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| author | Rusty Russell <rusty@rustcorp.com.au> | 2015-09-24 11:02:34 +0930 |
|---|---|---|
| committer | bitcoindev <bitcoindev@gnusha.org> | 2015-09-24 01:33:12 +0000 |
| commit | 6f3b1209507f68f33190fff26ea4a6faca995bf7 (patch) | |
| tree | f9ab57763e98ccf3c20b02ebe6314059461f7242 | |
| parent | 71e0eb4c2a6a0c7a0c7b068aa3c774421fa10de5 (diff) | |
| download | pi-bitcoindev-6f3b1209507f68f33190fff26ea4a6faca995bf7.tar.gz pi-bitcoindev-6f3b1209507f68f33190fff26ea4a6faca995bf7.zip | |
Re: [bitcoin-dev] Weak block thoughts...
| -rw-r--r-- | 7f/fbe7e5d81540c4b9787ed92df625f11f47fab4 | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/7f/fbe7e5d81540c4b9787ed92df625f11f47fab4 b/7f/fbe7e5d81540c4b9787ed92df625f11f47fab4 new file mode 100644 index 000000000..7fa816c09 --- /dev/null +++ b/7f/fbe7e5d81540c4b9787ed92df625f11f47fab4 @@ -0,0 +1,85 @@ +Return-Path: <rusty@ozlabs.org> +Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org + [172.17.192.35]) + by mail.linuxfoundation.org (Postfix) with ESMTPS id 7669615A3 + for <bitcoin-dev@lists.linuxfoundation.org>; + Thu, 24 Sep 2015 01:33:12 +0000 (UTC) +X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 +Received: from ozlabs.org (ozlabs.org [103.22.144.67]) + by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 4A0AE19E + for <bitcoin-dev@lists.linuxfoundation.org>; + Thu, 24 Sep 2015 01:33:11 +0000 (UTC) +Received: by ozlabs.org (Postfix, from userid 1011) + id 536B6140281; Thu, 24 Sep 2015 11:33:08 +1000 (AEST) +From: Rusty Russell <rusty@rustcorp.com.au> +To: Gavin Andresen <gavinandresen@gmail.com>, + Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org> +In-Reply-To: <CABsx9T2+dG0AE+MgKRAU97KhkHTU1MuxXuwHKv3BgpJswZ5vVg@mail.gmail.com> +References: <CABsx9T2+dG0AE+MgKRAU97KhkHTU1MuxXuwHKv3BgpJswZ5vVg@mail.gmail.com> +User-Agent: Notmuch/0.17 (http://notmuchmail.org) Emacs/24.4.1 + (x86_64-pc-linux-gnu) +Date: Thu, 24 Sep 2015 11:02:34 +0930 +Message-ID: <87twqk38lp.fsf@rustcorp.com.au> +MIME-Version: 1.0 +Content-Type: text/plain +X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, + RP_MATCHES_RCVD autolearn=ham version=3.3.1 +X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on + smtp1.linux-foundation.org +Subject: Re: [bitcoin-dev] Weak block thoughts... +X-BeenThere: bitcoin-dev@lists.linuxfoundation.org +X-Mailman-Version: 2.1.12 +Precedence: list +List-Id: Bitcoin Development Discussion <bitcoin-dev.lists.linuxfoundation.org> +List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>, + <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe> +List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/> +List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org> +List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help> +List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>, + <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe> +X-List-Received-Date: Thu, 24 Sep 2015 01:33:12 -0000 + +Gavin Andresen via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> +writes: +> I've been thinking about 'weak blocks' and SPV mining, and it seems to me +> weak blocks will make things better, not worse, if we improve the mining +> code a little bit. +> +> First: the idea of 'weak blocks' (hat tip to Rusty for the term) is for +> miners to pre-announce blocks that they're working on, before they've +> solved the proof-of-work puzzle. To prevent DoS attacks, assume that some +> amount of proof-of-work is done (hence the term 'weak block') to rate-limit +> how many 'weak block' messages are relayed across the network. +> +> +> Today, miners are incentivized to start mining an empty block as soon as +> they see a block with valid proof-of-work, because they want to spend as +> little time as possible mining a not-best chain. +> +> 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. +> +> 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. + +The bandwidth/latency argument is solid. And if a block encodes to < +~3k, then we can just spray it to (some?) peers rather than using INV. + +But validation is only trivially cachable if the delta to the previous +weak block is zero. The "partially validated" cases need to be coded +with care (eg. total opcode constraints, tx order). + +I was thinking as a first cut we do the opposite: don't validate weak +blocks at all (other than PoW), and just use them as a bandwidth +optimization. + +Ambition is good though! + +Chers, +Rusty. +PS. Original idea came to me from Greg Maxwell; Peter Todd called it + "near blocks" and extolled their virtues 2 years ago... + |