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- /*
- * Copyright (C) 2011, Google Inc.
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- package org.eclipse.jgit.storage.dht;
-
- import java.text.MessageFormat;
- import java.util.Collections;
- import java.util.List;
-
- import org.eclipse.jgit.lib.AnyObjectId;
- import static org.eclipse.jgit.lib.Constants.*;
- import org.eclipse.jgit.lib.ObjectId;
- import org.eclipse.jgit.transport.PackedObjectInfo;
- import org.eclipse.jgit.util.NB;
-
- /** Index into a {@link PackChunk}. */
- public abstract class ChunkIndex {
- private static final int V1 = 0x01;
-
- static ChunkIndex fromBytes(ChunkKey key, byte[] index, int ptr, int len)
- throws DhtException {
- int v = index[ptr] & 0xff;
- switch (v) {
- case V1: {
- final int offsetFormat = index[ptr + 1] & 7;
- switch (offsetFormat) {
- case 1:
- return new Offset1(index, ptr, len, key);
- case 2:
- return new Offset2(index, ptr, len, key);
- case 3:
- return new Offset3(index, ptr, len, key);
- case 4:
- return new Offset4(index, ptr, len, key);
- default:
- throw new DhtException(MessageFormat.format(
- DhtText.get().unsupportedChunkIndex,
- Integer.toHexString(NB.decodeUInt16(index, ptr)), key));
- }
- }
- default:
- throw new DhtException(MessageFormat.format(
- DhtText.get().unsupportedChunkIndex,
- Integer.toHexString(v), key));
- }
- }
-
- /**
- * Format the chunk index and return its binary representation.
- *
- * @param list
- * the list of objects that appear in the chunk. This list will
- * be sorted in-place if it has more than 1 element.
- * @return binary representation of the chunk's objects and their starting
- * offsets. The format is private to this class.
- */
- @SuppressWarnings("null")
- static byte[] create(List<? extends PackedObjectInfo> list) {
- int cnt = list.size();
- sortObjectList(list);
-
- int fanoutFormat = 0;
- int[] buckets = null;
- if (64 < cnt) {
- buckets = new int[256];
- for (PackedObjectInfo oe : list)
- buckets[oe.getFirstByte()]++;
- fanoutFormat = selectFanoutFormat(buckets);
- }
-
- int offsetFormat = selectOffsetFormat(list);
- byte[] index = new byte[2 // header
- + 256 * fanoutFormat // (optional) fanout
- + cnt * OBJECT_ID_LENGTH // ids
- + cnt * offsetFormat // offsets
- ];
- index[0] = V1;
- index[1] = (byte) ((fanoutFormat << 3) | offsetFormat);
-
- int ptr = 2;
-
- switch (fanoutFormat) {
- case 0:
- break;
- case 1:
- for (int i = 0; i < 256; i++, ptr++)
- index[ptr] = (byte) buckets[i];
- break;
- case 2:
- for (int i = 0; i < 256; i++, ptr += 2)
- NB.encodeInt16(index, ptr, buckets[i]);
- break;
- case 3:
- for (int i = 0; i < 256; i++, ptr += 3)
- encodeUInt24(index, ptr, buckets[i]);
- break;
- case 4:
- for (int i = 0; i < 256; i++, ptr += 4)
- NB.encodeInt32(index, ptr, buckets[i]);
- break;
- }
-
- for (PackedObjectInfo oe : list) {
- oe.copyRawTo(index, ptr);
- ptr += OBJECT_ID_LENGTH;
- }
-
- switch (offsetFormat) {
- case 1:
- for (PackedObjectInfo oe : list)
- index[ptr++] = (byte) oe.getOffset();
- break;
-
- case 2:
- for (PackedObjectInfo oe : list) {
- NB.encodeInt16(index, ptr, (int) oe.getOffset());
- ptr += 2;
- }
- break;
-
- case 3:
- for (PackedObjectInfo oe : list) {
- encodeUInt24(index, ptr, (int) oe.getOffset());
- ptr += 3;
- }
- break;
-
- case 4:
- for (PackedObjectInfo oe : list) {
- NB.encodeInt32(index, ptr, (int) oe.getOffset());
- ptr += 4;
- }
- break;
- }
-
- return index;
- }
-
- private static int selectFanoutFormat(int[] buckets) {
- int fmt = 1;
- int max = 1 << (8 * fmt);
-
- for (int cnt : buckets) {
- while (max <= cnt && fmt < 4) {
- if (++fmt == 4)
- return fmt;
- max = 1 << (8 * fmt);
- }
- }
- return fmt;
- }
-
- private static int selectOffsetFormat(List<? extends PackedObjectInfo> list) {
- int fmt = 1;
- int max = 1 << (8 * fmt);
-
- for (PackedObjectInfo oe : list) {
- while (max <= oe.getOffset() && fmt < 4) {
- if (++fmt == 4)
- return fmt;
- max = 1 << (8 * fmt);
- }
- }
- return fmt;
- }
-
- @SuppressWarnings("unchecked")
- private static void sortObjectList(List<? extends PackedObjectInfo> list) {
- Collections.sort(list);
- }
-
- private final byte[] indexBuf;
-
- private final int indexPtr;
-
- private final int indexLen;
-
- private final int[] fanout;
-
- private final int idTable;
-
- private final int offsetTable;
-
- private final int count;
-
- ChunkIndex(byte[] indexBuf, int ptr, int len, ChunkKey key)
- throws DhtException {
- final int ctl = indexBuf[ptr + 1];
- final int fanoutFormat = (ctl >>> 3) & 7;
- final int offsetFormat = ctl & 7;
-
- switch (fanoutFormat) {
- case 0:
- fanout = null; // no fanout, too small
- break;
-
- case 1: {
- int last = 0;
- fanout = new int[256];
- for (int i = 0; i < 256; i++) {
- last += indexBuf[ptr + 2 + i] & 0xff;
- fanout[i] = last;
- }
- break;
- }
- case 2: {
- int last = 0;
- fanout = new int[256];
- for (int i = 0; i < 256; i++) {
- last += NB.decodeUInt16(indexBuf, ptr + 2 + i * 2);
- fanout[i] = last;
- }
- break;
- }
- case 3: {
- int last = 0;
- fanout = new int[256];
- for (int i = 0; i < 256; i++) {
- last += decodeUInt24(indexBuf, ptr + 2 + i * 3);
- fanout[i] = last;
- }
- break;
- }
- case 4: {
- int last = 0;
- fanout = new int[256];
- for (int i = 0; i < 256; i++) {
- last += NB.decodeInt32(indexBuf, ptr + 2 + i * 4);
- fanout[i] = last;
- }
- break;
- }
- default:
- throw new DhtException(MessageFormat.format(
- DhtText.get().unsupportedChunkIndex,
- Integer.toHexString(NB.decodeUInt16(indexBuf, ptr)), key));
- }
-
- this.indexBuf = indexBuf;
- this.indexPtr = ptr;
- this.indexLen = len;
- this.idTable = indexPtr + 2 + 256 * fanoutFormat;
-
- int recsz = OBJECT_ID_LENGTH + offsetFormat;
- this.count = (indexLen - (idTable - indexPtr)) / recsz;
- this.offsetTable = idTable + count * OBJECT_ID_LENGTH;
- }
-
- /**
- * Get the total number of objects described by this index.
- *
- * @return number of objects in this index and its associated chunk.
- */
- public final int getObjectCount() {
- return count;
- }
-
- /**
- * Get an ObjectId from this index.
- *
- * @param nth
- * the object to return. Must be in range [0, getObjectCount).
- * @return the object id.
- */
- public final ObjectId getObjectId(int nth) {
- return ObjectId.fromRaw(indexBuf, idPosition(nth));
- }
-
- /**
- * Get the offset of an object in the chunk.
- *
- * @param nth
- * offset to return. Must be in range [0, getObjectCount).
- * @return the offset.
- */
- public final int getOffset(int nth) {
- return getOffset(indexBuf, offsetTable, nth);
- }
-
- /** @return the size of this index, in bytes. */
- int getIndexSize() {
- int sz = indexBuf.length;
- if (fanout != null)
- sz += 12 + 256 * 4;
- return sz;
- }
-
- /**
- * Search for an object in the index.
- *
- * @param objId
- * the object to locate.
- * @return offset of the object in the corresponding chunk; -1 if not found.
- */
- final int findOffset(AnyObjectId objId) {
- int hi, lo;
-
- if (fanout != null) {
- int fb = objId.getFirstByte();
- lo = fb == 0 ? 0 : fanout[fb - 1];
- hi = fanout[fb];
- } else {
- lo = 0;
- hi = count;
- }
-
- while (lo < hi) {
- final int mid = (lo + hi) >>> 1;
- final int cmp = objId.compareTo(indexBuf, idPosition(mid));
- if (cmp < 0)
- hi = mid;
- else if (cmp == 0)
- return getOffset(mid);
- else
- lo = mid + 1;
- }
- return -1;
- }
-
- abstract int getOffset(byte[] indexArray, int offsetTableStart, int nth);
-
- private int idPosition(int nth) {
- return idTable + (nth * OBJECT_ID_LENGTH);
- }
-
- private static class Offset1 extends ChunkIndex {
- Offset1(byte[] index, int ptr, int len, ChunkKey key)
- throws DhtException {
- super(index, ptr, len, key);
- }
-
- int getOffset(byte[] index, int offsetTable, int nth) {
- return index[offsetTable + nth] & 0xff;
- }
- }
-
- private static class Offset2 extends ChunkIndex {
- Offset2(byte[] index, int ptr, int len, ChunkKey key)
- throws DhtException {
- super(index, ptr, len, key);
- }
-
- int getOffset(byte[] index, int offsetTable, int nth) {
- return NB.decodeUInt16(index, offsetTable + (nth * 2));
- }
- }
-
- private static class Offset3 extends ChunkIndex {
- Offset3(byte[] index, int ptr, int len, ChunkKey key)
- throws DhtException {
- super(index, ptr, len, key);
- }
-
- int getOffset(byte[] index, int offsetTable, int nth) {
- return decodeUInt24(index, offsetTable + (nth * 3));
- }
- }
-
- private static class Offset4 extends ChunkIndex {
- Offset4(byte[] index, int ptr, int len, ChunkKey key)
- throws DhtException {
- super(index, ptr, len, key);
- }
-
- int getOffset(byte[] index, int offsetTable, int nth) {
- return NB.decodeInt32(index, offsetTable + (nth * 4));
- }
- }
-
- private static void encodeUInt24(byte[] intbuf, int offset, int v) {
- intbuf[offset + 2] = (byte) v;
- v >>>= 8;
-
- intbuf[offset + 1] = (byte) v;
- v >>>= 8;
-
- intbuf[offset] = (byte) v;
- }
-
- private static int decodeUInt24(byte[] intbuf, int offset) {
- int r = (intbuf[offset] & 0xff) << 8;
-
- r |= intbuf[offset + 1] & 0xff;
- r <<= 8;
-
- r |= intbuf[offset + 2] & 0xff;
- return r;
- }
- }
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