HADOOP-11534. Minor improvements for raw erasure coders ( Contributed by Kai Zheng )

hadoop-common-project/hadoop-common/CHANGES-HDFS-EC-7285.txt

@@ -1,4 +1,7 @@
   BREAKDOWN OF HADOOP-11264 SUBTASKS AND RELATED JIRAS (Common part of HDFS-7285)
 
     HADOOP-11514. Raw Erasure Coder API for concrete encoding and decoding
-    (Kai Zheng via umamahesh)
+    (Kai Zheng via umamahesh)
+
+    HADOOP-11534. Minor improvements for raw erasure coders
+    ( Kai Zheng via vinayakumarb )

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/ECChunk.java

@@ -66,15 +66,26 @@ public class ECChunk {
   }
 
   /**
-   * Convert an array of this chunks to an array of byte array
+   * Convert an array of this chunks to an array of byte array.
+   * Note the chunk buffers are not affected.
    * @param chunks
    * @return an array of byte array
    */
   public static byte[][] toArray(ECChunk[] chunks) {
     byte[][] bytesArr = new byte[chunks.length][];
 
+    ByteBuffer buffer;
     for (int i = 0; i < chunks.length; i++) {
-      bytesArr[i] = chunks[i].getBuffer().array();
+      buffer = chunks[i].getBuffer();
+      if (buffer.hasArray()) {
+        bytesArr[i] = buffer.array();
+      } else {
+        bytesArr[i] = new byte[buffer.remaining()];
+        // Avoid affecting the original one
+        buffer.mark();
+        buffer.get(bytesArr[i]);
+        buffer.reset();
+      }
     }
 
     return bytesArr;

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/rawcoder/AbstractRawErasureCoder.java

@@ -24,26 +24,26 @@ package org.apache.hadoop.io.erasurecode.rawcoder;
  */
 public abstract class AbstractRawErasureCoder implements RawErasureCoder {
 
-  private int dataSize;
-  private int paritySize;
+  private int numDataUnits;
+  private int numParityUnits;
   private int chunkSize;
 
   @Override
   public void initialize(int numDataUnits, int numParityUnits,
                          int chunkSize) {
-    this.dataSize = numDataUnits;
-    this.paritySize = numParityUnits;
+    this.numDataUnits = numDataUnits;
+    this.numParityUnits = numParityUnits;
     this.chunkSize = chunkSize;
   }
 
   @Override
   public int getNumDataUnits() {
-    return dataSize;
+    return numDataUnits;
   }
 
   @Override
   public int getNumParityUnits() {
-    return paritySize;
+    return numParityUnits;
   }
 
   @Override