HBASE-2635. ImmutableBytesWritable ignores offset in several cases

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@950242 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -366,6 +366,7 @@ Release 0.21.0 - Unreleased
                (Jeff Hammerbacher via Todd Lipcon)
    HBASE-2371  Fix 'list' command in shell (Alexey Kovyrin via Todd Lipcon)
    HBASE-2620  REST tests don't use ephemeral ports
+   HBASE-2635  ImmutableBytesWritable ignores offset in several cases
 
   IMPROVEMENTS
    HBASE-1760  Cleanup TODOs in HTable

src/main/java/org/apache/hadoop/hbase/io/ImmutableBytesWritable.java

@@ -83,7 +83,7 @@ implements WritableComparable<ImmutableBytesWritable> {
 
   /**
    * Get the data from the BytesWritable.
-   * @return The data is only valid between 0 and getSize() - 1.
+   * @return The data is only valid between offset and offset+length.
    */
   public byte [] get() {
     if (this.bytes == null) {
@@ -112,7 +112,7 @@ implements WritableComparable<ImmutableBytesWritable> {
   }
 
   /**
-   * @return the current size of the buffer.
+   * @return the number of valid bytes in the buffer
    */
   public int getSize() {
     if (this.bytes == null) {
@@ -123,7 +123,7 @@ implements WritableComparable<ImmutableBytesWritable> {
   }
 
   /**
-   * @return the current length of the buffer. same as getSize()
+   * @return the number of valid bytes in the buffer
    */
   //Should probably deprecate getSize() so that we keep the same calls for all
   //byte []
@@ -155,20 +155,24 @@ implements WritableComparable<ImmutableBytesWritable> {
   }
 
   // Below methods copied from BytesWritable
-
   @Override
   public int hashCode() {
-    return WritableComparator.hashBytes(bytes, this.length);
+    int hash = 1;
+    for (int i = offset; i < offset + length; i++)
+      hash = (31 * hash) + (int)bytes[i];
+    return hash;
   }
 
   /**
    * Define the sort order of the BytesWritable.
-   * @param right_obj The other bytes writable
+   * @param that The other bytes writable
    * @return Positive if left is bigger than right, 0 if they are equal, and
    *         negative if left is smaller than right.
    */
-  public int compareTo(ImmutableBytesWritable right_obj) {
-    return compareTo(right_obj.get());
+  public int compareTo(ImmutableBytesWritable that) {
+    return WritableComparator.compareBytes(
+      this.bytes, this.offset, this.length,
+      that.bytes, that.offset, that.length);
   }
 
   /**
@@ -178,8 +182,9 @@ implements WritableComparable<ImmutableBytesWritable> {
    *         negative if left is smaller than right.
    */
   public int compareTo(final byte [] that) {
-    return WritableComparator.compareBytes(this.bytes, 0, this.length, that,
-        0, that.length);
+    return WritableComparator.compareBytes(
+      this.bytes, this.offset, this.length,
+      that, 0, that.length);
   }
 
   /**
@@ -202,9 +207,9 @@ implements WritableComparable<ImmutableBytesWritable> {
   @Override
   public String toString() {
     StringBuilder sb = new StringBuilder(3*this.bytes.length);
-    for (int idx = 0; idx < this.bytes.length; idx++) {
+    for (int idx = offset; idx < offset + length; idx++) {
       // if not the first, put a blank separator in
-      if (idx != 0) {
+      if (idx != offset) {
         sb.append(' ');
       }
       String num = Integer.toHexString(bytes[idx]);

src/test/java/org/apache/hadoop/hbase/io/TestImmutableBytesWritable.java

@@ -28,6 +28,18 @@ import java.io.DataOutputStream;
 import java.io.IOException;
 
 public class TestImmutableBytesWritable extends TestCase {
+  public void testHash() throws Exception {
+    assertEquals(
+      new ImmutableBytesWritable(Bytes.toBytes("xxabc"), 2, 3).hashCode(),
+      new ImmutableBytesWritable(Bytes.toBytes("abc")).hashCode());
+    assertEquals(
+      new ImmutableBytesWritable(Bytes.toBytes("xxabcd"), 2, 3).hashCode(),
+      new ImmutableBytesWritable(Bytes.toBytes("abc")).hashCode());
+    assertNotSame(
+      new ImmutableBytesWritable(Bytes.toBytes("xxabc"), 2, 3).hashCode(),
+      new ImmutableBytesWritable(Bytes.toBytes("xxabc"), 2, 2).hashCode());
+  }
+
   public void testComparison() throws Exception {
     runTests("aa", "b", -1);
     runTests("aa", "aa", 0);
@@ -46,6 +58,22 @@ public class TestImmutableBytesWritable extends TestCase {
 
     doComparisonsOnObjects(a, b, signum);
     doComparisonsOnRaw(a, b, signum);
+
+    // Tests for when the offset is non-zero
+    a = new ImmutableBytesWritable(Bytes.toBytes("xxx" + aStr),
+                                   3, aStr.length());
+    b = new ImmutableBytesWritable(Bytes.toBytes("yy" + bStr),
+                                   2, bStr.length());
+    doComparisonsOnObjects(a, b, signum);
+    doComparisonsOnRaw(a, b, signum);
+
+    // Tests for when offset is nonzero and length doesn't extend to end
+    a = new ImmutableBytesWritable(Bytes.toBytes("xxx" + aStr + "zzz"),
+                                   3, aStr.length());
+    b = new ImmutableBytesWritable(Bytes.toBytes("yy" + bStr + "aaa"),
+                                   2, bStr.length());
+    doComparisonsOnObjects(a, b, signum);
+    doComparisonsOnRaw(a, b, signum);
   }
 
 
@@ -93,4 +121,4 @@ public class TestImmutableBytesWritable extends TestCase {
       "Comparing " + a + " and " + b + " as objects (inverse)",
       -signum(comparator.compare(b, a)), expectedSignum);
   }
-}
+}