Fix #967 (#973): BigDecimalParser performance for edge cases

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -51,6 +51,7 @@ JSON library.
 #912: Optional padding Base64Variant still throws exception on missing
   padding character
  (reported by @Vity01)
+#967: Address performance issue with `BigDecimalParser`
 
 2.14.2 (28-Jan-2023)
 

src/main/java/com/fasterxml/jackson/core/io/BigDecimalParser.java

@@ -202,6 +202,13 @@ private static BigDecimal toBigDecimalRec(final char[] chars, final int off, fin
             return left.add(right);
         }
 
-        return len == 0 ? BigDecimal.ZERO : new BigDecimal(chars, off, len).movePointRight(scale);
+        if (len == 0) {
+            return BigDecimal.ZERO;
+        }
+        // 02-Apr-2023, tatu: [core#967] Looks like "scaleByPowerOfThen" avoids performance issue
+        //    there would be with "movePointRight" (both doing about same thing), so)
+        return new BigDecimal(chars, off, len)
+//                .movePointRight(scale);
+                .scaleByPowerOfTen(scale);
     }
 }

src/test/java/com/fasterxml/jackson/failing/PerfBigDecimalParser967.java

@@ -11,7 +11,7 @@ public class PerfBigDecimalParser967
     private final JsonFactory JSON_F = new JsonFactory();
 
     // For [core#967]: shouldn't take multiple seconds
-    @Test(timeout = 35000)
+    @Test(timeout = 3000)
     public void bigDecimalFromString() throws Exception {
         // Jackson's BigDecimalParser seems to be slower than JDK's;
         // won't fail if using latter.