commit 9ea2c275cec7c5701d360a60f97a2670f0819b7a
parent 1c52203346f9049f6c3fe201f672960339d8273b
Author: ThomasV <thomasv@electrum.org>
Date: Mon, 22 Feb 2021 13:51:59 +0100
Merge pull request #7050 from bitromortac/mpp-send
Complete multipart payment sending support
Diffstat:
7 files changed, 423 insertions(+), 21 deletions(-)
diff --git a/electrum/lnonion.py b/electrum/lnonion.py
@@ -261,7 +261,7 @@ def new_onion_packet(payment_path_pubkeys: Sequence[bytes], session_key: bytes,
hmac=next_hmac)
-def calc_hops_data_for_payment(route: 'LNPaymentRoute', amount_msat: int,
+def calc_hops_data_for_payment(route: 'LNPaymentRoute', amount_msat: int, total_msat: int,
final_cltv: int, *, payment_secret: bytes = None) \
-> Tuple[List[OnionHopsDataSingle], int, int]:
"""Returns the hops_data to be used for constructing an onion packet,
@@ -277,8 +277,14 @@ def calc_hops_data_for_payment(route: 'LNPaymentRoute', amount_msat: int,
"amt_to_forward": {"amt_to_forward": amt},
"outgoing_cltv_value": {"outgoing_cltv_value": cltv},
}
+ # for multipart payments we need to tell the reciever about the total and
+ # partial amounts
if payment_secret is not None:
- hop_payload["payment_data"] = {"payment_secret": payment_secret, "total_msat": amt}
+ hop_payload["payment_data"] = {
+ "payment_secret": payment_secret,
+ "total_msat": total_msat,
+ "amount_msat": amt
+ }
hops_data = [OnionHopsDataSingle(is_tlv_payload=route[-1].has_feature_varonion(),
payload=hop_payload)]
# payloads, backwards from last hop (but excluding the first edge):
diff --git a/electrum/lnpeer.py b/electrum/lnpeer.py
@@ -1196,7 +1196,7 @@ class Peer(Logger):
self.send_message("commitment_signed", channel_id=chan.channel_id, signature=sig_64, num_htlcs=len(htlc_sigs), htlc_signature=b"".join(htlc_sigs))
def pay(self, *, route: 'LNPaymentRoute', chan: Channel, amount_msat: int,
- payment_hash: bytes, min_final_cltv_expiry: int,
+ total_msat: int, payment_hash: bytes, min_final_cltv_expiry: int,
payment_secret: bytes = None, fwd_trampoline_onion=None) -> UpdateAddHtlc:
assert amount_msat > 0, "amount_msat is not greater zero"
assert len(route) > 0
@@ -1206,8 +1206,13 @@ class Peer(Logger):
route[0].node_features |= self.features
local_height = self.network.get_local_height()
final_cltv = local_height + min_final_cltv_expiry
- hops_data, amount_msat, cltv = calc_hops_data_for_payment(route, amount_msat, final_cltv,
- payment_secret=payment_secret)
+ hops_data, amount_msat, cltv = calc_hops_data_for_payment(
+ route,
+ amount_msat,
+ total_msat,
+ final_cltv,
+ payment_secret=payment_secret
+ )
self.logger.info(f"lnpeer.pay len(route)={len(route)}")
for i in range(len(route)):
self.logger.info(f" {i}: edge={route[i].short_channel_id} hop_data={hops_data[i]!r}")
diff --git a/electrum/lnutil.py b/electrum/lnutil.py
@@ -290,6 +290,9 @@ class UpfrontShutdownScriptViolation(RemoteMisbehaving): pass
class NotFoundChanAnnouncementForUpdate(Exception): pass
class PaymentFailure(UserFacingException): pass
+class NoPathFound(PaymentFailure):
+ def __str__(self):
+ return _('No path found')
# TODO make some of these values configurable?
REDEEM_AFTER_DOUBLE_SPENT_DELAY = 30
diff --git a/electrum/lnworker.py b/electrum/lnworker.py
@@ -56,7 +56,8 @@ from .lnutil import (Outpoint, LNPeerAddr,
MIN_FINAL_CLTV_EXPIRY_FOR_INVOICE,
NUM_MAX_EDGES_IN_PAYMENT_PATH, SENT, RECEIVED, HTLCOwner,
UpdateAddHtlc, Direction, LnFeatures, ShortChannelID,
- HtlcLog, derive_payment_secret_from_payment_preimage)
+ HtlcLog, derive_payment_secret_from_payment_preimage,
+ NoPathFound)
from .lnutil import ln_dummy_address, ln_compare_features, IncompatibleLightningFeatures
from .lnrouter import TrampolineEdge
from .transaction import PartialTxOutput, PartialTransaction, PartialTxInput
@@ -75,6 +76,7 @@ from .channel_db import UpdateStatus
from .channel_db import get_mychannel_info, get_mychannel_policy
from .submarine_swaps import SwapManager
from .channel_db import ChannelInfo, Policy
+from .mpp_split import suggest_splits
if TYPE_CHECKING:
from .network import Network
@@ -199,11 +201,6 @@ class PaymentInfo(NamedTuple):
status: int
-class NoPathFound(PaymentFailure):
- def __str__(self):
- return _('No path found')
-
-
class ErrorAddingPeer(Exception): pass
@@ -1023,7 +1020,7 @@ class LNWallet(LNWorker):
key = payment_hash.hex()
payment_secret = lnaddr.payment_secret
invoice_pubkey = lnaddr.pubkey.serialize()
- invoice_features = lnaddr.get_tag('9') or 0
+ invoice_features = LnFeatures(lnaddr.get_tag('9') or 0)
r_tags = lnaddr.get_routing_info('r')
t_tags = lnaddr.get_routing_info('t')
amount_to_pay = lnaddr.get_amount_msat()
@@ -1094,7 +1091,7 @@ class LNWallet(LNWorker):
routes = [(route, amount_to_send)]
# 2. send htlcs
for route, amount_msat in routes:
- await self.pay_to_route(route, amount_msat, payment_hash, payment_secret, min_cltv_expiry, trampoline_onion)
+ await self.pay_to_route(route, amount_msat, amount_to_pay, payment_hash, payment_secret, min_cltv_expiry, trampoline_onion)
amount_inflight += amount_msat
util.trigger_callback('invoice_status', self.wallet, payment_hash.hex())
# 3. await a queue
@@ -1110,8 +1107,9 @@ class LNWallet(LNWorker):
# if we get a channel update, we might retry the same route and amount
self.handle_error_code_from_failed_htlc(htlc_log)
-
- async def pay_to_route(self, route: LNPaymentRoute, amount_msat:int, payment_hash:bytes, payment_secret:bytes, min_cltv_expiry:int, trampoline_onion:bytes =None):
+ async def pay_to_route(self, route: LNPaymentRoute, amount_msat: int,
+ total_msat: int, payment_hash: bytes, payment_secret: bytes,
+ min_cltv_expiry: int, trampoline_onion: bytes=None):
# send a single htlc
short_channel_id = route[0].short_channel_id
chan = self.get_channel_by_short_id(short_channel_id)
@@ -1123,6 +1121,7 @@ class LNWallet(LNWorker):
route=route,
chan=chan,
amount_msat=amount_msat,
+ total_msat=total_msat,
payment_hash=payment_hash,
min_final_cltv_expiry=min_cltv_expiry,
payment_secret=payment_secret,
@@ -1379,6 +1378,16 @@ class LNWallet(LNWorker):
node_features=trampoline_features))
return route
+ def channels_with_funds(self) -> Dict[bytes, int]:
+ """Determines a dict of channels (keyed by channel id in bytes) that
+ maps to their spendable amounts."""
+ with self.lock:
+ channels = {}
+ for cid, chan in self._channels.items():
+ spend_amount = int(chan.available_to_spend(HTLCOwner.LOCAL))
+ channels[cid] = spend_amount
+ return channels
+
@profiler
def create_routes_for_payment(
self,
@@ -1387,11 +1396,83 @@ class LNWallet(LNWorker):
min_cltv_expiry,
r_tags,
invoice_features,
- *, full_path: LNPaymentPath = None) -> LNPaymentRoute:
- # TODO: return multiples routes if we know that a single one will not work
- # initially, try with less htlcs
+ *, full_path: LNPaymentPath = None) -> Sequence[Tuple[LNPaymentRoute, int]]:
+ """Creates multiple routes for splitting a payment over the available
+ private channels.
+
+ We first try to conduct the payment over a single channel. If that fails
+ and mpp is supported by the receiver, we will split the payment."""
+
+ try: # to send over a single channel
+ routes = [self.create_route_for_payment(
+ amount_msat,
+ invoice_pubkey,
+ min_cltv_expiry,
+ r_tags,
+ invoice_features,
+ None,
+ full_path=full_path
+ )]
+ except NoPathFound:
+ if invoice_features & LnFeatures.BASIC_MPP_OPT:
+ # Create split configurations that are rated according to our
+ # preference (low rating=high preference).
+ split_configurations = suggest_splits(
+ amount_msat,
+ self.channels_with_funds()
+ )
+
+ self.logger.info("Created the following splitting configurations.")
+ for s in split_configurations:
+ self.logger.info(f"{s[0]} rating: {s[1]}")
+
+ routes = []
+ for s in split_configurations:
+ try:
+ for chanid, part_amount_msat in s[0].items():
+ if part_amount_msat:
+ channel = self.channels[chanid]
+ # It could happen that the pathfinding uses a channel
+ # in the graph multiple times, meaning we could exhaust
+ # its capacity. This could be dealt with by temporarily
+ # iteratively blacklisting channels for this mpp attempt.
+ route, amt = self.create_route_for_payment(
+ part_amount_msat,
+ invoice_pubkey,
+ min_cltv_expiry,
+ r_tags,
+ invoice_features,
+ channel,
+ full_path=None
+ )
+ routes.append((route, amt))
+ break
+ except NoPathFound:
+ routes = []
+ continue
+ else:
+ raise
+
+ if not routes:
+ raise NoPathFound
+ else:
+ return routes
+
+ def create_route_for_payment(
+ self,
+ amount_msat: int,
+ invoice_pubkey,
+ min_cltv_expiry,
+ r_tags,
+ invoice_features,
+ outgoing_channel: Channel = None,
+ *, full_path: Optional[LNPaymentPath]) -> Tuple[LNPaymentRoute, int]:
route = None
- channels = list(self.channels.values())
+ # we can constrain the payment to a single outgoing channel
+ if outgoing_channel:
+ channels = [outgoing_channel]
+ else:
+ channels = list(self.channels.values())
scid_to_my_channels = {chan.short_channel_id: chan for chan in channels
if chan.short_channel_id is not None}
@@ -1467,7 +1548,7 @@ class LNWallet(LNWorker):
# add features from invoice
route[-1].node_features |= invoice_features
# return a list of routes
- return [(route, amount_msat)]
+ return route, amount_msat
def add_request(self, amount_sat, message, expiry) -> str:
coro = self._add_request_coro(amount_sat, message, expiry)
diff --git a/electrum/mpp_split.py b/electrum/mpp_split.py
@@ -0,0 +1,227 @@
+import random
+from typing import List, Tuple, Optional, Sequence, Dict
+from collections import defaultdict
+from .util import profiler
+from .lnutil import NoPathFound
+
+PART_PENALTY = 1.0 # 1.0 results in avoiding splits
+MIN_PART_MSAT = 10_000_000 # we don't want to split indefinitely
+
+# these parameters determine the granularity of the newly suggested configurations
+REDISTRIBUTION_FRACTION = 10
+SPLIT_FRACTION = 10
+
+# these parameters affect the computational work in the probabilistic algorithm
+STARTING_CONFIGS = 30
+CANDIDATES_PER_LEVEL = 20
+REDISTRIBUTE = 5
+
+
+def unique_hierarchy(hierarchy: Dict[int, List[Dict[bytes, int]]]) -> Dict[int, List[Dict[bytes, int]]]:
+ new_hierarchy = defaultdict(list)
+ for number_parts, configs in hierarchy.items():
+ unique_configs = set()
+ for config in configs:
+ # config dict can be out of order, so sort, otherwise not unique
+ unique_configs.add(tuple((c, config[c]) for c in sorted(config.keys())))
+ for unique_config in unique_configs:
+ new_hierarchy[number_parts].append(
+ {t[0]: t[1] for t in unique_config})
+ return new_hierarchy
+
+
+def number_nonzero_parts(configuration: Dict[bytes, int]):
+ return len([v for v in configuration.values() if v])
+
+
+def create_starting_split_hierarchy(amount_msat: int, channels_with_funds: Dict[bytes, int]):
+ """Distributes the amount to send to a single or more channels in several
+ ways (randomly)."""
+ # TODO: find all possible starting configurations deterministically
+ # could try all permutations
+
+ split_hierarchy = defaultdict(list)
+ channels_order = list(channels_with_funds.keys())
+
+ for _ in range(STARTING_CONFIGS):
+ # shuffle to have different starting points
+ random.shuffle(channels_order)
+
+ configuration = {}
+ amount_added = 0
+ for c in channels_order:
+ s = channels_with_funds[c]
+ if amount_added == amount_msat:
+ configuration[c] = 0
+ else:
+ amount_to_add = amount_msat - amount_added
+ amt = min(s, amount_to_add)
+ configuration[c] = amt
+ amount_added += amt
+ if amount_added != amount_msat:
+ raise NoPathFound("Channels don't have enough sending capacity.")
+ split_hierarchy[number_nonzero_parts(configuration)].append(configuration)
+
+ return unique_hierarchy(split_hierarchy)
+
+
+def balances_are_not_ok(proposed_balance_from, channel_from, proposed_balance_to, channel_to, channels_with_funds):
+ check = (
+ proposed_balance_to < MIN_PART_MSAT or
+ proposed_balance_to > channels_with_funds[channel_to] or
+ proposed_balance_from < MIN_PART_MSAT or
+ proposed_balance_from > channels_with_funds[channel_from]
+ )
+ return check
+
+
+def propose_new_configuration(channels_with_funds: Dict[bytes, int], configuration: Dict[bytes, int],
+ amount_msat: int, preserve_number_parts=True) -> Dict[bytes, int]:
+ """Randomly alters a split configuration. If preserve_number_parts, the
+ configuration stays within the same class of number of splits."""
+
+ # there are three basic operations to reach different split configurations:
+ # redistribute, split, swap
+
+ def redistribute(config: dict):
+ # we redistribute the amount from a nonzero channel to a nonzero channel
+ redistribution_amount = amount_msat // REDISTRIBUTION_FRACTION
+ nonzero = [ck for ck, cv in config.items() if
+ cv >= redistribution_amount]
+ if len(nonzero) == 1: # we only have a single channel, so we can't redistribute
+ return config
+
+ channel_from = random.choice(nonzero)
+ channel_to = random.choice(nonzero)
+ if channel_from == channel_to:
+ return config
+ proposed_balance_from = config[channel_from] - redistribution_amount
+ proposed_balance_to = config[channel_to] + redistribution_amount
+ if balances_are_not_ok(proposed_balance_from, channel_from, proposed_balance_to, channel_to, channels_with_funds):
+ return config
+ else:
+ config[channel_from] = proposed_balance_from
+ config[channel_to] = proposed_balance_to
+ assert sum([cv for cv in config.values()]) == amount_msat
+ return config
+
+ def split(config: dict):
+ # we split off a certain amount from a nonzero channel and put it into a
+ # zero channel
+ nonzero = [ck for ck, cv in config.items() if cv != 0]
+ zero = [ck for ck, cv in config.items() if cv == 0]
+ try:
+ channel_from = random.choice(nonzero)
+ channel_to = random.choice(zero)
+ except IndexError:
+ return config
+ delta = config[channel_from] // SPLIT_FRACTION
+ proposed_balance_from = config[channel_from] - delta
+ proposed_balance_to = config[channel_to] + delta
+ if balances_are_not_ok(proposed_balance_from, channel_from, proposed_balance_to, channel_to, channels_with_funds):
+ return config
+ else:
+ config[channel_from] = proposed_balance_from
+ config[channel_to] = proposed_balance_to
+ assert sum([cv for cv in config.values()]) == amount_msat
+ return config
+
+ def swap(config: dict):
+ # we swap the amounts from a single channel with another channel
+ nonzero = [ck for ck, cv in config.items() if cv != 0]
+ all = list(config.keys())
+
+ channel_from = random.choice(nonzero)
+ channel_to = random.choice(all)
+
+ proposed_balance_to = config[channel_from]
+ proposed_balance_from = config[channel_to]
+ if balances_are_not_ok(proposed_balance_from, channel_from, proposed_balance_to, channel_to, channels_with_funds):
+ return config
+ else:
+ config[channel_to] = proposed_balance_to
+ config[channel_from] = proposed_balance_from
+ return config
+
+ initial_number_parts = number_nonzero_parts(configuration)
+
+ for _ in range(REDISTRIBUTE):
+ configuration = redistribute(configuration)
+ if not preserve_number_parts and number_nonzero_parts(
+ configuration) == initial_number_parts:
+ configuration = split(configuration)
+ configuration = swap(configuration)
+
+ return configuration
+
+
+@profiler
+def suggest_splits(amount_msat: int, channels_with_funds, exclude_single_parts=True) -> Sequence[Tuple[Dict[bytes, int], float]]:
+ """Creates split configurations for a payment over channels. Single channel
+ payments are excluded by default."""
+ def rate_configuration(config: dict) -> float:
+ """Defines an objective function to rate a split configuration.
+
+ We calculate the normalized L2 norm for a split configuration and
+ add a part penalty for each nonzero amount. The consequence is that
+ amounts that are equally distributed and have less parts are rated
+ lowest."""
+ F = 0
+ amount = sum([v for v in config.values()])
+
+ for channel, value in config.items():
+ if value:
+ value /= amount # normalize
+ F += value * value + PART_PENALTY * PART_PENALTY
+ return F
+
+ def rated_sorted_configurations(hierarchy: dict) -> Sequence[Tuple[Dict[bytes, int], float]]:
+ """Cleans up duplicate splittings, rates and sorts them according to
+ the rating. A lower rating is a better configuration."""
+ hierarchy = unique_hierarchy(hierarchy)
+ rated_configs = []
+ for level, configs in hierarchy.items():
+ for config in configs:
+ rated_configs.append((config, rate_configuration(config)))
+ sorted_rated_configs = sorted(rated_configs, key=lambda c: c[1], reverse=False)
+ return sorted_rated_configs
+
+ # create initial guesses
+ split_hierarchy = create_starting_split_hierarchy(amount_msat, channels_with_funds)
+
+ # randomize initial guesses
+ MAX_PARTS = 5
+ # generate splittings of different split levels up to number of channels
+ for level in range(2, min(MAX_PARTS, len(channels_with_funds) + 1)):
+ # generate a set of random configurations for each level
+ for _ in range(CANDIDATES_PER_LEVEL):
+ configurations = unique_hierarchy(split_hierarchy).get(level, None)
+ if configurations: # we have a splitting of the desired number of parts
+ configuration = random.choice(configurations)
+ # generate new splittings preserving the number of parts
+ configuration = propose_new_configuration(
+ channels_with_funds, configuration, amount_msat,
+ preserve_number_parts=True)
+ else:
+ # go one level lower and look for valid splittings,
+ # try to go one level higher by splitting a single outgoing amount
+ configurations = unique_hierarchy(split_hierarchy).get(level - 1, None)
+ if not configurations:
+ continue
+ configuration = random.choice(configurations)
+ # generate new splittings going one level higher in the number of parts
+ configuration = propose_new_configuration(
+ channels_with_funds, configuration, amount_msat,
+ preserve_number_parts=False)
+
+ # add the newly found configuration (doesn't matter if nothing changed)
+ split_hierarchy[number_nonzero_parts(configuration)].append(configuration)
+
+ if exclude_single_parts:
+ # we only want to return configurations that have at least two parts
+ try:
+ del split_hierarchy[1]
+ except:
+ pass
+
+ return rated_sorted_configurations(split_hierarchy)
diff --git a/electrum/tests/test_lnpeer.py b/electrum/tests/test_lnpeer.py
@@ -175,6 +175,7 @@ class MockLNWallet(Logger, NetworkRetryManager[LNPeerAddr]):
htlc_failed = LNWallet.htlc_failed
save_preimage = LNWallet.save_preimage
get_preimage = LNWallet.get_preimage
+ create_route_for_payment = LNWallet.create_route_for_payment
create_routes_for_payment = LNWallet.create_routes_for_payment
create_routes_from_invoice = LNWallet.create_routes_from_invoice
_check_invoice = staticmethod(LNWallet._check_invoice)
@@ -189,6 +190,7 @@ class MockLNWallet(Logger, NetworkRetryManager[LNPeerAddr]):
channels_for_peer = LNWallet.channels_for_peer
_calc_routing_hints_for_invoice = LNWallet._calc_routing_hints_for_invoice
handle_error_code_from_failed_htlc = LNWallet.handle_error_code_from_failed_htlc
+ channels_with_funds = LNWallet.channels_with_funds
class MockTransport:
@@ -497,6 +499,7 @@ class TestPeer(ElectrumTestCase):
route=route1,
chan=alice_channel,
amount_msat=lnaddr2.get_amount_msat(),
+ total_msat=lnaddr2.get_amount_msat(),
payment_hash=lnaddr2.paymenthash,
min_final_cltv_expiry=lnaddr2.get_min_final_cltv_expiry(),
payment_secret=lnaddr2.payment_secret,
@@ -509,6 +512,7 @@ class TestPeer(ElectrumTestCase):
route=route2,
chan=bob_channel,
amount_msat=lnaddr1.get_amount_msat(),
+ total_msat=lnaddr1.get_amount_msat(),
payment_hash=lnaddr1.paymenthash,
min_final_cltv_expiry=lnaddr1.get_min_final_cltv_expiry(),
payment_secret=lnaddr1.payment_secret,
@@ -663,6 +667,7 @@ class TestPeer(ElectrumTestCase):
htlc = p1.pay(route=route,
chan=alice_channel,
amount_msat=lnaddr.get_amount_msat(),
+ total_msat=lnaddr.get_amount_msat(),
payment_hash=lnaddr.paymenthash,
min_final_cltv_expiry=lnaddr.get_min_final_cltv_expiry(),
payment_secret=lnaddr.payment_secret)
@@ -771,7 +776,7 @@ class TestPeer(ElectrumTestCase):
min_cltv_expiry = lnaddr.get_min_final_cltv_expiry()
payment_hash = lnaddr.paymenthash
payment_secret = lnaddr.payment_secret
- pay = w1.pay_to_route(route, amount_msat, payment_hash, payment_secret, min_cltv_expiry)
+ pay = w1.pay_to_route(route, amount_msat, amount_msat, payment_hash, payment_secret, min_cltv_expiry)
await asyncio.gather(pay, p1._message_loop(), p2._message_loop(), p1.htlc_switch(), p2.htlc_switch())
with self.assertRaises(PaymentFailure):
run(f())
diff --git a/electrum/tests/test_mpp_split.py b/electrum/tests/test_mpp_split.py
@@ -0,0 +1,75 @@
+import random
+
+import electrum.mpp_split as mpp_split # side effect for PART_PENALTY
+from electrum.lnutil import NoPathFound
+
+from . import ElectrumTestCase
+
+PART_PENALTY = mpp_split.PART_PENALTY
+
+
+class TestMppSplit(ElectrumTestCase):
+ def setUp(self):
+ super().setUp()
+ random.seed(0) # split should only weakly depend on the seed
+ # test is dependent on the python version used, here 3.8
+ # undo side effect
+ mpp_split.PART_PENALTY = PART_PENALTY
+ self.channels_with_funds = {
+ 0: 1_000_000_000,
+ 1: 500_000_000,
+ 2: 302_000_000,
+ 3: 101_000_000,
+ }
+
+ def test_suggest_splits(self):
+ with self.subTest(msg="do a payment with the maximal amount spendable over a single channel"):
+ splits = mpp_split.suggest_splits(1_000_000_000, self.channels_with_funds, exclude_single_parts=True)
+ self.assertEqual({0: 500_000_000, 1: 500_000_000, 2: 0, 3: 0}, splits[0][0])
+
+ with self.subTest(msg="do a payment with a larger amount than what is supported by a single channel"):
+ splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds, exclude_single_parts=True)
+ self.assertEqual({0: 798_000_000, 1: 0, 2: 302_000_000, 3: 0}, splits[0][0])
+ self.assertEqual({0: 908_000_000, 1: 0, 2: 192_000_000, 3: 0}, splits[1][0])
+
+ with self.subTest(msg="do a payment with the maximal amount spendable over all channels"):
+ splits = mpp_split.suggest_splits(sum(self.channels_with_funds.values()), self.channels_with_funds, exclude_single_parts=True)
+ self.assertEqual({0: 1_000_000_000, 1: 500_000_000, 2: 302_000_000, 3: 101_000_000}, splits[0][0])
+
+ with self.subTest(msg="do a payment with the amount supported by all channels"):
+ splits = mpp_split.suggest_splits(101_000_000, self.channels_with_funds, exclude_single_parts=False)
+ for s in splits[:4]:
+ self.assertEqual(1, mpp_split.number_nonzero_parts(s[0]))
+
+ def test_payment_below_min_part_size(self):
+ amount = mpp_split.MIN_PART_MSAT // 2
+ splits = mpp_split.suggest_splits(amount, self.channels_with_funds, exclude_single_parts=False)
+ # we only get four configurations that end up spending the full amount
+ # in a single channel
+ self.assertEqual(4, len(splits))
+
+ def test_suggest_part_penalty(self):
+ """Test is mainly for documentation purposes.
+ Decreasing the part penalty from 1.0 towards 0.0 leads to an increase
+ in the number of parts a payment is split. A configuration which has
+ about equally distributed amounts will result."""
+ with self.subTest(msg="split payments with intermediate part penalty"):
+ mpp_split.PART_PENALTY = 0.3
+ splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds)
+ self.assertEqual({0: 408_000_000, 1: 390_000_000, 2: 302_000_000, 3: 0}, splits[0][0])
+
+ with self.subTest(msg="split payments with no part penalty"):
+ mpp_split.PART_PENALTY = 0.0
+ splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds)
+ self.assertEqual({0: 307_000_000, 1: 390_000_000, 2: 302_000_000, 3: 101_000_000}, splits[0][0])
+
+ def test_suggest_splits_single_channel(self):
+ channels_with_funds = {
+ 0: 1_000_000_000,
+ }
+
+ with self.subTest(msg="do a payment with the maximal amount spendable on a single channel"):
+ splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_parts=False)
+ self.assertEqual({0: 1_000_000_000}, splits[0][0])
+ with self.subTest(msg="test sending an amount greater than what we have available"):
+ self.assertRaises(NoPathFound, mpp_split.suggest_splits, *(1_100_000_000, channels_with_funds))
