1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
|
Return-Path: <gavinandresen@gmail.com>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
[172.17.192.35])
by mail.linuxfoundation.org (Postfix) with ESMTPS id 6012140D
for <bitcoin-dev@lists.linuxfoundation.org>;
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 <bitcoin-dev@lists.linuxfoundation.org>;
Thu, 30 Jul 2015 18:16:23 +0000 (UTC)
Received: by lbqc9 with SMTP id c9so7001523lbq.1
for <bitcoin-dev@lists.linuxfoundation.org>;
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: <CABm2gDoxr4yY6XPZOEG0CF_iPO+b1H3_yFoKnYa68Y4b=Tcwrw@mail.gmail.com>
References: <CABm2gDoxr4yY6XPZOEG0CF_iPO+b1H3_yFoKnYa68Y4b=Tcwrw@mail.gmail.com>
Date: Thu, 30 Jul 2015 14:16:22 -0400
Message-ID: <CABsx9T0c10SDHCBy5=iPKVvsNPmKr2ejUxLp0rJPZmPRPQpfig@mail.gmail.com>
From: Gavin Andresen <gavinandresen@gmail.com>
To: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= <jtimon@jtimon.cc>
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 <bitcoin-dev@lists.linuxfoundation.org>
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 <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, 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
<div dir=3D"ltr">I still think using the version and timestamp fields in th=
e block header are simplest and best.<div><br></div><div>Advantages:</div><=
div>=C2=A0 Available to SPV nodes with no change to the network protocol</d=
iv><div>=C2=A0 Available after headers downloaded, before full block data i=
s available</div><div>=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.</div><div><br></div><div>Disadvantages:</=
div><div>=C2=A0 Not monotonically increasing</div><div><br></div><div><br><=
/div><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.</div><di=
v><br></div><div>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).</div><div><br></div><div class=3D"gmail_extra"><div><br></div=
>-- <br><div class=3D"gmail_signature">--<br>Gavin Andresen<br></div><div c=
lass=3D"gmail_signature"><br></div>
</div></div>
--001a113492b857faf0051c1bb32f--
|
