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Merged
t-bast merged 2 commits into from
Oct 1, 2025
Merged

Send splice commit_sigs as a batch #787

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94d7ea1
Send and receive splice `commit_sig` as batch
t-bast May 16, 2025
b4ca791
Fix PR comments
t-bast Oct 1, 2025
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16 changes: 10 additions & 6 deletions modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -762,7 +762,7 @@ data class Commitments(
return failure?.let { Either.Left(it) } ?: Either.Right(copy(changes = changes1))
}

fun sendCommit(channelKeys: KeyManager.ChannelKeys, log: MDCLogger): Either<ChannelException, Pair<Commitments, List<CommitSig>>> {
fun sendCommit(channelKeys: KeyManager.ChannelKeys, log: MDCLogger): Either<ChannelException, Pair<Commitments, CommitSigs>> {
val remoteNextPerCommitmentPoint = remoteNextCommitInfo.right ?: return Either.Left(CannotSignBeforeRevocation(channelId))
if (!changes.localHasChanges()) return Either.Left(CannotSignWithoutChanges(channelId))
val (active1, sigs) = active.map { it.sendCommit(channelKeys, params, changes, remoteNextPerCommitmentPoint, active.size, log) }.unzip()
Expand All @@ -774,18 +774,22 @@ data class Commitments(
remoteChanges = changes.remoteChanges.copy(acked = emptyList(), signed = changes.remoteChanges.acked)
)
)
return Either.Right(Pair(commitments1, sigs))
return Either.Right(Pair(commitments1, CommitSigs.fromSigs(sigs)))
}

fun receiveCommit(commits: List<CommitSig>, channelKeys: KeyManager.ChannelKeys, log: MDCLogger): Either<ChannelException, Pair<Commitments, RevokeAndAck>> {
fun receiveCommit(commits: CommitSigs, channelKeys: KeyManager.ChannelKeys, log: MDCLogger): Either<ChannelException, Pair<Commitments, RevokeAndAck>> {
// We may receive more commit_sig than the number of active commitments, because there can be a race where we send splice_locked
// while our peer is sending us a batch of commit_sig. When that happens, we simply need to discard the commit_sig that belong
// to commitments we deactivated.
if (commits.size < active.size) {
return Either.Left(CommitSigCountMismatch(channelId, active.size, commits.size))
val sigs = when (commits) {
is CommitSigBatch -> commits.messages
is CommitSig -> listOf(commits)
}
if (sigs.size < active.size) {
return Either.Left(CommitSigCountMismatch(channelId, active.size, sigs.size))
}
// Signatures are sent in order (most recent first), calling `zip` will drop trailing sigs that are for deactivated/pruned commitments.
val active1 = active.zip(commits).map {
val active1 = active.zip(sigs).map {
when (val commitment1 = it.first.receiveCommit(channelKeys, params, changes, it.second, log)) {
is Either.Left -> return Either.Left(commitment1.value)
is Either.Right -> commitment1.value
Expand Down
16 changes: 0 additions & 16 deletions modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt
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Expand Up @@ -674,22 +674,6 @@ sealed class ChannelStateWithCommitments : PersistedChannelState() {
}
}
}

// in Normal and Shutdown we aggregate sigs for splices before processing
var sigStash = emptyList<CommitSig>()

/** For splices we will send one commit_sig per active commitments. */
internal fun ChannelContext.aggregateSigs(commit: CommitSig): List<CommitSig>? {
sigStash = sigStash + commit
logger.debug { "received sig for batch of size=${commit.batchSize}" }
return if (sigStash.size == commit.batchSize) {
val sigs = sigStash
sigStash = emptyList()
sigs
} else {
null
}
}
}

object Channel {
Expand Down
59 changes: 26 additions & 33 deletions modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Normal.kt
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Expand Up @@ -80,7 +80,7 @@ data class Normal(
val actions = buildList {
add(ChannelAction.Storage.StoreHtlcInfos(htlcInfos))
add(ChannelAction.Storage.StoreState(nextState))
addAll(result.value.second.map { ChannelAction.Message.Send(it) })
add(ChannelAction.Message.Send(result.value.second))
}
Pair(nextState, actions)
}
Expand Down Expand Up @@ -173,12 +173,12 @@ data class Normal(
is Either.Left -> handleLocalError(cmd, result.value)
is Either.Right -> Pair(this@Normal.copy(commitments = result.value), listOf())
}
is CommitSig -> when {
is CommitSigs -> when {
spliceStatus == SpliceStatus.Aborted -> {
logger.warning { "received commit_sig after sending tx_abort, they probably sent it before receiving our tx_abort, ignoring..." }
Pair(this@Normal, listOf())
}
spliceStatus is SpliceStatus.WaitingForSigs -> {
spliceStatus is SpliceStatus.WaitingForSigs && cmd.message is CommitSig -> {
val (signingSession1, action) = spliceStatus.session.receiveCommitSig(channelKeys(), commitments.params, cmd.message, currentBlockHeight.toLong(), logger)
when (action) {
is InteractiveTxSigningSessionAction.AbortFundingAttempt -> {
Expand All @@ -193,7 +193,7 @@ data class Normal(
is InteractiveTxSigningSessionAction.SendTxSigs -> sendSpliceTxSigs(spliceStatus.origins, action, spliceStatus.liquidityPurchase)
}
}
ignoreRetransmittedCommitSig(cmd.message) -> {
cmd.message is CommitSig && ignoreRetransmittedCommitSig(cmd.message) -> {
// We haven't received our peer's tx_signatures for the latest funding transaction and asked them to resend it on reconnection.
// They also resend their corresponding commit_sig, but we have already received it so we should ignore it.
// Note that the funding transaction may have confirmed while we were offline.
Expand All @@ -202,34 +202,29 @@ data class Normal(
}
// NB: in all other cases we process the commit_sig normally. We could do a full pattern matching on all splice statuses, but it would force us to handle
// corner cases like race condition between splice_init and a non-splice commit_sig
else -> {
when (val sigs = aggregateSigs(cmd.message)) {
is List<CommitSig> -> when (val result = commitments.receiveCommit(sigs, channelKeys(), logger)) {
is Either.Left -> handleLocalError(cmd, result.value)
is Either.Right -> {
val commitments1 = result.value.first
val spliceStatus1 = when {
spliceStatus is SpliceStatus.QuiescenceRequested && commitments1.localIsQuiescent() -> SpliceStatus.InitiatorQuiescent(spliceStatus.command)
spliceStatus is SpliceStatus.ReceivedStfu && commitments1.localIsQuiescent() -> SpliceStatus.NonInitiatorQuiescent
else -> spliceStatus
}
val nextState = this@Normal.copy(commitments = commitments1, spliceStatus = spliceStatus1)
val actions = mutableListOf<ChannelAction>()
actions.add(ChannelAction.Storage.StoreState(nextState))
actions.add(ChannelAction.Message.Send(result.value.second))
if (commitments1.changes.localHasChanges()) {
actions.add(ChannelAction.Message.SendToSelf(ChannelCommand.Commitment.Sign))
}
// If we're now quiescent, we may send our stfu message.
when {
spliceStatus is SpliceStatus.QuiescenceRequested && commitments1.localIsQuiescent() -> actions.add(ChannelAction.Message.Send(Stfu(channelId, initiator = true)))
spliceStatus is SpliceStatus.ReceivedStfu && commitments1.localIsQuiescent() -> actions.add(ChannelAction.Message.Send(Stfu(channelId, initiator = false)))
else -> {}
}
Pair(nextState, actions)
}
else -> when (val result = commitments.receiveCommit(cmd.message, channelKeys(), logger)) {
is Either.Left -> handleLocalError(cmd, result.value)
is Either.Right -> {
val commitments1 = result.value.first
val spliceStatus1 = when {
spliceStatus is SpliceStatus.QuiescenceRequested && commitments1.localIsQuiescent() -> SpliceStatus.InitiatorQuiescent(spliceStatus.command)
spliceStatus is SpliceStatus.ReceivedStfu && commitments1.localIsQuiescent() -> SpliceStatus.NonInitiatorQuiescent
else -> spliceStatus
}
val nextState = this@Normal.copy(commitments = commitments1, spliceStatus = spliceStatus1)
val actions = mutableListOf<ChannelAction>()
actions.add(ChannelAction.Storage.StoreState(nextState))
actions.add(ChannelAction.Message.Send(result.value.second))
if (commitments1.changes.localHasChanges()) {
actions.add(ChannelAction.Message.SendToSelf(ChannelCommand.Commitment.Sign))
}
else -> Pair(this@Normal, listOf())
// If we're now quiescent, we may send our stfu message.
when {
spliceStatus is SpliceStatus.QuiescenceRequested && commitments1.localIsQuiescent() -> actions.add(ChannelAction.Message.Send(Stfu(channelId, initiator = true)))
spliceStatus is SpliceStatus.ReceivedStfu && commitments1.localIsQuiescent() -> actions.add(ChannelAction.Message.Send(Stfu(channelId, initiator = false)))
else -> {}
}
Pair(nextState, actions)
}
}
}
Expand Down Expand Up @@ -822,8 +817,6 @@ data class Normal(
SpliceStatus.None
}
}
// reset the commit_sig batch
sigStash = emptyList()
Pair(Offline(this@Normal.copy(spliceStatus = spliceStatus1)), failedHtlcs)
}
is ChannelCommand.Connected -> unhandled(cmd)
Expand Down
41 changes: 17 additions & 24 deletions modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/ShuttingDown.kt
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Expand Up @@ -39,29 +39,26 @@ data class ShuttingDown(
is Either.Left -> handleLocalError(cmd, result.value)
is Either.Right -> Pair(this@ShuttingDown.copy(commitments = result.value), listOf())
}
is CommitSig -> when (val sigs = aggregateSigs(cmd.message)) {
is List<CommitSig> -> when (val result = commitments.receiveCommit(sigs, channelKeys(), logger)) {
is Either.Left -> handleLocalError(cmd, result.value)
is Either.Right -> {
val (commitments1, revocation) = result.value
when {
commitments1.hasNoPendingHtlcsOrFeeUpdate() -> startClosingNegotiation(closeCommand, commitments1, localShutdown, remoteShutdown, listOf(ChannelAction.Message.Send(revocation)))
else -> {
val nextState = this@ShuttingDown.copy(commitments = commitments1)
val actions = buildList {
add(ChannelAction.Storage.StoreState(nextState))
add(ChannelAction.Message.Send(revocation))
if (commitments1.changes.localHasChanges()) {
// if we have newly acknowledged changes let's sign them
add(ChannelAction.Message.SendToSelf(ChannelCommand.Commitment.Sign))
}
is CommitSigs -> when (val result = commitments.receiveCommit(cmd.message, channelKeys(), logger)) {
is Either.Left -> handleLocalError(cmd, result.value)
is Either.Right -> {
val (commitments1, revocation) = result.value
when {
commitments1.hasNoPendingHtlcsOrFeeUpdate() -> startClosingNegotiation(closeCommand, commitments1, localShutdown, remoteShutdown, listOf(ChannelAction.Message.Send(revocation)))
else -> {
val nextState = this@ShuttingDown.copy(commitments = commitments1)
val actions = buildList {
add(ChannelAction.Storage.StoreState(nextState))
add(ChannelAction.Message.Send(revocation))
if (commitments1.changes.localHasChanges()) {
// if we have newly acknowledged changes let's sign them
add(ChannelAction.Message.SendToSelf(ChannelCommand.Commitment.Sign))
}
Pair(nextState, actions)
}
Pair(nextState, actions)
}
}
}
else -> Pair(this@ShuttingDown, listOf())
}
is RevokeAndAck -> when (val result = commitments.receiveRevocation(cmd.message)) {
is Either.Left -> handleLocalError(cmd, result.value)
Expand Down Expand Up @@ -128,7 +125,7 @@ data class ShuttingDown(
val actions = buildList {
add(ChannelAction.Storage.StoreHtlcInfos(htlcInfos))
add(ChannelAction.Storage.StoreState(nextState))
addAll(result.value.second.map { ChannelAction.Message.Send(it) })
add(ChannelAction.Message.Send(result.value.second))
}
Pair(nextState, actions)
}
Expand Down Expand Up @@ -164,11 +161,7 @@ data class ShuttingDown(
is WatchSpentTriggered -> handlePotentialForceClose(watch)
}
is ChannelCommand.Commitment.CheckHtlcTimeout -> checkHtlcTimeout()
is ChannelCommand.Disconnected -> {
// reset the commit_sig batch
sigStash = emptyList()
Pair(Offline(this@ShuttingDown), listOf())
}
is ChannelCommand.Disconnected -> Pair(Offline(this@ShuttingDown), listOf())
else -> unhandled(cmd)
}
}
Expand Down
10 changes: 5 additions & 5 deletions modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Syncing.kt
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Expand Up @@ -413,29 +413,29 @@ data class Syncing(val state: PersistedChannelState, val channelReestablishSent:
val signedUpdates = commitments.changes.localChanges.signed
val channelParams = commitments.params
val batchSize = commitments.active.size
val commitSigs = commitments.active.mapNotNull { c ->
val commitSigs = CommitSigs.fromSigs(commitments.active.mapNotNull { c ->
val commitInput = c.commitInput
// Note that we ignore errors and simply skip failures to sign: we've already signed those updates before
// the disconnection, so we don't expect any error here unless our peer sends an invalid nonce. In that
// case, we simply won't send back our commit_sig until they fix their node.
c.nextRemoteCommit?.commit?.sign(channelKeys, channelParams, c.fundingTxIndex, c.remoteFundingPubkey, commitInput, batchSize)
}
})
val retransmit = when (retransmitRevocation) {
null -> buildList {
addAll(signedUpdates)
addAll(commitSigs)
add(commitSigs)
}
else -> if (commitments.localCommitIndex > rnci.value.sentAfterLocalCommitIndex) {
buildList {
addAll(signedUpdates)
addAll(commitSigs)
add(commitSigs)
add(retransmitRevocation)
}
} else {
buildList {
add(retransmitRevocation)
addAll(signedUpdates)
addAll(commitSigs)
add(commitSigs)
}
}
}
Expand Down
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