[Domify-cvs] better performance by making Domify more lazy !

[Kees K. <kee...@xs...>]

Hello,

I ran into some performance problems when using Domify with Xalan.

I have a bean "RegistrationMonth".
This bean has the methods :
- String getMonth()
- RegistrationBatch[] getBatches();

I queried the "RegistrationMonth" with the XPath 
"RegistrationMonth/item[month='January']".
I noticed that Domify also executed the method "getBatches()".  (Xalan 
searches all children
in search of the month-element)
This is an expensive method in my application and Xalan will do nothing 
with the content ! It
only wants the name !

So I decided to take a look at Domify and try to separate the MetaData 
(the name) and the
content (the beans). In order to get the metadata we don't need to get 
the content !
The trick is to initialize the variable wrapped (in ElementAdapter.java) 
as late as possible.
(Not when instantiating an ElementAdapter, but when accessing content !)

It was easy to do. I managed to do it with a bit of refactoring.

1. I made the object 'wrapped' private in ElementAdapter.java
2. I made a method getWrapped() and setWrapped() in ElementAdapter.java.
3. All access to the variable wrapped was replaced by calls to 
getWrapped() and
     setWrapped(). (Files: ElementAdaper.java, 
MapEntryElementAdapter.java, TypedElementAdapter.java)
4. I created a new Constructor for the ElementAdapter.java.
    The constructor needs the arguments "parentOfWrapped" and 
"methodToCreateWrapped". (It
     doesn't need the argument "wrapme" anymore).
5. I enhanced the getWrapped() method to work with the newly created 
Constructor.
    The method 'getWrapped()' will instantiate the wrapped-variable if 
"wrapped" is not set and
     "parentOfWrapped" and "methodToCreateWrapped" is set.

Until now nothing really has changed the working of domify .

6. I replaced the Constructor of ElementAdapter in the method 
"ElementAdapter.item(int index)" to
    the newly created one. This method also created through reflection 
the 'wrapped'-variable for
    the old constructor. That was removed.

Ready !

The change was remarkable. My application is flying now !
(NB: I'm using Xalan2.0 because Xalan 2.2 and Xalan 2.4 have major 
perfomance problems)

I attach all the changed files and hope somebody can put it in CVS.

Best Regards,
Kees Kuip.





The object wrapper in


This is what I did :







Domify instantiates


I have made Domify even more lazier than it is right now.