These enhancements sound great. Fabrizio - what do you think about adding them? Send patches!!
Matt > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Aaron Smuts > Sent: Monday, May 24, 2004 9:54 PM > To: [EMAIL PROTECTED] > Subject: [displaytag-devel] avoiding unecessary iterations--runSimple > > > Problem: > Large lists of objects are iterated pointlessly for > most uses of display tag. Except for on the first > iteration, the CulumnTag methods do almost nothing if > you specify the property for a column. Most of the > time and empty cell is added toa Row and the Row > added to the Table Model. However, adding a row to > the table is unnecesary for most purposes, as we shall > see. The typically unncessary iterations result in > numerous method calls that dramatically hurt > performance. > > The sample paging jsp's only use a few columns--about > 4. If you add a colum the number of additional method > calls is multiplied by the number of rows for each > column. Add 8 columns and a simple paging example > that displays only 10 rows of a list of 2000 can take > over 2 seconds of iteration time and then only 15-30 > millis of real work in the TableTag doEndTag method. > This makes the run time of display tag exponential. > > > Solution: > I wanted to skip the iterations and do only the work > required. I was able to do this and get the time to > nearly O(1), on non sorts. (There is still some > iteration on building the partial list, so it is > probably really O(N), but that iteration is > negligible. Sorting is merge sort time. ) > > To do this I did a couple of things. > > 1. If the pageSize is greater than zero, I return > SKIP_BODY from TableTag doAfterBody. I did it here to > let the first colum iteration take place for building > header. (The condition to skip should take into > account more options, however.) > > 2. I pass the original list of data to TableModel. > Then, if there is paging, in getViewable data of > TableTag, I build up the rows of the TableModel that I > want to use based on what is left of the orignal list > after pulling out the chunk for the page. > > 3. If there is a sort, I made the RowSorter > Implementation able to handle any object and not just > a Row, so I can pass it the original list and not the > Row wrapped list. This was easy. I just set object1 > = obj1 (the method param). The ability to do this is > key, since it makes the initial iteration largely > unnecessary. > > Also, with the RowSorter enhancement, I was able to > skip decoration for sorts. Another great boost. > > > Result: > With the plugable RowSorter enhancement and the > runSimple changes I was able to sort without > reflection. The total work takes about 16-30 millis > for a list of 2000 items with 8 columns, whereas > before it took 2 1/2 seconds. > > This makes display tag usable for very large result > sets. > > I'm not sure what features will be unavailable with > this enhancement. My proposed option should be > configurable by setting a property like runSimple=true > or something on the table. Also the condition to > skip_body should take into account more that just > whether or not the list can be paged. > > I may have left out a few details, but it works great > for probably 99% of what anyone will do with the > library. It should be an option to runSimple or > something similar, since you can get a 200X > performance boost at modest conditions. > > I'll submit patches if there are no obvious drawbacks. > > Cheers, > > Aaron Smuts > http://jakarta.apache.org/turbine/jcs/ > > > > > > __________________________________ > Do you Yahoo!? > Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/ ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id=3149&alloc_id=8166&op=click _______________________________________________ displaytag-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/displaytag-devel ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id=3149&alloc_id=8166&op=click _______________________________________________ displaytag-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/displaytag-devel
