org.spearce.jgit/src/org/spearce/jgit/lib/DeltaPackedObjectLoader.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.util.zip.DataFormatException;
  43
  44 import org.spearce.jgit.errors.CorruptObjectException;
  45
  46 /** Reader for a deltified object stored in a pack file. */
  47 abstract class DeltaPackedObjectLoader extends PackedObjectLoader {
  48         private static final int OBJ_COMMIT = Constants.OBJ_COMMIT;
  49
  50         private final int deltaSize;
  51
  52         DeltaPackedObjectLoader(final WindowCursor curs, final PackFile pr,
  53                         final long offset, final int deltaSz) {
  54                 super(curs, pr, offset);
  55                 objectType = -1;
  56                 deltaSize = deltaSz;
  57         }
  58
  59         public int getType() throws IOException {
  60                 if (objectType < 0)
  61                         getCachedBytes();
  62                 return objectType;
  63         }
  64
  65         public long getSize() throws IOException {
  66                 if (objectType < 0)
  67                         getCachedBytes();
  68                 return objectSize;
  69         }
  70
  71         @Override
  72         public byte[] getCachedBytes() throws IOException {
  73                 if (objectType != OBJ_COMMIT) {
  74                         final UnpackedObjectCache.Entry cache = pack.readCache(dataOffset);
  75                         if (cache != null) {
  76                                 curs.release();
  77                                 objectType = cache.type;
  78                                 objectSize = cache.data.length;
  79                                 return cache.data;
  80                         }
  81                 }
  82
  83                 try {
  84                         final PackedObjectLoader baseLoader = getBaseLoader();
  85                         final byte[] data = BinaryDelta.apply(baseLoader.getCachedBytes(),
  86                                         pack.decompress(dataOffset, deltaSize, curs));
  87                         curs.release();
  88                         objectType = baseLoader.getType();
  89                         objectSize = data.length;
  90                         if (objectType != OBJ_COMMIT)
  91                                 pack.saveCache(dataOffset, data, objectType);
  92                         return data;
  93                 } catch (DataFormatException dfe) {
  94                         final CorruptObjectException coe;
  95                         coe = new CorruptObjectException(getId(), "bad stream");
  96                         coe.initCause(dfe);
  97                         throw coe;
  98                 }
  99         }
 100
 101         /**
 102          * @return the object loader for the base object
 103          * @throws IOException
 104          */
 105         protected abstract PackedObjectLoader getBaseLoader() throws IOException;
 106 }