ARTEMIS-2390 Small improvement on UUID Conversion

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/ByteUtil.java

@@ -163,6 +163,30 @@ public class ByteUtil {
             | ((int) b[0] & 0xff) << 24;
    }
 
+   public static byte[] longToBytes(long value) {
+      byte[] output = new byte[8];
+      longToBytes(value, output, 0);
+      return output;
+   }
+
+   public static void longToBytes(long x, byte[] output, int offset) {
+      output[offset] = (byte)(x >> 56);
+      output[offset + 1] = (byte)(x >> 48);
+      output[offset + 2] = (byte)(x >> 40);
+      output[offset + 3] = (byte)(x >> 32);
+      output[offset + 4] = (byte)(x >> 24);
+      output[offset + 5] = (byte)(x >> 16);
+      output[offset + 6] = (byte)(x >>  8);
+      output[offset + 7] = (byte)(x);
+   }
+
+   public static byte[] doubleLongToBytes(long value1, long value2) {
+      byte[] output = new byte[16];
+      longToBytes(value1, output, 0);
+      longToBytes(value2, output, 8);
+      return output;
+   }
+
    public static byte[] hexToBytes(String hexStr) {
       byte[] bytes = new byte[hexStr.length() / 2];
       for (int i = 0; i < bytes.length; i++) {

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/UUID.java

@@ -107,10 +107,15 @@ public final class UUID {
       mId[UUID.INDEX_VARIATION] |= (byte) 0x80;
    }
 
-   public UUID(final byte[] data) {
+   private UUID(final byte[] data) {
       mId = data;
    }
 
+   /** This is for conversions between two types of UUID */
+   public UUID(java.util.UUID uuid) {
+      this(ByteUtil.doubleLongToBytes(uuid.getMostSignificantBits(), uuid.getLeastSignificantBits()));
+   }
+
    public byte[] asBytes() {
       return mId;
    }

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/UUIDGenerator.java

@@ -18,7 +18,6 @@ package org.apache.activemq.artemis.utils;
 
 import java.net.NetworkInterface;
 import java.net.SocketException;
-import java.nio.ByteBuffer;
 import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -111,15 +110,7 @@ public final class UUIDGenerator {
    }
 
    public UUID fromJavaUUID(java.util.UUID uuid) {
-      long msb = uuid.getMostSignificantBits();
-      long lsb = uuid.getLeastSignificantBits();
-
-      ByteBuffer buffer = ByteBuffer.allocate(16);
-      buffer.putLong(msb);
-      buffer.putLong(lsb);
-      byte[] contents = buffer.array();
-
-      return new UUID(contents);
+      return new UUID(uuid);
    }
 
    public byte[] generateDummyAddress() {

artemis-commons/src/test/java/org/apache/activemq/artemis/utils/ByteUtilTest.java

@@ -318,4 +318,32 @@ public class ByteUtilTest {
          assertEquals(randomInt, ByteUtil.bytesToInt(actual));
       }
    }
+
+   @Test
+   public void testLongToBytes() {
+      ByteBuffer buffer = ByteBuffer.allocate(8);
+      long randomLong = RandomUtil.randomLong();
+      buffer.putLong(randomLong);
+      byte[] longArrayAssert = buffer.array();
+
+      byte[] convertedArray = ByteUtil.longToBytes(randomLong);
+
+      assertArrayEquals(longArrayAssert, convertedArray);
+   }
+
+   @Test
+   public void testDoubleLongToBytes() {
+      long randomLong1 = RandomUtil.randomLong();
+      long randomLong2 = RandomUtil.randomLong();
+      ByteBuffer buffer = ByteBuffer.allocate(16);
+      buffer.putLong(randomLong1);
+      buffer.putLong(randomLong2);
+      byte[] assertContent = buffer.array();
+
+      byte[] convertedContent = ByteUtil.doubleLongToBytes(randomLong1, randomLong2);
+
+      assertArrayEquals(assertContent, convertedContent);
+   }
+
+
 }