org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/PackTest.java - jgit - Git at Google

 /*
  * Copyright (C) 2010, Google Inc. and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
  * https://www.eclipse.org/org/documents/edl-v10.php.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */

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

 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;

 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.security.MessageDigest;
 import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.zip.Deflater;

 import org.eclipse.jgit.errors.LargeObjectException;
 import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.internal.storage.pack.DeltaEncoder;
 import org.eclipse.jgit.internal.storage.pack.PackExt;
 import org.eclipse.jgit.junit.JGitTestUtil;
 import org.eclipse.jgit.junit.LocalDiskRepositoryTestCase;
 import org.eclipse.jgit.junit.TestRepository;
 import org.eclipse.jgit.junit.TestRng;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.NullProgressMonitor;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;
 import org.eclipse.jgit.lib.ObjectLoader;
 import org.eclipse.jgit.lib.ObjectStream;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevBlob;
 import org.eclipse.jgit.storage.file.WindowCacheConfig;
 import org.eclipse.jgit.transport.PackParser;
 import org.eclipse.jgit.transport.PackedObjectInfo;
 import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.NB;
 import org.eclipse.jgit.util.TemporaryBuffer;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;

 public class PackTest extends LocalDiskRepositoryTestCase {
 	private int streamThreshold = 16 * 1024;

 	private TestRng rng;

 	private FileRepository repo;

 	private TestRepository<Repository> tr;

 	private WindowCursor wc;

 	private TestRng getRng() {
 		if (rng == null)
 			rng = new TestRng(JGitTestUtil.getName());
 		return rng;
 	}

 	@Override
 	@Before
 	public void setUp() throws Exception {
 		super.setUp();

 		WindowCacheConfig cfg = new WindowCacheConfig();
 		cfg.setStreamFileThreshold(streamThreshold);
 		cfg.install();

 		repo = createBareRepository();
 		tr = new TestRepository<>(repo);
 		wc = (WindowCursor) repo.newObjectReader();
 	}

 	@Override
 	@After
 	public void tearDown() throws Exception {
 		if (wc != null)
 			wc.close();
 		new WindowCacheConfig().install();
 		super.tearDown();
 	}

 	@Test
 	public void testWhole_SmallObject() throws Exception {
 		final int type = Constants.OBJ_BLOB;
 		byte[] data = getRng().nextBytes(300);
 		RevBlob id = tr.blob(data);
 		tr.branch("master").commit().add("A", id).create();
 		tr.packAndPrune();
 		assertTrue("has blob", wc.has(id));

 		ObjectLoader ol = wc.open(id);
 		assertNotNull("created loader", ol);
 		assertEquals(type, ol.getType());
 		assertEquals(data.length, ol.getSize());
 		assertFalse("is not large", ol.isLarge());
 		assertTrue("same content", Arrays.equals(data, ol.getCachedBytes()));

 		try (ObjectStream in = ol.openStream()) {
 			assertNotNull("have stream", in);
 			assertEquals(type, in.getType());
 			assertEquals(data.length, in.getSize());
 			byte[] data2 = new byte[data.length];
 			IO.readFully(in, data2, 0, data.length);
 			assertTrue("same content", Arrays.equals(data2, data));
 			assertEquals("stream at EOF", -1, in.read());
 		}
 	}

 	@Test
 	public void testWhole_LargeObject() throws Exception {
 		final int type = Constants.OBJ_BLOB;
 		byte[] data = getRng().nextBytes(streamThreshold + 5);
 		RevBlob id = tr.blob(data);
 		tr.branch("master").commit().add("A", id).create();
 		tr.packAndPrune();
 		assertTrue("has blob", wc.has(id));

 		ObjectLoader ol = wc.open(id);
 		assertNotNull("created loader", ol);
 		assertEquals(type, ol.getType());
 		assertEquals(data.length, ol.getSize());
 		assertTrue("is large", ol.isLarge());
 		try {
 			ol.getCachedBytes();
 			fail("Should have thrown LargeObjectException");
 		} catch (LargeObjectException tooBig) {
 			assertEquals(MessageFormat.format(
 					JGitText.get().largeObjectException, id.name()), tooBig
 					.getMessage());
 		}

 		try (ObjectStream in = ol.openStream()) {
 			assertNotNull("have stream", in);
 			assertEquals(type, in.getType());
 			assertEquals(data.length, in.getSize());
 			byte[] data2 = new byte[data.length];
 			IO.readFully(in, data2, 0, data.length);
 			assertTrue("same content", Arrays.equals(data2, data));
 			assertEquals("stream at EOF", -1, in.read());
 		}
 	}

 	@Test
 	public void testDelta_SmallObjectChain() throws Exception {
 		try (ObjectInserter.Formatter fmt = new ObjectInserter.Formatter()) {
 			byte[] data0 = new byte[512];
 			Arrays.fill(data0, (byte) 0xf3);
 			ObjectId id0 = fmt.idFor(Constants.OBJ_BLOB, data0);

 			TemporaryBuffer.Heap pack = new TemporaryBuffer.Heap(64 * 1024);
 			packHeader(pack, 4);
 			objectHeader(pack, Constants.OBJ_BLOB, data0.length);
 			deflate(pack, data0);

 			byte[] data1 = clone(0x01, data0);
 			byte[] delta1 = delta(data0, data1);
 			ObjectId id1 = fmt.idFor(Constants.OBJ_BLOB, data1);
 			objectHeader(pack, Constants.OBJ_REF_DELTA, delta1.length);
 			id0.copyRawTo(pack);
 			deflate(pack, delta1);

 			byte[] data2 = clone(0x02, data1);
 			byte[] delta2 = delta(data1, data2);
 			ObjectId id2 = fmt.idFor(Constants.OBJ_BLOB, data2);
 			objectHeader(pack, Constants.OBJ_REF_DELTA, delta2.length);
 			id1.copyRawTo(pack);
 			deflate(pack, delta2);

 			byte[] data3 = clone(0x03, data2);
 			byte[] delta3 = delta(data2, data3);
 			ObjectId id3 = fmt.idFor(Constants.OBJ_BLOB, data3);
 			objectHeader(pack, Constants.OBJ_REF_DELTA, delta3.length);
 			id2.copyRawTo(pack);
 			deflate(pack, delta3);

 			digest(pack);
 			PackParser ip = index(pack.toByteArray());
 			ip.setAllowThin(true);
 			ip.parse(NullProgressMonitor.INSTANCE);

 			assertTrue("has blob", wc.has(id3));

 			ObjectLoader ol = wc.open(id3);
 			assertNotNull("created loader", ol);
 			assertEquals(Constants.OBJ_BLOB, ol.getType());
 			assertEquals(data3.length, ol.getSize());
 			assertFalse("is large", ol.isLarge());
 			assertNotNull(ol.getCachedBytes());
 			assertArrayEquals(data3, ol.getCachedBytes());

 			try (ObjectStream in = ol.openStream()) {
 				assertNotNull("have stream", in);
 				assertEquals(Constants.OBJ_BLOB, in.getType());
 				assertEquals(data3.length, in.getSize());
 				byte[] act = new byte[data3.length];
 				IO.readFully(in, act, 0, data3.length);
 				assertTrue("same content", Arrays.equals(act, data3));
 				assertEquals("stream at EOF", -1, in.read());
 			}
 		}
 	}

 	@Test
 	public void testDelta_FailsOver2GiB() throws Exception {
 		try (ObjectInserter.Formatter fmt = new ObjectInserter.Formatter()) {
 			byte[] base = new byte[] { 'a' };
 			ObjectId idA = fmt.idFor(Constants.OBJ_BLOB, base);
 			ObjectId idB = fmt.idFor(Constants.OBJ_BLOB, new byte[] { 'b' });

 			PackedObjectInfo a = new PackedObjectInfo(idA);
 			PackedObjectInfo b = new PackedObjectInfo(idB);

 			TemporaryBuffer.Heap packContents = new TemporaryBuffer.Heap(64 * 1024);
 			packHeader(packContents, 2);
 			a.setOffset(packContents.length());
 			objectHeader(packContents, Constants.OBJ_BLOB, base.length);
 			deflate(packContents, base);

 			ByteArrayOutputStream tmp = new ByteArrayOutputStream();
 			DeltaEncoder de = new DeltaEncoder(tmp, base.length, 3L << 30);
 			de.copy(0, 1);
 			byte[] delta = tmp.toByteArray();
 			b.setOffset(packContents.length());
 			objectHeader(packContents, Constants.OBJ_REF_DELTA, delta.length);
 			idA.copyRawTo(packContents);
 			deflate(packContents, delta);
 			byte[] footer = digest(packContents);

 			File dir = new File(repo.getObjectDatabase().getDirectory(),
 					"pack");
 			PackFile packName = new PackFile(dir, idA.name() + ".pack");
 			PackFile idxName = packName.create(PackExt.INDEX);

 			try (FileOutputStream f = new FileOutputStream(packName)) {
 				f.write(packContents.toByteArray());
 			}

 			try (FileOutputStream f = new FileOutputStream(idxName)) {
 				List<PackedObjectInfo> list = new ArrayList<>();
 				list.add(a);
 				list.add(b);
 				Collections.sort(list);
 				new PackIndexWriterV1(f).write(list, footer);
 			}

 			Pack pack = new Pack(repo.getConfig(), packName, null);
 			try {
 				pack.get(wc, b);
 				fail("expected LargeObjectException.ExceedsByteArrayLimit");
 			} catch (LargeObjectException.ExceedsByteArrayLimit bad) {
 				assertNull(bad.getObjectId());
 			} finally {
 				pack.close();
 			}
 		}
 	}

 	@Test
 	public void testConfigurableStreamFileThreshold() throws Exception {
 		byte[] data = getRng().nextBytes(300);
 		RevBlob id = tr.blob(data);
 		tr.branch("master").commit().add("A", id).create();
 		tr.packAndPrune();
 		assertTrue("has blob", wc.has(id));

 		ObjectLoader ol = wc.open(id);
 		try (ObjectStream in = ol.openStream()) {
 			assertTrue(in instanceof ObjectStream.SmallStream);
 			assertEquals(300, in.available());
 		}

 		wc.setStreamFileThreshold(299);
 		ol = wc.open(id);
 		try (ObjectStream in = ol.openStream()) {
 			assertTrue(in instanceof ObjectStream.Filter);
 			assertEquals(1, in.available());
 		}
 	}

 	private static byte[] clone(int first, byte[] base) {
 		byte[] r = new byte[base.length];
 		System.arraycopy(base, 1, r, 1, r.length - 1);
 		r[0] = (byte) first;
 		return r;
 	}

 	private static byte[] delta(byte[] base, byte[] dest) throws IOException {
 		ByteArrayOutputStream tmp = new ByteArrayOutputStream();
 		DeltaEncoder de = new DeltaEncoder(tmp, base.length, dest.length);
 		de.insert(dest, 0, 1);
 		de.copy(1, base.length - 1);
 		return tmp.toByteArray();
 	}

 	private static void packHeader(TemporaryBuffer.Heap pack, int cnt)
 			throws IOException {
 		final byte[] hdr = new byte[8];
 		NB.encodeInt32(hdr, 0, 2);
 		NB.encodeInt32(hdr, 4, cnt);
 		pack.write(Constants.PACK_SIGNATURE);
 		pack.write(hdr, 0, 8);
 	}

 	private static void objectHeader(TemporaryBuffer.Heap pack, int type, int sz)
 			throws IOException {
 		byte[] buf = new byte[8];
 		int nextLength = sz >>> 4;
 		buf[0] = (byte) ((nextLength > 0 ? 0x80 : 0x00) | (type << 4) | (sz & 0x0F));
 		sz = nextLength;
 		int n = 1;
 		while (sz > 0) {
 			nextLength >>>= 7;
 			buf[n++] = (byte) ((nextLength > 0 ? 0x80 : 0x00) | (sz & 0x7F));
 			sz = nextLength;
 		}
 		pack.write(buf, 0, n);
 	}

 	private static void deflate(TemporaryBuffer.Heap pack, byte[] content)
 			throws IOException {
 		final Deflater deflater = new Deflater();
 		final byte[] buf = new byte[128];
 		deflater.setInput(content, 0, content.length);
 		deflater.finish();
 		do {
 			final int n = deflater.deflate(buf, 0, buf.length);
 			if (n > 0)
 				pack.write(buf, 0, n);
 		} while (!deflater.finished());
 		deflater.end();
 	}

 	private static byte[] digest(TemporaryBuffer.Heap buf)
 			throws IOException {
 		MessageDigest md = Constants.newMessageDigest();
 		md.update(buf.toByteArray());
 		byte[] footer = md.digest();
 		buf.write(footer);
 		return footer;
 	}

 	private ObjectInserter inserter;

 	@After
 	public void release() {
 		if (inserter != null) {
 			inserter.close();
 		}
 	}

 	private PackParser index(byte[] raw) throws IOException {
 		if (inserter == null)
 			inserter = repo.newObjectInserter();
 		return inserter.newPackParser(new ByteArrayInputStream(raw));
 	}
 }
	/*
	* Copyright (C) 2010, Google Inc. and others
	*
	* This program and the accompanying materials are made available under the
	* terms of the Eclipse Distribution License v. 1.0 which is available at
	* https://www.eclipse.org/org/documents/edl-v10.php.
	*
	* SPDX-License-Identifier: BSD-3-Clause
	*/

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

	import static org.junit.Assert.assertArrayEquals;
	import static org.junit.Assert.assertEquals;
	import static org.junit.Assert.assertFalse;
	import static org.junit.Assert.assertNotNull;
	import static org.junit.Assert.assertNull;
	import static org.junit.Assert.assertTrue;
	import static org.junit.Assert.fail;

	import java.io.ByteArrayInputStream;
	import java.io.ByteArrayOutputStream;
	import java.io.File;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.security.MessageDigest;
	import java.text.MessageFormat;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collections;
	import java.util.List;
	import java.util.zip.Deflater;

	import org.eclipse.jgit.errors.LargeObjectException;
	import org.eclipse.jgit.internal.JGitText;
	import org.eclipse.jgit.internal.storage.pack.DeltaEncoder;
	import org.eclipse.jgit.internal.storage.pack.PackExt;
	import org.eclipse.jgit.junit.JGitTestUtil;
	import org.eclipse.jgit.junit.LocalDiskRepositoryTestCase;
	import org.eclipse.jgit.junit.TestRepository;
	import org.eclipse.jgit.junit.TestRng;
	import org.eclipse.jgit.lib.Constants;
	import org.eclipse.jgit.lib.NullProgressMonitor;
	import org.eclipse.jgit.lib.ObjectId;
	import org.eclipse.jgit.lib.ObjectInserter;
	import org.eclipse.jgit.lib.ObjectLoader;
	import org.eclipse.jgit.lib.ObjectStream;
	import org.eclipse.jgit.lib.Repository;
	import org.eclipse.jgit.revwalk.RevBlob;
	import org.eclipse.jgit.storage.file.WindowCacheConfig;
	import org.eclipse.jgit.transport.PackParser;
	import org.eclipse.jgit.transport.PackedObjectInfo;
	import org.eclipse.jgit.util.IO;
	import org.eclipse.jgit.util.NB;
	import org.eclipse.jgit.util.TemporaryBuffer;
	import org.junit.After;
	import org.junit.Before;
	import org.junit.Test;

	public class PackTest extends LocalDiskRepositoryTestCase {
	private int streamThreshold = 16 * 1024;

	private TestRng rng;

	private FileRepository repo;

	private TestRepository<Repository> tr;

	private WindowCursor wc;

	private TestRng getRng() {
	if (rng == null)
	rng = new TestRng(JGitTestUtil.getName());
	return rng;
	}

	@Override
	@Before
	public void setUp() throws Exception {
	super.setUp();

	WindowCacheConfig cfg = new WindowCacheConfig();
	cfg.setStreamFileThreshold(streamThreshold);
	cfg.install();

	repo = createBareRepository();
	tr = new TestRepository<>(repo);
	wc = (WindowCursor) repo.newObjectReader();
	}

	@Override
	@After
	public void tearDown() throws Exception {
	if (wc != null)
	wc.close();
	new WindowCacheConfig().install();
	super.tearDown();
	}

	@Test
	public void testWhole_SmallObject() throws Exception {
	final int type = Constants.OBJ_BLOB;
	byte[] data = getRng().nextBytes(300);
	RevBlob id = tr.blob(data);
	tr.branch("master").commit().add("A", id).create();
	tr.packAndPrune();
	assertTrue("has blob", wc.has(id));

	ObjectLoader ol = wc.open(id);
	assertNotNull("created loader", ol);
	assertEquals(type, ol.getType());
	assertEquals(data.length, ol.getSize());
	assertFalse("is not large", ol.isLarge());
	assertTrue("same content", Arrays.equals(data, ol.getCachedBytes()));

	try (ObjectStream in = ol.openStream()) {
	assertNotNull("have stream", in);
	assertEquals(type, in.getType());
	assertEquals(data.length, in.getSize());
	byte[] data2 = new byte[data.length];
	IO.readFully(in, data2, 0, data.length);
	assertTrue("same content", Arrays.equals(data2, data));
	assertEquals("stream at EOF", -1, in.read());
	}
	}

	@Test
	public void testWhole_LargeObject() throws Exception {
	final int type = Constants.OBJ_BLOB;
	byte[] data = getRng().nextBytes(streamThreshold + 5);
	RevBlob id = tr.blob(data);
	tr.branch("master").commit().add("A", id).create();
	tr.packAndPrune();
	assertTrue("has blob", wc.has(id));

	ObjectLoader ol = wc.open(id);
	assertNotNull("created loader", ol);
	assertEquals(type, ol.getType());
	assertEquals(data.length, ol.getSize());
	assertTrue("is large", ol.isLarge());
	try {
	ol.getCachedBytes();
	fail("Should have thrown LargeObjectException");
	} catch (LargeObjectException tooBig) {
	assertEquals(MessageFormat.format(
	JGitText.get().largeObjectException, id.name()), tooBig
	.getMessage());
	}

	try (ObjectStream in = ol.openStream()) {
	assertNotNull("have stream", in);
	assertEquals(type, in.getType());
	assertEquals(data.length, in.getSize());
	byte[] data2 = new byte[data.length];
	IO.readFully(in, data2, 0, data.length);
	assertTrue("same content", Arrays.equals(data2, data));
	assertEquals("stream at EOF", -1, in.read());
	}
	}

	@Test
	public void testDelta_SmallObjectChain() throws Exception {
	try (ObjectInserter.Formatter fmt = new ObjectInserter.Formatter()) {
	byte[] data0 = new byte[512];
	Arrays.fill(data0, (byte) 0xf3);
	ObjectId id0 = fmt.idFor(Constants.OBJ_BLOB, data0);

	TemporaryBuffer.Heap pack = new TemporaryBuffer.Heap(64 * 1024);
	packHeader(pack, 4);
	objectHeader(pack, Constants.OBJ_BLOB, data0.length);
	deflate(pack, data0);

	byte[] data1 = clone(0x01, data0);
	byte[] delta1 = delta(data0, data1);
	ObjectId id1 = fmt.idFor(Constants.OBJ_BLOB, data1);
	objectHeader(pack, Constants.OBJ_REF_DELTA, delta1.length);
	id0.copyRawTo(pack);
	deflate(pack, delta1);

	byte[] data2 = clone(0x02, data1);
	byte[] delta2 = delta(data1, data2);
	ObjectId id2 = fmt.idFor(Constants.OBJ_BLOB, data2);
	objectHeader(pack, Constants.OBJ_REF_DELTA, delta2.length);
	id1.copyRawTo(pack);
	deflate(pack, delta2);

	byte[] data3 = clone(0x03, data2);
	byte[] delta3 = delta(data2, data3);
	ObjectId id3 = fmt.idFor(Constants.OBJ_BLOB, data3);
	objectHeader(pack, Constants.OBJ_REF_DELTA, delta3.length);
	id2.copyRawTo(pack);
	deflate(pack, delta3);

	digest(pack);
	PackParser ip = index(pack.toByteArray());
	ip.setAllowThin(true);
	ip.parse(NullProgressMonitor.INSTANCE);

	assertTrue("has blob", wc.has(id3));

	ObjectLoader ol = wc.open(id3);
	assertNotNull("created loader", ol);
	assertEquals(Constants.OBJ_BLOB, ol.getType());
	assertEquals(data3.length, ol.getSize());
	assertFalse("is large", ol.isLarge());
	assertNotNull(ol.getCachedBytes());
	assertArrayEquals(data3, ol.getCachedBytes());

	try (ObjectStream in = ol.openStream()) {
	assertNotNull("have stream", in);
	assertEquals(Constants.OBJ_BLOB, in.getType());
	assertEquals(data3.length, in.getSize());
	byte[] act = new byte[data3.length];
	IO.readFully(in, act, 0, data3.length);
	assertTrue("same content", Arrays.equals(act, data3));
	assertEquals("stream at EOF", -1, in.read());
	}
	}
	}

	@Test
	public void testDelta_FailsOver2GiB() throws Exception {
	try (ObjectInserter.Formatter fmt = new ObjectInserter.Formatter()) {
	byte[] base = new byte[] { 'a' };
	ObjectId idA = fmt.idFor(Constants.OBJ_BLOB, base);
	ObjectId idB = fmt.idFor(Constants.OBJ_BLOB, new byte[] { 'b' });

	PackedObjectInfo a = new PackedObjectInfo(idA);
	PackedObjectInfo b = new PackedObjectInfo(idB);

	TemporaryBuffer.Heap packContents = new TemporaryBuffer.Heap(64 * 1024);
	packHeader(packContents, 2);
	a.setOffset(packContents.length());
	objectHeader(packContents, Constants.OBJ_BLOB, base.length);
	deflate(packContents, base);

	ByteArrayOutputStream tmp = new ByteArrayOutputStream();
	DeltaEncoder de = new DeltaEncoder(tmp, base.length, 3L << 30);
	de.copy(0, 1);
	byte[] delta = tmp.toByteArray();
	b.setOffset(packContents.length());
	objectHeader(packContents, Constants.OBJ_REF_DELTA, delta.length);
	idA.copyRawTo(packContents);
	deflate(packContents, delta);
	byte[] footer = digest(packContents);

	File dir = new File(repo.getObjectDatabase().getDirectory(),
	"pack");
	PackFile packName = new PackFile(dir, idA.name() + ".pack");
	PackFile idxName = packName.create(PackExt.INDEX);

	try (FileOutputStream f = new FileOutputStream(packName)) {
	f.write(packContents.toByteArray());
	}

	try (FileOutputStream f = new FileOutputStream(idxName)) {
	List<PackedObjectInfo> list = new ArrayList<>();
	list.add(a);
	list.add(b);
	Collections.sort(list);
	new PackIndexWriterV1(f).write(list, footer);
	}

	Pack pack = new Pack(repo.getConfig(), packName, null);
	try {
	pack.get(wc, b);
	fail("expected LargeObjectException.ExceedsByteArrayLimit");
	} catch (LargeObjectException.ExceedsByteArrayLimit bad) {
	assertNull(bad.getObjectId());
	} finally {
	pack.close();
	}
	}
	}

	@Test
	public void testConfigurableStreamFileThreshold() throws Exception {
	byte[] data = getRng().nextBytes(300);
	RevBlob id = tr.blob(data);
	tr.branch("master").commit().add("A", id).create();
	tr.packAndPrune();
	assertTrue("has blob", wc.has(id));

	ObjectLoader ol = wc.open(id);
	try (ObjectStream in = ol.openStream()) {
	assertTrue(in instanceof ObjectStream.SmallStream);
	assertEquals(300, in.available());
	}

	wc.setStreamFileThreshold(299);
	ol = wc.open(id);
	try (ObjectStream in = ol.openStream()) {
	assertTrue(in instanceof ObjectStream.Filter);
	assertEquals(1, in.available());
	}
	}

	private static byte[] clone(int first, byte[] base) {
	byte[] r = new byte[base.length];
	System.arraycopy(base, 1, r, 1, r.length - 1);
	r[0] = (byte) first;
	return r;
	}

	private static byte[] delta(byte[] base, byte[] dest) throws IOException {
	ByteArrayOutputStream tmp = new ByteArrayOutputStream();
	DeltaEncoder de = new DeltaEncoder(tmp, base.length, dest.length);
	de.insert(dest, 0, 1);
	de.copy(1, base.length - 1);
	return tmp.toByteArray();
	}

	private static void packHeader(TemporaryBuffer.Heap pack, int cnt)
	throws IOException {
	final byte[] hdr = new byte[8];
	NB.encodeInt32(hdr, 0, 2);
	NB.encodeInt32(hdr, 4, cnt);
	pack.write(Constants.PACK_SIGNATURE);
	pack.write(hdr, 0, 8);
	}

	private static void objectHeader(TemporaryBuffer.Heap pack, int type, int sz)
	throws IOException {
	byte[] buf = new byte[8];
	int nextLength = sz >>> 4;
	buf[0] = (byte) ((nextLength > 0 ? 0x80 : 0x00) \| (type << 4) \| (sz & 0x0F));
	sz = nextLength;
	int n = 1;
	while (sz > 0) {
	nextLength >>>= 7;
	buf[n++] = (byte) ((nextLength > 0 ? 0x80 : 0x00) \| (sz & 0x7F));
	sz = nextLength;
	}
	pack.write(buf, 0, n);
	}

	private static void deflate(TemporaryBuffer.Heap pack, byte[] content)
	throws IOException {
	final Deflater deflater = new Deflater();
	final byte[] buf = new byte[128];
	deflater.setInput(content, 0, content.length);
	deflater.finish();
	do {
	final int n = deflater.deflate(buf, 0, buf.length);
	if (n > 0)
	pack.write(buf, 0, n);
	} while (!deflater.finished());
	deflater.end();
	}

	private static byte[] digest(TemporaryBuffer.Heap buf)
	throws IOException {
	MessageDigest md = Constants.newMessageDigest();
	md.update(buf.toByteArray());
	byte[] footer = md.digest();
	buf.write(footer);
	return footer;
	}

	private ObjectInserter inserter;

	@After
	public void release() {
	if (inserter != null) {
	inserter.close();
	}
	}

	private PackParser index(byte[] raw) throws IOException {
	if (inserter == null)
	inserter = repo.newObjectInserter();
	return inserter.newPackParser(new ByteArrayInputStream(raw));
	}
	}