From f01a388a35e03b432b1f3a1ecab04ab2c99e9444 Mon Sep 17 00:00:00 2001
From: anoopsjohn <anoopsamjohn@gmail.com>
Date: Fri, 1 Jan 2016 23:11:59 +0530
Subject: [PATCH] HBASE-15063 Bug in MultiByteBuf#toBytes. (deepankar)

---
 .../hadoop/hbase/nio/MultiByteBuff.java       | 16 +--------
 .../hadoop/hbase/nio/TestMultiByteBuff.java   | 36 +++++++++++++++++++
 2 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java b/hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java
index 06652b82a4f..ab2b5eae33d 100644
--- a/hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java
+++ b/hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java
@@ -1065,21 +1065,7 @@ public class MultiByteBuff extends ByteBuff {
   @Override
   public byte[] toBytes(int offset, int length) {
     byte[] output = new byte[length];
-    int itemIndex = getItemIndex(offset);
-    ByteBuffer item = this.items[itemIndex];
-    int toRead = item.limit() - offset;
-    int destinationOffset = 0;
-    while (length > 0) {
-      toRead = Math.min(length, toRead);
-      ByteBufferUtils.copyFromBufferToArray(output, item, offset, destinationOffset, toRead);
-      length -= toRead;
-      if (length == 0)
-        break;
-      destinationOffset += toRead;
-      offset = 0;
-      item = items[++itemIndex];
-      toRead = item.remaining();
-    }
+    this.get(offset, output, 0, length);
     return output;
   }
 
diff --git a/hbase-common/src/test/java/org/apache/hadoop/hbase/nio/TestMultiByteBuff.java b/hbase-common/src/test/java/org/apache/hadoop/hbase/nio/TestMultiByteBuff.java
index 193fcff4ece..800c8e13e85 100644
--- a/hbase-common/src/test/java/org/apache/hadoop/hbase/nio/TestMultiByteBuff.java
+++ b/hbase-common/src/test/java/org/apache/hadoop/hbase/nio/TestMultiByteBuff.java
@@ -342,4 +342,40 @@ public class TestMultiByteBuff {
     assertEquals(2, dst[0]);
     assertEquals(12, mbb1.position());
   }
+
+  @Test
+  public void testToBytes() throws Exception {
+    byte[] b = new byte[4];
+    byte[] b1 = new byte[8];
+    for (int i = 0; i < b.length; i++) {
+      b[i] = (byte) i;
+    }
+    for (int i = 0; i < b1.length; i++) {
+      b1[i] = (byte) (b1.length + i);
+    }
+    ByteBuffer bb1 = ByteBuffer.wrap(b);
+    ByteBuffer bb2 = ByteBuffer.wrap(b1);
+    MultiByteBuff mbb1 = new MultiByteBuff(bb1, bb2);
+
+    // Test 1 Offset hitting exclusive second element
+    byte[] actual = mbb1.toBytes(6, 4);
+    assertTrue(Bytes.equals(actual, 0, actual.length,
+            b1, 2, 4));
+    // Test 2 offset hitting exclusive second element
+    // but continuing to the end of the second one
+    actual = mbb1.toBytes(5, 7);
+    assertTrue(Bytes.equals(actual, 0, actual.length,
+            b1, 1, 7));
+    // Test 3 with offset hitting in first element,
+    // continuing to next
+    actual = mbb1.toBytes(2, 7);
+    byte[] expected = new byte[7];
+    System.arraycopy(b, 2, expected, 0,  2);
+    System.arraycopy(b1, 0, expected, 2, 5);
+    assertTrue(Bytes.equals(actual, expected));
+    // Test 4 hitting only in first exclusively
+    actual = mbb1.toBytes(1, 3);
+    assertTrue(Bytes.equals(actual, 0, actual.length,
+            b, 1, 3));
+  }
 }