HDFS-2654. Make BlockReaderLocal not extend RemoteBlockReader2. Contributed by Eli Collins

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1213592 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -204,6 +204,8 @@ Release 0.23.1 - UNRELEASED
     HDFS-2604. Add a log message to show if WebHDFS is enabled and a
     configuration section in the forrest doc.  (szetszwo)
 
+    HDFS-2654. Make BlockReaderLocal not extend RemoteBlockReader2. (eli)
+
   OPTIMIZATIONS
 
     HDFS-2130. Switch default checksum to CRC32C. (todd)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/BlockReaderLocal.java

@@ -21,6 +21,7 @@
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
+import java.net.Socket;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.HashMap;
@@ -37,6 +38,7 @@
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.hdfs.server.datanode.BlockMetadataHeader;
 import org.apache.hadoop.hdfs.server.datanode.FSDataset;
+import org.apache.hadoop.hdfs.util.DirectBufferPool;
 import org.apache.hadoop.ipc.RPC;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
@@ -57,8 +59,8 @@
  * if security is enabled.</li>
  * </ul>
  */
-class BlockReaderLocal extends RemoteBlockReader2 {
-  public static final Log LOG = LogFactory.getLog(DFSClient.class);
+class BlockReaderLocal implements BlockReader {
+  private static final Log LOG = LogFactory.getLog(DFSClient.class);
 
   //Stores the cache and proxy for a local datanode.
   private static class LocalDatanodeInfo {
@@ -117,13 +119,24 @@ private void removeBlockLocalPathInfo(ExtendedBlock b) {
   private static Map<Integer, LocalDatanodeInfo> localDatanodeInfoMap = new HashMap<Integer, LocalDatanodeInfo>();
 
   private final FileInputStream dataIn; // reader for the data file
-
   private FileInputStream checksumIn;   // reader for the checksum file
 
   private int offsetFromChunkBoundary;
   
-  ByteBuffer dataBuff = null;
-  ByteBuffer checksumBuff = null;
+  private byte[] skipBuf = null;
+  private ByteBuffer dataBuff = null;
+  private ByteBuffer checksumBuff = null;
+  private DataChecksum checksum;
+  private final boolean verifyChecksum;
+
+  private static DirectBufferPool bufferPool = new DirectBufferPool();
+
+  private int bytesPerChecksum;
+  private int checksumSize;
+
+  /** offset in block where reader wants to actually read */
+  private long startOffset;
+  private final String filename;
   
   /**
    * The only way this object can be instantiated.
@@ -256,9 +269,14 @@ private BlockReaderLocal(Configuration conf, String hdfsfile,
       long length, BlockLocalPathInfo pathinfo, DataChecksum checksum,
       boolean verifyChecksum, FileInputStream dataIn, long firstChunkOffset,
       FileInputStream checksumIn) throws IOException {
-    super(hdfsfile, block.getBlockPoolId(), block.getBlockId(), dataIn
-        .getChannel(), checksum, verifyChecksum, startOffset, firstChunkOffset,
-        length, null);
+    this.filename = hdfsfile;
+    this.checksum = checksum;
+    this.verifyChecksum = verifyChecksum;
+    this.startOffset = Math.max(startOffset, 0);
+
+    bytesPerChecksum = this.checksum.getBytesPerChecksum();
+    checksumSize = this.checksum.getChecksumSize();
+
     this.dataIn = dataIn;
     this.checksumIn = checksumIn;
     this.offsetFromChunkBoundary = (int) (startOffset-firstChunkOffset);
@@ -322,10 +340,8 @@ public synchronized int read(byte[] buf, int off, int len) throws IOException {
         readIntoBuffer(checksumIn, checksumBuff);
         checksumBuff.flip();
         dataBuff.flip();
-        if (verifyChecksum) {
         checksum.verifyChunkedSums(dataBuff, checksumBuff, filename,
             this.startOffset);
-        }
       } else {
         dataRead = dataBuff.remaining();
       }
@@ -356,9 +372,24 @@ public synchronized long skip(long n) throws IOException {
     }
     if (!verifyChecksum) {
       return dataIn.skip(n);
-    } else {
-     return super.skip(n);
     }
+    // Skip by reading the data so we stay in sync with checksums.
+    // This could be implemented more efficiently in the future to
+    // skip to the beginning of the appropriate checksum chunk
+    // and then only read to the middle of that chunk.
+    if (skipBuf == null) {
+      skipBuf = new byte[bytesPerChecksum];
+    }
+    long nSkipped = 0;
+    while ( nSkipped < n ) {
+      int toSkip = (int)Math.min(n-nSkipped, skipBuf.length);
+      int ret = read(skipBuf, 0, toSkip);
+      if ( ret <= 0 ) {
+        return nSkipped;
+      }
+      nSkipped += ret;
+    }
+    return nSkipped;
   }
 
   @Override
@@ -375,6 +406,27 @@ public synchronized void close() throws IOException {
       bufferPool.returnBuffer(checksumBuff);
       checksumBuff = null;
     }
-    super.close();
+    startOffset = -1;
+    checksum = null;
+  }
+
+  @Override
+  public int readAll(byte[] buf, int offset, int len) throws IOException {
+    return BlockReaderUtil.readAll(this, buf, offset, len);
+  }
+
+  @Override
+  public void readFully(byte[] buf, int off, int len) throws IOException {
+    BlockReaderUtil.readFully(this, buf, off, len);
+  }
+
+  @Override
+  public Socket takeSocket() {
+    return null;
+  }
+
+  @Override
+  public boolean hasSentStatusCode() {
+    return false;
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader2.java

@@ -85,7 +85,7 @@ public class RemoteBlockReader2  implements BlockReader {
   
   Socket dnSock; //for now just sending the status code (e.g. checksumOk) after the read.
   private ReadableByteChannel in;
-  protected DataChecksum checksum;
+  private DataChecksum checksum;
   
   private PacketHeader curHeader;
   private ByteBuffer curPacketBuf = null;
@@ -96,25 +96,24 @@ public class RemoteBlockReader2  implements BlockReader {
   private long lastSeqNo = -1;
 
   /** offset in block where reader wants to actually read */
-  protected long startOffset;
-  protected final String filename;
+  private long startOffset;
+  private final String filename;
 
-  protected static DirectBufferPool bufferPool =
-    new DirectBufferPool();
+  private static DirectBufferPool bufferPool = new DirectBufferPool();
   private ByteBuffer headerBuf = ByteBuffer.allocate(
       PacketHeader.PKT_HEADER_LEN);
 
-  protected int bytesPerChecksum;
-  protected int checksumSize;
+  private int bytesPerChecksum;
+  private int checksumSize;
 
   /**
    * The total number of bytes we need to transfer from the DN.
    * This is the amount that the user has requested plus some padding
    * at the beginning so that the read can begin on a chunk boundary.
    */
-  protected long bytesNeededToFinish;
+  private long bytesNeededToFinish;
 
-  protected final boolean verifyChecksum;
+  private final boolean verifyChecksum;
 
   private boolean sentStatusCode = false;
   
@@ -389,29 +388,12 @@ public static String getFileName(final InetSocketAddress s,
 
   @Override
   public int readAll(byte[] buf, int offset, int len) throws IOException {
-    int n = 0;
-    for (;;) {
-      int nread = read(buf, offset + n, len - n);
-      if (nread <= 0) 
-        return (n == 0) ? nread : n;
-      n += nread;
-      if (n >= len)
-        return n;
-    }
+    return BlockReaderUtil.readAll(this, buf, offset, len);
   }
 
   @Override
-  public void readFully(byte[] buf, int off, int len)
-      throws IOException {
-    int toRead = len;
-    while (toRead > 0) {
-      int ret = read(buf, off, toRead);
-      if (ret < 0) {
-        throw new IOException("Premature EOF from inputStream");
-      }
-      toRead -= ret;
-      off += ret;
-    }    
+  public void readFully(byte[] buf, int off, int len) throws IOException {
+    BlockReaderUtil.readFully(this, buf, off, len);
   }
   
   /**