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[166.176.184.208]) by smtp.gmail.com with ESMTPSA id 131sm56971216pfx.92.2016.11.16.14.21.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Nov 2016 14:21:55 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (1.0) From: Eric Voskuil <eric@voskuil.org> X-Mailer: iPhone Mail (14B100) In-Reply-To: <20161116210100.GC5639@savin.petertodd.org> Date: Wed, 16 Nov 2016 14:21:53 -0800 Content-Transfer-Encoding: quoted-printable Message-Id: <1DD0AEAC-ACC9-4F09-B922-8235D528BBC5@voskuil.org> References: <CAFp6fsGmynRXLCqKAA+iBXObGOZ2h3DVW8k5L9kSfbPmL1Y-QQ@mail.gmail.com> <CEDAD65E-512A-43CA-9BD6-56F7D9E6897C@voskuil.org> <CADJgMzunxU2-7Z_ZPafNY4BPRu0x9oeh6v2dg0nUYqxJbXeGYA@mail.gmail.com> <33BFC318-0BB4-48DB-B5DC-08247FAC6E5A@voskuil.org> <CADL_X_dJ8YuDevKR4xA+PTy9D089dAeZ1F3ZwSYG6MrMvkLweg@mail.gmail.com> <A98BB7F2-7AE2-4D84-9F38-7E7E9D5D3210@voskuil.org> <CAE-z3OXdiyS_5HEFu1VLG1DH_K1QUBTSy49nXh1M4tcuoi6D_w@mail.gmail.com> <CAPWm=eUQjpELFB2A9vJ8j6Y5Zvts9YqkZYNCO0aDnNSb+VwFvg@mail.gmail.com> <20161116210100.GC5639@savin.petertodd.org> To: Peter Todd <pete@petertodd.org>, Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org> X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, MIME_QP_LONG_LINE, RCVD_IN_DNSWL_NONE 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, 16 Nov 2016 22:24:34 +0000 Subject: Re: [bitcoin-dev] [BIP Proposal] Buried Deployments X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion <bitcoin-dev.lists.linuxfoundation.org> List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>, <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe> List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/> List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org> List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help> List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>, <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe> X-List-Received-Date: Wed, 16 Nov 2016 22:21:57 -0000 I would suggest that, before discussing how best to fork the chain to meet t= his objective, we consider the objective. The implementers have acknowledged that this does not represent a performanc= e improvement. Especially given that this was apparently not initially under= stood, that alone is good reason for them to reconsider. The remaining stated objective is reduction of code complexity. Let us be ve= ry clear, a proposal to change the protocol must be considered independently= of any particular implementation of the protocol. While the implementation o= f BIP34 style activation may be hugely complex in the satoshi code, it is de= finitely not complex as a matter of necessity. Activation constitutes maybe a dozen lines of additional code in libbitcoin.= The need to hit the chain (or cache) to obtain historical header info will r= emain for proof of work, so this change doesn't even accomplish some sort of= beneficial isolation from blockchain history. So, at best, we are talking about various ways to introduce a consensus fork= so that a well designed implementation can remove a tiny amount of already= -written code and associated tests. In my opinion this is embarrassingly poo= r reasoning. It would be much more productive to reduce satoshi code complex= ity in ways that do not impact the protocol. There are a *huge* number of su= ch opportunities, and in fact activation is one of them. Once that is done, w= e can talk about forking to reduce source code complexity. These fork suggestions actually increase *necessary* complexity for any impl= antation that takes a rational approach to forks. By rational I mean *additi= ve*. Deleting rules from Bitcoin code is simply bad design. Rules are never r= emoved, they are added. A new rule to modify an old rule is simply a new rul= e. This is new and additional code. So please don't assume in this "proposal= " that this makes development simpler for other implementations, that is not= a necessary conclusion. e > On Nov 16, 2016, at 1:01 PM, Peter Todd via bitcoin-dev <bitcoin-dev@lists= .linuxfoundation.org> wrote: >=20 >> On Wed, Nov 16, 2016 at 09:32:24AM -0500, Alex Morcos via bitcoin-dev wro= te: >> I think we are misunderstanding the effect of this change. >> It's still "OK" for a 50k re-org to happen. >> We're just saying that if it does, we will now have potentially introduce= d >> a hard fork between new client and old clients if the reorg contains >> earlier signaling for the most recent ISM soft fork and then blocks which= >> do not conform to that soft fork before the block height encoded activati= on. >>=20 >> I think the argument is this doesn't substantially add to the confusion o= r >> usability of the system as its likely that old software won't even handle= >> 50k block reorgs cleanly anyway and there will clearly have to be human >> coordination at the time of the event. In the unlikely event that the ne= w >> chain does cause such a hard fork, that coordination can result in everyo= ne >> upgrading to software that supports the new rules anyway. >>=20 >> So no, I don't think we should add a checkpoint. I think we should all >> just agree to a hard fork that only has a very very slim chance of any >> practical effect. >=20 > So, conceptually, another way to deal with this is to hardcode a blockhash= > where we allow blocks in a chain ending with that blockhash to _not_ follo= w > BIP65, up until that blockhash, and any blockchain without that blockhash m= ust > respect BIP65 for all blocks in the chain. >=20 > This is a softfork: we've only added rules that made otherwise valid chain= s > invalid, and at the same time we are still accepting large reorgs (albeit u= nder > stricter rules than before). >=20 > I'd suggest we call this a exemption hash - we've exempted a particular > blockchains from a soft-forked rule that we would otherwise enforce. >=20 > --=20 > https://petertodd.org 'peter'[:-1]@petertodd.org > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev