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From: Tamas Blummer <tamas@bitsofproof.com>
In-Reply-To: <CABm2gDr_ePfPeWB8pEO8QNHDjUZpybVuCAdDmMxJxMaC8+2bGA@mail.gmail.com>
Date: Thu, 20 Aug 2015 09:14:11 +0200
Message-Id: <C4EA4A39-1920-4F33-822C-FBD12DF81004@bitsofproof.com>
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To: =?utf-8?Q?Jorge_Tim=C3=B3n?= <jtimon@jtimon.cc>
Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>,
	Libbitcoin <libbitcoin@lists.dyne.org>
Subject: Re: [bitcoin-dev] Libconsensus separated repository (was Bitcoin
	Core and hard forks)
Precedence: list


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Jorge,

separating script engine into libconsensus was very helpful, since =
wrapped the piece of consensus
that would least likely to be captured exactly with an implementation =
from scratch. Thank you for your
effort there.  Bits of Proof now uses its own or alternatively =
libconsensus for full validation.

I am sceptical however that a =E2=80=9Cfull=E2=80=9D consensus lib =
extracted from satoshi=E2=80=99s code is worth trying.
Not because it was impossible, but because the result would not be =
higher quality, if measured on agreement
with satoshi, than other re-implementations. It would actually be lower =
quality because of the antique tool set.

The rules outside script engine are simpler, therefore much easier to =
capture exactly. They are however
scattered around in the spaghetti and are often just a single if =
statement, also repeated elsewhere.

You would either have to very extensively refactor the code, that =
unlikely goes through as a PR, or
do what me and others did. Read satoshi code and rewrite the same. You =
have
a slight advantage of copy-paste small fragments, but I doubt the =
consensus relevant advantage of that.

Tamas Blummer

> On Aug 20, 2015, at 02:53, Jorge Tim=C3=B3n via bitcoin-dev =
<bitcoin-dev@lists.linuxfoundation.org> wrote:
>=20
>=20
> 1) Finish the libconsensus separation in an independent branch on top
> of a given version, for example 0.11.
> 2) Separate a repository from that. Alternative implementations can
> start using a full libconsensus
> 3) Rebase that branch on top of bitcoin/master and start to PR small
> groups of commits. Once the whole branch has been merged, Bitcoin Core
> can replace the consensus folder with the libconsensus subtree, so
> that Bitcoin Core itself can start using a full libconsensus.
>=20
> Ironically with this plan Bitcoin Core may not be the full node first
> implementation to use a full libconsensus.
> There will be some consensus fork bug risks during 3 (which at the
> current speed I estimate it could easily take 3 or 4 years) and there
> would be some redundant work (replicating every consensus change in
> both Bitcoin Core and libconsensus).
> On the bright side, we may be able to have a full libconsensus this
> year (which was my goal after we exposed VerifyScript in the first
> libconsensus).
>=20
> Thoughts?
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev


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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
class=3D""><div class=3D"">Jorge,</div><div class=3D""><br =
class=3D""></div><div class=3D"">separating script engine into =
libconsensus was very helpful, since wrapped the piece of =
consensus</div><div class=3D"">that would least likely to be captured =
exactly with an implementation from scratch. Thank you for =
your</div><div class=3D"">effort there. &nbsp;Bits of Proof now uses its =
own or alternatively libconsensus for full validation.</div><div =
class=3D""><br class=3D""></div><div class=3D"">I am sceptical however =
that a =E2=80=9Cfull=E2=80=9D consensus lib extracted from satoshi=E2=80=99=
s code is worth trying.&nbsp;</div><div class=3D"">Not because it was =
impossible, but because the result would not be higher quality, if =
measured on agreement</div><div class=3D"">with satoshi, than other =
re-implementations. It would actually be lower quality because of the =
antique tool set.</div><div class=3D""><br class=3D""></div><div =
class=3D"">The rules outside script engine are simpler, therefore much =
easier to capture exactly. They are however&nbsp;</div><div =
class=3D"">scattered around in the spaghetti and are often just a single =
if statement, also repeated elsewhere.</div><div class=3D""><br =
class=3D""></div><div class=3D"">You would either have to very =
extensively refactor the code, that unlikely goes through as a PR, =
or</div><div class=3D"">do what me and others did. Read satoshi code and =
rewrite the same. You have&nbsp;</div><div class=3D"">a slight advantage =
of copy-paste small fragments, but I doubt the consensus relevant =
advantage of that.</div><div class=3D""><br class=3D""></div><div =
apple-content-edited=3D"true" class=3D"">
<div style=3D"color: rgb(0, 0, 0); font-family: Helvetica; font-size: =
12px; font-style: normal; font-variant: normal; font-weight: normal; =
letter-spacing: normal; line-height: normal; orphans: auto; text-align: =
start; text-indent: 0px; text-transform: none; white-space: normal; =
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" =
class=3D"">Tamas Blummer</div><div style=3D"color: rgb(0, 0, 0); =
font-family: Helvetica; font-size: 12px; font-style: normal; =
font-variant: normal; font-weight: normal; letter-spacing: normal; =
line-height: normal; orphans: auto; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; widows: auto; word-spacing: =
0px; -webkit-text-stroke-width: 0px;" class=3D""><br =
class=3D""></div></div><div><blockquote type=3D"cite" class=3D""><div =
class=3D"">On Aug 20, 2015, at 02:53, Jorge Tim=C3=B3n via bitcoin-dev =
&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" =
class=3D"">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><br class=3D"">1) =
Finish the libconsensus separation in an independent branch on top<br =
class=3D"">of a given version, for example 0.11.<br class=3D"">2) =
Separate a repository from that. Alternative implementations can<br =
class=3D"">start using a full libconsensus<br class=3D"">3) Rebase that =
branch on top of bitcoin/master and start to PR small<br class=3D"">groups=
 of commits. Once the whole branch has been merged, Bitcoin Core<br =
class=3D"">can replace the consensus folder with the libconsensus =
subtree, so<br class=3D"">that Bitcoin Core itself can start using a =
full libconsensus.<br class=3D""><br class=3D"">Ironically with this =
plan Bitcoin Core may not be the full node first<br =
class=3D"">implementation to use a full libconsensus.<br class=3D"">There =
will be some consensus fork bug risks during 3 (which at the<br =
class=3D"">current speed I estimate it could easily take 3 or 4 years) =
and there<br class=3D"">would be some redundant work (replicating every =
consensus change in<br class=3D"">both Bitcoin Core and =
libconsensus).<br class=3D"">On the bright side, we may be able to have =
a full libconsensus this<br class=3D"">year (which was my goal after we =
exposed VerifyScript in the first<br class=3D"">libconsensus).<br =
class=3D""><br class=3D"">Thoughts?<br =
class=3D"">_______________________________________________<br =
class=3D"">bitcoin-dev mailing list<br class=3D""><a =
href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" =
class=3D"">bitcoin-dev@lists.linuxfoundation.org</a><br =
class=3D"">https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev<=
br class=3D""></div></blockquote></div><br class=3D""></body></html>=

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