HADOOP-4012. Provide splitting support for bzip2 compressed files. Contributed by Abdul Qadeer

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@813581 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -187,6 +187,9 @@ Trunk (unreleased changes)
     HADOOP-5073. Add annotation mechanism for interface classification.
     (Jakob Homan via suresh)
 
+    HADOOP-4012. Provide splitting support for bzip2 compressed files. (Abdul
+    Qadeer via cdouglas)
+
   IMPROVEMENTS
 
     HADOOP-4565. Added CombineFileInputFormat to use data locality information

src/java/org/apache/hadoop/fs/FSInputChecker.java

@@ -296,12 +296,12 @@ abstract public class FSInputChecker extends FSInputStream {
   
   @Override
   public synchronized long getPos() throws IOException {
-    return chunkPos-(count-pos);
+    return chunkPos-Math.max(0L, count - pos);
   }
 
   @Override
   public synchronized int available() throws IOException {
-    return count-pos;
+    return Math.max(0, count - pos);
   }
   
   /**

src/java/org/apache/hadoop/io/compress/BZip2Codec.java

@@ -23,6 +23,9 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 
+
+import org.apache.hadoop.fs.Seekable;
+import org.apache.hadoop.io.compress.bzip2.BZip2Constants;
 import org.apache.hadoop.io.compress.bzip2.BZip2DummyCompressor;
 import org.apache.hadoop.io.compress.bzip2.BZip2DummyDecompressor;
 import org.apache.hadoop.io.compress.bzip2.CBZip2InputStream;
@@ -35,17 +38,17 @@ import org.apache.hadoop.io.compress.bzip2.CBZip2OutputStream;
  * CompressionCodec which have a Compressor or Decompressor type argument, throw
  * UnsupportedOperationException.
  */
-public class BZip2Codec implements
-    org.apache.hadoop.io.compress.CompressionCodec {
+public class BZip2Codec implements SplittableCompressionCodec {
 
   private static final String HEADER = "BZ";
   private static final int HEADER_LEN = HEADER.length();
+  private static final String SUB_HEADER = "h9";
+  private static final int SUB_HEADER_LEN = SUB_HEADER.length();
 
   /**
   * Creates a new instance of BZip2Codec
   */
-  public BZip2Codec() {
-  }
+  public BZip2Codec() { }
 
   /**
   * Creates CompressionOutputStream for BZip2
@@ -62,10 +65,10 @@ public class BZip2Codec implements
   }
 
   /**
-   * This functionality is currently not supported.
+  * Creates a compressor using given OutputStream.
    *
-   * @throws java.lang.UnsupportedOperationException
-   *             Throws UnsupportedOperationException
+  * @return CompressionOutputStream
+    @throws java.io.IOException
    */
   public CompressionOutputStream createOutputStream(OutputStream out,
       Compressor compressor) throws IOException {
@@ -75,8 +78,7 @@ public class BZip2Codec implements
   /**
   * This functionality is currently not supported.
   *
-  * @throws java.lang.UnsupportedOperationException
-  *             Throws UnsupportedOperationException
+  * @return BZip2DummyCompressor.class
   */
   public Class<? extends org.apache.hadoop.io.compress.Compressor> getCompressorType() {
     return BZip2DummyCompressor.class;
@@ -85,8 +87,7 @@ public class BZip2Codec implements
   /**
   * This functionality is currently not supported.
   *
-  * @throws java.lang.UnsupportedOperationException
-  *             Throws UnsupportedOperationException
+  * @return Compressor
   */
   public Compressor createCompressor() {
     return new BZip2DummyCompressor();
@@ -109,19 +110,72 @@ public class BZip2Codec implements
   /**
   * This functionality is currently not supported.
   *
-  * @throws java.lang.UnsupportedOperationException
-  *             Throws UnsupportedOperationException
+  * @return CompressionInputStream
   */
   public CompressionInputStream createInputStream(InputStream in,
       Decompressor decompressor) throws IOException {
     return createInputStream(in);
   }
 
+  /**
+   * Creates CompressionInputStream to be used to read off uncompressed data
+   * in one of the two reading modes. i.e. Continuous or Blocked reading modes
+   *
+   * @param seekableIn The InputStream
+   * @param start The start offset into the compressed stream
+   * @param end The end offset into the compressed stream
+   * @param readMode Controls whether progress is reported continuously or
+   *                 only at block boundaries.
+   *
+   * @return CompressionInputStream for BZip2 aligned at block boundaries
+   */
+  public SplitCompressionInputStream createInputStream(InputStream seekableIn,
+      Decompressor decompressor, long start, long end, READ_MODE readMode)
+      throws IOException {
+
+    if (!(seekableIn instanceof Seekable)) {
+      throw new IOException("seekableIn must be an instance of " +
+          Seekable.class.getName());
+    }
+
+    //find the position of first BZip2 start up marker
+    ((Seekable)seekableIn).seek(0);
+
+    // BZip2 start of block markers are of 6 bytes.  But the very first block
+    // also has "BZh9", making it 10 bytes.  This is the common case.  But at
+    // time stream might start without a leading BZ.
+    final long FIRST_BZIP2_BLOCK_MARKER_POSITION =
+      CBZip2InputStream.numberOfBytesTillNextMarker(seekableIn);
+    long adjStart = Math.max(0L, start - FIRST_BZIP2_BLOCK_MARKER_POSITION);
+
+    ((Seekable)seekableIn).seek(adjStart);
+    SplitCompressionInputStream in =
+      new BZip2CompressionInputStream(seekableIn, adjStart, end, readMode);
+
+
+    // The following if clause handles the following case:
+    // Assume the following scenario in BZip2 compressed stream where
+    // . represent compressed data.
+    // .....[48 bit Block].....[48 bit   Block].....[48 bit Block]...
+    // ........................[47 bits][1 bit].....[48 bit Block]...
+    // ................................^[Assume a Byte alignment here]
+    // ........................................^^[current position of stream]
+    // .....................^^[We go back 10 Bytes in stream and find a Block marker]
+    // ........................................^^[We align at wrong position!]
+    // ...........................................................^^[While this pos is correct]
+
+    if (in.getPos() <= start) {
+      ((Seekable)seekableIn).seek(start);
+      in = new BZip2CompressionInputStream(seekableIn, start, end, readMode);
+    }
+
+    return in;
+  }
+
   /**
   * This functionality is currently not supported.
   *
-  * @throws java.lang.UnsupportedOperationException
-  *             Throws UnsupportedOperationException
+  * @return BZip2DummyDecompressor.class
   */
   public Class<? extends org.apache.hadoop.io.compress.Decompressor> getDecompressorType() {
     return BZip2DummyDecompressor.class;
@@ -130,8 +184,7 @@ public class BZip2Codec implements
   /**
   * This functionality is currently not supported.
   *
-  * @throws java.lang.UnsupportedOperationException
-  *             Throws UnsupportedOperationException
+  * @return Decompressor
   */
   public Decompressor createDecompressor() {
     return new BZip2DummyDecompressor();
@@ -146,7 +199,8 @@ public class BZip2Codec implements
     return ".bz2";
   }
 
-  private static class BZip2CompressionOutputStream extends CompressionOutputStream {
+  private static class BZip2CompressionOutputStream extends
+      CompressionOutputStream {
 
     // class data starts here//
     private CBZip2OutputStream output;
@@ -221,26 +275,79 @@ public class BZip2Codec implements
 
   }// end of class BZip2CompressionOutputStream
 
-  private static class BZip2CompressionInputStream extends CompressionInputStream {
+  /**
+   * This class is capable to de-compress BZip2 data in two modes;
+   * CONTINOUS and BYBLOCK.  BYBLOCK mode makes it possible to
+   * do decompression starting any arbitrary position in the stream.
+   *
+   * So this facility can easily be used to parallelize decompression
+   * of a large BZip2 file for performance reasons.  (It is exactly
+   * done so for Hadoop framework.  See LineRecordReader for an
+   * example).  So one can break the file (of course logically) into
+   * chunks for parallel processing.  These "splits" should be like
+   * default Hadoop splits (e.g as in FileInputFormat getSplit metod).
+   * So this code is designed and tested for FileInputFormat's way
+   * of splitting only.
+   */
+
+  private static class BZip2CompressionInputStream extends
+      SplitCompressionInputStream {
 
     // class data starts here//
     private CBZip2InputStream input;
     boolean needsReset;
+    private BufferedInputStream bufferedIn;
+    private boolean isHeaderStripped = false;
+    private boolean isSubHeaderStripped = false;
+    private READ_MODE readMode = READ_MODE.CONTINUOUS;
+    private long startingPos = 0L;
+
+    // Following state machine handles different states of compressed stream
+    // position
+    // HOLD : Don't advertise compressed stream position
+    // ADVERTISE : Read 1 more character and advertise stream position
+    // See more comments about it before updatePos method.
+    private enum POS_ADVERTISEMENT_STATE_MACHINE {
+      HOLD, ADVERTISE
+    };
+
+    POS_ADVERTISEMENT_STATE_MACHINE posSM = POS_ADVERTISEMENT_STATE_MACHINE.HOLD;
+    long compressedStreamPosition = 0;
+
     // class data ends here//
 
     public BZip2CompressionInputStream(InputStream in) throws IOException {
+      this(in, 0L, Long.MAX_VALUE, READ_MODE.CONTINUOUS);
+    }
 
-      super(in);
-      needsReset = true;
+    public BZip2CompressionInputStream(InputStream in, long start, long end,
+        READ_MODE readMode) throws IOException {
+      super(in, start, end);
+      needsReset = false;
+      bufferedIn = new BufferedInputStream(super.in);
+      this.startingPos = super.getPos();
+      this.readMode = readMode;
+      if (this.startingPos == 0) {
+        // We only strip header if it is start of file
+        bufferedIn = readStreamHeader();
+      }
+      input = new CBZip2InputStream(bufferedIn, readMode);
+      if (this.isHeaderStripped) {
+        input.updateReportedByteCount(HEADER_LEN);
+      }
+
+      if (this.isSubHeaderStripped) {
+        input.updateReportedByteCount(SUB_HEADER_LEN);
+      }
+
+      this.updatePos(false);
     }
 
     private BufferedInputStream readStreamHeader() throws IOException {
       // We are flexible enough to allow the compressed stream not to
       // start with the header of BZ. So it works fine either we have
       // the header or not.
-      BufferedInputStream bufferedIn = null;
       if (super.in != null) {
-        bufferedIn = new BufferedInputStream(super.in);
         bufferedIn.mark(HEADER_LEN);
         byte[] headerBytes = new byte[HEADER_LEN];
         int actualRead = bufferedIn.read(headerBytes, 0, HEADER_LEN);
@@ -248,6 +355,17 @@ public class BZip2Codec implements
           String header = new String(headerBytes);
           if (header.compareTo(HEADER) != 0) {
             bufferedIn.reset();
+          } else {
+            this.isHeaderStripped = true;
+            // In case of BYBLOCK mode, we also want to strip off
+            // remaining two character of the header.
+            if (this.readMode == READ_MODE.BYBLOCK) {
+              actualRead = bufferedIn.read(headerBytes, 0,
+                  SUB_HEADER_LEN);
+              if (actualRead != -1) {
+                this.isSubHeaderStripped = true;
+              }
+            }
           }
         }
       }
@@ -267,33 +385,96 @@ public class BZip2Codec implements
       }
     }
 
+    /**
+    * This method updates compressed stream position exactly when the
+    * client of this code has read off at least one byte passed any BZip2
+    * end of block marker.
+    *
+    * This mechanism is very helpful to deal with data level record
+    * boundaries. Please see constructor and next methods of
+    * org.apache.hadoop.mapred.LineRecordReader as an example usage of this
+    * feature.  We elaborate it with an example in the following:
+    *
+    * Assume two different scenarios of the BZip2 compressed stream, where
+    * [m] represent end of block, \n is line delimiter and . represent compressed
+    * data.
+    *
+    * ............[m]......\n.......
+    *
+    * ..........\n[m]......\n.......
+    *
+    * Assume that end is right after [m].  In the first case the reading
+    * will stop at \n and there is no need to read one more line.  (To see the
+    * reason of reading one more line in the next() method is explained in LineRecordReader.)
+    * While in the second example LineRecordReader needs to read one more line
+    * (till the second \n).  Now since BZip2Codecs only update position
+    * at least one byte passed a maker, so it is straight forward to differentiate
+    * between the two cases mentioned.
+    *
+    */
+
     public int read(byte[] b, int off, int len) throws IOException {
       if (needsReset) {
         internalReset();
       }
-      return this.input.read(b, off, len);
 
+      int result = 0;
+      result = this.input.read(b, off, len);
+      if (result == BZip2Constants.END_OF_BLOCK) {
+        this.posSM = POS_ADVERTISEMENT_STATE_MACHINE.ADVERTISE;
+      }
+
+      if (this.posSM == POS_ADVERTISEMENT_STATE_MACHINE.ADVERTISE) {
+        result = this.input.read(b, off, off + 1);
+        // This is the precise time to update compressed stream position
+        // to the client of this code.
+        this.updatePos(true);
+        this.posSM = POS_ADVERTISEMENT_STATE_MACHINE.HOLD;
+      }
+
+      return result;
+
+    }
+
+    public int read() throws IOException {
+      byte b[] = new byte[1];
+      int result = this.read(b, 0, 1);
+      return (result < 0) ? result : b[0];
     }
 
     private void internalReset() throws IOException {
       if (needsReset) {
         needsReset = false;
         BufferedInputStream bufferedIn = readStreamHeader();
-        input = new CBZip2InputStream(bufferedIn);
+        input = new CBZip2InputStream(bufferedIn, this.readMode);
       }
     }    
     
     public void resetState() throws IOException {
-      // Cannot read from bufferedIn at this point because bufferedIn might not be ready
+      // Cannot read from bufferedIn at this point because bufferedIn
+      // might not be ready
       // yet, as in SequenceFile.Reader implementation.
       needsReset = true;
     }
 
-    public int read() throws IOException {
-      if (needsReset) {
-        internalReset();
+    public long getPos() {
+      return this.compressedStreamPosition;
       }
-      return this.input.read();
+
+    /*
+     * As the comments before read method tell that
+     * compressed stream is advertised when at least
+     * one byte passed EOB have been read off.  But
+     * there is an exception to this rule.  When we
+     * construct the stream we advertise the position
+     * exactly at EOB.  In the following method
+     * shouldAddOn boolean captures this exception.
+     *
+     */
+    private void updatePos(boolean shouldAddOn) {
+      int addOn = shouldAddOn ? 1 : 0;
+      this.compressedStreamPosition = this.startingPos
+          + this.input.getProcessedByteCount() + addOn;
     }
 
   }// end of BZip2CompressionInputStream

src/java/org/apache/hadoop/io/compress/BlockDecompressorStream.java

@@ -38,9 +38,10 @@ public class BlockDecompressorStream extends DecompressorStream {
    * @param in input stream
    * @param decompressor decompressor to use
    * @param bufferSize size of buffer
+ * @throws IOException
    */
   public BlockDecompressorStream(InputStream in, Decompressor decompressor, 
-                                 int bufferSize) {
+                                 int bufferSize) throws IOException {
     super(in, decompressor, bufferSize);
   }
   
@@ -49,12 +50,13 @@ public class BlockDecompressorStream extends DecompressorStream {
    * 
    * @param in input stream
    * @param decompressor decompressor to use
+ * @throws IOException
    */
-  public BlockDecompressorStream(InputStream in, Decompressor decompressor) {
+  public BlockDecompressorStream(InputStream in, Decompressor decompressor) throws IOException {
     super(in, decompressor);
   }
 
-  protected BlockDecompressorStream(InputStream in) {
+  protected BlockDecompressorStream(InputStream in) throws IOException {
     super(in);
   }
 

src/java/org/apache/hadoop/io/compress/CompressionInputStream.java

@@ -21,6 +21,8 @@ package org.apache.hadoop.io.compress;
 import java.io.IOException;
 import java.io.InputStream;
 
+import org.apache.hadoop.fs.PositionedReadable;
+import org.apache.hadoop.fs.Seekable;
 /**
  * A compression input stream.
  *
@@ -28,19 +30,25 @@ import java.io.InputStream;
  * reposition the underlying input stream then call {@link #resetState()},
  * without having to also synchronize client buffers.
  */
-public abstract class CompressionInputStream extends InputStream {
+
+public abstract class CompressionInputStream extends InputStream implements Seekable {
   /**
    * The input stream to be compressed. 
    */
   protected final InputStream in;
+  protected long maxAvailableData = 0L;
 
   /**
    * Create a compression input stream that reads
    * the decompressed bytes from the given stream.
    * 
    * @param in The input stream to be compressed.
+   * @throws IOException
    */
-  protected CompressionInputStream(InputStream in) {
+  protected CompressionInputStream(InputStream in) throws IOException {
+    if (!(in instanceof Seekable) || !(in instanceof PositionedReadable)) {
+        this.maxAvailableData = in.available();
+    }
     this.in = in;
   }
 
@@ -60,4 +68,40 @@ public abstract class CompressionInputStream extends InputStream {
    */
   public abstract void resetState() throws IOException;
   
+  /**
+   * This method returns the current position in the stream.
+   *
+   * @return Current position in stream as a long
+   */
+  public long getPos() throws IOException {
+    if (!(in instanceof Seekable) || !(in instanceof PositionedReadable)){
+      //This way of getting the current position will not work for file
+      //size which can be fit in an int and hence can not be returned by
+      //available method.
+      return (this.maxAvailableData - this.in.available());
+    }
+    else{
+      return ((Seekable)this.in).getPos();
+    }
+
+  }
+
+  /**
+   * This method is current not supported.
+   *
+   * @throws UnsupportedOperationException
+   */
+
+  public void seek(long pos) throws UnsupportedOperationException {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * This method is current not supported.
+   *
+   * @throws UnsupportedOperationException
+   */
+  public boolean seekToNewSource(long targetPos) throws UnsupportedOperationException {
+    throw new UnsupportedOperationException();
+  }
 }

src/java/org/apache/hadoop/io/compress/DecompressorStream.java

@@ -30,7 +30,7 @@ public class DecompressorStream extends CompressionInputStream {
   protected boolean eof = false;
   protected boolean closed = false;
   
-  public DecompressorStream(InputStream in, Decompressor decompressor, int bufferSize) {
+  public DecompressorStream(InputStream in, Decompressor decompressor, int bufferSize) throws IOException {
     super(in);
 
     if (in == null || decompressor == null) {
@@ -43,7 +43,7 @@ public class DecompressorStream extends CompressionInputStream {
     buffer = new byte[bufferSize];
   }
 
-  public DecompressorStream(InputStream in, Decompressor decompressor) {
+  public DecompressorStream(InputStream in, Decompressor decompressor) throws IOException {
     this(in, decompressor, 512);
   }
 
@@ -51,8 +51,9 @@ public class DecompressorStream extends CompressionInputStream {
    * Allow derived classes to directly set the underlying stream.
    * 
    * @param in Underlying input stream.
+ * @throws IOException
    */
-  protected DecompressorStream(InputStream in) {
+  protected DecompressorStream(InputStream in) throws IOException {
     super(in);
   }
   

src/java/org/apache/hadoop/io/compress/GzipCodec.java

@@ -103,8 +103,9 @@ public class GzipCodec extends DefaultCodec {
     
     /**
      * Allow subclasses to directly set the inflater stream.
+     * @throws IOException
      */
-    protected GzipInputStream(DecompressorStream in) {
+    protected GzipInputStream(DecompressorStream in) throws IOException {
       super(in);
     }
 

src/java/org/apache/hadoop/io/compress/SplitCompressionInputStream.java

@@ -0,0 +1,66 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.io.compress;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * An InputStream covering a range of compressed data. The start and end
+ * offsets requested by a client may be modified by the codec to fit block
+ * boundaries or other algorithm-dependent requirements.
+ */
+public abstract class SplitCompressionInputStream
+    extends CompressionInputStream {
+
+  private long start;
+  private long end;
+
+  public SplitCompressionInputStream(InputStream in, long start, long end)
+      throws IOException {
+    super(in);
+    this.start = start;
+    this.end = end;
+  }
+
+  protected void setStart(long start) {
+    this.start = start;
+  }
+
+  protected void setEnd(long end) {
+    this.end = end;
+  }
+
+  /**
+   * After calling createInputStream, the values of start or end
+   * might change.  So this method can be used to get the new value of start.
+   * @return The changed value of start
+   */
+  public long getAdjustedStart() {
+    return start;
+  }
+
+  /**
+   * After calling createInputStream, the values of start or end
+   * might change.  So this method can be used to get the new value of end.
+   * @return The changed value of end
+   */
+  public long getAdjustedEnd() {
+    return end;
+  }
+}

src/java/org/apache/hadoop/io/compress/SplittableCompressionCodec.java

@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.io.compress;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+
+/**
+ * This interface is meant to be implemented by those compression codecs
+ * which are capable to compress / de-compress a stream starting at any
+ * arbitrary position.
+ *
+ * Especially the process of de-compressing a stream starting at some arbitrary
+ * position is challenging.  Most of the codecs are only able to successfully
+ * de-compress a stream, if they start from the very beginning till the end.
+ * One of the reasons is the stored state at the beginning of the stream which
+ * is crucial for de-compression.
+ *
+ * Yet there are few codecs which do not save the whole state at the beginning
+ * of the stream and hence can be used to de-compress stream starting at any
+ * arbitrary points.  This interface is meant to be used by such codecs.  Such
+ * codecs are highly valuable, especially in the context of Hadoop, because
+ * an input compressed file can be split and hence can be worked on by multiple
+ * machines in parallel.
+ */
+public interface SplittableCompressionCodec extends CompressionCodec {
+
+  /**
+   * During decompression, data can be read off from the decompressor in two
+   * modes, namely continuous and blocked.  Few codecs (e.g. BZip2) are capable
+   * of compressing data in blocks and then decompressing the blocks.  In
+   * Blocked reading mode codecs inform 'end of block' events to its caller.
+   * While in continuous mode, the caller of codecs is unaware about the blocks
+   * and uncompressed data is spilled out like a continuous stream.
+   */
+  public enum READ_MODE {CONTINUOUS, BYBLOCK};
+
+  /**
+   * Create a stream as dictated by the readMode.  This method is used when
+   * the codecs wants the ability to work with the underlying stream positions.
+   *
+   * @param seekableIn  The seekable input stream (seeks in compressed data)
+   * @param start The start offset into the compressed stream. May be changed
+   *              by the underlying codec.
+   * @param end The end offset into the compressed stream. May be changed by
+   *            the underlying codec.
+   * @param readMode Controls whether stream position is reported continuously
+   *                 from the compressed stream only only at block boundaries.
+   * @return  a stream to read uncompressed bytes from
+   */
+  SplitCompressionInputStream createInputStream(InputStream seekableIn,
+      Decompressor decompressor, long start, long end, READ_MODE readMode)
+      throws IOException;
+
+}

src/java/org/apache/hadoop/io/compress/bzip2/BZip2Constants.java

@@ -44,6 +44,14 @@ public interface BZip2Constants {
   int N_ITERS = 4;
   int MAX_SELECTORS = (2 + (900000 / G_SIZE));
   int NUM_OVERSHOOT_BYTES = 20;
+  /**
+   * End of a BZip2 block
+   */
+  public static final int END_OF_BLOCK = -2;
+  /**
+   * End of BZip2 stream.
+   */
+  public static final int END_OF_STREAM = -1;
 
   /**
   * This array really shouldn't be here. Again, for historical purposes it

src/java/org/apache/hadoop/io/compress/bzip2/CBZip2InputStream.java

@@ -23,9 +23,13 @@
  */
 package org.apache.hadoop.io.compress.bzip2;
 
+import java.io.BufferedInputStream;
 import java.io.InputStream;
 import java.io.IOException;
 
+import org.apache.hadoop.io.compress.SplittableCompressionCodec.READ_MODE;
+
+
 /**
  * An input stream that decompresses from the BZip2 format (without the file
  * header chars) to be read as any other stream.
@@ -45,30 +49,43 @@ import java.io.IOException;
  * </p>
  *
  * <p>
+ * This Ant code was enhanced so that it can de-compress blocks of bzip2 data.
+ * Current position in the stream is an important statistic for Hadoop. For
+ * example in LineRecordReader, we solely depend on the current position in the
+ * stream to know about the progess. The notion of position becomes complicated
+ * for compressed files. The Hadoop splitting is done in terms of compressed
+ * file. But a compressed file deflates to a large amount of data. So we have
+ * handled this problem in the following way.
+ *
+ * On object creation time, we find the next block start delimiter. Once such a
+ * marker is found, the stream stops there (we discard any read compressed data
+ * in this process) and the position is updated (i.e. the caller of this class
+ * will find out the stream location). At this point we are ready for actual
+ * reading (i.e. decompression) of data.
+ *
+ * The subsequent read calls give out data. The position is updated when the
+ * caller of this class has read off the current block + 1 bytes. In between the
+ * block reading, position is not updated. (We can only update the postion on
+ * block boundaries).
+ * </p>
+ *
+ * <p>
  * Instances of this class are not threadsafe.
  * </p>
  */
 public class CBZip2InputStream extends InputStream implements BZip2Constants {
 
-  private static void reportCRCError() throws IOException {
-
-    throw new IOException("BZip2 CRC error");
-
-  }
-
-  private void makeMaps() {
-    final boolean[] inUse = this.data.inUse;
-    final byte[] seqToUnseq = this.data.seqToUnseq;
-
-    int nInUseShadow = 0;
-
-    for (int i = 0; i < 256; i++) {
-      if (inUse[i])
-        seqToUnseq[nInUseShadow++] = (byte) i;
-    }
 
-    this.nInUse = nInUseShadow;
-  }
+  public static final long BLOCK_DELIMITER = 0X314159265359L;// start of block
+  public static final long EOS_DELIMITER = 0X177245385090L;// end of bzip2 stream
+  private static final int DELIMITER_BIT_LENGTH = 48;
+  READ_MODE readMode = READ_MODE.CONTINUOUS;
+  // The variable records the current advertised position of the stream.
+  private long reportedBytesReadFromCompressedStream = 0L;
+  // The following variable keep record of compressed bytes read.
+  private long bytesReadFromCompressedStream = 0L;
+  private boolean lazyInitialization = false;
+  private byte array[] = new byte[1];
 
   /**
   * Index of the last char in the block, so the block size == last + 1.
@@ -86,32 +103,34 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
   */
   private int blockSize100k;
 
-  private boolean blockRandomised;
+  private boolean blockRandomised = false;
 
-  private int bsBuff;
-  private int bsLive;
+  private long bsBuff;
+  private long bsLive;
   private final CRC crc = new CRC();
 
   private int nInUse;
 
-  private InputStream in;
+  private BufferedInputStream in;
 
   private int currentChar = -1;
 
-  private static final int EOF = 0;
-  private static final int START_BLOCK_STATE = 1;
-  private static final int RAND_PART_A_STATE = 2;
-  private static final int RAND_PART_B_STATE = 3;
-  private static final int RAND_PART_C_STATE = 4;
-  private static final int NO_RAND_PART_A_STATE = 5;
-  private static final int NO_RAND_PART_B_STATE = 6;
-  private static final int NO_RAND_PART_C_STATE = 7;
+  /**
+   * A state machine to keep track of current state of the de-coder
+   *
+   */
+  public enum STATE {
+    EOF, START_BLOCK_STATE, RAND_PART_A_STATE, RAND_PART_B_STATE, RAND_PART_C_STATE, NO_RAND_PART_A_STATE, NO_RAND_PART_B_STATE, NO_RAND_PART_C_STATE, NO_PROCESS_STATE
+  };
 
-  private int currentState = START_BLOCK_STATE;
+  private STATE currentState = STATE.START_BLOCK_STATE;
 
   private int storedBlockCRC, storedCombinedCRC;
   private int computedBlockCRC, computedCombinedCRC;
 
+  private boolean skipResult = false;// used by skipToNextMarker
+  private static boolean skipDecompression = false;
+
   // Variables used by setup* methods exclusively
 
   private int su_count;
@@ -129,6 +148,121 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
   */
   private CBZip2InputStream.Data data;
 
+  /**
+  * This method reports the processed bytes so far. Please note that this
+  * statistic is only updated on block boundaries and only when the stream is
+  * initiated in BYBLOCK mode.
+  */
+  public long getProcessedByteCount() {
+    return reportedBytesReadFromCompressedStream;
+  }
+
+  /**
+   * This method keeps track of raw processed compressed
+   * bytes.
+   *
+   * @param count count is the number of bytes to be
+   *           added to raw processed bytes
+   */
+
+  protected void updateProcessedByteCount(int count) {
+    this.bytesReadFromCompressedStream += count;
+  }
+
+  /**
+   * This method is called by the client of this
+   * class in case there are any corrections in
+   * the stream position.  One common example is
+   * when client of this code removes starting BZ
+   * characters from the compressed stream.
+   *
+   * @param count count bytes are added to the reported bytes
+   *
+   */
+  public void updateReportedByteCount(int count) {
+    this.reportedBytesReadFromCompressedStream += count;
+    this.updateProcessedByteCount(count);
+  }
+
+  /**
+  * This method reads a Byte from the compressed stream. Whenever we need to
+  * read from the underlying compressed stream, this method should be called
+  * instead of directly calling the read method of the underlying compressed
+  * stream. This method does important record keeping to have the statistic
+  * that how many bytes have been read off the compressed stream.
+  */
+  private int readAByte(InputStream inStream) throws IOException {
+    int read = inStream.read();
+    if (read >= 0) {
+      this.updateProcessedByteCount(1);
+    }
+    return read;
+  }
+
+  /**
+  * This method tries to find the marker (passed to it as the first parameter)
+  * in the stream.  It can find bit patterns of length <= 63 bits.  Specifically
+  * this method is used in CBZip2InputStream to find the end of block (EOB)
+  * delimiter in the stream, starting from the current position of the stream.
+  * If marker is found, the stream position will be right after marker at the
+  * end of this call.
+  *
+  * @param marker  The bit pattern to be found in the stream
+  * @param markerBitLength  No of bits in the marker
+  *
+  * @throws IOException
+  * @throws IllegalArgumentException  if marketBitLength is greater than 63
+  */
+  public boolean skipToNextMarker(long marker, int markerBitLength)
+      throws IOException, IllegalArgumentException {
+    try {
+      if (markerBitLength > 63) {
+        throw new IllegalArgumentException(
+            "skipToNextMarker can not find patterns greater than 63 bits");
+      }
+      // pick next marketBitLength bits in the stream
+      long bytes = 0;
+      bytes = this.bsR(markerBitLength);
+      if (bytes == -1) {
+        return false;
+      }
+      while (true) {
+        if (bytes == marker) {
+          return true;
+
+        } else {
+          bytes = bytes << 1;
+          bytes = bytes & ((1L << markerBitLength) - 1);
+          int oneBit = (int) this.bsR(1);
+          if (oneBit != -1) {
+            bytes = bytes | oneBit;
+          } else
+            return false;
+        }
+      }
+    } catch (IOException ex) {
+      return false;
+    }
+  }
+
+  protected void reportCRCError() throws IOException {
+    throw new IOException("crc error");
+  }
+
+  private void makeMaps() {
+    final boolean[] inUse = this.data.inUse;
+    final byte[] seqToUnseq = this.data.seqToUnseq;
+
+    int nInUseShadow = 0;
+
+    for (int i = 0; i < 256; i++) {
+      if (inUse[i])
+        seqToUnseq[nInUseShadow++] = (byte) i;
+    }
+
+    this.nInUse = nInUseShadow;
+  }
+
   /**
   * Constructs a new CBZip2InputStream which decompresses bytes read from the
   * specified stream.
@@ -145,21 +279,99 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
   * @throws NullPointerException
   *             if <tt>in == null</tt>
   */
-  public CBZip2InputStream(final InputStream in) throws IOException {
-    super();
+  public CBZip2InputStream(final InputStream in, READ_MODE readMode)
+      throws IOException {
 
-    this.in = in;
+    super();
+    int blockSize = 0X39;// i.e 9
+    this.blockSize100k = blockSize - '0';
+    this.in = new BufferedInputStream(in, 1024 * 9);// >1 MB buffer
+    this.readMode = readMode;
+    if (readMode == READ_MODE.CONTINUOUS) {
+      currentState = STATE.START_BLOCK_STATE;
+      lazyInitialization = (in.available() == 0)?true:false;
+      if(!lazyInitialization){
     init();
   }
+    } else if (readMode == READ_MODE.BYBLOCK) {
+      this.currentState = STATE.NO_PROCESS_STATE;
+      skipResult = this.skipToNextMarker(CBZip2InputStream.BLOCK_DELIMITER,DELIMITER_BIT_LENGTH);
+      this.reportedBytesReadFromCompressedStream = this.bytesReadFromCompressedStream;
+      if(!skipDecompression){
+        changeStateToProcessABlock();
+      }
+    }
+  }
+
+  /**
+   * Returns the number of bytes between the current stream position
+   * and the immediate next BZip2 block marker.
+   *
+   * @param in
+   *             The InputStream
+   *
+   * @return long Number of bytes between current stream position and the
+   * next BZip2 block start marker.
+ * @throws IOException
+   *
+   */
+  public static long numberOfBytesTillNextMarker(final InputStream in) throws IOException{
+    CBZip2InputStream.skipDecompression = true;
+    CBZip2InputStream anObject = null;
+
+    anObject = new CBZip2InputStream(in, READ_MODE.BYBLOCK);
+
+    return anObject.getProcessedByteCount();
+  }
+
+  public CBZip2InputStream(final InputStream in) throws IOException {
+    this(in, READ_MODE.CONTINUOUS);
+  }
+
+  private void changeStateToProcessABlock() throws IOException {
+    if (skipResult == true) {
+      initBlock();
+      setupBlock();
+    } else {
+      this.currentState = STATE.EOF;
+    }
+  }
+
 
   public int read() throws IOException {
+
     if (this.in != null) {
-      return read0();
+      int result = this.read(array, 0, 1);
+      int value = 0XFF & array[0];
+      return (result > 0 ? value : result);
+
     } else {
       throw new IOException("stream closed");
     }
   }
 
+  /**
+   * In CONTINOUS reading mode, this read method starts from the
+   * start of the compressed stream and end at the end of file by
+   * emitting un-compressed data.  In this mode stream positioning
+   * is not announced and should be ignored.
+   *
+   * In BYBLOCK reading mode, this read method informs about the end
+   * of a BZip2 block by returning EOB.  At this event, the compressed
+   * stream position is also announced.  This announcement tells that
+   * how much of the compressed stream has been de-compressed and read
+   * out of this class.  In between EOB events, the stream position is
+   * not updated.
+   *
+   *
+   * @throws IOException
+   *             if the stream content is malformed or an I/O error occurs.
+   *
+   * @return int The return value greater than 0 are the bytes read.  A value
+   * of -1 means end of stream while -2 represents end of block
+   */
+
+
   public int read(final byte[] dest, final int offs, final int len)
       throws IOException {
     if (offs < 0) {
@@ -176,13 +388,39 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
       throw new IOException("stream closed");
     }
 
+    if(lazyInitialization){
+      this.init();
+      this.lazyInitialization = false;
+    }
+
+    if(skipDecompression){
+      changeStateToProcessABlock();
+      CBZip2InputStream.skipDecompression = false;
+    }
+
     final int hi = offs + len;
     int destOffs = offs;
-    for (int b; (destOffs < hi) && ((b = read0()) >= 0);) {
+    int b = 0;
+
+
+
+    for (; ((destOffs < hi) && ((b = read0())) >= 0);) {
       dest[destOffs++] = (byte) b;
+
     }
 
-    return (destOffs == offs) ? -1 : (destOffs - offs);
+    int result = destOffs - offs;
+    if (result == 0) {
+      //report 'end of block' or 'end of stream'
+      result = b;
+
+      skipResult = this.skipToNextMarker(CBZip2InputStream.BLOCK_DELIMITER, DELIMITER_BIT_LENGTH);
+      //Exactly when we are about to start a new block, we advertise the stream position.
+      this.reportedBytesReadFromCompressedStream = this.bytesReadFromCompressedStream;
+
+      changeStateToProcessABlock();
+    }
+    return result;
   }
 
   private int read0() throws IOException {
@@ -190,7 +428,10 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
 
     switch (this.currentState) {
     case EOF:
-      return -1;
+      return END_OF_STREAM;// return -1
+
+    case NO_PROCESS_STATE:
+      return END_OF_BLOCK;// return -2
 
     case START_BLOCK_STATE:
       throw new IllegalStateException();
@@ -225,13 +466,13 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
   }
 
   private void init() throws IOException {
-    int magic2 = this.in.read();
+    int magic2 = this.readAByte(in);
     if (magic2 != 'h') {
       throw new IOException("Stream is not BZip2 formatted: expected 'h'"
           + " as first byte but got '" + (char) magic2 + "'");
     }
 
-    int blockSize = this.in.read();
+    int blockSize = this.readAByte(in);
     if ((blockSize < '1') || (blockSize > '9')) {
       throw new IOException("Stream is not BZip2 formatted: illegal "
           + "blocksize " + (char) blockSize);
@@ -244,6 +485,27 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
   }
 
   private void initBlock() throws IOException {
+    if (this.readMode == READ_MODE.BYBLOCK) {
+      // this.checkBlockIntegrity();
+      this.storedBlockCRC = bsGetInt();
+      this.blockRandomised = bsR(1) == 1;
+
+      /**
+      * Allocate data here instead in constructor, so we do not allocate
+      * it if the input file is empty.
+      */
+      if (this.data == null) {
+        this.data = new Data(this.blockSize100k);
+      }
+
+      // currBlockNo++;
+      getAndMoveToFrontDecode();
+
+      this.crc.initialiseCRC();
+      this.currentState = STATE.START_BLOCK_STATE;
+      return;
+    }
+
     char magic0 = bsGetUByte();
     char magic1 = bsGetUByte();
     char magic2 = bsGetUByte();
@@ -261,7 +523,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
         magic4 != 0x53 || // 'S'
         magic5 != 0x59 // 'Y'
     ) {
-      this.currentState = EOF;
+      this.currentState = STATE.EOF;
       throw new IOException("bad block header");
     } else {
       this.storedBlockCRC = bsGetInt();
@@ -279,7 +541,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
       getAndMoveToFrontDecode();
 
       this.crc.initialiseCRC();
-      this.currentState = START_BLOCK_STATE;
+      this.currentState = STATE.START_BLOCK_STATE;
     }
   }
 
@@ -304,7 +566,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
 
   private void complete() throws IOException {
     this.storedCombinedCRC = bsGetInt();
-    this.currentState = EOF;
+    this.currentState = STATE.EOF;
     this.data = null;
 
     if (this.storedCombinedCRC != this.computedCombinedCRC) {
@@ -326,14 +588,14 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
     }
   }
 
-  private int bsR(final int n) throws IOException {
-    int bsLiveShadow = this.bsLive;
-    int bsBuffShadow = this.bsBuff;
+  private long bsR(final long n) throws IOException {
+    long bsLiveShadow = this.bsLive;
+    long bsBuffShadow = this.bsBuff;
 
     if (bsLiveShadow < n) {
       final InputStream inShadow = this.in;
       do {
-        int thech = inShadow.read();
+        int thech = readAByte(inShadow);
 
         if (thech < 0) {
           throw new IOException("unexpected end of stream");
@@ -347,15 +609,15 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
     }
 
     this.bsLive = bsLiveShadow - n;
-    return (bsBuffShadow >> (bsLiveShadow - n)) & ((1 << n) - 1);
+    return (bsBuffShadow >> (bsLiveShadow - n)) & ((1L << n) - 1);
   }
 
   private boolean bsGetBit() throws IOException {
-    int bsLiveShadow = this.bsLive;
-    int bsBuffShadow = this.bsBuff;
+    long bsLiveShadow = this.bsLive;
+    long bsBuffShadow = this.bsBuff;
 
     if (bsLiveShadow < 1) {
-      int thech = this.in.read();
+      int thech = this.readAByte(in);
 
       if (thech < 0) {
         throw new IOException("unexpected end of stream");
@@ -375,7 +637,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
   }
 
   private int bsGetInt() throws IOException {
-    return (((((bsR(8) << 8) | bsR(8)) << 8) | bsR(8)) << 8) | bsR(8);
+    return (int) ((((((bsR(8) << 8) | bsR(8)) << 8) | bsR(8)) << 8) | bsR(8));
   }
 
   /**
@@ -454,8 +716,8 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
     final int alphaSize = this.nInUse + 2;
 
     /* Now the selectors */
-    final int nGroups = bsR(3);
-    final int nSelectors = bsR(15);
+    final int nGroups = (int) bsR(3);
+    final int nSelectors = (int) bsR(15);
 
     for (int i = 0; i < nSelectors; i++) {
       int j = 0;
@@ -486,7 +748,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
 
     /* Now the coding tables */
     for (int t = 0; t < nGroups; t++) {
-      int curr = bsR(5);
+      int curr = (int) bsR(5);
       final char[] len_t = len[t];
       for (int i = 0; i < alphaSize; i++) {
         while (bsGetBit()) {
@@ -532,7 +794,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
   }
 
   private void getAndMoveToFrontDecode() throws IOException {
-    this.origPtr = bsR(24);
+    this.origPtr = (int) bsR(24);
     recvDecodingTables();
 
     final InputStream inShadow = this.in;
@@ -562,8 +824,8 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
     int groupPos = G_SIZE - 1;
     final int eob = this.nInUse + 1;
     int nextSym = getAndMoveToFrontDecode0(0);
-    int bsBuffShadow = this.bsBuff;
-    int bsLiveShadow = this.bsLive;
+    int bsBuffShadow = (int) this.bsBuff;
+    int bsLiveShadow = (int) this.bsLive;
     int lastShadow = -1;
     int zt = selector[groupNo] & 0xff;
     int[] base_zt = base[zt];
@@ -597,10 +859,8 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
 
           int zn = minLens_zt;
 
-          // Inlined:
-          // int zvec = bsR(zn);
           while (bsLiveShadow < zn) {
-            final int thech = inShadow.read();
+            final int thech = readAByte(inShadow);
             if (thech >= 0) {
               bsBuffShadow = (bsBuffShadow << 8) | thech;
               bsLiveShadow += 8;
@@ -609,14 +869,14 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
               throw new IOException("unexpected end of stream");
             }
           }
-          int zvec = (bsBuffShadow >> (bsLiveShadow - zn))
+          long zvec = (bsBuffShadow >> (bsLiveShadow - zn))
               & ((1 << zn) - 1);
           bsLiveShadow -= zn;
 
           while (zvec > limit_zt[zn]) {
             zn++;
             while (bsLiveShadow < 1) {
-              final int thech = inShadow.read();
+              final int thech = readAByte(inShadow);
               if (thech >= 0) {
                 bsBuffShadow = (bsBuffShadow << 8) | thech;
                 bsLiveShadow += 8;
@@ -630,7 +890,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
             zvec = (zvec << 1)
                 | ((bsBuffShadow >> bsLiveShadow) & 1);
           }
-          nextSym = perm_zt[zvec - base_zt[zn]];
+          nextSym = perm_zt[(int) (zvec - base_zt[zn])];
         }
 
         final byte ch = seqToUnseq[yy[0]];
@@ -680,10 +940,8 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
 
         int zn = minLens_zt;
 
-        // Inlined:
-        // int zvec = bsR(zn);
         while (bsLiveShadow < zn) {
-          final int thech = inShadow.read();
+          final int thech = readAByte(inShadow);
           if (thech >= 0) {
             bsBuffShadow = (bsBuffShadow << 8) | thech;
             bsLiveShadow += 8;
@@ -699,7 +957,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
         while (zvec > limit_zt[zn]) {
           zn++;
           while (bsLiveShadow < 1) {
-            final int thech = inShadow.read();
+            final int thech = readAByte(inShadow);
             if (thech >= 0) {
               bsBuffShadow = (bsBuffShadow << 8) | thech;
               bsLiveShadow += 8;
@@ -709,7 +967,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
             }
           }
           bsLiveShadow--;
-          zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
+          zvec = ((zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1));
         }
         nextSym = perm_zt[zvec - base_zt[zn]];
       }
@@ -726,14 +984,14 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
     final int zt = dataShadow.selector[groupNo] & 0xff;
     final int[] limit_zt = dataShadow.limit[zt];
     int zn = dataShadow.minLens[zt];
-    int zvec = bsR(zn);
-    int bsLiveShadow = this.bsLive;
-    int bsBuffShadow = this.bsBuff;
+    int zvec = (int) bsR(zn);
+    int bsLiveShadow = (int) this.bsLive;
+    int bsBuffShadow = (int) this.bsBuff;
 
     while (zvec > limit_zt[zn]) {
       zn++;
       while (bsLiveShadow < 1) {
-        final int thech = inShadow.read();
+        final int thech = readAByte(inShadow);
 
         if (thech >= 0) {
           bsBuffShadow = (bsBuffShadow << 8) | thech;
@@ -807,12 +1065,16 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
       this.su_ch2 = su_ch2Shadow ^= (this.su_rNToGo == 1) ? 1 : 0;
       this.su_i2++;
       this.currentChar = su_ch2Shadow;
-      this.currentState = RAND_PART_B_STATE;
+      this.currentState = STATE.RAND_PART_B_STATE;
       this.crc.updateCRC(su_ch2Shadow);
     } else {
       endBlock();
+      if (readMode == READ_MODE.CONTINUOUS) {
       initBlock();
       setupBlock();
+      } else if (readMode == READ_MODE.BYBLOCK) {
+        this.currentState = STATE.NO_PROCESS_STATE;
+      }
     }
   }
 
@@ -824,19 +1086,23 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
       this.su_tPos = this.data.tt[this.su_tPos];
       this.su_i2++;
       this.currentChar = su_ch2Shadow;
-      this.currentState = NO_RAND_PART_B_STATE;
+      this.currentState = STATE.NO_RAND_PART_B_STATE;
       this.crc.updateCRC(su_ch2Shadow);
     } else {
-      this.currentState = NO_RAND_PART_A_STATE;
+      this.currentState = STATE.NO_RAND_PART_A_STATE;
       endBlock();
+      if (readMode == READ_MODE.CONTINUOUS) {
       initBlock();
       setupBlock();
+      } else if (readMode == READ_MODE.BYBLOCK) {
+        this.currentState = STATE.NO_PROCESS_STATE;
+      }
     }
   }
 
   private void setupRandPartB() throws IOException {
     if (this.su_ch2 != this.su_chPrev) {
-      this.currentState = RAND_PART_A_STATE;
+      this.currentState = STATE.RAND_PART_A_STATE;
       this.su_count = 1;
       setupRandPartA();
     } else if (++this.su_count >= 4) {
@@ -851,13 +1117,13 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
         this.su_rNToGo--;
       }
       this.su_j2 = 0;
-      this.currentState = RAND_PART_C_STATE;
+      this.currentState = STATE.RAND_PART_C_STATE;
       if (this.su_rNToGo == 1) {
         this.su_z ^= 1;
       }
       setupRandPartC();
     } else {
-      this.currentState = RAND_PART_A_STATE;
+      this.currentState = STATE.RAND_PART_A_STATE;
       setupRandPartA();
     }
   }
@@ -868,7 +1134,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
       this.crc.updateCRC(this.su_ch2);
       this.su_j2++;
     } else {
-      this.currentState = RAND_PART_A_STATE;
+      this.currentState = STATE.RAND_PART_A_STATE;
       this.su_i2++;
       this.su_count = 0;
       setupRandPartA();
@@ -895,7 +1161,7 @@ public class CBZip2InputStream extends InputStream implements BZip2Constants {
       this.currentChar = su_ch2Shadow;
       this.crc.updateCRC(su_ch2Shadow);
       this.su_j2++;
-      this.currentState = NO_RAND_PART_C_STATE;
+      this.currentState = STATE.NO_RAND_PART_C_STATE;
     } else {
       this.su_i2++;
       this.su_count = 0;

src/test/core/org/apache/hadoop/io/compress/TestCodec.java

@@ -19,31 +19,38 @@ package org.apache.hadoop.io.compress;
 
 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
+import java.io.ByteArrayInputStream;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.util.Random;
 
-import junit.framework.TestCase;
-
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.io.DataInputBuffer;
 import org.apache.hadoop.io.DataOutputBuffer;
+import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.io.RandomDatum;
 import org.apache.hadoop.io.SequenceFile;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.io.Writable;
-import org.apache.hadoop.util.ReflectionUtils;
 import org.apache.hadoop.io.SequenceFile.CompressionType;
 import org.apache.hadoop.io.compress.CompressionOutputStream;
 import org.apache.hadoop.io.compress.zlib.ZlibFactory;
+import org.apache.hadoop.util.LineReader;
+import org.apache.hadoop.util.ReflectionUtils;
 
-public class TestCodec extends TestCase {
+import org.apache.commons.codec.binary.Base64;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class TestCodec {
 
   private static final Log LOG= 
     LogFactory.getLog(TestCodec.class);
@@ -51,17 +58,20 @@ public class TestCodec extends TestCase {
   private Configuration conf = new Configuration();
   private int count = 10000;
   private int seed = new Random().nextInt();
-  
+
+  @Test
   public void testDefaultCodec() throws IOException {
     codecTest(conf, seed, 0, "org.apache.hadoop.io.compress.DefaultCodec");
     codecTest(conf, seed, count, "org.apache.hadoop.io.compress.DefaultCodec");
   }
-  
+
+  @Test
   public void testGzipCodec() throws IOException {
     codecTest(conf, seed, 0, "org.apache.hadoop.io.compress.GzipCodec");
     codecTest(conf, seed, count, "org.apache.hadoop.io.compress.GzipCodec");
   }
-  
+
+  @Test
   public void testBZip2Codec() throws IOException {
     codecTest(conf, seed, 0, "org.apache.hadoop.io.compress.BZip2Codec");
     codecTest(conf, seed, count, "org.apache.hadoop.io.compress.BZip2Codec");
@@ -133,6 +143,109 @@ public class TestCodec extends TestCase {
     LOG.info("SUCCESS! Completed checking " + count + " records");
   }
 
+  @Test
+  public void testSplitableCodecs() throws Exception {
+    testSplitableCodec(BZip2Codec.class);
+  }
+
+  private void testSplitableCodec(
+      Class<? extends SplittableCompressionCodec> codecClass)
+      throws IOException {
+    final long DEFLBYTES = 2 * 1024 * 1024;
+    final Configuration conf = new Configuration();
+    final Random rand = new Random();
+    final long seed = rand.nextLong();
+    LOG.info("seed: " + seed);
+    rand.setSeed(seed);
+    SplittableCompressionCodec codec =
+      ReflectionUtils.newInstance(codecClass, conf);
+    final FileSystem fs = FileSystem.getLocal(conf);
+    final FileStatus infile =
+      fs.getFileStatus(writeSplitTestFile(fs, rand, codec, DEFLBYTES));
+    if (infile.getLen() > Integer.MAX_VALUE) {
+      fail("Unexpected compression: " + DEFLBYTES + " -> " + infile.getLen());
+    }
+    final int flen = (int) infile.getLen();
+    final Text line = new Text();
+    final Decompressor dcmp = CodecPool.getDecompressor(codec);
+    try {
+      for (int pos = 0; pos < infile.getLen(); pos += rand.nextInt(flen / 8)) {
+        // read from random positions, verifying that there exist two sequential
+        // lines as written in writeSplitTestFile
+        final SplitCompressionInputStream in =
+          codec.createInputStream(fs.open(infile.getPath()), dcmp,
+              pos, flen, SplittableCompressionCodec.READ_MODE.BYBLOCK);
+        if (in.getAdjustedStart() >= flen) {
+          break;
+        }
+        LOG.info("SAMPLE " + in.getAdjustedStart() + "," + in.getAdjustedEnd());
+        final LineReader lreader = new LineReader(in);
+        lreader.readLine(line); // ignore; likely partial
+        if (in.getPos() >= flen) {
+          break;
+        }
+        lreader.readLine(line);
+        final int seq1 = readLeadingInt(line);
+        lreader.readLine(line);
+        if (in.getPos() >= flen) {
+          break;
+        }
+        final int seq2 = readLeadingInt(line);
+        assertEquals("Mismatched lines", seq1 + 1, seq2);
+      }
+    } finally {
+      CodecPool.returnDecompressor(dcmp);
+    }
+    // remove on success
+    fs.delete(infile.getPath().getParent(), true);
+  }
+
+  private static int readLeadingInt(Text txt) throws IOException {
+    DataInputStream in =
+      new DataInputStream(new ByteArrayInputStream(txt.getBytes()));
+    return in.readInt();
+  }
+
+  /** Write infLen bytes (deflated) to file in test dir using codec.
+   * Records are of the form
+   * &lt;i&gt;&lt;b64 rand&gt;&lt;i+i&gt;&lt;b64 rand&gt;
+   */
+  private static Path writeSplitTestFile(FileSystem fs, Random rand,
+      CompressionCodec codec, long infLen) throws IOException {
+    final int REC_SIZE = 1024;
+    final Path wd = new Path(new Path(
+          System.getProperty("test.build.data", "/tmp")).makeQualified(fs),
+        codec.getClass().getSimpleName());
+    final Path file = new Path(wd, "test" + codec.getDefaultExtension());
+    final byte[] b = new byte[REC_SIZE];
+    final Base64 b64 = new Base64();
+    DataOutputStream fout = null;
+    Compressor cmp = CodecPool.getCompressor(codec);
+    try {
+      fout = new DataOutputStream(codec.createOutputStream(
+            fs.create(file, true), cmp));
+      final DataOutputBuffer dob = new DataOutputBuffer(REC_SIZE * 4 / 3 + 4);
+      int seq = 0;
+      while (infLen > 0) {
+        rand.nextBytes(b);
+        final byte[] b64enc = b64.encode(b); // ensures rand printable, no LF
+        dob.reset();
+        dob.writeInt(seq);
+        System.arraycopy(dob.getData(), 0, b64enc, 0, dob.getLength());
+        fout.write(b64enc);
+        fout.write('\n');
+        ++seq;
+        infLen -= b64enc.length;
+      }
+      LOG.info("Wrote " + seq + " records to " + file);
+    } finally {
+      IOUtils.cleanup(LOG, fout);
+      CodecPool.returnCompressor(cmp);
+    }
+    return file;
+  }
+
+  @Test
   public void testCodecPoolGzipReuse() throws Exception {
     Configuration conf = new Configuration();
     conf.setBoolean("hadoop.native.lib", true);
@@ -149,19 +262,21 @@ public class TestCodec extends TestCase {
     assertTrue("Got mismatched ZlibCompressor", c2 != CodecPool.getCompressor(gzc));
   }
 
-  public void testSequenceFileDefaultCodec() throws IOException, ClassNotFoundException, 
+  @Test
+  public void testSequenceFileDefaultCodec() throws IOException, ClassNotFoundException,
       InstantiationException, IllegalAccessException {
     sequenceFileCodecTest(conf, 100, "org.apache.hadoop.io.compress.DefaultCodec", 100);
     sequenceFileCodecTest(conf, 200000, "org.apache.hadoop.io.compress.DefaultCodec", 1000000);
   }
-  
-  public void testSequenceFileBZip2Codec() throws IOException, ClassNotFoundException, 
+
+  @Test
+  public void testSequenceFileBZip2Codec() throws IOException, ClassNotFoundException,
       InstantiationException, IllegalAccessException {
     sequenceFileCodecTest(conf, 0, "org.apache.hadoop.io.compress.BZip2Codec", 100);
     sequenceFileCodecTest(conf, 100, "org.apache.hadoop.io.compress.BZip2Codec", 100);
     sequenceFileCodecTest(conf, 200000, "org.apache.hadoop.io.compress.BZip2Codec", 1000000);
   }
-  
+
   private static void sequenceFileCodecTest(Configuration conf, int lines, 
                                 String codecClass, int blockSize) 
     throws IOException, ClassNotFoundException, InstantiationException, IllegalAccessException {
@@ -242,8 +357,4 @@ public class TestCodec extends TestCase {
     
   }
 
-  public TestCodec(String name) {
-    super(name);
-  }
-
 }