sweepbatcher: notify caller about confirmations #919

starius · 2025-04-09T03:08:59Z

Add fields ConfChan and ConfErrChan to sweepbatcher.SpendNotifier type which is a part of SweepRequest passed to AddSweep method.

This is needed to reuse confirmation notifications on the calling side the same way it is done for spending notifications.

Also fixed many small bugs and issues and added missing tests for notifications sent through channels of SpendNotifier.

Fixed TODO left from #891 re-add sweeps to new batches only after fully confirmed.
In case of a reorg sweeps should not go to another batch but stay in the current batch until it is fully confirmed. Only after that the remaining sweeps are re-added to another batch. Field sweep.completed is now set to true only for fully-confirmed sweeps.

Fixed OnChainFeePortion values. There were two mistakes. In case of a swap with multiple sweeps only the fee of the first sweep of a swap was accounted. Another issue is that rounding diff (the remainder) was attributed to all the sweeps rather than to the first (primary) sweep of the batch. The sweep to attribute the remainder was chosen by comparing SignatureScript which is always empty. New approach is to find the primary sweep and to compare its outpoint directly.

Pull Request Checklist

Update release_notes.md if your PR contains major features, breaking changes or bugfixes

sputn1ck · 2025-04-10T10:02:16Z

sweepbatcher/store.go

@@ -213,8 +213,8 @@ type dbBatch struct {
 	// ID is the unique identifier of the batch.


Maybe stupid question, but missing lots of context. This commit changes more than the mock, and feels a bit complicated, can you maybe elaborate what the changes to the other files are?

I updated the commit message:

sweepbatcher: align dbBatch type with DB schema Previously, dbBatch had a State field (enum: Open, Closed, Confirmed), but in the database it is represented as a boolean Confirmed. The Closed state was stored the same way as Open. This wasn't an issue in practice, since an Open batch is quickly transitioned to Closed after startup. However, the in-memory mock stores plain dbBatch instances, leading to inconsistent behavior between the mock and the real DB-backed store. This commit updates dbBatch to match the database representation by replacing

Also added a note to the description of Closed const:

// Closed is the state in which the batch is no longer able to accept // new sweeps. NOTE: this state exists only in-memory. In the database // it is stored as Open and converted to Closed after a spend // notification arrives (quickly after start of Batch.Run). Closed batchState = 1

bhandras

Looks good. Perhaps we don't even need the "closed" state?

sweepbatcher/sweep_batcher.go

bhandras · 2025-04-10T11:53:03Z

sweepbatcher/sweep_batch.go

+		// If the sweep's notifier is empty then this means that a swap
+		// is not waiting to read an update from it, so we can skip
+		// the notification part.
+		if s.notifier == nil || *s.notifier == (SpendNotifier{}) {


Why check *s.notifier == (SpendNotifier{} ?

It was a copy-paste. I updated this line:

if s.notifier == nil || s.notifier.SpendErrChan == nil {

sweepbatcher/store_mock.go

bhandras · 2025-04-10T12:08:40Z

sweepbatcher/store.go

@@ -259,7 +259,7 @@ func convertBatchRow(row sqlc.SweepBatch) *dbBatch {
 	}

 	if row.Confirmed {
-		batch.State = batchOpen
+		batch.State = batchConfirmed


I assume this just resulted in the batches restarting (and then getting to confirmed state again after spend notification received)?

Yes, and then after confirmation notification (after 3 confs).

Open -(spend notif)-> Closed -(conf notif)-> Confirmed

bhandras · 2025-04-10T12:13:46Z

sweepbatcher/sweep_batcher.go


 	// Then we get the total amount that was swept by the batch.
 	totalSwept, err := b.store.TotalSweptAmount(ctx, parentBatchID)
 	if err != nil {
+		cancel()


Hmm, this is a great fix, but how did we ever not get cancelled?

This code path is executed only when a fully confirmed sweep is added again to the sweeper. This may happen if the daemon was down when the sweep was fully confirmed (got 3rd confirmation). This is not the main code path.

bhandras · 2025-04-10T12:22:09Z

sweepbatcher/sweep_batcher.go

+			// manages to be added during this time, it will be
+			// detected as missing when analyzing the spend
+			// notification and will be added to new batch.
+			batch.state = Open


But this also means that any new sweeps could be added, and then we just would try to publish the batch again (and fail as inputs are spent). It's robust so not a huge issue, but perhaps we could avoid.

Avoiding this would require a DB migration, which doesn’t seem worthwhile just to improve this edge case.

sweepbatcher/sweep_batch.go

starius · 2025-04-13T21:09:59Z

Looks good. Perhaps we don't even need the "closed" state?

I think it makes sense to keep Closed to make this thing easier to understand / debug.

Also maybe greedy batch selection can work worse if we let it add to Closed.

starius · 2025-04-26T04:36:26Z

Converting to draft. I'm working to add more commits here and to rebase it on top of #891

lightninglabs-deploy · 2025-05-05T00:05:50Z

@sputn1ck: review reminder
@bhandras: review reminder

Forgot to return the calculated total value.

Support sending errors to error channels returned by RegisterSpendNtfn and RegisterConfirmationsNtfn.

Function monitorSpendAndNotify used to cancel the context passed to RegisterSpendNtfn right after starting the goroutine processing results. Spend notifications were missed. Now the context is canceled when the goroutine finishes.

The loop always had exactly one iteration.

If monitorConfirmations fails, we still want to persist the state to DB.

Previously, dbBatch had a State field (enum: Open, Closed, Confirmed), but in the database it is represented as a boolean Confirmed. The Closed state was stored the same way as Open. This wasn't an issue in practice, since an Open batch is quickly transitioned to Closed after startup. However, the in-memory mock stores plain dbBatch instances, leading to inconsistent behavior between the mock and the real DB-backed store. This commit updates dbBatch to match the database representation by replacing the State field with a Confirmed boolean.

Add fields ConfChan and ConfErrChan to SpendNotifier type which is a part of SweepRequest passed to AddSweep method. This is needed to reuse confirmation notifications on the calling side the same way it is done for spending notifications.

This is needed to have multiple spending registrations running and to send a notification to a specific spending registration.

In case of a reorg sweeps should not go to another batch but stay in the current batch until it is fully confirmed. Only after that the remaining sweeps are re-added to another batch. Field sweep.completed is now set to true only for fully-confirmed sweeps.

There were two mistakes. In case of a swap with multiple sweeps only the fee of the first sweep of a swap was accounted. Rounding diff (the remainder) was attributed to all the sweeps rather than to the first (primary) sweep of the batch. The sweep to attribute the remainder was chosen by comparing SignatureScript which is always empty. New approach is to find the primary sweep and to compare its outpoint directly.

This is needed because sweepbatcher can use this channel in multiple select statements to unblock itself if the caller cancels.

It doesn't need loopdb, so remove that code.

Make sure that broadcasted tx has feeRate >= minRelayFee. Make sure that feeRate of broadcasted tx doesn't decrease.

bhandras

Really nice set of fixes! Making sweep-batcher more robust one step at a time 🚀
LGTM 🎉

bhandras · 2025-05-09T17:42:23Z

sweepbatcher/sweep_batch.go

-	// new sweeps.
+	// new sweeps. NOTE: this state exists only in-memory. In the database
+	// it is stored as Open and converted to Closed after a spend
+	// notification arrives (quickly after start of Batch.Run).


bhandras · 2025-05-09T17:43:16Z

sweepbatcher/sweep_batcher.go

+			// manages to be added during this time, it will be
+			// detected as missing when analyzing the spend
+			// notification and will be added to new batch.
+			batch.state = Open


sweepbatcher/sweep_batch.go

bhandras · 2025-05-09T18:40:33Z

sweepbatcher/sweep_batch.go

+
+		spendDetail := SpendDetail{
+			Tx: spendTx,
+			OnChainFeePortion: getFeePortionPaidBySweep(


Alternatively we could communicate the fee portion once the sweep is fully-confirmed. wdyt?

starius force-pushed the conf-chan branch from 391bef5 to 270ecbc Compare April 9, 2025 03:19

starius marked this pull request as ready for review April 9, 2025 04:06

starius requested review from bhandras, sputn1ck and hieblmi April 9, 2025 04:15

sputn1ck reviewed Apr 10, 2025

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bhandras reviewed Apr 10, 2025

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levmi assigned starius Apr 10, 2025

starius force-pushed the conf-chan branch from 270ecbc to 7a7e996 Compare April 13, 2025 20:56

starius requested review from sputn1ck and bhandras April 13, 2025 21:15

levmi removed the request for review from hieblmi April 15, 2025 15:29

starius marked this pull request as draft April 26, 2025 04:35

starius changed the title ~~sweepbatcher: notify caller about confirmations~~ [WIP] sweepbatcher: notify caller about confirmations Apr 26, 2025

starius force-pushed the conf-chan branch 2 times, most recently from a67a666 to e234022 Compare April 29, 2025 03:52

starius changed the title ~~[WIP] sweepbatcher: notify caller about confirmations~~ sweepbatcher: notify caller about confirmations Apr 29, 2025

starius marked this pull request as ready for review April 29, 2025 03:53

starius force-pushed the conf-chan branch 3 times, most recently from 5217a80 to 494ebfb Compare May 2, 2025 04:40

starius force-pushed the conf-chan branch from 494ebfb to c292ec2 Compare May 5, 2025 20:46

levmi requested review from hieblmi and removed request for sputn1ck May 6, 2025 14:22

starius added 3 commits May 8, 2025 17:44

sweepbatcher: mark channels receive- or send-only

51d74c1

sweepbatcher: unblock sending if notifier quits

5f9c93d

sweepbatcher: send spend error to notifier

abff8d9

starius added 19 commits May 8, 2025 17:44

test: fix error messages

538e4fe

sweepbatcher: fix mock TotalSweptAmount

26e6e2c

Forgot to return the calculated total value.

sweepbatcher: fix mistake in batch reading from DB

91cb7d6

test/chainnotifier_mock: support errors

5475d48

Support sending errors to error channels returned by RegisterSpendNtfn and RegisterConfirmationsNtfn.

sweepbatcher: cancel spendCtx after processing

712e0d6

Function monitorSpendAndNotify used to cancel the context passed to RegisterSpendNtfn right after starting the goroutine processing results. Spend notifications were missed. Now the context is canceled when the goroutine finishes.

sweepbatcher: remove unneded for loops

edc0ba3

The loop always had exactly one iteration.

sweepbatcher: store batch status before monitoring

dbb41bf

If monitorConfirmations fails, we still want to persist the state to DB.

sweepbatcher: test spending notification and error

3e2062c

test/chainnotifier: send to specific spend reg

7adf106

This is needed to have multiple spending registrations running and to send a notification to a specific spending registration.

loopout: close sweepbatcher quitChan

fa622ba

This is needed because sweepbatcher can use this channel in multiple select statements to unblock itself if the caller cancels.

sweepbatcher: pass utxo to fee provider

a7fa800

sweepbatcher: make sure dest pkscript is filled

c543473

sweepbatcher: simplify presigned/purging test

0b44763

It doesn't need loopdb, so remove that code.

sweepbatcher: make sure HTLC.PkScript is filled

50352ae

sweepbatcher/presigned: minRelayFee edge cases

ef315c3

Make sure that broadcasted tx has feeRate >= minRelayFee. Make sure that feeRate of broadcasted tx doesn't decrease.

starius force-pushed the conf-chan branch from 0190178 to ef315c3 Compare May 8, 2025 20:44

starius requested a review from sputn1ck May 8, 2025 21:29

bhandras approved these changes May 9, 2025

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sweepbatcher: notify caller about confirmations #919

sweepbatcher: notify caller about confirmations #919

starius commented Apr 9, 2025 •

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bhandras May 9, 2025

		@@ -213,8 +213,8 @@ type dbBatch struct {
		// ID is the unique identifier of the batch.

sweepbatcher: notify caller about confirmations #919

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sweepbatcher: notify caller about confirmations #919

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starius commented Apr 9, 2025 •

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