Re: [Bitcoin-development] Version bits proposal
Thanks for all the comments. I plan to address the feedback and work on an implementation next week. On Tue, May 26, 2015 at 6:48 PM, Pieter Wuille pieter.wui...@gmail.com wrote: Hello everyone, here is a proposal for how to coordinate future soft-forking consensus changes: https://gist.github.com/sipa/bf69659f43e763540550 It supports multiple parallel changes, as well as changes that get permanently rejected without obstructing the rollout of others. Feel free to comment. As the gist does not support notifying participants of new comments, I would suggest using the mailing list instead. This is joint work with Peter Todd and Greg Maxwell. -- Pieter -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
Agreed, there is no need to misuse the version field as well. There is more than enough variability you could roll in the merkle tree including and excluding transactions, and the scriptSig of the coinbase transaction, which also influences the merkle root. I have a fundamental dislike of retroactively changing semantics, and the version field should be used just for that: a version. I don't even particularly like flagging support for a fork in the version field, but since I have no better solution, count me as supporting Sipa's proposal. We definitely need a more comfortable way of rolling out new features. Regards, Chris On Thu, May 28, 2015 at 3:08 AM Patrick Strateman patrick.strate...@gmail.com wrote: There is absolutely no reason to do this. Any reasonable micro-controller can build merkle tree roots significantly faster than is necessary. 1 Th/s walks the nonce range once every 4.3ms. The largest valid merkle trees are 14 nodes high. That translates to 28 SHA256 ops per 4.3ms or 6511 SHA256 ops/second. For reference an RPi 1 model B does 2451050 SHA256 ops/second. On 05/27/2015 03:52 PM, Sergio Lerner wrote: I like the idea but I think we should leave at least 16 bits of the version fixed as an extra-nonce. If we don't then miners may use them as a nonce anyway, and mess with the soft-fork voting system. My original proposal was this: https://github.com/bitcoin/bitcoin/pull/5102 Best regards -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
I think it would be better to have the deadlines set as block counts. That eliminates the need to use the median time mechanism. The deadline could be matched to a start-line. The definition would then be something like BIP 105 Start block: 325000 End block: 35 Activation: 750 of 1000 Implication: 950 of 1000 Bit: 9 This would allow creation of a simple table of known BIPs. It also keeps multiple users of the bit as strictly separate. The alternative to the start time is that it is set equal to the deadline or implication time of the previous user of the bit. Was the intention to change the 95% rule. You need 750 of the last 1000 to activate and then must wait at least 1000 for implication? On Wed, May 27, 2015 at 4:51 AM, Jorge Timón jti...@jtimon.cc wrote: It would also help to see the actual code changes required, which I'm sure will be much shorter than the explanation itself. On May 27, 2015 5:47 AM, Luke Dashjr l...@dashjr.org wrote: On Wednesday, May 27, 2015 1:48:05 AM Pieter Wuille wrote: Feel free to comment. As the gist does not support notifying participants of new comments, I would suggest using the mailing list instead. I suggest adding a section describing how this interacts with and changes GBT. Currently, the client tells the server what the highest block version it supports is, and the server indicates a block version to use in its template, as well as optional instructions for the client to forcefully use this version despite its own maximum version number. Making the version a bitfield contradicts the increment-only assumption of this design, and since GBT clients are not aware of overall network consensus state, reused bits can easily become confused. I suggest, therefore, that GBT clients should indicate (instead of a maximum supported version number) a list of softforks by identifier keyword, and the GBT server respond with a template indicating: - An object of softfork keywords to bit values, that the server will accept. - The version number, as presently conveyed, indicating the preferred softfork flags. Does this sound reasonable, and/or am I missing anything else? Luke -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
On Wed, May 27, 2015 at 11:15 AM, Peter Todd p...@petertodd.org wrote:
The median time mechanism is basically a way for hashing power to show
what time they think it is. Equally, the nVersion soft-fork mechanism is
a way for hashing power to show what features they want to support.
Fair enough. It means slightly more processing, but the median time could
be cached in the header index, so no big deal.
Block counts are inconvenient for planning, as there's no guarantee
they'll actually happen in any particular time frame, forward and back.
I don't think the deadline needs to be set that accurately. A roughly 6
month deadline should be fine, but as you say a majority of miners is
needed to abuse the median time and it is already a miner poll.
Perhaps the number of blocks used in the median could be increased to
reduce noise.
The median time could be median of the last 144 blocks plus 12 hours.
If you assume no large reorganizations, your table of known BIPs can
just as easily be a list of block heights even if the median time
mechanism is used.
I think it makes it easier to write the code. It reduced the state that
needs to be stored per BIP. You don't need to check if the previous bips
were all accepted.
Each bit is assigned to a particular BIP for a particular range of times
(or blocks).
If block numbers were used for the deadline, you just need to check the
block index for the deadline block.
enum {
BIP_INACTIVE = 0,
BIP_ACTIVE,
BIP_LOCKED
BIP_INVALID_BLOCK,
}
int GetBIPState(block, bip)
{
if (block.height == bip.deadline) // Bit must be set to match
locked/unlocked at deadline
{
int bipState = check_supermajority(...);
if (bipState == BIP_LOCKED (block.nVersion bip.bit)
return BIP_LOCKED;
if (bipState != BIP_LOCKED (block.nVersion (~bip.bit)))
return BIP_INACTIVE;
return BIP_INVALID_BLOCK;
}
if (block.height deadline) // Look at the deadline block to determine
if the BIP is locked
return (block_index[deadline].nVersion bip_bit) != 0 ? BIP_LOCKED
: BIP_INACTIVE;
if (block.height startline + I) // BIP cannot activate/lock until
startline + implicit window size
return INACTIVE;
return check_supermajority() // Check supermajority of bit
}
The block at height deadline would indicate if the BIP was locked in.
Block time could still be used as long as the block height was set after
that. The deadline_time could be in six months. The startline height
could be the current block height and the deadline_height could be
startline + 35000.
The gives roughly
start time = now
deadline time = now + six months
deadline height = now + eight months
The deadline height is the block height when the bit is returned to the
pool but the deadline time is when the BIP has to be accepted.
It also helps with the warning system. For each block height, there is a
set of known BIP bits that are allowed. Once the final deadline is passed,
the expected mask is zeros.
On Wed, May 27, 2015 at 11:15 AM, Jorge Timón jti...@jtimon.cc wrote:
On May 27, 2015 11:35 AM, Tier Nolan tier.no...@gmail.com wrote:
Was the intention to change the 95% rule. You need 750 of the last 1000
to activate and then must wait at least 1000 for implication?
You need 75% to start applying it, 95% to start rejecting blocks that
don't apply it.
I think the phrasing is ambiguous. I was just asking for clarification.
Whenever I out of any W *subsequent* blocks (regardless of the block
itself) have bit B set,
That suggests that the I of W blocks for the 95% rule must happen after
activation. This makes the rule checking harder. Easier to use the
current system, where blocks that were part of the 750 rule also count
towards the 95% rule.
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Re: [Bitcoin-development] Version bits proposal
On Wed, May 27, 2015 at 10:35:03AM +0100, Tier Nolan wrote: I think it would be better to have the deadlines set as block counts. That eliminates the need to use the median time mechanism. The median time mechanism is basically a way for hashing power to show what time they think it is. Equally, the nVersion soft-fork mechanism is a way for hashing power to show what features they want to support. Block counts are inconvenient for planning, as there's no guarantee they'll actually happen in any particular time frame, forward and back. There's no particular incentive problems here - the median time clearly shows support by a majority of hashing power - so I don't see any reason to make planning more difficult. The deadline could be matched to a start-line. The definition would then be something like BIP 105 Start block: 325000 End block: 35 Activation: 750 of 1000 Implication: 950 of 1000 Bit: 9 This would allow creation of a simple table of known BIPs. It also keeps multiple users of the bit as strictly separate. If you assume no large reorganizations, your table of known BIPs can just as easily be a list of block heights even if the median time mechanism is used. If you do assume there may be large reorganizations you can't have a simple table -- 'peter'[:-1]@petertodd.org 01643f7706f3dcbc3a386e4c1bfba852ff628d8024f875b6 signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
On May 27, 2015 11:35 AM, Tier Nolan tier.no...@gmail.com wrote: Was the intention to change the 95% rule. You need 750 of the last 1000 to activate and then must wait at least 1000 for implication? You need 75% to start applying it, 95% to start rejecting blocks that don't apply it. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
There is absolutely no reason to do this. Any reasonable micro-controller can build merkle tree roots significantly faster than is necessary. 1 Th/s walks the nonce range once every 4.3ms. The largest valid merkle trees are 14 nodes high. That translates to 28 SHA256 ops per 4.3ms or 6511 SHA256 ops/second. For reference an RPi 1 model B does 2451050 SHA256 ops/second. On 05/27/2015 03:52 PM, Sergio Lerner wrote: I like the idea but I think we should leave at least 16 bits of the version fixed as an extra-nonce. If we don't then miners may use them as a nonce anyway, and mess with the soft-fork voting system. My original proposal was this: https://github.com/bitcoin/bitcoin/pull/5102 Best regards -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
I like the idea but I think we should leave at least 16 bits of the version fixed as an extra-nonce. If we don't then miners may use them as a nonce anyway, and mess with the soft-fork voting system. My original proposal was this: https://github.com/bitcoin/bitcoin/pull/5102 Best regards -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 2015/5/26 21:48, Pieter Wuille wrote: here is a proposal for how to coordinate future soft-forking consensus changes: https://gist.github.com/sipa/bf69659f43e763540550 It supports multiple parallel changes, as well as changes that get permanently rejected without obstructing the rollout of others. Feel free to comment. As the gist does not support notifying participants of new comments, I would suggest using the mailing list instead. Hi Pieter. Thanks for posting the proposal. I think the concept itself is pretty solid. I know some people have been proposing alternate methods too. I hope they'll share here, assuming they haven't already. As is, my comments concern typos and general copy editing. - - Just speaking in general, I found the BIP to be a bit hard to read. AFAIK, the basic facts are accurate. I just found myself having to re-read certain passages two or three times. A little polish wouldn't hurt. For example, using the it pronoun can be confusing, such as multiple uses in the abstract. Specifying what it is (e.g., The proposed change relies on...) would really help. In addition, the way the W value is handled seems like it could be improved a bit. I know the wording is accurate. Seeing 1000 change to 1001 is still a little weird. - - In Multi-stage soft forks, I presume the second sentence should end as follows: [...] with additional validation rules that get enabled one by _one_. Depending on semantics, I'd consider changing one by one to incremental steps, but that's your call. - - I found the High bits section to be confusing at first. It looks like you chose to show everything as little endian data, matching what's actually in the block. My personal preference would be to represent the data, for readability purposes, as big endian. I doubt I'm the only one who finds big endian to be much easier to process mentally. - - Some sort of legend showing A, I, W, etc. would really help, as opposed to just running into them as one goes along. Otherwise, the alphabet soup can be a bit confusing. Thanks again. - -- - --- Douglas Roark Senior Developer Armory Technologies, Inc. d...@bitcoinarmory.com PGP key ID: 92ADC0D7 -BEGIN PGP SIGNATURE- Version: GnuPG/MacGPG2 v2.0.22 (Darwin) Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJVZSx5AAoJEGybVGGSrcDXrYEQAOIrsggoZv0LdJHZjPGpEkeb 7ULhO4krZtQmKXjWDP0KnHAsFiyo5EOh1fYFRZz11OCqO4QmteTLPbodZFz47tKp tIYv5uc0qYhjfo5uLkzxuUky08VE4dUoELfqdbNciC45xHras7Wh/+KXc1a20Fib TaisWx9aL6VfPf7urM8b6mQ9XMba4YB3e2syAY8AA+qAEEP4DK2V6tuOQJD3kxP2 tbHtJnDvkDoXEY6tnL7fePo9X/IrlXLi8vNWGqPIf/hoiHmdvU+ORwHta7z9YeIO zi4LRs8n8sYmifY4nt6Wkkc1aoPsmpoXmI3tKgFM2h5bfdg0n3fN3K0nTMWtnR6z HUq8JhrQkZUP8uunN/23bt94FZolvnHTdL9YuWoyrlJ0gQri5YxV1BAN4hM9oCZy 1SqlSmFRplIFWu45q8/I5duDSphmA4NP2qc59QRjftcGYpNxmzaeSViiCDWzAjI9 qTLZgLTa/nf3TFN8oU8RwquGpwD82/fFo9V+uKdNGj79kdV8WOv4sa9q63OTVimJ w+r4l1gDZYyToe0heKtV2kL9Tt4HTn23bj7EvU+98uaKEpfWSP8a3BN9mPR7ork/ lNRGEGQ0tvkeDUzKy9IHuAjXo2XkKctbBRJwZJCGc5WW2sN0HdSu/GFPXrOOLf0J JXqeKpfaS0UriFXkxVHO =8uNL -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
On Wednesday, May 27, 2015 1:48:05 AM Pieter Wuille wrote: Feel free to comment. As the gist does not support notifying participants of new comments, I would suggest using the mailing list instead. I suggest adding a section describing how this interacts with and changes GBT. Currently, the client tells the server what the highest block version it supports is, and the server indicates a block version to use in its template, as well as optional instructions for the client to forcefully use this version despite its own maximum version number. Making the version a bitfield contradicts the increment-only assumption of this design, and since GBT clients are not aware of overall network consensus state, reused bits can easily become confused. I suggest, therefore, that GBT clients should indicate (instead of a maximum supported version number) a list of softforks by identifier keyword, and the GBT server respond with a template indicating: - An object of softfork keywords to bit values, that the server will accept. - The version number, as presently conveyed, indicating the preferred softfork flags. Does this sound reasonable, and/or am I missing anything else? Luke -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Version bits proposal
It would also help to see the actual code changes required, which I'm sure will be much shorter than the explanation itself. On May 27, 2015 5:47 AM, Luke Dashjr l...@dashjr.org wrote: On Wednesday, May 27, 2015 1:48:05 AM Pieter Wuille wrote: Feel free to comment. As the gist does not support notifying participants of new comments, I would suggest using the mailing list instead. I suggest adding a section describing how this interacts with and changes GBT. Currently, the client tells the server what the highest block version it supports is, and the server indicates a block version to use in its template, as well as optional instructions for the client to forcefully use this version despite its own maximum version number. Making the version a bitfield contradicts the increment-only assumption of this design, and since GBT clients are not aware of overall network consensus state, reused bits can easily become confused. I suggest, therefore, that GBT clients should indicate (instead of a maximum supported version number) a list of softforks by identifier keyword, and the GBT server respond with a template indicating: - An object of softfork keywords to bit values, that the server will accept. - The version number, as presently conveyed, indicating the preferred softfork flags. Does this sound reasonable, and/or am I missing anything else? Luke -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
