8309959: JFR: Display N/A for missing data amount

Reviewed-by: stuefe, sgehwolf
Backport-of: 9872a14192ce3964b934c19ab685342ffd396986

Author: fthevenet

src/jdk.jfr/share/classes/jdk/jfr/internal/Utils.java

@@ -126,11 +126,13 @@ private static enum TimespanUnit {
         }
     }
 
-    // handle Long.MIN_VALUE as a special case since its absolute value is negative
     private static String formatDataAmount(String formatter, long amount) {
-        int exp = (amount == Long.MIN_VALUE) ? 6 : (int) (Math.log(Math.abs(amount)) / Math.log(1024));
-        char unitPrefix = "kMGTPE".charAt(exp - 1);
-        return String.format(formatter, amount / Math.pow(1024, exp), unitPrefix);
+        if (amount == Long.MIN_VALUE) {
+            return "N/A";
+        }
+        int exp = (int) (Math.log(Math.abs(amount)) / Math.log(1024));
+        char unit = "kMGTPE".charAt(exp - 1);
+        return String.format(formatter, amount / Math.pow(1024, exp), unit);
     }
 
     public static String formatBytesCompact(long bytes) {