contractcourt: offer second-level outputs at CSV-1

This commit moves the offering of second-level outputs one block
earlier. The sweeper will check the required locktime and wait until it
matures. This is needed so the second-level outputs can be aggregated
properly.

contractcourt/htlc_success_resolver.go

@@ -349,6 +349,25 @@ func (h *htlcSuccessResolver) broadcastReSignedSuccessTx() (
 			"height %v", h, h.htlc.RHash[:], waitHeight)
 	}
 
+	// Deduct one block so this input is offered to the sweeper one block
+	// earlier since the sweeper will wait for one block to trigger the
+	// sweeping.
+	//
+	// TODO(yy): this is done so the outputs can be aggregated
+	// properly. Suppose CSV locks of five 2nd-level outputs all
+	// expire at height 840000, there is a race in block digestion
+	// between contractcourt and sweeper:
+	// - G1: block 840000 received in contractcourt, it now offers
+	//   the outputs to the sweeper.
+	// - G2: block 840000 received in sweeper, it now starts to
+	//   sweep the received outputs - there's no guarantee all
+	//   fives have been received.
+	// To solve this, we either offer the outputs earlier, or
+	// implement `blockbeat`, and force contractcourt and sweeper
+	// to consume each block sequentially.
+	waitHeight--
+
+	// TODO(yy): let sweeper handles the wait?
 	err := waitForHeight(waitHeight, h.Notifier, h.quit)
 	if err != nil {
 		return nil, err
@@ -364,10 +383,6 @@ func (h *htlcSuccessResolver) broadcastReSignedSuccessTx() (
 		Index: commitSpend.SpenderInputIndex,
 	}
 
-	// Finally, let the sweeper sweep the second-level output.
-	log.Infof("%T(%x): CSV lock expired, offering second-layer "+
-		"output to sweeper: %v", h, h.htlc.RHash[:], op)
-
 	// Let the sweeper sweep the second-level output now that the
 	// CSV/CLTV locks have expired.
 	var witType input.StandardWitnessType
@@ -380,7 +395,7 @@ func (h *htlcSuccessResolver) broadcastReSignedSuccessTx() (
 		op, witType,
 		input.LeaseHtlcAcceptedSuccessSecondLevel,
 		&h.htlcResolution.SweepSignDesc,
-		h.htlcResolution.CsvDelay, h.broadcastHeight,
+		h.htlcResolution.CsvDelay, uint32(commitSpend.SpendingHeight),
 		h.htlc.RHash,
 	)
 
@@ -392,7 +407,8 @@ func (h *htlcSuccessResolver) broadcastReSignedSuccessTx() (
 	)
 
 	log.Infof("%T(%x): offering second-level success tx output to sweeper "+
-		"with no deadline and budget=%v", h, h.htlc.RHash[:], budget)
+		"with no deadline and budget=%v at height=%v", h,
+		h.htlc.RHash[:], budget, waitHeight)
 
 	// TODO(roasbeef): need to update above for leased types
 	_, err = h.Sweeper.SweepInput(

contractcourt/htlc_timeout_resolver.go

@@ -706,6 +706,25 @@ func (h *htlcTimeoutResolver) handleCommitSpend(
 				"height %v", h, h.htlc.RHash[:], waitHeight)
 		}
 
+		// Deduct one block so this input is offered to the sweeper one
+		// block earlier since the sweeper will wait for one block to
+		// trigger the sweeping.
+		//
+		// TODO(yy): this is done so the outputs can be aggregated
+		// properly. Suppose CSV locks of five 2nd-level outputs all
+		// expire at height 840000, there is a race in block digestion
+		// between contractcourt and sweeper:
+		// - G1: block 840000 received in contractcourt, it now offers
+		//   the outputs to the sweeper.
+		// - G2: block 840000 received in sweeper, it now starts to
+		//   sweep the received outputs - there's no guarantee all
+		//   fives have been received.
+		// To solve this, we either offer the outputs earlier, or
+		// implement `blockbeat`, and force contractcourt and sweeper
+		// to consume each block sequentially.
+		waitHeight--
+
+		// TODO(yy): let sweeper handles the wait?
 		err := waitForHeight(waitHeight, h.Notifier, h.quit)
 		if err != nil {
 			return nil, err
@@ -735,8 +754,8 @@ func (h *htlcTimeoutResolver) handleCommitSpend(
 			op, csvWitnessType,
 			input.LeaseHtlcOfferedTimeoutSecondLevel,
 			&h.htlcResolution.SweepSignDesc,
-			h.htlcResolution.CsvDelay, h.broadcastHeight,
-			h.htlc.RHash,
+			h.htlcResolution.CsvDelay,
+			uint32(commitSpend.SpendingHeight), h.htlc.RHash,
 		)
 		// Calculate the budget for this sweep.
 		budget := calculateBudget(
@@ -746,8 +765,8 @@ func (h *htlcTimeoutResolver) handleCommitSpend(
 		)
 
 		log.Infof("%T(%x): offering second-level timeout tx output to "+
-			"sweeper with no deadline and budget=%v", h,
-			h.htlc.RHash[:], budget)
+			"sweeper with no deadline and budget=%v at height=%v",
+			h, h.htlc.RHash[:], budget, waitHeight)
 
 		_, err = h.Sweeper.SweepInput(
 			inp,

sweep/sweeper.go

@@ -652,7 +652,7 @@ func (s *UtxoSweeper) collector(blockEpochs <-chan *chainntnfs.BlockEpoch) {
 		// failed, or excluded from the sweeper and return inputs that
 		// are either new or has been published but failed back, which
 		// will be retried again here.
-		inputs := s.updateSweeperInputs()
+		s.updateSweeperInputs()
 
 		select {
 		// A new inputs is offered to the sweeper. We check to see if
@@ -670,7 +670,7 @@ func (s *UtxoSweeper) collector(blockEpochs <-chan *chainntnfs.BlockEpoch) {
 			// If this input is forced, we perform an sweep
 			// immediately.
 			if input.params.Force {
-				inputs = s.updateSweeperInputs()
+				inputs := s.updateSweeperInputs()
 				s.sweepPendingInputs(inputs)
 			}
 
@@ -716,6 +716,9 @@ func (s *UtxoSweeper) collector(blockEpochs <-chan *chainntnfs.BlockEpoch) {
 			// Update the sweeper to the best height.
 			s.currentHeight = epoch.Height
 
+			// Update the inputs with the latest height.
+			inputs := s.updateSweeperInputs()
+
 			log.Debugf("Received new block: height=%v, attempt "+
 				"sweeping %d inputs", epoch.Height, len(inputs))
 
@@ -1497,6 +1500,17 @@ func (s *UtxoSweeper) updateSweeperInputs() InputsMap {
 			continue
 		}
 
+		// If the input has a CSV that's not yet reached, we will skip
+		// this input and wait for the expiry.
+		locktime = input.BlocksToMaturity() + input.HeightHint()
+		if s.currentHeight < int32(locktime)-1 {
+			log.Infof("Skipping input %v due to CSV expiry=%v not "+
+				"reached, current height is %v", op, locktime,
+				s.currentHeight)
+
+			continue
+		}
+
 		// If this input is new or has been failed to be published,
 		// we'd retry it. The assumption here is that when an error is
 		// returned from `PublishTransaction`, it means the tx has

sweep/sweeper_test.go

@@ -2479,6 +2479,8 @@ func TestUpdateSweeperInputs(t *testing.T) {
 	defer inp1.AssertExpectations(t)
 	inp2 := &input.MockInput{}
 	defer inp2.AssertExpectations(t)
+	inp3 := &input.MockInput{}
+	defer inp3.AssertExpectations(t)
 
 	// Create a list of inputs using all the states.
 	//
@@ -2486,6 +2488,8 @@ func TestUpdateSweeperInputs(t *testing.T) {
 	// returned.
 	inp1.On("RequiredLockTime").Return(
 		uint32(s.currentHeight), false).Once()
+	inp1.On("BlocksToMaturity").Return(uint32(0)).Once()
+	inp1.On("HeightHint").Return(uint32(s.currentHeight)).Once()
 	input0 := &SweeperInput{state: Init, Input: inp1}
 
 	// These inputs won't hit RequiredLockTime so we won't mock.
@@ -2496,6 +2500,8 @@ func TestUpdateSweeperInputs(t *testing.T) {
 	// returned.
 	inp1.On("RequiredLockTime").Return(
 		uint32(s.currentHeight), false).Once()
+	inp1.On("BlocksToMaturity").Return(uint32(0)).Once()
+	inp1.On("HeightHint").Return(uint32(s.currentHeight)).Once()
 	input3 := &SweeperInput{state: PublishFailed, Input: inp1}
 
 	// These inputs won't hit RequiredLockTime so we won't mock.
@@ -2509,6 +2515,14 @@ func TestUpdateSweeperInputs(t *testing.T) {
 		uint32(s.currentHeight+1), true).Once()
 	input7 := &SweeperInput{state: Init, Input: inp2}
 
+	// Mock the input to have a CSV expiry in the future so it will NOT be
+	// returned.
+	inp3.On("RequiredLockTime").Return(
+		uint32(s.currentHeight), false).Once()
+	inp3.On("BlocksToMaturity").Return(uint32(2)).Once()
+	inp3.On("HeightHint").Return(uint32(s.currentHeight)).Once()
+	input8 := &SweeperInput{state: Init, Input: inp3}
+
 	// Add the inputs to the sweeper. After the update, we should see the
 	// terminated inputs being removed.
 	s.inputs = map[wire.OutPoint]*SweeperInput{
@@ -2520,6 +2534,7 @@ func TestUpdateSweeperInputs(t *testing.T) {
 		{Index: 5}: input5,
 		{Index: 6}: input6,
 		{Index: 7}: input7,
+		{Index: 8}: input8,
 	}
 
 	// We expect the inputs with `Swept`, `Excluded`, and `Failed` to be
@@ -2530,6 +2545,7 @@ func TestUpdateSweeperInputs(t *testing.T) {
 		{Index: 2}: input2,
 		{Index: 3}: input3,
 		{Index: 7}: input7,
+		{Index: 8}: input8,
 	}
 
 	// We expect only the inputs with `Init` and `PublishFailed` to be