haveObjs = new ArrayList<>(haveEst);
		List<RevTag> wantTags = new ArrayList<>(want.size());

		// Retrieve the RevWalk's versions of "want" and "have" objects to
		// maintain any state previously set in the RevWalk.
		AsyncRevObjectQueue q = walker.parseAny(all, true);
		try {
			for (;;) {
				try {
					RevObject o = q.next();
					if (o == null)
						break;
					if (have.contains(o))
						haveObjs.add(o);
					if (want.contains(o)) {
						o.add(include);
						wantObjs.add(o);
						if (o instanceof RevTag)
							wantTags.add((RevTag) o);
					}
				} catch (MissingObjectException e) {
					if (ignoreMissingUninteresting
							&& have.contains(e.getObjectId()))
						continue;
					throw e;
				}
			}
		} finally {
			q.release();
		}

		if (!wantTags.isEmpty()) {
			all = new ArrayList<>(wantTags.size());
			for (RevTag tag : wantTags)
				all.add(tag.getObject());
			q = walker.parseAny(all, true);
			try {
				while (q.next() != null) {
					// Just need to pop the queue item to parse the object.
				}
			} finally {
				q.release();
			}
		}

		if (walker instanceof DepthWalk.ObjectWalk) {
			DepthWalk.ObjectWalk depthWalk = (DepthWalk.ObjectWalk) walker;
			for (RevObject obj : wantObjs) {
				depthWalk.markRoot(obj);
			}
			// Mark the tree objects associated with "have" commits as
			// uninteresting to avoid writing redundant blobs. A normal RevWalk
			// lazily propagates the "uninteresting" state from a commit to its
			// tree during the walk, but DepthWalks can terminate early so
			// preemptively propagate that state here.
			for (RevObject obj : haveObjs) {
				if (obj instanceof RevCommit) {
					RevTree t = ((RevCommit) obj).getTree();
					depthWalk.markUninteresting(t);
				}
			}

			if (unshallowObjects != null) {
				for (ObjectId id : unshallowObjects) {
					depthWalk.markUnshallow(walker.parseAny(id));
				}
			}
		} else {
			for (RevObject obj : wantObjs)
				walker.markStart(obj);
		}
		for (RevObject obj : haveObjs)
			walker.markUninteresting(obj);

		final int maxBases = config.getDeltaSearchWindowSize();
		Set<RevTree> baseTrees = new HashSet<>();
		BlockList<RevCommit> commits = new BlockList<>();
		Set<ObjectId> roots = new HashSet<>();
		RevCommit c;
		while ((c = walker.next()) != null) {
			if (exclude(c))
				continue;
			if (c.has(RevFlag.UNINTERESTING)) {
				if (baseTrees.size() <= maxBases)
					baseTrees.add(c.getTree());
				continue;
			}

			commits.add(c);
			if (c.getParentCount() == 0) {
				roots.add(c.copy());
			}
			countingMonitor.update(1);
		}
		stats.rootCommits = Collections.unmodifiableSet(roots);

		if (shallowPack) {
			for (RevCommit cmit : commits) {
				addObject(cmit, 0);
			}
		} else {
			int commitCnt = 0;
			boolean putTagTargets = false;
			for (RevCommit cmit : commits) {
				if (!cmit.has(added)) {
					cmit.add(added);
					addObject(cmit, 0);
					commitCnt++;
				}

				for (int i = 0; i < cmit.getParentCount(); i++) {
					RevCommit p = cmit.getParent(i);
					if (!p.has(added) && !p.has(RevFlag.UNINTERESTING)
							&& !exclude(p)) {
						p.add(added);
						addObject(p, 0);
						commitCnt++;
					}
				}

				if (!putTagTargets && 4096 < commitCnt) {
					for (ObjectId id : tagTargets) {
						RevObject obj = walker.lookupOrNull(id);
						if (obj instanceof RevCommit
								&& obj.has(include)
								&& !obj.has(RevFlag.UNINTERESTING)
								&& !obj.has(added)) {
							obj.add(added);
							addObject(obj, 0);
						}
					}
					putTagTargets = true;
				}
			}
		}
		commits = null;

		if (thin && !baseTrees.isEmpty()) {
			BaseSearch bases = new BaseSearch(countingMonitor, baseTrees, //
					objectsMap, edgeObjects, reader);
			RevObject o;
			while ((o = walker.nextObject()) != null) {
				if (o.has(RevFlag.UNINTERESTING))
					continue;
				if (exclude(o))
					continue;

				int pathHash = walker.getPathHashCode();
				byte[] pathBuf = walker.getPathBuffer();
				int pathLen = walker.getPathLength();
				bases.addBase(o.getType(), pathBuf, pathLen, pathHash);
				if (!depthSkip(o, walker)) {
					filterAndAddObject(o, o.getType(), pathHash, want);
				}
				countingMonitor.update(1);
			}
		} else {
			RevObject o;
			while ((o = walker.nextObject()) != null) {
				if (o.has(RevFlag.UNINTERESTING))
					continue;
				if (exclude(o))
					continue;
				if (!depthSkip(o, walker)) {
					filterAndAddObject(o, o.getType(), walker.getPathHashCode(),
									   want);
				}
				countingMonitor.update(1);
			}
		}

		for (CachedPack pack : cachedPacks)
			countingMonitor.update((int) pack.getObjectCount());
		endPhase(countingMonitor);
		stats.timeCounting = System.currentTimeMillis() - countingStart;
		stats.bitmapIndexMisses = -1;
	}

	private void findObjectsToPackUsingBitmaps(
			BitmapWalker bitmapWalker, Set<? extends ObjectId> want,
			Set<? extends ObjectId> have)
			throws MissingObjectException, IncorrectObjectTypeException,
			IOException {
		BitmapBuilder haveBitmap = bitmapWalker.findObjects(have, null, true);
		BitmapBuilder wantBitmap = bitmapWalker.findObjects(want, haveBitmap,
				false);
		BitmapBuilder needBitmap = wantBitmap.andNot(haveBitmap);

		if (useCachedPacks && reuseSupport != null && !reuseValidate
				&& (excludeInPacks == null || excludeInPacks.length == 0))
			cachedPacks.addAll(
					reuseSupport.getCachedPacksAndUpdate(needBitmap));

		for (BitmapObject obj : needBitmap) {
			ObjectId objectId = obj.getObjectId();
			if (exclude(objectId)) {
				needBitmap.remove(objectId);
				continue;
			}
			filterAndAddObject(objectId, obj.getType(), 0, want);
		}

		if (thin)
			haveObjects = haveBitmap;
	}

	private static void pruneEdgesFromObjectList(List<ObjectToPack> list) {
		final int size = list.size();
		int src = 0;
		int dst = 0;

		for (; src < size; src++) {
			ObjectToPack obj = list.get(src);
			if (obj.isEdge())
				continue;
			if (dst != src)
				list.set(dst, obj);
			dst++;
		}

		while (dst < list.size())
			list.remove(list.size() - 1);
	}

	
Include one object to the output file.

Objects are written in the order they are added. If the same object is
added twice, it may be written twice, creating a larger than necessary
file.
Params:
object – 
           the object to add.
Throws:
IncorrectObjectTypeException – 
            the object is an unsupported type./**
	 * Include one object to the output file.
	 * <p>
	 * Objects are written in the order they are added. If the same object is
	 * added twice, it may be written twice, creating a larger than necessary
	 * file.
	 *
	 * @param object
	 *            the object to add.
	 * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
	 *             the object is an unsupported type.
	 */
	public void addObject(RevObject object)
			throws IncorrectObjectTypeException {
		if (!exclude(object))
			addObject(object, 0);
	}

	private void addObject(RevObject object, int pathHashCode) {
		addObject(object, object.getType(), pathHashCode);
	}

	private void addObject(
			final AnyObjectId src, final int type, final int pathHashCode) {
		final ObjectToPack otp;
		if (reuseSupport != null)
			otp = reuseSupport.newObjectToPack(src, type);
		else
			otp = new ObjectToPack(src, type);
		otp.setPathHash(pathHashCode);
		objectsLists[type].add(otp);
		objectsMap.add(otp);
	}

	
Determines if the object should be omitted from the pack as a result of
its depth (probably because of the tree: filter).
 Causes walker to skip traversing the current tree, which ought to have just started traversal, assuming this method is called as soon as a new depth is reached. 
 This method increments the treesTraversed statistic. 
Params:
obj – 
           the object to check whether it should be omitted.
walker – 
           the walker being used for traveresal.
Returns:
whether the given object should be skipped./**
	 * Determines if the object should be omitted from the pack as a result of
	 * its depth (probably because of the tree:<depth> filter).
	 * <p>
	 * Causes {@code walker} to skip traversing the current tree, which ought to
	 * have just started traversal, assuming this method is called as soon as a
	 * new depth is reached.
	 * <p>
	 * This method increments the {@code treesTraversed} statistic.
	 *
	 * @param obj
	 *            the object to check whether it should be omitted.
	 * @param walker
	 *            the walker being used for traveresal.
	 * @return whether the given object should be skipped.
	 */
	private boolean depthSkip(@NonNull RevObject obj, ObjectWalk walker) {
		long treeDepth = walker.getTreeDepth();

		// Check if this object needs to be rejected because it is a tree or
		// blob that is too deep from the root tree.

		// A blob is considered one level deeper than the tree that contains it.
		if (obj.getType() == OBJ_BLOB) {
			treeDepth++;
		} else {
			stats.treesTraversed++;
		}

		if (filterSpec.getTreeDepthLimit() < 0 ||
			treeDepth <= filterSpec.getTreeDepthLimit()) {
			return false;
		}

		walker.skipTree();
		return true;
	}

	// Adds the given object as an object to be packed, first performing
	// filtering on blobs at or exceeding a given size.
	private void filterAndAddObject(@NonNull AnyObjectId src, int type,
			int pathHashCode, @NonNull Set<? extends AnyObjectId> want)
			throws IOException {

		// Check if this object needs to be rejected, doing the cheaper
		// checks first.
		boolean reject = filterSpec.getBlobLimit() >= 0 &&
			type == OBJ_BLOB &&
			!want.contains(src) &&
			reader.getObjectSize(src, OBJ_BLOB) > filterSpec.getBlobLimit();
		if (!reject) {
			addObject(src, type, pathHashCode);
		}
	}

	private boolean exclude(AnyObjectId objectId) {
		if (excludeInPacks == null)
			return false;
		if (excludeInPackLast.contains(objectId))
			return true;
		for (ObjectIdSet idx : excludeInPacks) {
			if (idx.contains(objectId)) {
				excludeInPackLast = idx;
				return true;
			}
		}
		return false;
	}

	
Select an object representation for this writer.
 An ObjectReader implementation should invoke this method once for each representation available for an object, to allow the writer to find the most suitable one for the output. 
Params:
otp – 
           the object being packed.
next – 
           the next available representation from the repository./**
	 * Select an object representation for this writer.
	 * <p>
	 * An {@link org.eclipse.jgit.lib.ObjectReader} implementation should invoke
	 * this method once for each representation available for an object, to
	 * allow the writer to find the most suitable one for the output.
	 *
	 * @param otp
	 *            the object being packed.
	 * @param next
	 *            the next available representation from the repository.
	 */
	public void select(ObjectToPack otp, StoredObjectRepresentation next) {
		int nFmt = next.getFormat();

		if (!cachedPacks.isEmpty()) {
			if (otp.isEdge())
				return;
			if (nFmt == PACK_WHOLE || nFmt == PACK_DELTA) {
				for (CachedPack pack : cachedPacks) {
					if (pack.hasObject(otp, next)) {
						otp.setEdge();
						otp.clearDeltaBase();
						otp.clearReuseAsIs();
						pruneCurrentObjectList = true;
						return;
					}
				}
			}
		}

		if (nFmt == PACK_DELTA && reuseDeltas && reuseDeltaFor(otp)) {
			ObjectId baseId = next.getDeltaBase();
			ObjectToPack ptr = objectsMap.get(baseId);
			if (ptr != null && !ptr.isEdge()) {
				otp.setDeltaBase(ptr);
				otp.setReuseAsIs();
			} else if (thin && have(ptr, baseId)) {
				otp.setDeltaBase(baseId);
				otp.setReuseAsIs();
			} else {
				otp.clearDeltaBase();
				otp.clearReuseAsIs();
			}
		} else if (nFmt == PACK_WHOLE && config.isReuseObjects()) {
			int nWeight = next.getWeight();
			if (otp.isReuseAsIs() && !otp.isDeltaRepresentation()) {
				// We've chosen another PACK_WHOLE format for this object,
				// choose the one that has the smaller compressed size.
				//
				if (otp.getWeight() <= nWeight)
					return;
			}
			otp.clearDeltaBase();
			otp.setReuseAsIs();
			otp.setWeight(nWeight);
		} else {
			otp.clearDeltaBase();
			otp.clearReuseAsIs();
		}

		otp.setDeltaAttempted(reuseDeltas && next.wasDeltaAttempted());
		otp.select(next);
	}

	private final boolean have(ObjectToPack ptr, AnyObjectId objectId) {
		return (ptr != null && ptr.isEdge())
				|| (haveObjects != null && haveObjects.contains(objectId));
	}

	
Prepares the bitmaps to be written to the bitmap index file.

Bitmaps can be used to speed up fetches and clones by storing the entire
object graph at selected commits. Writing a bitmap index is an optional
feature that not all pack users may require.
 Called after writeIndex(OutputStream). 
 To reduce memory internal state is cleared during this method, rendering the PackWriter instance useless for anything further than a call to write out the new bitmaps with writeBitmapIndex(OutputStream). 
Params:
pm – 
           progress monitor to report bitmap building work.
Throws:
IOException – 
            when some I/O problem occur during reading objects.
Returns:
whether a bitmap index may be written./**
	 * Prepares the bitmaps to be written to the bitmap index file.
	 * <p>
	 * Bitmaps can be used to speed up fetches and clones by storing the entire
	 * object graph at selected commits. Writing a bitmap index is an optional
	 * feature that not all pack users may require.
	 * <p>
	 * Called after {@link #writeIndex(OutputStream)}.
	 * <p>
	 * To reduce memory internal state is cleared during this method, rendering
	 * the PackWriter instance useless for anything further than a call to write
	 * out the new bitmaps with {@link #writeBitmapIndex(OutputStream)}.
	 *
	 * @param pm
	 *            progress monitor to report bitmap building work.
	 * @return whether a bitmap index may be written.
	 * @throws java.io.IOException
	 *             when some I/O problem occur during reading objects.
	 */
	public boolean prepareBitmapIndex(ProgressMonitor pm) throws IOException {
		if (!canBuildBitmaps || getObjectCount() > Integer.MAX_VALUE
				|| !cachedPacks.isEmpty())
			return false;

		if (pm == null)
			pm = NullProgressMonitor.INSTANCE;

		int numCommits = objectsLists[OBJ_COMMIT].size();
		List<ObjectToPack> byName = sortByName();
		sortedByName = null;
		objectsLists = null;
		objectsMap = null;
		writeBitmaps = new PackBitmapIndexBuilder(byName);
		byName = null;

		PackWriterBitmapPreparer bitmapPreparer = new PackWriterBitmapPreparer(
				reader, writeBitmaps, pm, stats.interestingObjects, config);

		Collection<PackWriterBitmapPreparer.BitmapCommit> selectedCommits = bitmapPreparer
				.selectCommits(numCommits, excludeFromBitmapSelection);

		beginPhase(PackingPhase.BUILDING_BITMAPS, pm, selectedCommits.size());

		BitmapWalker walker = bitmapPreparer.newBitmapWalker();
		AnyObjectId last = null;
		for (PackWriterBitmapPreparer.BitmapCommit cmit : selectedCommits) {
			if (!cmit.isReuseWalker()) {
				walker = bitmapPreparer.newBitmapWalker();
			}
			BitmapBuilder bitmap = walker.findObjects(
					Collections.singleton(cmit), null, false);

			if (last != null && cmit.isReuseWalker() && !bitmap.contains(last))
				throw new IllegalStateException(MessageFormat.format(
						JGitText.get().bitmapMissingObject, cmit.name(),
						last.name()));
			last = cmit;
			writeBitmaps.addBitmap(cmit, bitmap.build(), cmit.getFlags());

			pm.update(1);
		}

		endPhase(pm);
		return true;
	}

	private boolean reuseDeltaFor(ObjectToPack otp) {
		int type = otp.getType();
		if ((type & 2) != 0) // OBJ_TREE(2) or OBJ_BLOB(3)
			return true;
		if (type == OBJ_COMMIT)
			return reuseDeltaCommits;
		if (type == OBJ_TAG)
			return false;
		return true;
	}

	private class MutableState {
		
Estimated size of a single ObjectToPack instance. /** Estimated size of a single ObjectToPack instance. */
		// Assume 64-bit pointers, since this is just an estimate.
		private static final long OBJECT_TO_PACK_SIZE =
				(2 * 8)               // Object header
				+ (2 * 8) + (2 * 8)   // ObjectToPack fields
				+ (8 + 8)             // PackedObjectInfo fields
				+ 8                   // ObjectIdOwnerMap fields
				+ 40                  // AnyObjectId fields
				+ 8;                  // Reference in BlockList

		private final long totalDeltaSearchBytes;

		private volatile PackingPhase phase;

		MutableState() {
			phase = PackingPhase.COUNTING;
			if (config.isDeltaCompress()) {
				int threads = config.getThreads();
				if (threads <= 0)
					threads = Runtime.getRuntime().availableProcessors();
				totalDeltaSearchBytes = (threads * config.getDeltaSearchMemoryLimit())
						+ config.getBigFileThreshold();
			} else
				totalDeltaSearchBytes = 0;
		}

		State snapshot() {
			long objCnt = 0;
			BlockList<ObjectToPack>[] lists = objectsLists;
			if (lists != null) {
				objCnt += lists[OBJ_COMMIT].size();
				objCnt += lists[OBJ_TREE].size();
				objCnt += lists[OBJ_BLOB].size();
				objCnt += lists[OBJ_TAG].size();
				// Exclude CachedPacks.
			}

			long bytesUsed = OBJECT_TO_PACK_SIZE * objCnt;
			PackingPhase curr = phase;
			if (curr == PackingPhase.COMPRESSING)
				bytesUsed += totalDeltaSearchBytes;
			return new State(curr, bytesUsed);
		}
	}

	
Possible states that a PackWriter can be in. /** Possible states that a PackWriter can be in. */
	public static enum PackingPhase {
		
Counting objects phase. /** Counting objects phase. */
		COUNTING,

		
Getting sizes phase. /** Getting sizes phase. */
		GETTING_SIZES,

		
Finding sources phase. /** Finding sources phase. */
		FINDING_SOURCES,

		
Compressing objects phase. /** Compressing objects phase. */
		COMPRESSING,

		
Writing objects phase. /** Writing objects phase. */
		WRITING,

		
Building bitmaps phase. /** Building bitmaps phase. */
		BUILDING_BITMAPS;
	}

	
Summary of the current state of a PackWriter. /** Summary of the current state of a PackWriter. */
	public class State {
		private final PackingPhase phase;

		private final long bytesUsed;

		State(PackingPhase phase, long bytesUsed) {
			this.phase = phase;
			this.bytesUsed = bytesUsed;
		}

		
Returns:
the PackConfig used to build the writer./** @return the PackConfig used to build the writer. */
		public PackConfig getConfig() {
			return config;
		}

		
Returns:
the current phase of the writer./** @return the current phase of the writer. */
		public PackingPhase getPhase() {
			return phase;
		}

		
Returns:
an estimate of the total memory used by the writer./** @return an estimate of the total memory used by the writer. */
		public long estimateBytesUsed() {
			return bytesUsed;
		}

		@SuppressWarnings("nls")
		@Override
		public String toString() {
			return "PackWriter.State[" + phase + ", memory=" + bytesUsed + "]";
		}
	}

	
Configuration related to the packfile URI feature.
Since:
5.5/**
	 * Configuration related to the packfile URI feature.
	 *
	 * @since 5.5
	 */
	public static class PackfileUriConfig {
		@NonNull
		private final PacketLineOut pckOut;

		@NonNull
		private final Collection<String> protocolsSupported;

		@NonNull
		private final CachedPackUriProvider cachedPackUriProvider;

		
Params:
pckOut – where to write "packfile-uri" lines to (should
    output to the same stream as the one passed to
    PackWriter#writePack)
protocolsSupported – list of protocols supported (e.g. "https")
cachedPackUriProvider – provider of URIs corresponding
    to cached packs
Since:
5.5/**
		 * @param pckOut where to write "packfile-uri" lines to (should
		 *     output to the same stream as the one passed to
		 *     PackWriter#writePack)
		 * @param protocolsSupported list of protocols supported (e.g. "https")
		 * @param cachedPackUriProvider provider of URIs corresponding
		 *     to cached packs
		 * @since 5.5
		 */
		public PackfileUriConfig(@NonNull PacketLineOut pckOut,
				@NonNull Collection<String> protocolsSupported,
				@NonNull CachedPackUriProvider cachedPackUriProvider) {
			this.pckOut = pckOut;
			this.protocolsSupported = protocolsSupported;
			this.cachedPackUriProvider = cachedPackUriProvider;
		}
	}
}