Merge pull request #5214 from carlaKC/4788-terminalshard

routing: handle failure to launch shard after permanent failure

channeldb/payment_control.go

@@ -290,18 +290,19 @@ func (p *PaymentControl) RegisterAttempt(paymentHash lntypes.Hash,
 			return err
 		}
 
-		// Ensure the payment is in-flight.
-		if err := ensureInFlight(p); err != nil {
-			return err
-		}
-
 		// We cannot register a new attempt if the payment already has
-		// reached a terminal condition:
+		// reached a terminal condition. We check this before
+		// ensureInFlight because it is a more general check.
 		settle, fail := p.TerminalInfo()
 		if settle != nil || fail != nil {
 			return ErrPaymentTerminal
 		}
 
+		// Ensure the payment is in-flight.
+		if err := ensureInFlight(p); err != nil {
+			return err
+		}
+
 		// Make sure any existing shards match the new one with regards
 		// to MPP options.
 		mpp := attempt.Route.FinalHop().MPP

channeldb/payment_control_test.go

@@ -1013,19 +1013,15 @@ func TestPaymentControlMultiShard(t *testing.T) {
 		// up in the Succeeded state. If both failed the payment should
 		// also be Failed at this poinnt.
 		finalStatus := StatusFailed
-		expRegErr := ErrPaymentAlreadyFailed
 		if test.settleFirst || test.settleLast {
 			finalStatus = StatusSucceeded
-			expRegErr = ErrPaymentAlreadySucceeded
 		}
 
 		assertPaymentStatus(t, pControl, info.PaymentHash, finalStatus)
 
 		// Finally assert we cannot register more attempts.
 		_, err = pControl.RegisterAttempt(info.PaymentHash, &b)
-		if err != expRegErr {
+		require.Equal(t, ErrPaymentTerminal, err)
-			t.Fatalf("expected error %v, got: %v", expRegErr, err)
-		}
 	}
 
 	for _, test := range tests {

routing/mock_test.go

@@ -83,7 +83,8 @@ func (m *mockPaymentAttemptDispatcher) setPaymentResult(
 }
 
 type mockPaymentSessionSource struct {
-	routes []*route.Route
+	routes       []*route.Route
+	routeRelease chan struct{}
 }
 
 var _ PaymentSessionSource = (*mockPaymentSessionSource)(nil)
@@ -91,7 +92,10 @@ var _ PaymentSessionSource = (*mockPaymentSessionSource)(nil)
 func (m *mockPaymentSessionSource) NewPaymentSession(
 	_ *LightningPayment) (PaymentSession, error) {
 
-	return &mockPaymentSession{m.routes}, nil
+	return &mockPaymentSession{
+		routes:  m.routes,
+		release: m.routeRelease,
+	}, nil
 }
 
 func (m *mockPaymentSessionSource) NewPaymentSessionForRoute(
@@ -137,6 +141,11 @@ func (m *mockMissionControl) GetProbability(fromNode, toNode route.Vertex,
 
 type mockPaymentSession struct {
 	routes []*route.Route
+
+	// release is a channel that optionally blocks requesting a route
+	// from our mock payment channel. If this value is nil, we will just
+	// release the route automatically.
+	release chan struct{}
 }
 
 var _ PaymentSession = (*mockPaymentSession)(nil)
@@ -144,6 +153,10 @@ var _ PaymentSession = (*mockPaymentSession)(nil)
 func (m *mockPaymentSession) RequestRoute(_, _ lnwire.MilliSatoshi,
 	_, height uint32) (*route.Route, error) {
 
+	if m.release != nil {
+		m.release <- struct{}{}
+	}
+
 	if len(m.routes) == 0 {
 		return nil, errNoPathFound
 	}
@@ -155,10 +168,9 @@ func (m *mockPaymentSession) RequestRoute(_, _ lnwire.MilliSatoshi,
 }
 
 type mockPayer struct {
-	sendResult       chan error
+	sendResult    chan error
-	paymentResultErr chan error
+	paymentResult chan *htlcswitch.PaymentResult
-	paymentResult    chan *htlcswitch.PaymentResult
+	quit          chan struct{}
-	quit             chan struct{}
 }
 
 var _ PaymentAttemptDispatcher = (*mockPayer)(nil)
@@ -180,12 +192,16 @@ func (m *mockPayer) GetPaymentResult(paymentID uint64, _ lntypes.Hash,
 	_ htlcswitch.ErrorDecrypter) (<-chan *htlcswitch.PaymentResult, error) {
 
 	select {
-	case res := <-m.paymentResult:
+	case res, ok := <-m.paymentResult:
 		resChan := make(chan *htlcswitch.PaymentResult, 1)
-		resChan <- res
+		if !ok {
+			close(resChan)
+		} else {
+			resChan <- res
+		}
+
 		return resChan, nil
-	case err := <-m.paymentResultErr:
+
-		return nil, err
 	case <-m.quit:
 		return nil, fmt.Errorf("test quitting")
 	}
@@ -248,13 +264,13 @@ func makeMockControlTower() *mockControlTower {
 func (m *mockControlTower) InitPayment(phash lntypes.Hash,
 	c *channeldb.PaymentCreationInfo) error {
 
-	m.Lock()
-	defer m.Unlock()
-
 	if m.init != nil {
 		m.init <- initArgs{c}
 	}
 
+	m.Lock()
+	defer m.Unlock()
+
 	// Don't allow re-init a successful payment.
 	if _, ok := m.successful[phash]; ok {
 		return channeldb.ErrAlreadyPaid
@@ -279,27 +295,49 @@ func (m *mockControlTower) InitPayment(phash lntypes.Hash,
 func (m *mockControlTower) RegisterAttempt(phash lntypes.Hash,
 	a *channeldb.HTLCAttemptInfo) error {
 
-	m.Lock()
-	defer m.Unlock()
-
 	if m.registerAttempt != nil {
 		m.registerAttempt <- registerAttemptArgs{a}
 	}
 
-	// Cannot register attempts for successful or failed payments.
+	m.Lock()
-	if _, ok := m.successful[phash]; ok {
+	defer m.Unlock()
-		return channeldb.ErrPaymentAlreadySucceeded
-	}
-
-	if _, ok := m.failed[phash]; ok {
-		return channeldb.ErrPaymentAlreadyFailed
-	}
 
+	// Lookup payment.
 	p, ok := m.payments[phash]
 	if !ok {
 		return channeldb.ErrPaymentNotInitiated
 	}
 
+	var inFlight bool
+	for _, a := range p.attempts {
+		if a.Settle != nil {
+			continue
+		}
+
+		if a.Failure != nil {
+			continue
+		}
+
+		inFlight = true
+	}
+
+	// Cannot register attempts for successful or failed payments.
+	_, settled := m.successful[phash]
+	_, failed := m.failed[phash]
+
+	if settled || failed {
+		return channeldb.ErrPaymentTerminal
+	}
+
+	if settled && !inFlight {
+		return channeldb.ErrPaymentAlreadySucceeded
+	}
+
+	if failed && !inFlight {
+		return channeldb.ErrPaymentAlreadyFailed
+	}
+
+	// Add attempt to payment.
 	p.attempts = append(p.attempts, channeldb.HTLCAttempt{
 		HTLCAttemptInfo: *a,
 	})
@@ -312,13 +350,13 @@ func (m *mockControlTower) SettleAttempt(phash lntypes.Hash,
 	pid uint64, settleInfo *channeldb.HTLCSettleInfo) (
 	*channeldb.HTLCAttempt, error) {
 
-	m.Lock()
-	defer m.Unlock()
-
 	if m.settleAttempt != nil {
 		m.settleAttempt <- settleAttemptArgs{settleInfo.Preimage}
 	}
 
+	m.Lock()
+	defer m.Unlock()
+
 	// Only allow setting attempts if the payment is known.
 	p, ok := m.payments[phash]
 	if !ok {
@@ -353,13 +391,13 @@ func (m *mockControlTower) SettleAttempt(phash lntypes.Hash,
 func (m *mockControlTower) FailAttempt(phash lntypes.Hash, pid uint64,
 	failInfo *channeldb.HTLCFailInfo) (*channeldb.HTLCAttempt, error) {
 
-	m.Lock()
-	defer m.Unlock()
-
 	if m.failAttempt != nil {
 		m.failAttempt <- failAttemptArgs{failInfo}
 	}
 
+	m.Lock()
+	defer m.Unlock()
+
 	// Only allow failing attempts if the payment is known.
 	p, ok := m.payments[phash]
 	if !ok {
@@ -437,13 +475,13 @@ func (m *mockControlTower) FetchPayment(phash lntypes.Hash) (
 func (m *mockControlTower) FetchInFlightPayments() (
 	[]*channeldb.InFlightPayment, error) {
 
-	m.Lock()
-	defer m.Unlock()
-
 	if m.fetchInFlight != nil {
 		m.fetchInFlight <- struct{}{}
 	}
 
+	m.Lock()
+	defer m.Unlock()
+
 	// In flight are all payments not successful or failed.
 	var fl []*channeldb.InFlightPayment
 	for hash, p := range m.payments {

routing/payment_lifecycle.go

@@ -115,6 +115,7 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 
 	// We'll continue until either our payment succeeds, or we encounter a
 	// critical error during path finding.
+lifecycle:
 	for {
 		// Start by quickly checking if there are any outcomes already
 		// available to handle before we reevaluate our state.
@@ -171,7 +172,7 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 			if err := shardHandler.waitForShard(); err != nil {
 				return [32]byte{}, nil, err
 			}
-			continue
+			continue lifecycle
 		}
 
 		// Before we attempt any new shard, we'll check to see if
@@ -195,7 +196,7 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 				return [32]byte{}, nil, saveErr
 			}
 
-			continue
+			continue lifecycle
 
 		case <-p.router.quit:
 			return [32]byte{}, nil, ErrRouterShuttingDown
@@ -234,7 +235,7 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 					return [32]byte{}, nil, saveErr
 				}
 
-				continue
+				continue lifecycle
 			}
 
 			// We still have active shards, we'll wait for an
@@ -242,12 +243,23 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 			if err := shardHandler.waitForShard(); err != nil {
 				return [32]byte{}, nil, err
 			}
-			continue
+			continue lifecycle
 		}
 
 		// We found a route to try, launch a new shard.
 		attempt, outcome, err := shardHandler.launchShard(rt)
-		if err != nil {
+		switch {
+		// We may get a terminal error if we've processed a shard with
+		// a terminal state (settled or permanent failure), while we
+		// were pathfinding. We know we're in a terminal state here,
+		// so we can continue and wait for our last shards to return.
+		case err == channeldb.ErrPaymentTerminal:
+			log.Infof("Payment: %v in terminal state, abandoning "+
+				"shard", p.paymentHash)
+
+			continue lifecycle
+
+		case err != nil:
 			return [32]byte{}, nil, err
 		}
 
@@ -270,7 +282,7 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 
 			// Error was handled successfully, continue to make a
 			// new attempt.
-			continue
+			continue lifecycle
 		}
 
 		// Now that the shard was successfully sent, launch a go