Remove AvailableBalances::balance_msat #2476

wvanlint · 2023-08-06T00:46:53Z

This PR removes the AvailableBalances::balance_msat field.

After a discussion on Discord, it was mentioned ChannelMonitor::get_claimable_balances provides a more straightforward approach to the balance of a channel, which satisfies most use cases. The computation of AvailableBalances::balance_msat is complex and originally had a different purpose that is not applicable anymore.

Its computation takes into account holding cell HTLCs and fulfills inbound-claimed HTLCs since https://github.com/lightningdevkit/rust-lightning/pull/1268/files. However, the root cause of the underflow that was the motivation of that PR does not exist anymore. At that time, the amount in send_htlc was verified against the CommitmentStats (and this commitment transaction resolves the pending HTLC in the InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::Fulfill(_)) state). Currently, we're verifying against AvailableBalances::next_outbound_htlc_limit_msat which does not resolve such pending HTLCs. I copied and reran the test in #1268 from the main branch and it is not possible to send an HTLC back anymore and cause an underflow (sending the return payment fails with Cannot send more than our next-HTLC maximum). This is likely why the test has been removed.

codecov-commenter · 2023-08-06T02:29:26Z

Codecov Report

Patch coverage has no change and project coverage change: -0.01% ⚠️

Comparison is base (a24626b) 90.40% compared to head (ef5be58) 90.40%.

❗ Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the Github App Integration for your organization. Read more.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2476      +/-   ##
==========================================
- Coverage   90.40%   90.40%   -0.01%     
==========================================
  Files         106      106              
  Lines       56328    56321       -7     
  Branches    56328    56321       -7     
==========================================
- Hits        50926    50916      -10     
- Misses       5402     5405       +3

Files Changed	Coverage Δ
lightning/src/chain/chainmonitor.rs	`95.03% <ø> (ø)`
lightning/src/ln/channel.rs	`89.44% <ø> (-0.02%)`	⬇️
lightning/src/ln/channelmanager.rs	`85.69% <ø> (-0.01%)`	⬇️
lightning/src/routing/router.rs	`93.60% <ø> (-0.04%)`	⬇️

... and 2 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

valentinewallace · 2023-08-08T00:22:42Z

Could you add a release note regarding serialization compatibility to the pending_changelog folder and a bit more detail to the commit message? Basically LGTM otherwise. thanks!

lightning/src/ln/channelmanager.rs

TheBlueMatt

Nice, thanks.

lightning/src/ln/channelmanager.rs

alecchendev · 2023-08-10T04:17:27Z

lightning/src/ln/channel.rs

-	/// The amount that would go to us if we close the channel, ignoring any on-chain fees.
-	pub balance_msat: u64,


If we remove this, is there still a way to calculate our balance with msat precision since ChannelMonitor::get_claimable_balances will be rounded to sats?

Not currently. With regard to AvailableBalances::balance_msat, its computation was very specific to a use case that is not applicable anymore and its value is likely not what is expected. For introspection at msat precision, perhaps Channel::value_to_self_msat and the pending HTLCs can be exposed? For the latter, see #2442.

perhaps Channel::value_to_self_msat

Hm, perhaps. Will take a look at #2442, thanks!

Hmm, what would the use case be for getting a claimable balance in msat? on-chain doesn't have msats

I was thinking just to get our channel balance in general, not necessarily on-chain

Ah okay. It's nice to have a specific use case for a balance IMO, pretty vague term in lightning. Maybe something like that would be useful for accounting reasons, though 🤷‍♀️

Yea it's probably not a big deal to not have it for now

wvanlint · 2023-08-10T06:57:12Z

Adjusted documentation and serialization compatibility.

valentinewallace

LGTM

pending_changelog/remove_balance_msat.txt

valentinewallace · 2023-08-10T19:53:51Z

lightning/src/ln/channel.rs

-	/// The amount that would go to us if we close the channel, ignoring any on-chain fees.
-	pub balance_msat: u64,


Hmm, what would the use case be for getting a claimable balance in msat? on-chain doesn't have msats

TheBlueMatt · 2023-08-15T00:45:59Z

lightning/src/ln/channelmanager.rs

@@ -7550,7 +7542,7 @@ impl Readable for ChannelDetails {
 			(10, channel_value_satoshis, required),
 			(12, unspendable_punishment_reserve, option),
 			(14, user_channel_id_low, required),
-			(16, balance_msat, required),
+			(16, _balance_msat, option),  // Backwards compatibility for removed balance_msat field.


God rustc pisses me off for doing this - it just blindly picks a type (IIRC i64, so we're okay) and assumes that that's the type we want here. Its completely nonsense and results in code that does surprising things. Can you re-add the let _balance_msat: Option<u64> = _balance_msat below?

Ah thanks for catching this! Re-added the type hint.

The ChannelMonitor::get_claimable_balances method provides a more straightforward approach to the balance of a channel, which satisfies most use cases. The computation of AvailableBalances::balance_msat is complex and originally had a different purpose that is not applicable anymore.

wvanlint force-pushed the remove_balance_msat branch from 31b7419 to 124d2a9 Compare August 6, 2023 00:47

valentinewallace reviewed Aug 8, 2023

View reviewed changes

lightning/src/ln/channelmanager.rs Show resolved Hide resolved

TheBlueMatt reviewed Aug 9, 2023

View reviewed changes

lightning/src/ln/channelmanager.rs Outdated Show resolved Hide resolved

lightning/src/ln/channelmanager.rs Outdated Show resolved Hide resolved

wvanlint force-pushed the remove_balance_msat branch 3 times, most recently from 817548d to c1bb5d3 Compare August 9, 2023 23:40

alecchendev reviewed Aug 10, 2023

View reviewed changes

wvanlint marked this pull request as ready for review August 10, 2023 06:56

wvanlint requested review from TheBlueMatt and valentinewallace August 10, 2023 18:37

valentinewallace reviewed Aug 10, 2023

View reviewed changes

wvanlint force-pushed the remove_balance_msat branch 2 times, most recently from fb4b56f to 67b47bf Compare August 10, 2023 22:38

valentinewallace previously approved these changes Aug 11, 2023

View reviewed changes

TheBlueMatt reviewed Aug 15, 2023

View reviewed changes

wvanlint dismissed valentinewallace’s stale review via 5184606 August 15, 2023 18:41

wvanlint force-pushed the remove_balance_msat branch from 67b47bf to 5184606 Compare August 15, 2023 18:41

wvanlint force-pushed the remove_balance_msat branch from 5184606 to ef5be58 Compare August 15, 2023 18:42

wvanlint requested review from TheBlueMatt and valentinewallace August 15, 2023 18:43

TheBlueMatt approved these changes Aug 15, 2023

View reviewed changes

valentinewallace approved these changes Aug 15, 2023

View reviewed changes

TheBlueMatt merged commit 645e056 into lightningdevkit:main Aug 15, 2023
13 of 14 checks passed

TheBlueMatt mentioned this pull request Sep 29, 2023

Include an outbound_payment flag in MaybeTimeoutClaimableHTLC #2618

Closed

tnull mentioned this pull request Feb 21, 2024

Expose unified list_balances interface method lightningdevkit/ldk-node#250

Merged

dunxen mentioned this pull request Jul 31, 2024

Accuracy fixes and differentiating sources for Balance #3212

Merged

dunxen mentioned this pull request Aug 15, 2024

Remove AvailableBalances::balance_msat #3243

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Remove AvailableBalances::balance_msat #2476

Remove AvailableBalances::balance_msat #2476

wvanlint commented Aug 6, 2023

codecov-commenter commented Aug 6, 2023 •

edited

Loading

valentinewallace commented Aug 8, 2023

TheBlueMatt left a comment

alecchendev Aug 10, 2023

wvanlint Aug 10, 2023 •

edited

Loading

alecchendev Aug 10, 2023

valentinewallace Aug 10, 2023

alecchendev Aug 10, 2023

valentinewallace Aug 11, 2023

alecchendev Aug 11, 2023

wvanlint commented Aug 10, 2023

valentinewallace left a comment

valentinewallace Aug 10, 2023

TheBlueMatt Aug 15, 2023

wvanlint Aug 15, 2023

		/// The amount that would go to us if we close the channel, ignoring any on-chain fees.
		pub balance_msat: u64,

Remove AvailableBalances::balance_msat #2476

Remove AvailableBalances::balance_msat #2476

Conversation

wvanlint commented Aug 6, 2023

codecov-commenter commented Aug 6, 2023 • edited Loading

Codecov Report

valentinewallace commented Aug 8, 2023

TheBlueMatt left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

wvanlint Aug 10, 2023 • edited Loading

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

wvanlint commented Aug 10, 2023

valentinewallace left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

codecov-commenter commented Aug 6, 2023 •

edited

Loading

wvanlint Aug 10, 2023 •

edited

Loading