DO NOT REPLY [Bug 23924] New: - Enhanced performance for TagUtils.filter()

[bu...@apache.org]

DO NOT REPLY TO THIS EMAIL, BUT PLEASE POST YOUR BUG 
RELATED COMMENTS THROUGH THE WEB INTERFACE AVAILABLE AT
<http://nagoya.apache.org/bugzilla/show_bug.cgi?id=23924>.
ANY REPLY MADE TO THIS MESSAGE WILL NOT BE COLLECTED AND 
INSERTED IN THE BUG DATABASE.

http://nagoya.apache.org/bugzilla/show_bug.cgi?id=23924

Enhanced performance for TagUtils.filter()

           Summary: Enhanced performance for TagUtils.filter()
           Product: Struts
           Version: Nightly Build
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: Enhancement
          Priority: Other
         Component: Custom Tags
        AssignedTo: struts-dev@jakarta.apache.org
        ReportedBy: srowen@yahoo.com


The TagUtils.filter() method, which replaces certain characters with
corresponding XML entity references, can be easily enhanced to run much faster
and require less memory.

To summarize it can be made faster in two ways:

* Instead of building up the escape string character by character, with a call
to StringBuffer.append() for each character, it can be rewritten to copy chunks
of input at a time, avoiding many method calls, which is most of the overhead of
this method.

* In fact the method does not even need to allocate a StringBuffer until it
knows that some character in the input must be escaped. In the common case where
the input has no such characters, this avoids allocating any additional memory
at all.

Performance improvements is large when the string has no characters to be
escaped -- 1000% or more on the small and medium-sized strings I tested on. It
offers more modest improvement when the string has some escapable characters --
50-100% on small and medium-sized strings. It is only slower in contrived cases
like "<<<<>>>>".

While it is a small method, it is called many times by the Struts framework.
This is an easy and reliable change to squeeze out a little better performance
in time and memory for all applications.

Note that I created a JUnit test for this change (included) in order to verify
that the new method works as well as the current one.

Please find attached files which implement this enhancement:
* TagUtils.patchfile.txt
  Patch against the 10/19/2003 nightly build to implement the change to filter()
* TestTagUtils
  A new JUnit test case covering the filter() method
* build-test.xml.patchfile.txt
  Patch against the 10/19/2003 build-test.xml file to invoke TestTagUtils

I posted this change to the list once before with no result -- I hope this even
better version, with unit test this time, can be considered for inclusion in
Struts -- thanks!

---------------------------------------------------------------------
To unsubscribe, e-mail: struts-dev-unsubscribe@jakarta.apache.org
For additional commands, e-mail: struts-dev-help@jakarta.apache.org