Liquidity Ads

[t-bast]

The initiator of open_channel2, tx_init_rbf and splice_init can request funding from the remote node. The non-initiator node will:

• let the open-channel-interceptor plugin decide whether to lease liquidity for new channels or not, and how much
• always honor liquidity requests on existing channels (RBF and splice)

We currently don't modify commitment transactions to enforce the lease. This is different from https://github.com/lightning/bolts/pull/878 and instead matches https://github.com/lightning/bolts/pull/1145.

We currently use the temporary tlv tag 1337 while we're waiting for feedback on our spec proposal.

Liquidity ads are included in the node_announcement message, which lets buyers compare sellers and connect to sellers that provide rates they are comfortable with.

We store every liquidity purchase (whether we're buyer or seller) in the audit DB. This is important information when choosing which peers are worth keeping channels with.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 93.85475% with 22 lines in your changes are missing coverage. Please review.

Project coverage is 86.07%. Comparing base (c8184b3) to head (74f2c0d).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2550      +/-   ##
==========================================
+ Coverage   85.96%   86.07%   +0.11%     
==========================================
  Files         219      220       +1     
  Lines       18441    18709     +268     
  Branches      762      809      +47     
==========================================
+ Hits        15853    16104     +251     
- Misses       2588     2605      +17     

Files	Coverage Δ
...r-core/src/main/scala/fr/acinq/eclair/Eclair.scala	56.61% <100.00%> (+0.18%)	:arrow_up:
.../src/main/scala/fr/acinq/eclair/PluginParams.scala	66.66% <ø> (ø)
...in/scala/fr/acinq/eclair/channel/ChannelData.scala	100.00% <ø> (ø)
.../scala/fr/acinq/eclair/channel/ChannelEvents.scala	100.00% <100.00%> (ø)
...c/main/scala/fr/acinq/eclair/channel/Helpers.scala	94.56% <100.00%> (+0.02%)	:arrow_up:
...in/scala/fr/acinq/eclair/channel/fsm/Channel.scala	85.47% <100.00%> (+0.27%)	:arrow_up:
...inq/eclair/channel/fund/InteractiveTxBuilder.scala	91.80% <100.00%> (+0.42%)	:arrow_up:
...cinq/eclair/channel/fund/InteractiveTxFunder.scala	92.80% <100.00%> (+0.32%)	:arrow_up:
...c/main/scala/fr/acinq/eclair/db/pg/PgAuditDb.scala	99.73% <100.00%> (+0.04%)	:arrow_up:
...cala/fr/acinq/eclair/db/sqlite/SqliteAuditDb.scala	99.72% <100.00%> (+0.04%)	:arrow_up:
... and 16 more

... and 1 file with indirect coverage changes

[pm47]

FYI, here is a patch on channel/Monitoring.scala to track liquidity splices:

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/channel/Monitoring.scala b/eclair-core/src/main/scala/fr/acinq/eclair/channel/Monitoring.scala
index fa15594cc0..4900a46467 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/channel/Monitoring.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/channel/Monitoring.scala
@@ -57,10 +57,18 @@ object Monitoring {
      */
     def recordSplice(fundingParams: InteractiveTxParams, sharedTx: SharedTransaction): Unit = {
       if (fundingParams.localContribution > 0.sat) {
-        Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Local).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceIn).record(fundingParams.localContribution.toLong)
+        if (fundingParams.isInitiator) {
+          Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Local).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceIn).record(fundingParams.localContribution.toLong)
+        } else {
+          Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Local).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceLiquidity).record(fundingParams.localContribution.toLong)
+        }
       }
       if (fundingParams.remoteContribution > 0.sat) {
-        Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Remote).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceIn).record(fundingParams.remoteContribution.toLong)
+        if (fundingParams.isInitiator) {
+          Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Remote).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceLiquidity).record(fundingParams.remoteContribution.toLong)
+        } else {
+          Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Remote).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceIn).record(fundingParams.remoteContribution.toLong)
+        }
       }
       if (sharedTx.localOnlyNonChangeOutputs.nonEmpty) {
         Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Local).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceOut).record(sharedTx.localOnlyNonChangeOutputs.map(_.amount).sum.toLong)
@@ -68,10 +76,10 @@ object Monitoring {
       if (sharedTx.remoteOutputs.nonEmpty) {
         Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Remote).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceOut).record(sharedTx.remoteOutputs.map(_.amount).sum.toLong)
       }
-      if (fundingParams.localContribution < 0.sat && sharedTx.localOutputs.isEmpty) {
+      if (fundingParams.localContribution < 0.sat && sharedTx.localOutputs.isEmpty && fundingParams.remoteContribution == 0.sat) {
         Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Local).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceCpfp).record(Math.abs(fundingParams.localContribution.toLong))
       }
-      if (fundingParams.remoteContribution < 0.sat && sharedTx.remoteOutputs.isEmpty) {
+      if (fundingParams.remoteContribution < 0.sat && sharedTx.remoteOutputs.isEmpty && fundingParams.localContribution == 0.sat) {
         Metrics.Splices.withTag(Tags.Origin, Tags.Origins.Remote).withTag(Tags.SpliceType, Tags.SpliceTypes.SpliceCpfp).record(Math.abs(fundingParams.remoteContribution.toLong))
       }
     }
@@ -114,6 +122,7 @@ object Monitoring {
       val SpliceIn = "splice-in"
       val SpliceOut = "splice-out"
       val SpliceCpfp = "splice-cpfp"
+      val SpliceLiquidity = "splice-liquidity"
     }
   }

A "purer" way would have been to add a isInitiator tag, instead of a SpliceLiquidity type, but it's also less user friendly. Here we are arbitrarily categorizing splices anyway. Will see how it goes on feature branches.

[pm47]

Please rebase 🙏

[t-bast]

Rebased and squashed! I'll work on porting the annoying-to-rebase parts to master to simplify future rebases.

[t-bast]

Superseded by #2848