npub1s8…5yaw4 on Nostr: 📅 Original date posted:2018-02-21 📝 Original message: On 20 February 2018 at ...

📅 Original date posted:2018-02-21
📝 Original message:
On 20 February 2018 at 02:08, Rusty Russell <rusty at rustcorp.com.au> wrote:
> Hi all,
>
> This consumed much of our lightning dev interop call today! But
> I think we have a way forward, which is in three parts, gated by a new
> feature bitpair:

We've built a prototype with a new feature bit `channel_range_queries`
and the following logic:
When you receive their init message and check their local features
- if they set `initial_routing_sync` and `channel_range_queries` then
do nothing (they will send you a `query_channel_range`)
- if they set `initial_routing_sync` and not `channel_range_queries`
then send your routing table (as before)
- if you support `channel_range_queries` then send a
`query_channel_range` message

This way new and old nodes should be able to understand each other

> 1. query_short_channel_id
> =========================
>
> 1. type: 260 (`query_short_channel_id`)
> 2. data:
> * [`32`:`chain_hash`]
> * [`8`:`short_channel_id`]

We could add a `data` field which contains zipped ids like in
`reply_channel_range` so we can query several items with a single
message ?

> 1. type: 262 (`reply_channel_range`)
> 2. data:
> * [`32`:`chain_hash`]
> * [`4`:`first_blocknum`]
> * [`4`:`number_of_blocks`]
> * [`2`:`len`]
> * [`len`:`data`]

We could add an additional `encoding_type` field before `data` (or it
could be the first byte of `data`)

> Appendix A: Encoding Sizes
> ==========================
>
> I tried various obvious compression schemes, in increasing complexity
> order (see source below, which takes stdin and spits out stdout):
>
> Raw = raw 8-byte stream of ordered channels.
> gzip -9: gzip -9 of raw.
> splitgz: all blocknums first, then all txnums, then all outnums, then gzip -9
> delta: CVarInt encoding: blocknum_delta,num,num*txnum_delta,num*outnum.
> deltagz: delta, with gzip -9
>
> Corpus 1: LN mainnet dump, 1830 channels.[1]
>
> Raw: 14640 bytes
> gzip -9: 6717 bytes
> splitgz: 6464 bytes
> delta: 6624 bytes
> deltagz: 4171 bytes
>
> Corpus 2: All P2SH outputs between blocks 508000-508999 incl, 790844 channels.[2]
>
> Raw: 6326752 bytes
> gzip -9: 1861710 bytes
> splitgz: 964332 bytes
> delta: 1655255 bytes
> deltagz: 595469 bytes
>
> [1] http://ozlabs.org/~rusty/short_channels-mainnet.xz
> [2] http://ozlabs.org/~rusty/short_channels-all-p2sh-508000-509000.xz
>

Impressive!