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From: Eric Voskuil <eric@voskuil.org>
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Date: Sat, 6 Mar 2021 02:26:32 -0800
Message-Id: <BFE9416D-BAC6-4772-ABA0-DC3B4784C7B7@voskuil.org>
References: <20210306092931.6jmw6o2u7a2gewwb@erisian.com.au>
In-Reply-To: <20210306092931.6jmw6o2u7a2gewwb@erisian.com.au>
To: Anthony Towns <aj@erisian.com.au>,
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Taproot activation proposal "Speedy Trial"
Precedence: list

The most sensible approach I=E2=80=99ve seen yet.

e

> On Mar 6, 2021, at 01:29, Anthony Towns via bitcoin-dev <bitcoin-dev@lists=
.linuxfoundation.org> wrote:
>=20
> =EF=BB=BFOn Fri, Mar 05, 2021 at 05:43:43PM -1000, David A. Harding via bi=
tcoin-dev wrote:
>> ## Example timeline
>> - T+0: release of one or more full nodes with activation code
>> - T+14: signal tracking begins
>> - T+28: earliest possible lock in
>> - T+104: locked in by this date or need to try a different activation pro=
cess
>> - T+194: activation (if lockin occurred)
>=20
>> ### Base activation protocol
>> The idea can be implemented on top of either Bitcoin Core's existing
>> BIP9 code or its proposed BIP8 patchset.[6]
>>    BIP9 is already part of Bitcoin Core and I think the changes being
>>    proposed would be relatively small, resulting in a small patch that
>>    could be easy to review.
>=20
> To get to specifics, here's a PR, based on #21334, that updates bip9
> to support an extra parameter to delay the transition from LOCKED_IN
> to ACTIVE until a particular timestamp is reached, and to reduce the
> activation threshold to 90%:
>=20
>  https://github.com/bitcoin/bitcoin/pull/21377
>=20
> With that in mind, I think the example timeline above could translate
> to taproot parameters of:
>=20
>  nStartTime =3D 1618358400; // April 14, 2021
>  nTimeout =3D 1626220800; // July 14 2021
>  activation_time =3D 1633046400; // October 1 2021
>=20
> That is, signalling begins with the first retarget period whose parent's
> median time is at least April 14th; and concludes with the last retarget
> period whose final block's median time is prior to July 14th; that's
> 91 days which should be about ~6.5 retarget periods, so should cover 6
> full retarget periods, but could only cover 5.  Activation is delayed
> until the first retarget period where the final block of the previous
> retarget period has a timestamp of at least October 1st.
>=20
> Note that the timeout there is prior to the expected timestamp of the
> startheight block specified in the proposal for bip8 parameters:
>=20
>  https://en.bitcoin.it/wiki/Taproot_activation_proposal_202102
>=20
> and earliest activation is after the expected release of 22.0 and hence
> the maintenance end of 0.20.
>=20
> Note also that the PR above specifies the delay as a deadline, not a
> delta between lockin and activation; so earlier lockin does not produce
> an earlier activation with the code referenced above.
>=20
> Cheers,
> aj
>=20
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