fixes

Author: prdoyle

server/src/main/java/org/elasticsearch/common/unit/ByteSizeValue.java

@@ -14,6 +14,7 @@
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.logging.DeprecationLogger;
+import org.elasticsearch.core.SuppressForbidden;
 import org.elasticsearch.xcontent.ToXContentFragment;
 import org.elasticsearch.xcontent.XContentBuilder;
 
@@ -213,10 +214,10 @@ public String toString() {
     }
 
     /**
-     * Strictly speaking, this is only <em>guaranteed</em> to return the exact right two decimals
+     * Strictly speaking, this is only <em>guaranteed</em> to return the exact right string
      * when {@code numerator} is the rounded value of some multiple of 1% of {@code denominator}.
-     * Other arbitrary values, where {@code numerator / denominator} exceeds the precision of a
-     * {@code double}, may be off by a little.
+     * Other arbitrary values could yield surprising results; for example, you might see
+     * {@code 123.0} or even {@code 1221.00} in place of {@code 123}.
      */
     static String format2Decimals(long numerator, long denominator) {
         // If numerator >> denominator, we risk exceeding the precision of a double, so we enlist
@@ -231,7 +232,12 @@ static String format2Decimals(long numerator, long denominator) {
         }
     }
 
-    private static final DecimalFormat MAX_TWO_DECIMALS = new DecimalFormat(".##");
+    private static final DecimalFormat MAX_TWO_DECIMALS = maxTwoDecimalsFormat();
+
+    @SuppressForbidden(reason="We truly just want two decimals; Locale settings don't matter here")
+    private static DecimalFormat maxTwoDecimalsFormat() {
+        return new DecimalFormat(".##");
+    }
 
     public static ByteSizeValue parseBytesSizeValue(String sValue, String settingName) throws ElasticsearchParseException {
         return parseBytesSizeValue(sValue, null, settingName);
@@ -322,7 +328,7 @@ private static ByteSizeValue parse(
                     BigDecimal decimalValue = new BigDecimal(s);
                     if (decimalValue.scale() > 2) {
                         throw new ElasticsearchParseException(
-                            "more than two decimal places in setting [{}]: [{}]",
+                            "more than two decimal places in setting [{}] with value [{}]",
                             settingName,
                             initialInput
                         );

server/src/test/java/org/elasticsearch/common/unit/ByteSizeValueTests.java

@@ -315,7 +315,8 @@ public void testParseInvalidNumber() throws IOException {
             exception.getMessage()
         );
 
-        String unitSuffix = (randomBoolean() ? " " : "") + randomFrom(ByteSizeUnit.values()).getSuffix();
+        ByteSizeUnit unit = randomFrom(ByteSizeUnit.values());
+        String unitSuffix = (randomBoolean() ? " " : "") + unit.getSuffix();
         exception = expectThrows(
             ElasticsearchParseException.class,
             () -> ByteSizeValue.parseBytesSizeValue("notANumber" + unitSuffix, "test")
@@ -330,7 +331,12 @@ public void testParseInvalidNumber() throws IOException {
         );
 
         exception = expectThrows(ElasticsearchParseException.class, () -> ByteSizeValue.parseBytesSizeValue("1.234" + unitSuffix, "test"));
-        assertEquals("more than two decimal places in setting [test]: [1.234" + unitSuffix + "]", exception.getMessage());
+        if (unit == BYTES) {
+            // Decimals aren't allowed at all for bytes
+            assertEquals("failed to parse setting [test] with value [1.234" + unitSuffix + "]", exception.getMessage());
+        } else {
+            assertEquals("more than two decimal places in setting [test] with value [1.234" + unitSuffix + "]", exception.getMessage());
+        }
     }
 
     public void testParseFractionalNumber() throws IOException {