Bitcoin dev IRC meeting in layman's terms (2015-11-26)

Once again my attempt to summarize and explain the weekly bitcoin developer meeting in layman's terms.
Link to last weeks summarization

Disclaimer

Please bear in mind I'm not a developer and I'd have problems coding "hello world!", so some things might be incorrect or plain wrong.
Like any other write-up it likely contains personal biases, although I try to stay as neutral as I can.
There are no decisions being made in these meetings, so if I say "everyone agrees" this means everyone present in the meeting, that's not consensus, but since a fair amount of devs are present it's a good representation.
The dev IRC and mailinglist are for bitcoin development purposes. If you have not contributed actual code to a bitcoin-implementation, this is probably not the place you want to reach out to. There are many places to discuss things that the developers read, including this forum.

link to this week logs
Meeting minutes by meetbot

Main topics discussed where:

CLTV activation
BIP68/BIP112 implementation
Replace-by-fee

Short topics/notes

It was an American holiday (thanksgiving), so there weren't a lot of people in the meeting, which started later as well.

Personal note: My weekly posts are being read by more people than I ever anticipated and people are expecting these to come weekly.
Next year Mid-February I'll be on vacation for a month, so that's 4 or 5 meetings I won't be able to do.
If there's anyone who's up for the challenge to take over during those weeks (or maybe just 1 week and share the load with others) feel free to pm me.
I'm announcing well in advance, so there's more chance to find someone and to not make this a last minute thing.
I'd prefer someone who doesn't work in the bitcoin space (coding), as I much rather have people work on the future of money instead of enlightening us noobs

CLTV activation

- background

CheckLockTimeVerify (CLTV) aka "how you thought nLockTime worked before you actually tried to use it" aka OP_HODL.

- meeting comments

It's plausible the CLTV softfork will activate within just a few weeks, as everyone but a few big miners have adopted it.
About 20% of the nodes currently run CLTV-supporting versions. The negative effect of not upgrading is a degraded validation (SPV).

- meeting conclusion

Do a social media reminder to upgrade nodes to v0.11.2/v0.10.4

BIP68/BIP112 implementation

- background

BIP 68 Consensus-enforced transaction replacement signaled via sequence numbers , and current implementation.
BIP 112 CHECKSEQUENCEVERIFY, and current implementation.
In short: BIP 68 changes the meaning of the sequence number field to a relative locktime. BIP 112 makes that field accessible to the bitcoin scripting system.

- meeting comments

The BIP68 and BIP112 texts have been updated to match the implementations.
There's been a call and discussion to rename CHECKSEQUENCEVERIFY on the mailinglist.
btcdrak wants both pull-requests to be merged soon, others feel more hesitant as people seem to only recently started looking at it seriously.

- meeting conclusion

Merge updated BIP-texts

Replace-by-fee

- background

Currently when a node sees a transaction that spends the same output it ignores it. With replace-by-fee it replaces the current transaction in the mempool if it has a higher fee.
This allows for things like spending "stuck" transactions, adding more recipients to a transaction in order to prevent chaining, etc.

Since there are people that accept 0-confirmation transactions and this would make it extremely easy to double spend them, this is made opt-in.
The sender can choose to opt-in to replace-by-fee by changing the nSequence field of all inputs.
This is a mempool policy for the upcoming 0.12 release.
There's a good FAQ-ish post on reddit about it.

- meeting comments

petertodd ran some tests with the mempool limiter turned way down and saw no issues.
It should be technically easy to merge first-seen-safe and full-unconditional as options if there's people who want to write it.

- meeting conclusion

test and ACK replace-by-fee (Has been merged meanwhile).

Participants

Code:

    btcdrak      btcdrak  
    petertodd    Peter Todd  
    Luke-Jr      Luke Dashjr  
    CodeShark    Eric Lombrozo  
    sipa         Pieter Wuille  
    jtimon       Jorge Timón

Comic relief

Code:

    19:17	btcdrak		wumpus: so no meeting today then?  
    19:17	CodeShark	btcdrak: so no wumpus today then? :)  
    19:17	petertodd	btcdrak: since when do you listen to authority? :P  

    19:22	CodeShark	is there a quorum? or can we meet anyhow? :)  
    19:22	petertodd	CodeShark: I'm in a mcdonalds right now, working on increasing my influence, as measured by mass...  
    19:22	petertodd	CodeShark: so yes  

    19:49	btcdrak		### 10 minutes left. are there any other topic suggestions?  
    19:50	petertodd	btcdrak: rbf  
    19:50	btcdrak		#topic RBF    
    19:51	CodeShark	anyone have a topic that pays a higher fee? :)    
    19:51	Luke-Jr		this fee is too low, I'm leaving early!     

    19:24	btcdrak		#meetingstart  
    19:24	btcdrak		#startmeeting  
    19:24	lightningbot	Meeting started Thu Nov 26 19:24:40 2015 UTC. The chair is btcdrak. Information about MeetBot at http://wiki.debian.org/MeetBot.

    20:00	btcdrak		#endmeeting  
    20:00	btcdrak		#meetingend  
    20:00	btcdrak		oh ffs, not this problem again  
    20:00	lightningbot	Meeting ended Thu Nov 26 20:00:24 2015 UTC. Information about MeetBot at http://wiki.debian.org/MeetBot . (v 0.1.4)