<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Sep 23, 2015 at 4:43 PM, Gavin Andresen via bitcoin-dev <span dir="ltr"><<a href="mailto:bitcoin-dev@lists.linuxfoundation.org" target="_blank">bitcoin-dev@lists.linuxfoundation.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Imagine miners always pre-announce the blocks they're working on to their peers, and peers validate those 'weak blocks' as quickly as they are able.<div><div><br></div><div>Because weak blocks are pre-validated, when a full-difficulty block based on a previously announced weak block is found, block propagation should be insanely fast-- basically, as fast as a single packet can be relayed across the network the whole network could be mining on the new block.</div><div><br></div><div>I don't see any barrier to making accepting the full-difficulty block and CreateNewBlock() insanely fast, and if those operations take just a microsecond or three, miners will have an incentive to create blocks with fee-paying transactions that weren't in the last block, rather than mining empty blocks.</div></div></div></blockquote><div><br></div><div>You can create these blocks in advance too.<br><br></div><div>- receive weak block<br></div><div>- validate<br></div><div>- create child block <br></div><div><br></div><div>It becomes a pure array lookup to get the new header that builds on top of that block. The child blocks would need to be updated as the memory pool changes though.<br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>A miner could try to avoid validation work by just taking a weak block announced by somebody else, replacing the coinbase and re-computing the merkle root, and then mining. They will be at a slight disadvantage to fully validating miners, though, because they WOULD have to mine empty blocks between the time a full block is found and a fully-validating miner announced their next weak block.</div></div></blockquote><div><br></div><div>This also speeds up propagation for the miner. The first weak block that is broadcast could end up being copied by many other miners.<br><br></div><div>A miner who is copying a block could send coinbase + original header if he hits a block. Weak blocks that are just coinbase + header could have lower POW requirements, since they use up much less bandwidth.<br><br></div><div>Miners would mostly copy other miners once they had verified their blocks. The IBLT system works well here. A miner could pick a weak block that is close to what it actually wants to broadcast.<br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Weak block announcements are great for the network; they give transaction creators a pretty good idea of whether or not their transactions are likely to be confirmed in the next block.</div></div></blockquote><div><br></div><div>Aggregator nodes could offer a service to show/prove how many weak blocks that the transaction has been accepted in.<br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div> And if we're smart about implementing them, they shouldn't increase bandwidth or CPU usage significantly, because all the weak blocks at a given point in time are likely to contain the same transactions.</div></div></blockquote><div><br></div><div>This assumes other compression systems for handling block propagation.<br></div> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><span class="HOEnZb"><font color="#888888"><div><div><br></div>-- <br><div>--<br>Gavin Andresen<br></div><div><br></div> </div></font></span></div></div> <br>_______________________________________________<br> bitcoin-dev mailing list<br> <a href="mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linuxfoundation.org</a><br> <a href="https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" rel="noreferrer" target="_blank">https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev</a><br> <br></blockquote></div><br></div></div>