Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id D281CC0D for ; Wed, 9 Dec 2015 06:36:27 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-io0-f180.google.com (mail-io0-f180.google.com [209.85.223.180]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 9503F107 for ; Wed, 9 Dec 2015 06:36:23 +0000 (UTC) Received: by iofh3 with SMTP id h3so49344087iof.3 for ; Tue, 08 Dec 2015 22:36:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=KjntKa94AFzQaXw9/NOynwpqP9pbEidQw8e6n3mXng4=; b=qweWKikYu7SMVWHmDEmmB6cnXB0/bnkSyQaTDJUgTXhcPyPDw/meOynTBez77C74vh RqckCSQWyrhaLso1VQmp7snGYMwfZQ3cqNGvRTypv8Xkj6Ah61QIhcFC+Pjoxdv9aRpb cOQgxxST3P/e2aAZ5F6AQxBpgjwpBTDgjejJ5gBAioPxhZF0DcpJEXH6B5KlX0Nfa8fh /QthmifaUs/yKHuavzRsr/VyhlFjplfPPOMlz/uT4ls7cbwlFvX6Zppm1XDhbndzFvRv 2v+3JnTI6yvlnosxM4dcPwyxQcnvPJU0EybdyrchvF32fgibLQqlqbEvrtF0c0VQDrNO r1Xw== MIME-Version: 1.0 X-Received: by 10.107.14.137 with SMTP id 131mr3607442ioo.69.1449642983023; Tue, 08 Dec 2015 22:36:23 -0800 (PST) Received: by 10.107.137.226 with HTTP; Tue, 8 Dec 2015 22:36:22 -0800 (PST) In-Reply-To: References: <20151208110752.GA31180@amethyst.visucore.com> Date: Wed, 9 Dec 2015 00:36:22 -0600 Message-ID: From: Ryan Butler To: Gregory Maxwell Content-Type: multipart/alternative; boundary=001a113fdfd20e11cd0526714fff X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Wed, 09 Dec 2015 06:37:54 +0000 Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] Capacity increases for the Bitcoin system. X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Dec 2015 06:36:27 -0000 --001a113fdfd20e11cd0526714fff Content-Type: text/plain; charset=UTF-8 I see, thanks for clearing that up, I misread what Gavin stated. On Wed, Dec 9, 2015 at 12:29 AM, Gregory Maxwell wrote: > On Wed, Dec 9, 2015 at 4:44 AM, Ryan Butler wrote: > >>I agree, but nothing I have advocated creates significant technical > >>debt. It is also a bad engineering practice to combine functional > >>changes (especially ones with poorly understood system wide > >>consequences and low user autonomy) with structural tidying. > > > > I don't think I would classify placing things in consensus critical code > > when it doesn't need to be as "structural tidying". Gavin said "pile on" > > which you took as implying "a lot", he can correct me, but I believe he > > meant "add to". > > Nothing being discussed would move something from consensus critical > code to not consensus critical. > > What was being discussed was the location of the witness commitment; > which is consensus critical regardless of where it is placed. Should > it be placed in an available location which is compatible with the > existing network, or should the block hashing data structure > immediately be changed in an incompatible way to accommodate it in > order to satisfy an ascetic sense of purity and to make fraud proofs > somewhat smaller? > > I argue that the size difference in the fraud proofs is not > interesting, the disruption to the network in an incompatible upgrade > is interesting; and that if it really were desirable reorganization to > move the commitment point could be done as part of a separate change > that changes only the location of things (and/or other trivial > adjustments); and that proceeding int this fashion would minimize > disruption and risk... by making the incompatible changes that will > force network wide software updates be as small and as simple as > possible. > > >> (especially ones with poorly understood system wide consequences and low > >> user autonomy) > > > > This implies there you have no confidence in the unit tests and > functional > > testing around Bitcoin and should not be a reason to avoid refactoring. > > It's more a reason to increase testing so that you will have confidence > when > > you refactor. > > I am speaking from our engineering experience in a public, > world-wide, multi-vendor, multi-version, inter-operable, distributed > system which is constantly changing and in production contains private > code, unknown and assorted hardware, mixtures of versions, unreliable > networks, undisclosed usage patterns, and more sources of complex > behavior than can be counted-- including complex economic incentives > and malicious participants. > > Even if we knew the complete spectrum of possible states for the > system the combinatioric explosion makes complete testing infeasible. > > Though testing is essential one cannot "unit test" away all the risks > related to deploying a new behavior in the network. > --001a113fdfd20e11cd0526714fff Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I see, thanks for clearing that up, I misread what Gavin s= tated.

On We= d, Dec 9, 2015 at 12:29 AM, Gregory Maxwell <greg@xiph.org> wr= ote:
On Wed, Dec 9, 2015= at 4:44 AM, Ryan Butler <rryan= anizer@gmail.com> wrote:
>>I agree, but nothing I have advocated creates significant technical=
>>debt. It is also a bad engineering practice to combine functional >>changes (especially ones with poorly understood system wide
>>consequences and low user autonomy) with structural tidying.
>
> I don't think I would classify placing things in consensus critica= l code
> when it doesn't need to be as "structural tidying".=C2= =A0 Gavin said "pile on"
> which you took as implying "a lot", he can correct me, but I= believe he
> meant "add to".

Nothing being discussed would move something from consensus critical=
code to not consensus critical.

What was being discussed was the location of the witness commitment;
which is consensus critical regardless of where it is placed. Should
it be placed in an available location which is compatible with the
existing network, or should the block hashing data structure
immediately be changed in an incompatible way to accommodate it in
order to satisfy an ascetic sense of purity and to make fraud proofs
somewhat smaller?

I argue that the size difference in the fraud proofs is not
interesting, the disruption to the network in an incompatible upgrade
is interesting; and that if it really were desirable reorganization to
move the commitment point could be done as part of a separate change
that changes only the location of things (and/or other trivial
adjustments); and that proceeding int this fashion would minimize
disruption and risk... by making the incompatible changes that will
force network wide software updates be as small and as simple as
possible.

>> (especially ones with poorly understood system wide consequences a= nd low
>> user autonomy)
>
> This implies there you have no confidence in the unit tests and functi= onal
> testing around Bitcoin and should not be a reason to avoid refactoring= .
> It's more a reason to increase testing so that you will have confi= dence when
> you refactor.

I am speaking from our engineering experience in a=C2=A0 public,
world-wide, multi-vendor, multi-version, inter-operable, distributed
system which is constantly changing and in production contains private
code, unknown and assorted hardware, mixtures of versions, unreliable
networks, undisclosed usage patterns, and more sources of complex
behavior than can be counted-- including complex economic incentives
and malicious participants.

Even if we knew the complete spectrum of possible states for the
system the combinatioric explosion makes complete testing infeasible.

Though testing is essential one cannot "unit test" away all the r= isks
related to deploying a new behavior in the network.

--001a113fdfd20e11cd0526714fff--