From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Vwv9Y-00023E-KO for bitcoin-development@lists.sourceforge.net; Sat, 28 Dec 2013 14:46:12 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.214.181 as permitted sender) client-ip=209.85.214.181; envelope-from=mh.in.england@gmail.com; helo=mail-ob0-f181.google.com; Received: from mail-ob0-f181.google.com ([209.85.214.181]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1Vwv9X-0002gA-MY for bitcoin-development@lists.sourceforge.net; Sat, 28 Dec 2013 14:46:12 +0000 Received: by mail-ob0-f181.google.com with SMTP id uy5so10286707obc.40 for ; Sat, 28 Dec 2013 06:46:06 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.182.81.197 with SMTP id c5mr38348083oby.40.1388241965256; Sat, 28 Dec 2013 06:46:05 -0800 (PST) Sender: mh.in.england@gmail.com Received: by 10.76.95.200 with HTTP; Sat, 28 Dec 2013 06:46:05 -0800 (PST) In-Reply-To: References: Date: Sat, 28 Dec 2013 14:46:05 +0000 X-Google-Sender-Auth: uchY5o9Dy_I2nuveGR8PeaU9zRw Message-ID: From: Mike Hearn To: Jeremy Spilman Content-Type: multipart/alternative; boundary=047d7b2e4d583397dd04ee9945ce X-Spam-Score: -0.5 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (mh.in.england[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 1.0 HTML_MESSAGE BODY: HTML included in message 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1Vwv9X-0002gA-MY Cc: "bitcoin-development@lists.sourceforge.net" Subject: Re: [Bitcoin-development] Access to Mempool X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 28 Dec 2013 14:46:12 -0000 --047d7b2e4d583397dd04ee9945ce Content-Type: text/plain; charset=UTF-8 > > I was reading there are some commands to access a peer's mempool state. > The purpose being to allow miners to recover faster after a reboot, I > think? > The "mempool" command allows nodes to request the contents of a peers memory pool, yes. It is currently used by SPV clients to find transactions that were broadcast before they were started up (but not yet confirmed). > Reading peer mempool definitely allows recovering faster after a reboot. > So does persisting mempool in a database locally. 0.9 has code to save the mempool to disk. > But what can you learn about a node from its mempool? Basically, are there > distinguishing > features in the mempool, or could there be? > Er, you mean, distinguishing features beyond the nodes IP address? The contents of the mempool may vary depending on when the node was started and what it saw at what times. I guess it's distinguishing in a way, but not in any important way. Nodes are not intended to be completely indistinguishable, just indistinguishable enough that it doesn't matter which you connect to. > Are there transactions you can receive which go into your own mempool but > which you don't forward? I don't think so, unless there are quirks to do with sendrawtransaction RPCs or strangely crafted wallet spends. Normally if a tx is in the mempool it will be relayed. > By the way, are there recommended places to go to compare features > implemented by different wallet software? > I don't know of any such place, but I'm sure people have compiled tables somewhere. --047d7b2e4d583397dd04ee9945ce Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I was reading there are some commands to access = a peer's mempool state.
The purpose being to allow miners to recover faster after a reboot, I
think?

The "mempool" command = allows nodes to request the contents of a peers memory pool, yes.

It is currently used by SPV clients to find transactions th= at were broadcast before they were started up (but not yet confirmed).=C2= =A0
=C2=A0
Reading peer mempool defini= tely allows recovering faster after a reboot.
So does persisting mempool in a database locally.

0.9 has code to save the mempool to disk.
=C2=A0
But what can you learn=C2=A0about a node from its mempool? Basically, are = there distinguishing
features in the mempool, or could there be?

=
Er, you mean, distinguishing features beyond the nodes IP address?=C2= =A0

The contents of the mempool may vary depending= on when the node was started and what it saw at what times. I guess it'= ;s distinguishing in a way, but not in any important way. Nodes are not int= ended to be completely indistinguishable, just indistinguishable enough tha= t it doesn't matter which you connect to.
=C2=A0
Are there transactions you = can receive which go into your own mempool but
which you don't forward?

I don't th= ink so, unless there are quirks to do with sendrawtransaction RPCs or stran= gely crafted wallet spends. Normally if a tx is in the mempool it will be r= elayed.
=C2=A0
By the way, are there recom= mended places to go to compare features
implemented by different wallet software?

I don't know of any such place, but I'm sure people have compile= d tables somewhere.
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