On a flood-fill network, you don't want to create a storm of "I already have this" replies.
On Fri, Jul 18, 2014 at 1:39 PM, Kaz Wesley <kezi...@gmail.com> wrote: > Peers exchanging mempool priority policies is great; that accomplishes > the flexibility in what txes to remember that I was going for with the > forget-filters, but much more neatly, with less overhead and some side > benefits. > > Here's what I'm picturing now: > - exchange priority policies in peer introductions > - assign unique sequential IDs in the order the transactions were > inved (per peer) > - receiving a getdata for a tx updates last-known-peer-received inv to > all invs up to the one referenced > - include ID-last-received, last-known-peer-received in sparse block > - reference txes in sparse block by index in receiver's > prioritiziation with peer's sent invs up to ID-last-received and > sender's prior invs up to last-known-peer-received > > Possible new messages: > - sparseblock > - invack message a node can send at times when it's received a bunch > of invs it already has, so it hasn't acked with a getdata in a while > - gettx: getdata, but using new sequential ID to save 28 bytes per tx > > It seems important for ordering policies to be able to be specified in > as much detail as possible. Parameters that should be available: > - total inputs > - total outputs > - bytes > - coin days destroyed > - net UTXO size change > - sigops > - is data carrier > - is output raw multisig > - age in mempool > - what else? > This parameter set should be extensible to allow for unforeseen future > factors. > > Ordering policies should allow arbitrary algebraic combinations of > their parameters, as well as thresholds. Boolean combinations of > sub-policies would also be desirable. This could be implemented with a > tx-script-like stack-based language, in which each supported tx > property is pushed onto the stack by a particular opcode, and > +-*//min/max/boolean operators combine them to yield the sort key. > > Difficult parameters: > * Coin-days-destroyed: changes, peers need agreement on when (if?) > it's recalculated. Probably can just not recalculate, but peers still > need agreement on "time seen" to get CDD. > * Age in mempool: seems intractable in terms of time, but could be > done easily in terms of "how many txes old is this sequential ID" > > One potential pitfall: this allows for an environment of completely > heterogeneous mempool policies. I think that's a good thing, but we > need to avoid a situation where only least-common-denominator > transactions make it farther than a hop or two, and we don't want > nodes to have a strong preference for connecting to like-minded peers > since clustering reduces overall connectivity. It may be worthwhile to > add a parallel mechanism for relay policies, to differentiate between > what a node would keep in its mempool vs. what it wouldn't even relay > and doesn't want to see at all. Relay policies could be specified just > like prioritization policies, but with the final stack value evaluated > in a boolean context. > > An interesting additional use of policy-scripts would be a > standardized way for miners to include a policy script in a coinbase, > allowing miners a mechanism to advertise things like their relative > price of sigops vs bytes. Nodes may then choose to take this > information into account in order to optimize their mempool policies > for likelihood of consistency with future blocks. Since policy scripts > provide only relative information on prices of different transaction > properties rather than an absolute fee, this should not allow miners > to "vote fees up", although care would need to be taken they wouldn't > be able to drive up prices by claiming common transaction types are at > the high end of the fee scale. > > ------------------------------------------------------------------------------ > Want fast and easy access to all the code in your enterprise? Index and > search up to 200,000 lines of code with a free copy of Black Duck > Code Sight - the same software that powers the world's largest code > search on Ohloh, the Black Duck Open Hub! Try it now. > http://p.sf.net/sfu/bds > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/ ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
