Reimplement DateTimeUtils.convertScale() without BigDecimal

h2/src/main/org/h2/util/DateTimeUtils.java

@@ -6,7 +6,6 @@
  */
 package org.h2.util;
 
-import java.math.BigDecimal;
 import java.sql.Date;
 import java.sql.Time;
 import java.sql.Timestamp;
@@ -20,7 +19,6 @@ import org.h2.engine.Mode;
 import org.h2.message.DbException;
 import org.h2.value.Value;
 import org.h2.value.ValueDate;
-import org.h2.value.ValueDecimal;
 import org.h2.value.ValueNull;
 import org.h2.value.ValueTime;
 import org.h2.value.ValueTimestamp;
@@ -71,6 +69,12 @@ public class DateTimeUtils {
     private static final int[] DAYS_OFFSET = { 0, 31, 61, 92, 122, 153, 184,
             214, 245, 275, 306, 337, 366 };
 
+    /**
+     * Multipliers for {@link #convertScale(long, int)}.
+     */
+    private static final int[] CONVERT_SCALE_TABLE = { 1_000_000_000, 100_000_000,
+            10_000_000, 1_000_000, 100_000, 10_000, 1_000, 100, 10 };
+
     /**
      * The thread local. Can not override initialValue because this would result
      * in an inner class, which would not be garbage collected in a web
@@ -1458,11 +1462,16 @@ public class DateTimeUtils {
      * @return scaled value
      */
     public static long convertScale(long nanosOfDay, int scale) {
-        BigDecimal bd = BigDecimal.valueOf(nanosOfDay);
-        bd = bd.movePointLeft(9);
-        bd = ValueDecimal.setScale(bd, scale);
-        bd = bd.movePointRight(9);
-        return bd.longValue();
+        if (scale >= 9) {
+            return nanosOfDay;
+        }
+        int m = CONVERT_SCALE_TABLE[scale];
+        long r = nanosOfDay / m;
+        int d = (int) (nanosOfDay - (r * m));
+        if (d >= m >>> 1) {
+            r++;
+        }
+        return r * m;
     }
 
 }

h2/src/test/org/h2/test/unit/TestDateTimeUtils.java

@@ -46,6 +46,7 @@ public class TestDateTimeUtils extends TestBase {
         testWeekOfYear();
         testDateValueFromDenormalizedDate();
         testUTC2Value(false);
+        testConvertScale();
     }
 
     private void testParseTimeNanosDB2Format() {
@@ -160,4 +161,37 @@ public class TestDateTimeUtils extends TestBase {
         }
     }
 
+    private void testConvertScale() {
+        assertEquals(555_555_555_555L, DateTimeUtils.convertScale(555_555_555_555L, 9));
+        assertEquals(555_555_555_550L, DateTimeUtils.convertScale(555_555_555_554L, 8));
+        assertEquals(555_555_555_500L, DateTimeUtils.convertScale(555_555_555_549L, 7));
+        assertEquals(555_555_555_000L, DateTimeUtils.convertScale(555_555_555_499L, 6));
+        assertEquals(555_555_550_000L, DateTimeUtils.convertScale(555_555_554_999L, 5));
+        assertEquals(555_555_500_000L, DateTimeUtils.convertScale(555_555_549_999L, 4));
+        assertEquals(555_555_000_000L, DateTimeUtils.convertScale(555_555_499_999L, 3));
+        assertEquals(555_550_000_000L, DateTimeUtils.convertScale(555_554_999_999L, 2));
+        assertEquals(555_500_000_000L, DateTimeUtils.convertScale(555_549_999_999L, 1));
+        assertEquals(555_000_000_000L, DateTimeUtils.convertScale(555_499_999_999L, 0));
+        assertEquals(555_555_555_555L, DateTimeUtils.convertScale(555_555_555_555L, 9));
+        assertEquals(555_555_555_560L, DateTimeUtils.convertScale(555_555_555_555L, 8));
+        assertEquals(555_555_555_600L, DateTimeUtils.convertScale(555_555_555_550L, 7));
+        assertEquals(555_555_556_000L, DateTimeUtils.convertScale(555_555_555_500L, 6));
+        assertEquals(555_555_560_000L, DateTimeUtils.convertScale(555_555_555_000L, 5));
+        assertEquals(555_555_600_000L, DateTimeUtils.convertScale(555_555_550_000L, 4));
+        assertEquals(555_556_000_000L, DateTimeUtils.convertScale(555_555_500_000L, 3));
+        assertEquals(555_560_000_000L, DateTimeUtils.convertScale(555_555_000_000L, 2));
+        assertEquals(555_600_000_000L, DateTimeUtils.convertScale(555_550_000_000L, 1));
+        assertEquals(556_000_000_000L, DateTimeUtils.convertScale(555_500_000_000L, 0));
+        assertEquals(100_999_999_999L, DateTimeUtils.convertScale(100_999_999_999L, 9));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 8));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 7));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 6));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 5));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 4));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 3));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 2));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 1));
+        assertEquals(101_000_000_000L, DateTimeUtils.convertScale(100_999_999_999L, 0));
+    }
+
 }