Re: [Monotone-devel] Re: Support for binary files, scalability andWindows port

[Zbynek Winkler]

graydon hoare wrote:

> [snip] as of 2 nights ago, I have a prototype working which 
> synchronizes block collections in a pair of sqlite databases, over a 
> TCP connection. it shows pretty good promise; the interactive protocol 
> isn't *quite* pipelined enough, plus the encodings could use some 
> tuning; it's at least twice as bulky as it needs to be. even now it 
> finds and sends the 50 missing random 512-byte blocks amongst a 
> collection of 10,000 such, with only 16k written and 130k received 
> (including the 34.7k worth of base64-encoded data blocks). it will add 
> a little overhead in the case of small collections, but the cost curve 
> is a very flat logarithm of the collection size.
>
> I'm not certain a 256-ary tree is the best fan-out though; I only 
> chose it because it's easy to prototype in ASCII. a 16-ary tree is 
> equally easy, so maybe I'll run through that too.. it is a subtle 
> issue: larger nodes mean fewer round trips and less protocol chatter, 
> but also more retransmission of hash values for unchanged portions of 
> the tree and a bit more asymmetry in the transmit/receive load (as in 
> this instance). I'll see if it's sufficiently easy to make the whole 
> protocol and hashtree calculator depend on a couple template 
> constants, and try to write it that way so we can wiggle it around and 
> find a sweet spot.

How is it going?
Zbynek

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Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic