Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 27779982 for ; Fri, 10 Jul 2015 17:16:42 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ig0-f179.google.com (mail-ig0-f179.google.com [209.85.213.179]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 8A21A11F for ; Fri, 10 Jul 2015 17:16:41 +0000 (UTC) Received: by igrv9 with SMTP id v9so17687718igr.1 for ; Fri, 10 Jul 2015 10:16:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; bh=cy36sxs34P54L3mMeDBs1cIw0prGssWtrVeRWemsY7s=; b=A9XzfMXHX8Ic0Q2bKuXfXsqz+S9bDgXFV5nhkbsTJqWTrFoI1/jLEx5+rAQ9/7mtEB shvsOEONt2D+ojdzd1BwuvhmXOPphpLFOBOEKuDsYHcC1CJx2snZrj1yLM8fmwyh6lUG i3mgky9vb0BrSbs4f8OVrQ7JKFFKid0UIEM88DSedcL3IYryisYVUcREG9TRtAQm/oIA rJ95/ZEM/J1iHGv+714MN9O29KihFtxMwJ+BpBYdhxKqDbGPcuMX57NxDGJqaD9ZcJ4S BqQ1ZkWHRimPq323l0teB22EkJJw0XZQy5bxa54uioZf+H5F6daksp5VpjrBf+JWaRQa tnog== MIME-Version: 1.0 X-Received: by 10.50.97.33 with SMTP id dx1mr4169606igb.1.1436548600976; Fri, 10 Jul 2015 10:16:40 -0700 (PDT) Received: by 10.107.17.212 with HTTP; Fri, 10 Jul 2015 10:16:40 -0700 (PDT) In-Reply-To: <559FFAB3.2010309@openbitcoinprivacyproject.org> References: <6D3AACE5-D6CD-4785-8A55-F6DF0B94D927@ricmoo.com>

<559FFAB3.2010309@openbitcoinprivacyproject.org> Date: Fri, 10 Jul 2015 12:16:40 -0500 Message-ID: From: Dan Bryant To: Justus Ranvier Content-Type: text/plain; charset=UTF-8 X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, 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@lists.linuxfoundation.org Subject: Re: [bitcoin-dev] Why not Child-Pays-For-Parent? X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list Reply-To: DKBryant@gmail.com List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 10 Jul 2015 17:16:42 -0000 On Fri, Jul 10, 2015 at 11:31 AM, Jeff Garzik wrote: > This is a good explanation but it does not address reachability. TX_a, the > first tx sent out on the network, presumably has insufficient fee to get > mined - which also means it did not necessarily even reach all miners. > > Simply sending out TX_b with added fee does not guarantee that nodes > suddenly have TX_a, which they may have ignored/dropped before. True... there are two propagation thresholds... "-minrelaytxfee" (defaults to 1000 sotoshi/kbyte) and "relaypriority" (defaults to True). If -relaypriority is True, then items with a priority above 57600000 (currently ) will still be relayed, even if their TxFee is below MinRelayTxFee. Therefore even if miners are using bitcoind rules for mempool tx creation, they can still configure how and what they propagate. The flip-side of this is that a transactions priority will go up the longer it ages (in the mempool). So it would be possible (if relaypriority was on) for even a lowfee transaction to become relayable eventually simply based on relaypriority ref1: https://en.bitcoin.it/wiki/Transaction_fees On Fri, Jul 10, 2015 at 12:02 PM, Justus Ranvier wrote: > CPFP is initiated by the recipient of the parent transaction, and so if > the recipient is creating this transaction in the first place they must > have a copy of the parent transaction which can/should broadcast at the > same time. > > If the child reaches a CPFP miner, then presumably the parents made it > as well (any path between the sender and the miner that doesn't relay > the parent should reject the child as trying to spend non-existent > coins), so both of the transactions can be mined at the same time. If the recipient is running a full node with incoming connections. I'm not sure if SPV clients rebroadcast both spend and receive transactions.