From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 6012140D for ; Thu, 30 Jul 2015 18:16:24 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-lb0-f173.google.com (mail-lb0-f173.google.com [209.85.217.173]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A793C112 for ; Thu, 30 Jul 2015 18:16:23 +0000 (UTC) Received: by lbqc9 with SMTP id c9so7001523lbq.1 for ; Thu, 30 Jul 2015 11:16:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=J+wyuS+jEDa3ue6BGa0BLVlNbgUkmflZ2xsEe/epPR4=; b=qDNVE1pnV7AFmCRihr4i4k80H3MIM/1un8P6Sf0WDkSURmS1oyDn2K+vVtfPtVDR7j BRujzcMCJTQcP2xDdJjJkMCR+zTpJ8sOgUrEMlBJdf6fC/uGVblp4KZgUstc2AtAsuxi NR9jeL341gKu+CUhIgOilhA5HHpK9Gj6uKVqhuRyY9U0UBSjCn9HnBEIZJBYsdzHRLBi yaeDC7LqwH+IvxKfwhWIiYFJmOJFME6Vc4v8zfqyy7ZxGf9sFMCnbrogtKsNl6Z/qeqL yEPS7vmptiL7ej97BhXKmaA2IuJ8p+rvbiEWmHu+2vdhaNREUCc7e9Rcp1yieTTnkVsi W+dw== MIME-Version: 1.0 X-Received: by 10.112.239.43 with SMTP id vp11mr42667153lbc.75.1438280182133; Thu, 30 Jul 2015 11:16:22 -0700 (PDT) Received: by 10.25.18.228 with HTTP; Thu, 30 Jul 2015 11:16:22 -0700 (PDT) In-Reply-To: References: Date: Thu, 30 Jul 2015 14:16:22 -0400 Message-ID: From: Gavin Andresen To: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= Content-Type: multipart/alternative; boundary=001a113492b857faf0051c1bb32f X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] Consensus fork activation thresholds: Block.nTime vs median time vs block.nHeight X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Jul 2015 18:16:24 -0000 --001a113492b857faf0051c1bb32f Content-Type: text/plain; charset=UTF-8 I still think using the version and timestamp fields in the block header are simplest and best. Advantages: Available to SPV nodes with no change to the network protocol Available after headers downloaded, before full block data is available Once well past a fork, allows all block validation except validation against the UTXO to happen in parallel, out-of-order, independent of any other block. Disadvantages: Not monotonically increasing I think discussion about transactions in the memory pool are just a distraction: no matter what criteria is used (timestamp, height, median time), a blockchain re-organization could mean the validity of transactions you've accepted into the memory pool (if you're accepting transactions that switch from valid to invalid at the consensus change -- Core tries hard not to do that via IsStandard policy) must be re-evaluated. I don't strongly care if median time or block timestamp is used, I think either will work. I don't like height, there are too many cases where the time is known but the block height isn't (see, for example, the max-outputs-in-a-transaction sanity check computation at line 190 of bitcoin-tx.cpp -- bitcoin-tx.cpp has no idea what the current block height is). -- -- Gavin Andresen --001a113492b857faf0051c1bb32f Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I still think using the version and timestamp fields in th= e block header are simplest and best.

Advantages:
<= div>=C2=A0 Available to SPV nodes with no change to the network protocol
=C2=A0 Available after headers downloaded, before full block data i= s available
=C2=A0 Once well past a fork, allows all block valida= tion except validation against the UTXO to happen in parallel, out-of-order= , independent of any other block.

Disadvantages:
=C2=A0 Not monotonically increasing


<= /div>
I think discussion about transactions in the memory pool are just= a distraction: no matter what criteria is used (timestamp, height, median = time), a blockchain re-organization could mean the validity of transactions= you've accepted into the memory pool (if you're accepting transact= ions that switch from valid to invalid at the consensus change -- Core trie= s hard not to do that via IsStandard policy) must be re-evaluated.

I don't strongly care if median time or block timestam= p is used, I think either will work. I don't like height, there are too= many cases where the time is known but the block height isn't (see, fo= r example, the max-outputs-in-a-transaction sanity check computation at lin= e 190 of bitcoin-tx.cpp -- bitcoin-tx.cpp has no idea what the current bloc= k height is).


--
--
Gavin Andresen

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