[Catalog-sig] Mirror list detection/construction - PEP 381

[Tarek Ziadé]

On Thu, Jul 22, 2010 at 2:52 AM, Jesus Cea <jcea at jcea.es> wrote:
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> On 21/07/10 21:20, P.J. Eby wrote:
>> At 01:10 PM 7/21/2010 +0100, Paul Nasrat wrote:
>>> Given the fragility of this it seems that we might want to consider
>>> alternative mirrorlist discovery mechanism.
>>
>> As a fallback, you can of course probe addresses on a binary search, or
>> even just select a random mirror in the first place.  (If you overshoot
>> the list, you just decrease the max on your binary lookup.)
>>
>> Non-random selection is tougher to implement, since you'd need to keep
>> some kind of history to make it work effectively.  Determining the
>> length of the list is a trivial problem by comparison.
>
> Well a random shuffle is a standard operation in "random" module :-).
>
> What I usually do is to pick a random server and my previous selection
> (the first time, you choose a second random server). Then do some
> operations in BOTH and choose the faster. Complete the operation on it
> and keep it for the next time.
>
> This way you always go the fast route, but randomly and gently probe
> other nodes trying to find even other faster.

There's one more parameter to take into account I guess: the "freshness"
of the mirror, e.g. when it was last synced.