Display more fee information when opening a DLC channel #2062

luckysori · 2024-02-19T16:19:38Z

Fixes #2042.

channel-fee-info.mp4

The video does not correspond to the latest version, but it's close enough.

See get10101/rust-dlc#5 for the rust-dlc side of things.

bonomat · 2024-02-21T09:56:00Z

crates/ln-dlc-node/src/tests/dlc_channel.rs

+    // spots.
+    let epsilon = *fund_output_amount as i64 - expected_fund_output_amount.to_sat() as i64;
+
+    assert!(


Should this test really panic? If it panics, why do we need an assert, or is the assert panicking?

bonomat · 2024-02-21T09:56:40Z

crates/ln-dlc-node/src/tests/dlc_channel.rs

@@ -307,7 +307,6 @@ async fn funding_transaction_pays_expected_fees() {

 #[tokio::test(flavor = "multi_thread")]
 #[ignore]
-#[should_panic]


ah, got it, you made the test fail first, then fixed it, very nice :)

bonomat · 2024-02-21T09:59:59Z

mobile/native/src/ln_dlc/mod.rs

+pub fn estimated_fee_reserve() -> Result<Amount> {
+    let node = state::get_node();
+
+    // TODO: Here we assume that the coordinator will use the same confirmation target AND that


I don't think this needs to be a TODO, it can just be a note given this function is just estimating.

bonomat · 2024-02-21T10:11:05Z

mobile/native/src/ln_dlc/mod.rs

-                        // this is not 100% correct as fees are not exactly divided by 2. The fee a
-                        // user has to pay depends on his final address.
-                        reserved_fee_sats: details.fee.map(|fee| fee / 2),
+                        // this is not 100% correct as fees are not exactly divided by 2. The share


Maybe we should just fix this in rust-dlc and say the fee is always 50:50

Hmm, I don't think it should be fixed there, because it wouldn't make sense to me to charge the user more just because we as the coordinator bring 7 inputs or something.

I think it would be nicer to record all the fee contributions in a channel metadata table. I think this is something we should be able to achieve after the new model is introduced.

bonomat · 2024-02-21T10:13:15Z

justfile

@@ -289,10 +289,19 @@ coordinator args="":

    cargo run --bin coordinator -- {{args}}

+run_maker_args := if os() == "linux" {


Nice, alternatively you could use

docker run -d --name maker ghcr.io/get10101/aristides/aristides:main regtest --orderbook http://172.17.0.1:8000

It seems that on Linux 172.17.0.1 is always localhost

That being said, can you update the CI file to use this api as well?

10101/.github/workflows/ci.yml

Line 276 in d29baf6

docker run --pull always -d --name maker ghcr.io/get10101/aristides/aristides:main regtest --orderbook http://172.17.0.1:8000

bonomat

Looks good.

luckysori · 2024-02-26T10:24:30Z

I will keep this open until #2094 merges.

luckysori · 2024-03-01T07:39:47Z

Now looking into those annoying UI test failures: https://github.com/get10101/10101/actions/runs/8107349092/job/22158820647?pr=2062#step:10:180.

Soon `rust-dlc` will enforce including at least one change output per party in the funding transaction, so that either party can fee-bump it. The original `can_open_channel_with_min_inputs` test actually forced `rust-dlc` to generate a change-output-less funding transaction. This is valid for now, but it doesn't help to build on assumptions that are going to change soon. The new test simply checks that the funding transaction pays fees at the expected fee rate. If we can trust `rust-dlc` to respect the fee rate we give it, we can confidently display this information to a user who is about to open a channel, so that they know the transaction fee cost of their action.

The funding tx fee is just an estimate and it is usually slightly overestimated. We've had to further increase the size of the bottom sheets to fit all the information on screen.

On the confirmation bottom sheet, we tell the user that some coins will be locked up in the DLC channel. This message seems to imply that these coins will still be owned by the user. The margin and the collateral reserve make sense, but any fee paid or reserved should probably be excluded. We could summarise this information elswhere on the screen, but I don't think it is necessary as all the information is already present separately.

The value that we were displaying corresponded to half of the funding transaction fee. The fee reserve cannot be derived just by looking at the funding transaction, as it is included in the funding transaction shared output. Eventually, we should display the fee reserve in the corresponding wallet history entry (and perhaps in a channel details section too).

luckysori · 2024-03-01T13:02:32Z

mobile/lib/features/trade/channel_configuration.dart

@@ -48,7 +50,7 @@ channelConfiguration({
                },
                child: SingleChildScrollView(
                  child: SizedBox(
-                    height: 450,
+                    height: 500,


I've had to bump this number even further because otherwise the unit tests fail 🙈

Noo 🫣 I worked so long to get the tests pass with the correct size 😅

luckysori requested review from bonomat and holzeis February 19, 2024 16:19

luckysori self-assigned this Feb 19, 2024

luckysori force-pushed the feat/show-channel-tx-fees branch from 87b5c5c to 9198125 Compare February 19, 2024 16:25

bonomat reviewed Feb 21, 2024

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bonomat approved these changes Feb 21, 2024

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luckysori mentioned this pull request Feb 22, 2024

Improve fee handling get10101/rust-dlc#5

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luckysori force-pushed the feat/show-channel-tx-fees branch from 9198125 to d147aed Compare February 22, 2024 03:03

luckysori enabled auto-merge February 22, 2024 03:05

luckysori mentioned this pull request Mar 1, 2024

Update bdk to version 1.0.0-alpha.6 #2094

Merged

luckysori force-pushed the feat/show-channel-tx-fees branch 2 times, most recently from 94c3783 to e89d7b7 Compare March 1, 2024 06:11

luckysori added 4 commits March 1, 2024 23:41

chore(ln-dlc-node): Reproduce bug when calculating DLC channel fees

d0349ef

fix(ln-dlc-node): Calculate DLC channel fee reserve correctly

10047c7

chore: Extract function to estimate DLC channel fee reserve

a9d20ff

luckysori force-pushed the feat/show-channel-tx-fees branch from e89d7b7 to 6629230 Compare March 1, 2024 12:41

luckysori added 3 commits March 2, 2024 00:01

feat(app): Display fee reserve and funding TX fee estimate

b42ff54

The funding tx fee is just an estimate and it is usually slightly overestimated. We've had to further increase the size of the bottom sheets to fit all the information on screen.

luckysori force-pushed the feat/show-channel-tx-fees branch from 6629230 to 0d8c36c Compare March 1, 2024 13:01

luckysori commented Mar 1, 2024

View reviewed changes

luckysori added this pull request to the merge queue Mar 1, 2024

Merged via the queue into main with commit e48d93e Mar 1, 2024
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luckysori deleted the feat/show-channel-tx-fees branch March 1, 2024 13:25

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Display more fee information when opening a DLC channel #2062

Display more fee information when opening a DLC channel #2062

luckysori commented Feb 19, 2024 •

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		@@ -289,10 +289,19 @@ coordinator args="":

		cargo run --bin coordinator -- {{args}}

		run_maker_args := if os() == "linux" {

Display more fee information when opening a DLC channel #2062

Display more fee information when opening a DLC channel #2062

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