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From "George Sexton" <gsex...@mhsoftware.com>
Subject RE: Code Submission - Wild Card Aliases
Date Tue, 03 May 2005 15:46:59 GMT
Oops, my bad.

In actuality, 1 million requests is taking 8,000,000 microseconds on my
computer, or 8 microseconds per mapper call.

The modification adds 0.5 microseconds to the call. I think given hideous
monstrosities like Struts that are layered on top of Tomcat, 0.5
microseconds per call is hardly worth caring about. The real reason the code
is slower is because I simplified the list management. The list management
code is extra-ordinarily difficult to follow. It is filled with a lot of
special case items that required a deep understanding of the whole in order
to modify it. An example of this is the find routine that returns the
position of the item, or the insert position. This leaves the code filled
with oddities like getting back a result, and then doing a case-insensitive
string comparison to see if found really found the right thing.

If the mapper were modified very often, it would be a major source of
problems. In general I favor maintainability and correctness over raw speed.

The DOS issue raised by Jin Yu could be a real issue. I'll think it over
some more.


George Sexton
MH Software, Inc.
http://www.mhsoftware.com/
Voice: 303 438 9585
  

> -----Original Message-----
> From: Remy Maucherat [mailto:remm@apache.org] 
> Sent: Tuesday, May 03, 2005 8:04 AM
> To: Tomcat Developers List
> Subject: Re: Code Submission - Wild Card Aliases
> 
> George Sexton wrote:
> > I have completed the coding in o.a.t.u.http.mapper.Mapper 
> to implement
> > wild-card aliases.
> > 
> > If a request for a host is made, and that host is not 
> found, the code tests
> > the host and aliases list and looks for wild-cards.
> > 
> > So, a host name of www.mydomain.com would match an alias of 
> *.mydomain.com.
> > This additional level of testing is only done if the the 
> presented host name
> > is not found in the standard host list. Once a host is 
> found via wild-card,
> > it is added to the standard host list. Subsequent requests 
> for that host
> > name will find it via the standard search mechanism.
> > 
> > As part of the conversion, I re-worked the test harness 
> code and expanded it
> > to be a lot more complete. The output of the new test 
> harness with the
> > unmodified Mapper code matches identically the output of 
> the modified
> > mapper. IOW, I'm 99% confident that the behavior of the 
> Mapper matches the
> > old Mapper.
> > 
> > The time differential between the two runs is around 500ms 
> over 1 million
> > iterations. I.E. the original code runs in 8000 ms for 1 
> million iterations
> > of the testing code, while the new code takes 8500ms. The 
> new code adds
> > approximately 0.05 % to the time for a lookup.
> > 
> > I am running the modified mapper code with 5.5.9 on an 
> installation that has
> > 40 hosts configured and it seems to be working correctly.
> > 
> > I'd really appreciate it if a committer would get this 
> added to the source
> > tree.
> > 
> > The complete modified Mapper.java file can be downloaded from:
> > 
> > http://www.mhsoftware.com/~gsexton/Mapper.java
> > 
> > If a decision is made to reject this patch, I'd appreciate 
> knowing why. If
> > there's something wrong from a coding or style perspective, 
> I'd be happy to
> > fix things.
> 
> -1 for lower performance and questionable use case.
> (I didn't get the patch, but I don't really wish to)
> 
> Rémy
> 
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