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| author | Rusty Russell <rusty@rustcorp.com.au> | 2018-01-09 21:52:18 +1030 |
|---|---|---|
| committer | bitcoindev <bitcoindev@gnusha.org> | 2018-01-09 11:24:02 +0000 |
| commit | 53c45b4ff0e07b9ffc89b7b741af4c541405e11d (patch) | |
| tree | dbd4f2a768192b620fcd38662867808ec5539b61 | |
| parent | 3ddc72f3369c38b30b96828495f112e0ff8de4e9 (diff) | |
| download | pi-bitcoindev-53c45b4ff0e07b9ffc89b7b741af4c541405e11d.tar.gz pi-bitcoindev-53c45b4ff0e07b9ffc89b7b741af4c541405e11d.zip | |
[bitcoin-dev] BIP 117 Feedback
| -rw-r--r-- | 26/c6105f7ee15bc01e4ddc5e70cca6001bacc8d4 | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/26/c6105f7ee15bc01e4ddc5e70cca6001bacc8d4 b/26/c6105f7ee15bc01e4ddc5e70cca6001bacc8d4 new file mode 100644 index 000000000..e13e40955 --- /dev/null +++ b/26/c6105f7ee15bc01e4ddc5e70cca6001bacc8d4 @@ -0,0 +1,69 @@ +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 0FD7C103E + for <bitcoin-dev@lists.linuxfoundation.org>; + Tue, 9 Jan 2018 11:24:02 +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 E3FC112E + for <bitcoin-dev@lists.linuxfoundation.org>; + Tue, 9 Jan 2018 11:23:59 +0000 (UTC) +Received: by ozlabs.org (Postfix, from userid 1011) + id 3zG8sn6Z27z9sNr; Tue, 9 Jan 2018 22:23:57 +1100 (AEDT) +From: Rusty Russell <rusty@rustcorp.com.au> +To: "Bitcoin Protocol Discussion" <bitcoin-dev@lists.linuxfoundation.org> +Date: Tue, 09 Jan 2018 21:52:18 +1030 +Message-ID: <87608btgyd.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, + T_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 +Cc: Russell O'Connor <roconnor@blockstream.com>, + Kalle Alm <kalle.alm@gmail.com> +Subject: [bitcoin-dev] BIP 117 Feedback +X-BeenThere: bitcoin-dev@lists.linuxfoundation.org +X-Mailman-Version: 2.1.12 +Precedence: list +List-Id: Bitcoin Protocol 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: Tue, 09 Jan 2018 11:24:02 -0000 + +I've just re-read BIP 117, and I'm concerned about its flexibility. It +seems to be doing too much. + +The use of altstack is awkward, and makes me query this entire approach. +I understand that CLEANSTACK painted us into a corner here :( + +The simplest implementation of tail recursion would be a single blob: if +a single element is left on the altstack, pop and execute it. That +seems trivial to specify. The treatment of concatenation seems like +trying to run before we can walk. + +Note that if we restrict this for a specific tx version, we can gain +experience first and get fancier later. + +BIP 117 also drops SIGOP and opcode limits. This requires more +justification, in particular, measurements and bounds on execution +times. If this analysis has been done, I'm not aware of it. + +We could restore statically analyzability by rules like so: +1. Only applied for tx version 3 segwit txs. +2. For version 3, top element of stack is counted for limits (perhaps + with discount). +3. The blob popped off for tail recursion must be identical to that top + element of the stack (ie. the one counted above). + +Again, future tx versions could drop such restrictions. + +Cheers, +Rusty. + |