š
Original date posted:2015-10-15
š Original message:Adam,
The remaining 14 bits can be used to soft fork in finer granularity in the
future.
Alex
On Thu, Oct 15, 2015 at 12:37 PM, Adam Back <adam at cypherspace.org> wrote:
> Does that pre-judge that block interval would never change from
> 10mins? Eg say with IBLT or fountain codes etc and security arguments
> for the current limitations of them are found, such that orphan rates
> can remain low in a decentralised way with 1min blocks, then the
> locktime granularity would be coarse relative to the block interval
> (with 512s locktime granularity.
>
> Adam
>
> On 15 October 2015 at 18:27, Btc Drak via bitcoin-dev
> <bitcoin-dev at lists.linuxfoundation.org> wrote:
> > Alex,
> >
> > I am sorry for not communicating more clearly. Mark and I discussed your
> > concerns from the last meeting and he made the change. The BIP text still
> > needs to be updated, but the discussed change was added to the PR, albeit
> > squashed making it more non-obvious. BIP68 now explicitly uses 16 bits
> with
> > a bitmask. Please see the use of SEQUENCE_LOCKTIME_MASK and
> > SEQUENCE_LOCKTIME_GRANULARITY in the PR
> > https://github.com/bitcoin/bitcoin/pull/6312.
> >
> > /* If CTxIn::nSequence encodes a relative lock-time, this mask is
> > * applied to extract that lock-time from the sequence field. */
> > static const uint32_t SEQUENCE_LOCKTIME_MASK = 0x0000ffff;
> >
> > /* In order to use the same number of bits to encode roughly the
> > * same wall-clock duration, and because blocks are naturally
> > * limited to occur every 600s on average, the minimum granularity
> > * for time-based relative lock-time is fixed at 512 seconds.
> > * Converting from CTxIn::nSequence to seconds is performed by
> > * multiplying by 512 = 2^9, or equivalently shifting up by
> > * 9 bits. */
> > static const int SEQUENCE_LOCKTIME_GRANULARITY = 9;
> >
> > I am also much happier with this last tightening up of the specification
> > because it removes ambiguity. 512s granularity makes sense within the
> > context of the 10 minute block target.
> >
> > Thank you for spending so much time carefully considering this BIP and
> > reference implementation and please let me know if there there are any
> > remaining nits so we can get those addressed.
> >
> >
> >
> >
> >
> > On Thu, Oct 15, 2015 at 2:47 PM, Alex Morcos via bitcoin-dev
> > <bitcoin-dev at lists.linuxfoundation.org> wrote:
> >>
> >> Mark,
> >>
> >> You seemed interested in changing BIP 68 to use 16 bits for sequence
> >> number in both the block and time versions, making time based sequence
> >> numbers have a resolution of 512 seconds.
> >>
> >> I'm in favor of this approach because it leaves aside 14 bits for
> further
> >> soft forks within the semantics of BIP 68.
> >>
> >> It would be nice to know if you're planning this change, and perhaps
> >> people can hold off on review until things are finalized.
> >>
> >> I'd cast my "vote" against BIP 68 without this change, but am also open
> to
> >> being convinced otherwise.
> >>
> >> What are other peoples opinions on this?
> >>
> >> On Thu, Oct 8, 2015 at 9:38 PM, Rusty Russell via bitcoin-dev
> >> <bitcoin-dev at lists.linuxfoundation.org> wrote:
> >>>
> >>> Peter Todd <pete at petertodd.org> writes:
> >>> > On Tue, Oct 06, 2015 at 12:28:49PM +1030, Rusty Russell wrote:
> >>> >> Peter Todd via bitcoin-dev <bitcoin-dev at lists.linuxfoundation.org>
> >>> >> writes:
> >>> >> > However I don't think we've done a good job showing why we need to
> >>> >> > implement this feature via nSequence.
> >>> >>
> >>> >> It could be implemented in other ways, but nSequence is the neatest
> >>> >> and
> >>> >> most straightforward I've seen.
> >>> >>
> >>> >> - I'm not aware of any other (even vague) proposal for its use?
> >>> >> Enlighten?
> >>> >
> >>> > There's three that immediately come to mind:
> >>> >
> >>> > Gregory Maxwell has proposed it as a way of discouraging miners from
> >>> > reorging chains, by including some of the low-order bits of a
> previous
> >>> > block header in nSequence.
> >>> >
> >>> > A few people have proposed implementing proof-of-stake blocksize
> voting
> >>> > with nSequence.
> >>>
> >>> Excellent, thanks! It's good to have such ideas as a compass. PoS
> >>> voting seems like it won't be a problem in 5 bits.
> >>>
> >>> The "prevbits" idea would want more bits; naively 64 would be good, but
> >>> I think there are some tricks we can use to make 32 work OK. We would
> >>> have to then split between nLocktime (if available) and multiple
> >>> nSequence fields, and it would weaken it for some txs.
> >>>
> >>> There is one easy solution: change the BIP wording from:
> >>>
> >>> -For transactions with an nVersion of 2 or greater,
> >>> +For transactions with an nVersion of 2,
> >>>
> >>> And on every tx bump, we decide whether to keep this scheme (mempool
> >>> would enforce it always).
> >>>
> >>> Cheers,
> >>> Rusty.
> >>> _______________________________________________
> >>> bitcoin-dev mailing list
> >>> bitcoin-dev at lists.linuxfoundation.org
> >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >>
> >>
> >>
> >> _______________________________________________
> >> bitcoin-dev mailing list
> >> bitcoin-dev at lists.linuxfoundation.org
> >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >>
> >
> >
> > _______________________________________________
> > bitcoin-dev mailing list
> > bitcoin-dev at lists.linuxfoundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >
>
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Alex Morcos [ARCHIVE] /
npub10zā¦3xfzw
2023-06-07 19:42:30
in reply to nevent1qā¦a38x
Author Public Key
npub10z4xjfgftd3fm9dfu7dw6mkemgyhxgumcmhd7yd0ggjq7rsaw4wqa3xfzwPublished at
2023-06-07 19:42:30Event JSON
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Original date posted:2015-10-15\nš Original message:Adam,\n\nThe remaining 14 bits can be used to soft fork in finer granularity in the\nfuture.\n\nAlex\n\n\nOn Thu, Oct 15, 2015 at 12:37 PM, Adam Back \u003cadam at cypherspace.org\u003e wrote:\n\n\u003e Does that pre-judge that block interval would never change from\n\u003e 10mins? Eg say with IBLT or fountain codes etc and security arguments\n\u003e for the current limitations of them are found, such that orphan rates\n\u003e can remain low in a decentralised way with 1min blocks, then the\n\u003e locktime granularity would be coarse relative to the block interval\n\u003e (with 512s locktime granularity.\n\u003e\n\u003e Adam\n\u003e\n\u003e On 15 October 2015 at 18:27, Btc Drak via bitcoin-dev\n\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e \u003e Alex,\n\u003e \u003e\n\u003e \u003e I am sorry for not communicating more clearly. Mark and I discussed your\n\u003e \u003e concerns from the last meeting and he made the change. The BIP text still\n\u003e \u003e needs to be updated, but the discussed change was added to the PR, albeit\n\u003e \u003e squashed making it more non-obvious. BIP68 now explicitly uses 16 bits\n\u003e with\n\u003e \u003e a bitmask. Please see the use of SEQUENCE_LOCKTIME_MASK and\n\u003e \u003e SEQUENCE_LOCKTIME_GRANULARITY in the PR\n\u003e \u003e https://github.com/bitcoin/bitcoin/pull/6312.\n\u003e \u003e\n\u003e \u003e /* If CTxIn::nSequence encodes a relative lock-time, this mask is\n\u003e \u003e * applied to extract that lock-time from the sequence field. */\n\u003e \u003e static const uint32_t SEQUENCE_LOCKTIME_MASK = 0x0000ffff;\n\u003e \u003e\n\u003e \u003e /* In order to use the same number of bits to encode roughly the\n\u003e \u003e * same wall-clock duration, and because blocks are naturally\n\u003e \u003e * limited to occur every 600s on average, the minimum granularity\n\u003e \u003e * for time-based relative lock-time is fixed at 512 seconds.\n\u003e \u003e * Converting from CTxIn::nSequence to seconds is performed by\n\u003e \u003e * multiplying by 512 = 2^9, or equivalently shifting up by\n\u003e \u003e * 9 bits. */\n\u003e \u003e static const int SEQUENCE_LOCKTIME_GRANULARITY = 9;\n\u003e \u003e\n\u003e \u003e I am also much happier with this last tightening up of the specification\n\u003e \u003e because it removes ambiguity. 512s granularity makes sense within the\n\u003e \u003e context of the 10 minute block target.\n\u003e \u003e\n\u003e \u003e Thank you for spending so much time carefully considering this BIP and\n\u003e \u003e reference implementation and please let me know if there there are any\n\u003e \u003e remaining nits so we can get those addressed.\n\u003e \u003e\n\u003e \u003e\n\u003e \u003e\n\u003e \u003e\n\u003e \u003e\n\u003e \u003e On Thu, Oct 15, 2015 at 2:47 PM, Alex Morcos via bitcoin-dev\n\u003e \u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e \u003e\u003e\n\u003e \u003e\u003e Mark,\n\u003e \u003e\u003e\n\u003e \u003e\u003e You seemed interested in changing BIP 68 to use 16 bits for sequence\n\u003e \u003e\u003e number in both the block and time versions, making time based sequence\n\u003e \u003e\u003e numbers have a resolution of 512 seconds.\n\u003e \u003e\u003e\n\u003e \u003e\u003e I'm in favor of this approach because it leaves aside 14 bits for\n\u003e further\n\u003e \u003e\u003e soft forks within the semantics of BIP 68.\n\u003e \u003e\u003e\n\u003e \u003e\u003e It would be nice to know if you're planning this change, and perhaps\n\u003e \u003e\u003e people can hold off on review until things are finalized.\n\u003e \u003e\u003e\n\u003e \u003e\u003e I'd cast my \"vote\" against BIP 68 without this change, but am also open\n\u003e to\n\u003e \u003e\u003e being convinced otherwise.\n\u003e \u003e\u003e\n\u003e \u003e\u003e What are other peoples opinions on this?\n\u003e \u003e\u003e\n\u003e \u003e\u003e On Thu, Oct 8, 2015 at 9:38 PM, Rusty Russell via bitcoin-dev\n\u003e \u003e\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e \u003e\u003e\u003e\n\u003e \u003e\u003e\u003e Peter Todd \u003cpete at petertodd.org\u003e writes:\n\u003e \u003e\u003e\u003e \u003e On Tue, Oct 06, 2015 at 12:28:49PM +1030, Rusty Russell wrote:\n\u003e \u003e\u003e\u003e \u003e\u003e Peter Todd via bitcoin-dev \u003cbitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e \u003e\u003e\u003e \u003e\u003e writes:\n\u003e \u003e\u003e\u003e \u003e\u003e \u003e However I don't think we've done a good job showing why we need to\n\u003e \u003e\u003e\u003e \u003e\u003e \u003e implement this feature via nSequence.\n\u003e \u003e\u003e\u003e \u003e\u003e\n\u003e \u003e\u003e\u003e \u003e\u003e It could be implemented in other ways, but nSequence is the neatest\n\u003e \u003e\u003e\u003e \u003e\u003e and\n\u003e \u003e\u003e\u003e \u003e\u003e most straightforward I've seen.\n\u003e \u003e\u003e\u003e \u003e\u003e\n\u003e \u003e\u003e\u003e \u003e\u003e - I'm not aware of any other (even vague) proposal for its use?\n\u003e \u003e\u003e\u003e \u003e\u003e Enlighten?\n\u003e \u003e\u003e\u003e \u003e\n\u003e \u003e\u003e\u003e \u003e There's three that immediately come to mind:\n\u003e \u003e\u003e\u003e \u003e\n\u003e \u003e\u003e\u003e \u003e Gregory Maxwell has proposed it as a way of discouraging miners from\n\u003e \u003e\u003e\u003e \u003e reorging chains, by including some of the low-order bits of a\n\u003e previous\n\u003e \u003e\u003e\u003e \u003e block header in nSequence.\n\u003e \u003e\u003e\u003e \u003e\n\u003e \u003e\u003e\u003e \u003e A few people have proposed implementing proof-of-stake blocksize\n\u003e voting\n\u003e \u003e\u003e\u003e \u003e with nSequence.\n\u003e \u003e\u003e\u003e\n\u003e \u003e\u003e\u003e Excellent, thanks! It's good to have such ideas as a compass. PoS\n\u003e \u003e\u003e\u003e voting seems like it won't be a problem in 5 bits.\n\u003e \u003e\u003e\u003e\n\u003e \u003e\u003e\u003e The \"prevbits\" idea would want more bits; naively 64 would be good, but\n\u003e \u003e\u003e\u003e I think there are some tricks we can use to make 32 work OK. We would\n\u003e \u003e\u003e\u003e have to then split between nLocktime (if available) and multiple\n\u003e \u003e\u003e\u003e nSequence fields, and it would weaken it for some txs.\n\u003e \u003e\u003e\u003e\n\u003e \u003e\u003e\u003e There is one easy solution: change the BIP wording from:\n\u003e \u003e\u003e\u003e\n\u003e \u003e\u003e\u003e -For transactions with an nVersion of 2 or greater,\n\u003e \u003e\u003e\u003e +For transactions with an nVersion of 2,\n\u003e \u003e\u003e\u003e\n\u003e \u003e\u003e\u003e And on every tx bump, we decide whether to keep this scheme (mempool\n\u003e \u003e\u003e\u003e would enforce it always).\n\u003e \u003e\u003e\u003e\n\u003e \u003e\u003e\u003e Cheers,\n\u003e \u003e\u003e\u003e Rusty.\n\u003e \u003e\u003e\u003e _______________________________________________\n\u003e \u003e\u003e\u003e bitcoin-dev mailing list\n\u003e \u003e\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003e\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e \u003e\u003e\n\u003e \u003e\u003e\n\u003e \u003e\u003e\n\u003e \u003e\u003e _______________________________________________\n\u003e \u003e\u003e bitcoin-dev mailing list\n\u003e \u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e \u003e\u003e\n\u003e \u003e\n\u003e \u003e\n\u003e \u003e _______________________________________________\n\u003e \u003e bitcoin-dev mailing list\n\u003e \u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e \u003e\n\u003e\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20151015/fabd688e/attachment-0001.html\u003e",
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