From 8e08d89a50928a6757c0e8db90c6fb36e4a47eda Mon Sep 17 00:00:00 2001
From: Keith Turner <kturner@apache.org>
Date: Tue, 8 Nov 2016 08:18:25 -0500
Subject: [PATCH] Use faster byte comparison

---
 .../java/org/apache/fluo/api/data/Bytes.java  | 23 ++++++++++------
 .../org/apache/fluo/api/data/BytesTest.java   | 27 +++++++++++++++++++
 2 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/modules/api/src/main/java/org/apache/fluo/api/data/Bytes.java b/modules/api/src/main/java/org/apache/fluo/api/data/Bytes.java
index 290277261..89b111b47 100644
--- a/modules/api/src/main/java/org/apache/fluo/api/data/Bytes.java
+++ b/modules/api/src/main/java/org/apache/fluo/api/data/Bytes.java
@@ -29,6 +29,7 @@
 import java.util.Objects;
 
 import com.google.common.base.Preconditions;
+import com.google.common.primitives.UnsignedBytes;
 
 /**
  * Represents bytes in Fluo. Bytes is an immutable wrapper around a byte array. Bytes always copies
@@ -155,7 +156,7 @@ public InputStream toInputStream() {
   }
 
   public void writeTo(OutputStream out) throws IOException {
-    // since Bytes is immutable, its important the we do not let the internal byte array escape
+    // since Bytes is immutable, its important that we do not let the internal byte array escape
     if (length <= 32) {
       int end = offset + length;
       for (int i = offset; i < end; i++) {
@@ -177,17 +178,23 @@ public void writeTo(OutputStream out) throws IOException {
    */
   @Override
   public final int compareTo(Bytes other) {
-    int minLen = Math.min(this.length(), other.length());
+    if (this == other) {
+      return 0;
+    } else if (this.length == this.data.length && other.length == other.data.length) {
+      return UnsignedBytes.lexicographicalComparator().compare(this.data, other.data);
+    } else {
+      int minLen = Math.min(this.length(), other.length());
 
-    for (int i = 0; i < minLen; i++) {
-      int a = (this.byteAt(i) & 0xff);
-      int b = (other.byteAt(i) & 0xff);
+      for (int i = 0; i < minLen; i++) {
+        int a = (this.byteAt(i) & 0xff);
+        int b = (other.byteAt(i) & 0xff);
 
-      if (a != b) {
-        return a - b;
+        if (a != b) {
+          return a - b;
+        }
       }
+      return this.length() - other.length();
     }
-    return this.length() - other.length();
   }
 
   /**
diff --git a/modules/api/src/test/java/org/apache/fluo/api/data/BytesTest.java b/modules/api/src/test/java/org/apache/fluo/api/data/BytesTest.java
index 641c9bfe4..720a1a30b 100644
--- a/modules/api/src/test/java/org/apache/fluo/api/data/BytesTest.java
+++ b/modules/api/src/test/java/org/apache/fluo/api/data/BytesTest.java
@@ -86,9 +86,36 @@ public void testCompare() {
     Assert.assertEquals(-1, b1.compareTo(b2));
     Assert.assertEquals(1, b2.compareTo(b1));
     Assert.assertEquals(0, b1.compareTo(b3));
+    Assert.assertEquals(0, b1.compareTo(b1));
     Assert.assertEquals(1, b1.compareTo(Bytes.EMPTY));
   }
 
+  @Test
+  public void testCompareSubsequence() {
+    Bytes b1 = Bytes.of("abcd");
+    Bytes b2 = b1.subSequence(0, 3);
+    Bytes b3 = Bytes.of("abc");
+    Bytes b4 = Bytes.of("~abcde");
+    Bytes b5 = b4.subSequence(1, 4);
+    Bytes b6 = b4.subSequence(1, 5);
+
+    for (Bytes ba : Arrays.asList(b2, b3, b5, b1.subSequence(0, 3))) {
+      for (Bytes bb : Arrays.asList(b2, b3, b5)) {
+        Assert.assertEquals(0, ba.compareTo(bb));
+      }
+    }
+
+    Assert.assertEquals(1, b1.compareTo(b2));
+    Assert.assertEquals(-1, b2.compareTo(b1));
+
+    for (Bytes less : Arrays.asList(b2, b3, b5)) {
+      for (Bytes greater : Arrays.asList(b1, b4, b6)) {
+        Assert.assertTrue(less.compareTo(greater) < 0);
+        Assert.assertTrue(greater.compareTo(less) > 0);
+      }
+    }
+  }
+
   @Test
   public void testToByteBuffer() {
     Bytes b1 = Bytes.of("fluofluo");