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Re: Better resolver callbacks.
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From: Daniel Stenberg via curl-library <curl-library_at_cool.haxx.se>
Date: Fri, 16 Oct 2020 15:18:04 +0200 (CEST)
On Thu, 15 Oct 2020, John Wiseman via curl-library wrote:
> I'm trying to avoid flooding the dns resolver when using multi interface. I
> know it's on the TODO list, but I think it may be doable from user side with
> callbacks.
What exactly do you want to limit? The number of names to resolve within a
certain period a time? Is this a real problem for you or are you just taking
precautions?
> For example, a callback to inform the start of lookup which passes in the
> name to be resolved. User can return some value in this callback to inform
> curl to pause on the beginning of lookup. Another callback to inform the end
> of lookup which passes in the name being resolved and the result.
It could proably get done that way, but I think that if we would work on
adding such an elaborate menanism, then couldn't we just as well add the
entire "reduce name resolver speed" thing in libcurl?
Or even: if you would be willing to add code in your application to limit the
name resolve frequency, couldn't you just as well then just hang on a little
before you add transfers using a new host name so that you can keep below the
threshold?
Date: Fri, 16 Oct 2020 15:18:04 +0200 (CEST)
On Thu, 15 Oct 2020, John Wiseman via curl-library wrote:
> I'm trying to avoid flooding the dns resolver when using multi interface. I
> know it's on the TODO list, but I think it may be doable from user side with
> callbacks.
What exactly do you want to limit? The number of names to resolve within a
certain period a time? Is this a real problem for you or are you just taking
precautions?
> For example, a callback to inform the start of lookup which passes in the
> name to be resolved. User can return some value in this callback to inform
> curl to pause on the beginning of lookup. Another callback to inform the end
> of lookup which passes in the name being resolved and the result.
It could proably get done that way, but I think that if we would work on
adding such an elaborate menanism, then couldn't we just as well add the
entire "reduce name resolver speed" thing in libcurl?
Or even: if you would be willing to add code in your application to limit the
name resolve frequency, couldn't you just as well then just hang on a little
before you add transfers using a new host name so that you can keep below the
threshold?
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Received on 2020-10-16