From: Gregory Maxwell <greg@xiph•org>
To: Suhas Daftuar <sdaftuar@gmail•com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] "Compressed" headers stream
Date: Wed, 13 Dec 2017 00:12:45 +0000 [thread overview]
Message-ID: <CAAS2fgQiicyUO31qJP7_xxAwRvp3rx8fHN+W+0jwq1Py=7+sFg@mail.gmail.com> (raw)
In-Reply-To: <CAFp6fsHwdAbcYVdPzuDdD1OV7ibCN-ebMBi113m5-JOoJtccPQ@mail.gmail.com>
On Tue, Dec 12, 2017 at 9:07 PM, Suhas Daftuar <sdaftuar@gmail•com> wrote:
> I agree with this. Specifically the way I envisioned this working is that
> we could introduce a new 'cmpctheaders'/'getcmpcthdrs' message pair for
> syncing using this new message type, while leaving the existing
> 'headers'/'getheaders' messages unchanged. So when communicating with
> upgraded peers, we'd never use 'getheaders' messages, and we'd only use
> 'headers' messages for potentially announcing new blocks.
The question becomes there-- how should it work.
In an ideal world, we'd decide what peers to fetch headers from based
on a compact proof of the total work in their chains... but we cannot
construct such proofs in Bitcoin today.
I think that instead of that a weak heuristic is to fetch first from
the peers with the tip at the highest difficulty. Then work backwards.
See: https://en.bitcoin.it/wiki/User:Gmaxwell/Reverse_header-fetching_sync
Which is the inspiration for the current headers first sync, but
without the reverse part because the protocol didn't permit it: you
can't request a linear wad of headers that come before a header. This
is the thing I was mostly thinking of when I mentioned that we may
want to change the interface.
next prev parent reply other threads:[~2017-12-13 0:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-11 20:40 Jim Posen
2017-12-11 21:04 ` Gregory Maxwell
2017-12-11 21:56 ` Jim Posen
2017-12-11 22:41 ` Tier Nolan
2017-12-11 23:11 ` Gregory Maxwell
2017-12-12 21:07 ` Suhas Daftuar
2017-12-13 0:01 ` Gregory Maxwell
2017-12-13 0:12 ` Gregory Maxwell [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-08-28 15:50 Riccardo Casatta
2017-08-28 16:13 ` Greg Sanders
2017-08-28 16:25 ` Riccardo Casatta
2017-08-28 16:26 ` Greg Sanders
2017-09-04 14:10 ` Peter Todd
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