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Subject: [Bug 55611] Performance improvement (~7% up to ~27%) by adding a
 cache to DateUtil.isADateFormat(int, String)
Date: Sat, 19 Oct 2013 15:28:02 +0000
Message-ID: <bug-55611-47293-97giHsCjGf@https.issues.apache.org/bugzilla/>
In-Reply-To: <bug-55611-47293@https.issues.apache.org/bugzilla/>
References: <bug-55611-47293@https.issues.apache.org/bugzilla/>
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https://issues.apache.org/bugzilla/show_bug.cgi?id=3D55611

--- Comment #7 from Luca Della Toffola <luca.dellatoffola@inf.ethz.ch> ---
Comment on attachment 30946
  --> https://issues.apache.org/bugzilla/attachment.cgi?id=3D30946
Patch for poi-3.9 (synchronized)

>diff -rupN -x '.*' poi-3.9/src/java/org/apache/poi/ss/usermodel/DateUtil.j=
ava poi-3.9-patch/src/java/org/apache/poi/ss/usermodel/DateUtil.java
>--- poi-3.9/src/java/org/apache/poi/ss/usermodel/DateUtil.java	2012-11-25 =
13:28:05.000000000 +0100
>+++ poi-3.9-patch/src/java/org/apache/poi/ss/usermodel/DateUtil.java	2013-=
10-17 17:32:51.000000000 +0200
>@@ -288,17 +288,31 @@ public class DateUtil {
>      * @param formatIndex The index of the format, eg from ExtendedFormat=
Record.getFormatIndex
>      * @param formatString The format string, eg from FormatRecord.getFor=
matString
>      * @see #isInternalDateFormat(int)
>-     */
>-    public static boolean isADateFormat(int formatIndex, String formatStr=
ing) {
>-        // First up, is this an internal date format?
>-        if(isInternalDateFormat(formatIndex)) {
>-            return true;
>-        }
>-
>-        // If we didn't get a real string, it can't be
>-        if(formatString =3D=3D null || formatString.length() =3D=3D 0) {
>-            return false;
>-        }
>+     */=20=20
>+    private static int lastFormatIndex =3D Integer.MIN_VALUE;
>+    private static String lastFormatString =3D null;
>+    private static boolean isADateFormatCache =3D false;
>+=20=20=20=20
>+    public static synchronized boolean isADateFormat(int formatIndex, Str=
ing formatString) {
>+=20=20=20=20=20=20=20
>+       if (formatIndex =3D=3D lastFormatIndex && formatString !=3D null &=
& formatString.equals(lastFormatString)) {
>+          return isADateFormatCache;
>+       }
>+=20=20=20=20=20=20=20
>+       lastFormatIndex =3D formatIndex;
>+       lastFormatString =3D formatString;
>+=20=20=20=20=20=20=20
>+       // First up, is this an internal date format?
>+       if (isInternalDateFormat(formatIndex)) {
>+          isADateFormatCache =3D true;
>+          return true;
>+       }
>+
>+       // If we didn't get a real string, it can't be
>+       if(formatString =3D=3D null || formatString.length() =3D=3D 0) {
>+          isADateFormatCache =3D false;
>+          return false;
>+       }
>=20
>         String fs =3D formatString;
>         /*if (false) {
>@@ -348,6 +362,7 @@ public class DateUtil {
>=20
>         // short-circuit if it indicates elapsed time: [h], [m] or [s]
>         if(date_ptrn4.matcher(fs).matches()){
>+            isADateFormatCache =3D true;
>             return true;
>         }
>=20
>@@ -367,7 +382,9 @@ public class DateUtil {
>         // Otherwise, check it's only made up, in any case, of:
>         //  y m d h s - \ / , . :
>         // optionally followed by AM/PM
>-        return date_ptrn3.matcher(fs).matches();
>+        boolean result =3D date_ptrn3.matcher(fs).matches();
>+        isADateFormatCache =3D result;
>+        return result;
>     }
>=20
>     /**

--=20
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