src/java.base/share/classes/java/lang/Long.java

*** 399,420 ****
       * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
       * @param buf the character buffer to write to
       * @param offset the offset in the destination buffer to start at
       * @param len the number of characters to write
       */
-      static void formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
-         // assert shift > 0 && shift <=5 : "Illegal shift value";
-         // assert offset >= 0 && offset < buf.length : "illegal offset";
-         // assert len > 0 && (offset + len) <= buf.length : "illegal length";
-         int charPos = offset + len;
-         int radix = 1 << shift;
-         int mask = radix - 1;
-         do {
-             buf[--charPos] = Integer.digits[((int) val) & mask];
-             val >>>= shift;
-         } while (charPos > offset);
-     }
  
      /** byte[]/LATIN1 version    */
      static void formatUnsignedLong0(long val, int shift, byte[] buf, int offset, int len) {
          int charPos = offset + len;
          int radix = 1 << shift;
--- 399,408 ----
*** 434,443 ****
--- 422,464 ----
              StringUTF16.putChar(buf, --charPos, Integer.digits[((int) val) & mask]);
              val >>>= shift;
          } while (charPos > offset);
      }
  
+     static String fastUUID(long lsb, long msb) {
+         if (COMPACT_STRINGS) {
+             byte[] buf = new byte[36];
+             formatUnsignedLong0(lsb,        4, buf, 24, 12);
+             formatUnsignedLong0(lsb >>> 48, 4, buf, 19, 4);
+             formatUnsignedLong0(msb,        4, buf, 14, 4);
+             formatUnsignedLong0(msb >>> 16, 4, buf, 9,  4);
+             formatUnsignedLong0(msb >>> 32, 4, buf, 0,  8);
+ 
+             buf[23] = '-';
+             buf[18] = '-';
+             buf[13] = '-';
+             buf[8]  = '-';
+ 
+             return new String(buf, LATIN1);
+         } else {
+             byte[] buf = new byte[72];
+ 
+             formatUnsignedLong0UTF16(lsb,        4, buf, 24, 12);
+             formatUnsignedLong0UTF16(lsb >>> 48, 4, buf, 19, 4);
+             formatUnsignedLong0UTF16(msb,        4, buf, 14, 4);
+             formatUnsignedLong0UTF16(msb >>> 16, 4, buf, 9,  4);
+             formatUnsignedLong0UTF16(msb >>> 32, 4, buf, 0,  8);
+ 
+             StringUTF16.putChar(buf, 23, '-');
+             StringUTF16.putChar(buf, 18, '-');
+             StringUTF16.putChar(buf, 13, '-');
+             StringUTF16.putChar(buf,  8, '-');
+ 
+             return new String(buf, UTF16);
+         }
+     }
+ 
      /**
       * Returns a {@code String} object representing the specified
       * {@code long}.  The argument is converted to signed decimal
       * representation and returned as a string, exactly as if the
       * argument and the radix 10 were given as arguments to the {@link