Re: About that host name resolution slowness
Re: About that host name resolution slowness
- Subject: Re: About that host name resolution slowness
- From: Stephane Sudre <email@hidden>
- Date: Wed, 2 Jun 2004 18:52:54 +0200
On mercredi, juin 2, 2004, at 06:47 PM, Allan Nathanson wrote:
On Jun 2, 2004, at 12:20 PM, Stephane Sudre wrote:
On mercredi, juin 2, 2004, at 06:02 PM, Quinn wrote:
At 17:46 +0200 2/6/04, Stephane Sudre wrote:
Stupid question: has something be made (new API, mechanism, etc...)
in Panther to improve the speed and thread safety of
gethostbyname()?
Mac OS X 10.3 introduces a new API, CFHost, that allows you to do
asynchronous lookup.
<http://developer.apple.com/samplecode/CFHostSample/
CFHostSample.html>
This should solve your threading issue. As to the speed, well
that's an entirely separate problem.
Speed is the top priority (i.e. I can give up the thread part if
needed) as I think I don't need all the extra work made by
gethostbyname to try to get an answer and a good one.
I will have a look at the res_query API suggested by J. Graessley.
Having to parse the answer (hoping that there's a RCF and it's
respected) is a minor pain if I can gain speed.
While I can understand your desire for speed I would like to make sure
you are not making any bold assumptions that a remote DNS server
should respond to a query in some finite amount of time. Yes,
ideally, all of our name-->address queries would return in less than a
second. Unfortunately, there some DNS servers that can be SLOW TO
RESPOND and the amount of network bandwidth available may be limited.
If your application says "give up after one second" then you'll miss
out on all of the queries that are answered one second after you've
given up. This is one reason why people have suggested you look
towards asynchronous solutions.
If I don't get all the answers or any answer for the query, it's fine.
My current logic is more to say: give up after 20 ms :-)
A quick look at the answer from res_query and RFC 1035 looks promising.
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