import time from datetime import timedelta from decouple import config from django.core.management.base import BaseCommand from django.utils import timezone from api.lightning.node import LNNode from api.logics import Logics from api.models import LNPayment, OnchainPayment, Order from api.tasks import follow_send_payment, send_notification def is_same_status(a: LNPayment.Status, b: LNPayment.Status) -> bool: """ Returns whether the state of two lnpayments is the same. LNpayment status can be either Cancelled or Returned. For LND these two are the same (Cancelled). """ cancel = LNPayment.Status.CANCEL retned = LNPayment.Status.RETNED return a == b or cancel in (a, b) and retned in (a, b) class Command(BaseCommand): help = "Follows all active hold invoices, sends out payments" rest = 5 # seconds between consecutive checks for invoice updates def handle(self, *args, **options): """Infinite loop to check invoices and retry payments. ever mind database locked error, keep going, print out""" while True: time.sleep(self.rest) try: self.follow_hold_invoices() except Exception as e: self.stderr.write(str(e)) try: self.send_payments() except Exception as e: self.stderr.write(str(e)) def is_same_status(a: LNPayment.Status, b: LNPayment.Status) -> bool: """ Returns whether the state of two lnpayments is the same. LNpayment status can be either Cancelled or Returned. For LND these two are the same (Cancelled). """ cancel = LNPayment.Status.CANCEL retned = LNPayment.Status.RETNED return a == b or cancel in (a, b) and retned in (a, b) def follow_hold_invoices(self): """Follows and updates LNpayment objects until settled or canceled LND Background: SubscribeInvoices stub iterator would be great to use here. However, it only sends updates when the invoice is OPEN (new) or SETTLED. We are very interested on the other two states (CANCELLED and ACCEPTED). Therefore, this thread (follow_invoices) will iterate over all LNpayments in INVGEN status and do InvoiceLookupV2 every X seconds to update their status. """ # time it for debugging t0 = time.time() queryset = LNPayment.objects.filter( type=LNPayment.Types.HOLD, status=LNPayment.Status.INVGEN, ) debug = {} debug["num_active_invoices"] = len(queryset) debug["invoices"] = [] at_least_one_changed = False for idx, hold_lnpayment in enumerate(queryset): old_status = hold_lnpayment.status new_status, expiry_height = LNNode.lookup_invoice_status(hold_lnpayment) # Only save the hold_payments that change (otherwise this function does not scale) changed = not old_status == new_status if changed: # there might be a few miliseconds to a full second delay when looping over many # invoices. We make sure the lnpayment status has not been changed already by re-reading # from DB. lnpayment = LNPayment.objects.get( payment_hash=hold_lnpayment.payment_hash ) # re-read if is_same_status(lnpayment.status, new_status): continue # if these are still different, we update the lnpayment with its new status. lnpayment.status = new_status lnpayment.expiry_height = expiry_height self.update_order_status(lnpayment) lnpayment.save(update_fields=["status", "expiry_height"]) # Report for debugging old = LNPayment.Status(old_status).label new = LNPayment.Status(lnpayment.status).label debug["invoices"].append( { idx: { "payment_hash": str(lnpayment.payment_hash), "old_status": old, "new_status": new, } } ) at_least_one_changed = at_least_one_changed or changed debug["time"] = time.time() - t0 if at_least_one_changed: self.stdout.write(str(timezone.now())) self.stdout.write(str(debug)) def send_payments(self): """ Checks for invoices and onchain payments that are due to be paid. Sends the payments. """ self.send_ln_payments() self.send_onchain_payments() def send_ln_payments(self): """ Checks for invoices that are due to pay; i.e., INFLIGHT status and 0 routing_attempts. Checks if any payment is due for retry, and tries to pay it. """ queryset = LNPayment.objects.filter( type=LNPayment.Types.NORM, status=LNPayment.Status.FLIGHT, in_flight=False, routing_attempts=0, ) queryset_retries = LNPayment.objects.filter( type=LNPayment.Types.NORM, status=LNPayment.Status.FAILRO, in_flight=False, routing_attempts__in=[1, 2], last_routing_time__lt=( timezone.now() - timedelta(minutes=int(config("RETRY_TIME"))) ), ) # Payments that still have the in_flight flag whose last payment attempt was +3 min ago # are probably stuck. We retry them. The follow_send_invoice() task can also do TrackPaymentV2 if the # previous attempt is still ongoing queryset_stuck = LNPayment.objects.filter( type=LNPayment.Types.NORM, status__in=[LNPayment.Status.FAILRO, LNPayment.Status.FLIGHT], in_flight=True, last_routing_time__lt=(timezone.now() - timedelta(minutes=3)), ) queryset = queryset.union(queryset_retries).union(queryset_stuck) for lnpayment in queryset: # Checks that this onchain payment is part of an order with a settled escrow if not hasattr(lnpayment, "order_paid_LN"): self.stderr.write(f"Ln payment {str(lnpayment)} has no parent order!") return order = lnpayment.order_paid_LN if ( order.trade_escrow.status == LNPayment.Status.SETLED and order.is_swap is False ): follow_send_payment.delay(lnpayment.payment_hash) def send_onchain_payments(self): queryset = OnchainPayment.objects.filter( status=OnchainPayment.Status.QUEUE, broadcasted=False, ) for onchainpayment in queryset: # Checks that this onchain payment is part of an order with a settled escrow if not hasattr(onchainpayment, "order_paid_TX"): self.stderr.write( f"Onchain payment {str(onchainpayment)} has no parent order!" ) return order = onchainpayment.order_paid_TX if ( order.trade_escrow.status == LNPayment.Status.SETLED and order.trade_escrow.num_satoshis >= onchainpayment.num_satoshis and order.is_swap is True ): # Sends out onchainpayment LNNode.pay_onchain( onchainpayment, OnchainPayment.Status.QUEUE, OnchainPayment.Status.MEMPO, ) else: self.stderr.write( f"Onchain payment {str(onchainpayment)} for order {str(order)} escrow is not settled!" ) def update_order_status(self, lnpayment): """Background process following LND hold invoices can catch LNpayments changing status. If they do, the order status might have to change too.""" # If the LNPayment goes to LOCKED (ACCEPTED) if lnpayment.status == LNPayment.Status.LOCKED: try: # It is a maker bond => Publish order. if hasattr(lnpayment, "order_made"): Logics.publish_order(lnpayment.order_made) send_notification.delay( order_id=lnpayment.order_made.id, message="order_published" ) return # It is a taker bond => close contract. elif hasattr(lnpayment, "order_taken"): if lnpayment.order_taken.status == Order.Status.TAK: Logics.finalize_contract(lnpayment.order_taken) return # It is a trade escrow => move foward order status. elif hasattr(lnpayment, "order_escrow"): Logics.trade_escrow_received(lnpayment.order_escrow) return # A locked invoice that has no order attached is an inconsistency (must be due to internal error). # This has been rarely observed in the experimental coordinator, but the invoice must be cancelled otherwise # it will take until CLTV expiry height to unlock (risking force closure). else: self.stderr.write( f"Weird! bond with hash {lnpayment.payment_hash} was locked, yet it is not related to any order. It will be instantly cancelled." ) if LNNode.cancel_return_hold_invoice(lnpayment.payment_hash): lnpayment.status = LNPayment.Status.RETNED lnpayment.save(update_fields=["status"]) return except Exception as e: self.stderr.write( f"Exception when handling newly LOCKED invoice with hash {lnpayment.payment_hash}: {str(e)}" ) # If the LNPayment goes to CANCEL from INVGEN, the invoice had expired # If it goes to CANCEL from LOCKED the bond was unlocked. Order had expired in both cases. # Testing needed for end of time trades! elif lnpayment.status == LNPayment.Status.CANCEL: if hasattr(lnpayment, "order_made"): Logics.order_expires(lnpayment.order_made) return elif hasattr(lnpayment, "order_taken"): Logics.order_expires(lnpayment.order_taken) return elif hasattr(lnpayment, "order_escrow"): Logics.order_expires(lnpayment.order_escrow) return # TODO If a lnpayment goes from LOCKED to INVGEN. Totally weird # halt the order elif lnpayment.status == LNPayment.Status.INVGEN: pass