org.spearce.jgit/src/org/spearce/jgit/lib/PackIndexV1.java

   1 /*
   2  * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
   3  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
   4  *
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or
   8  * without modification, are permitted provided that the following
   9  * conditions are met:
  10  *
  11  * - Redistributions of source code must retain the above copyright
  12  *   notice, this list of conditions and the following disclaimer.
  13  *
  14  * - Redistributions in binary form must reproduce the above
  15  *   copyright notice, this list of conditions and the following
  16  *   disclaimer in the documentation and/or other materials provided
  17  *   with the distribution.
  18  *
  19  * - Neither the name of the Git Development Community nor the
  20  *   names of its contributors may be used to endorse or promote
  21  *   products derived from this software without specific prior
  22  *   written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  25  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  26  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  29  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  32  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  33  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  34  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  36  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  37  */
  38
  39 package org.spearce.jgit.lib;
  40
  41 import java.io.IOException;
  42 import java.io.InputStream;
  43 import java.util.Arrays;
  44 import java.util.Iterator;
  45 import java.util.NoSuchElementException;
  46
  47 import org.spearce.jgit.errors.CorruptObjectException;
  48 import org.spearce.jgit.util.NB;
  49
  50 class PackIndexV1 extends PackIndex {
  51         private static final int IDX_HDR_LEN = 256 * 4;
  52
  53         private final long[] idxHeader;
  54
  55         private byte[][] idxdata;
  56
  57         private long objectCnt;
  58
  59         PackIndexV1(final InputStream fd, final byte[] hdr)
  60                         throws CorruptObjectException, IOException {
  61                 final byte[] fanoutTable = new byte[IDX_HDR_LEN];
  62                 System.arraycopy(hdr, 0, fanoutTable, 0, hdr.length);
  63                 NB.readFully(fd, fanoutTable, hdr.length, IDX_HDR_LEN - hdr.length);
  64
  65                 idxHeader = new long[256]; // really unsigned 32-bit...
  66                 for (int k = 0; k < idxHeader.length; k++)
  67                         idxHeader[k] = NB.decodeUInt32(fanoutTable, k * 4);
  68                 idxdata = new byte[idxHeader.length][];
  69                 for (int k = 0; k < idxHeader.length; k++) {
  70                         int n;
  71                         if (k == 0) {
  72                                 n = (int) (idxHeader[k]);
  73                         } else {
  74                                 n = (int) (idxHeader[k] - idxHeader[k - 1]);
  75                         }
  76                         if (n > 0) {
  77                                 idxdata[k] = new byte[n * (Constants.OBJECT_ID_LENGTH + 4)];
  78                                 NB.readFully(fd, idxdata[k], 0, idxdata[k].length);
  79                         }
  80                 }
  81                 objectCnt = idxHeader[255];
  82         }
  83
  84         long getObjectCount() {
  85                 return objectCnt;
  86         }
  87
  88         @Override
  89         long getOffset64Count() {
  90                 long n64 = 0;
  91                 for (final MutableEntry e : this) {
  92                         if (e.getOffset() >= Integer.MAX_VALUE)
  93                                 n64++;
  94                 }
  95                 return n64;
  96         }
  97
  98         @Override
  99         ObjectId getObjectId(final long nthPosition) {
 100                 int levelOne = Arrays.binarySearch(idxHeader, nthPosition + 1);
 101                 long base;
 102                 if (levelOne >= 0) {
 103                         // If we hit the bucket exactly the item is in the bucket, or
 104                         // any bucket before it which has the same object count.
 105                         //
 106                         base = idxHeader[levelOne];
 107                         while (levelOne > 0 && base == idxHeader[levelOne - 1])
 108                                 levelOne--;
 109                 } else {
 110                         // The item is in the bucket we would insert it into.
 111                         //
 112                         levelOne = -(levelOne + 1);
 113                 }
 114
 115                 base = levelOne > 0 ? idxHeader[levelOne - 1] : 0;
 116                 final int p = (int) (nthPosition - base);
 117                 final int dataIdx = ((4 + Constants.OBJECT_ID_LENGTH) * p) + 4;
 118                 return ObjectId.fromRaw(idxdata[levelOne], dataIdx);
 119         }
 120
 121         long findOffset(final AnyObjectId objId) {
 122                 final int levelOne = objId.getFirstByte();
 123                 byte[] data = idxdata[levelOne];
 124                 if (data == null)
 125                         return -1;
 126                 int high = data.length / (4 + Constants.OBJECT_ID_LENGTH);
 127                 int low = 0;
 128                 do {
 129                         final int mid = (low + high) / 2;
 130                         final int pos = ((4 + Constants.OBJECT_ID_LENGTH) * mid) + 4;
 131                         final int cmp = objId.compareTo(data, pos);
 132                         if (cmp < 0)
 133                                 high = mid;
 134                         else if (cmp == 0) {
 135                                 int b0 = data[pos - 4] & 0xff;
 136                                 int b1 = data[pos - 3] & 0xff;
 137                                 int b2 = data[pos - 2] & 0xff;
 138                                 int b3 = data[pos - 1] & 0xff;
 139                                 return (((long) b0) << 24) | (b1 << 16) | (b2 << 8) | (b3);
 140                         } else
 141                                 low = mid + 1;
 142                 } while (low < high);
 143                 return -1;
 144         }
 145
 146         public Iterator<MutableEntry> iterator() {
 147                 return new IndexV1Iterator();
 148         }
 149
 150         private class IndexV1Iterator extends EntriesIterator {
 151                 private int levelOne;
 152
 153                 private int levelTwo;
 154
 155                 public MutableEntry next() {
 156                         for (; levelOne < idxdata.length; levelOne++) {
 157                                 if (idxdata[levelOne] == null)
 158                                         continue;
 159
 160                                 if (levelTwo < idxdata[levelOne].length) {
 161                                         long offset = NB.decodeUInt32(idxdata[levelOne], levelTwo);
 162                                         objectId.setOffset(offset);
 163                                         objectId.fromRaw(idxdata[levelOne], levelTwo + 4);
 164                                         levelTwo += Constants.OBJECT_ID_LENGTH + 4;
 165                                         returnedNumber++;
 166                                         return objectId;
 167                                 } else {
 168                                         levelTwo = 0;
 169                                 }
 170                         }
 171                         throw new NoSuchElementException();
 172                 }
 173         }
 174 }