[Bug-wget] Behaviour of spanning to accepted domains

[ekrell]

Greetings,

I recently used wget in such a way that the result disagreed with my 
understanding of what should have happened. This came about during a 
small programming exercise I am currently working on; I am attempting to 
see if a large number of domains (from '-D' option) would be processed 
more quickly by using the hashtable included in hash.c. While comparing 
the speed of my hashed implementation of host checking against an 
unmodified version of wget, the standard wget did not seem to respect my 
list of accepted domains.

For the hash table version, I did the following:
In recur.c, I init a hashtable with all of the accepted domains from 
opt.domain. Ignoring (for the moment) increased memory usage, I assumed 
that this would surely be faster than the current method of checking the 
url's host.
However, when performing the check inside host.c's accept_domain 
function, I realized that I would need to parse u->host to get just the 
domain component. This involves some overhead that may make hashing not 
worth it. Also, during this entire operation, I am assuming that if it 
would provide any significant improvement, it would have most likely 
been done before my decision to try it out. Nonetheless, I've enjoyed 
playing around with it.

My first couple tests were against my own website, using a list over 
5000 domains. Both wget and wget-modified downloaded the same files, and 
at roughly the same speed. My website is so small, that I wanted 
something larger, but not so large that it would take more than a fre 
minutes. I know going around and mirroring random sites is perhaps not 
recommended behaviour (without a delay), but it worked.

I bring this up for one my two questions. Can someone recommend a better 
method of performance testing?

Having found my target website, I went ahead and ran the two wget 
versions, one after the other. When mine came out to be almost twice as 
fast, I knew to assume that something was amiss. Sure enough, wget has 
downloaded much more content.. and spanned to many more domains.

This is the command I ran for each:

<pathToVersion>/src/wget -rH -D $(cat trash/text.txt) 
williamstallings.com

Excusing the useless use of cat, text.txt contains the massive 
comma-separated list of domains.
Each of those domains is a randomly generated numeric value, expect for 
the final one: williamstallings.com

Previously, whenever I ran this test against a (smaller) website, both 
versions of wget would only recursively download those specified by my 
single "real" domain in the list. However, this time (and I did it twice 
to make sure) original wget went on to download from over 20 other 
domains.

I would appreciate it if someone could explain what is going on here. 
Seeing as this behaviour exists with the version I obtained from 
git://git.savannah.gnu.org/wget.git as well as wget from the package 
manager, I am not proclaiming "found a bug!". I imagine that I just 
misunderstand what should have taken place, since I expected to only 
have the single directory from williamstallings.com

Thanks,
Evan Krell