Re: Re: Query Hit bitprint

Hi Philippe,

When a download completes, LimeWire is doing an additional
verification of the entire file against the SHA1 hash.  During the
progress of a download, it is comparing it against the tiger tree
chunks, and sharing only those pieces which it has validated.

LimeWire downloads files randomly, but prefers to keep the number of
disparate chunks to a minimum.  Also, if the file it is downloading
can be previewed (and the computer has not been idle for a period of
time), it will prefer to continue extending the file from the
beginning.

Sam

On 9/12/07, Philippe Verdy <[email protected]> wrote:
>
>
> > -----Message d'origine-----
> > De: [email protected] [mailto:[email protected]] De la part
> > de Sam Berlin
> > Envoyé: mercredi 12 septembre 2007 17:25
> > À: [email protected]
> > Objet: Re: [the_gdf] Re: Query Hit bitprint
> >
> > Your knowledge of LimeWire's download verification appears to be a
> > little outdated, Philippe.
> >
> > LimeWire currently does everything you are describing, including
> > verifying pieces of the file as it downloads.
> >
> > (The only thing it does not do is know the tiger tree ahead of time,
> > but that isn't necessary for any of the other steps.  Swarmed
> > downloads can make an intelligent guess about the tree size and then
> > change their guess once the actual size is discovered.)
>
> Sam, what is LimeWire doing when a file download completes? It displays :
> "verifying file" which takes some time.
>
> Doesn't this mean that the downloads are NOT checked duing the long period
> of time when the content is being downloaded (and worse, LimeWire will still
> share the existing fragments without being sure they are correct).
>
> From what I have seen, LimeWire still downloads files linearily, even when
> there are multiple sources serving their data at different speed.
>
> I am still amazed to see that there are files shared sometimes by 50-200
> users for which none of them is responding, or just one from time to time,
> despite there are are tons of users waiting for that file and that could
> help distributing the work load securely. I've checked this many times, and
> these many sources were NOT spamming sources.
>
> My opinion is that as soon as the THEX data is available and usable for the
> fragments we have already downloaded, they should be checked immediately
> against that data, and then the validated fragments shared immediately, and
> the other fragments dropped and looked for from other sources. This will
> remain true, even if we find more finely grained THEX, but the most basic
> THEX data will contain the hashes for at least 100 fragments of the file,
> much enough to verify every source long before the download completes.
>
> If we still depend on the final verification, we are still wasting bandwidth
> and time, locally and remotely.
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>