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mpp_split: split algorithm with channel splits

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- The splitting algorithm is redesigned to use random distribution of
  subsplittings over channels.
- Splittings can include multiple subamounts within a channel.
- The single-channel splittings are implicitly activated once the
  liquidity hints don't support payments of large size.
This commit is contained in:
bitromortac
2021-04-08 09:05:12 +02:00
parent 3cd14a27bd
commit 3c521f4ce3
3 changed files with 207 additions and 266 deletions
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67
electrum/tests/test_mpp_split.py
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@@ -28,43 +28,58 @@ class TestMppSplit(ElectrumTestCase):
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, 0): 660_000_000, (1, 1): 340_000_000, (2, 0): 0, (3, 2): 0}, splits[0][0])
splits = mpp_split.suggest_splits(1_000_000_000, self.channels_with_funds, exclude_single_part_payments=True)
self.assertEqual({
(0, 0): [671_020_676],
(1, 1): [328_979_324],
(2, 0): [],
(3, 2): []},
splits[0].config
)
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(2, mpp_split.number_nonzero_parts(splits[0][0]))
splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds, exclude_single_part_payments=False)
self.assertEqual(2, mpp_split.number_parts(splits[0].config))
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, 0): 1_000_000_000, (1, 1): 500_000_000, (2, 0): 302_000_000, (3, 2): 101_000_000}, splits[0][0])
splits = mpp_split.suggest_splits(
sum(self.channels_with_funds.values()), self.channels_with_funds, exclude_single_part_payments=True)
self.assertEqual({
(0, 0): [1_000_000_000],
(1, 1): [500_000_000],
(2, 0): [302_000_000],
(3, 2): [101_000_000]},
splits[0].config
)
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]))
splits = mpp_split.suggest_splits(101_000_000, self.channels_with_funds, exclude_single_part_payments=False)
for split in splits[:3]:
self.assertEqual(1, mpp_split.number_nonzero_channels(split.config))
# due to exhaustion of the smallest channel, the algorithm favors
# a splitting of the parts into two
self.assertEqual(2, mpp_split.number_parts(splits[4].config))
def test_send_to_single_node(self):
splits = mpp_split.suggest_splits(1_000_000_000, self.channels_with_funds, exclude_single_parts=True, single_node=True)
self.assertEqual({(0, 0): 738_000_000, (1, 1): 0, (2, 0): 262_000_000, (3, 2): 0}, splits[0][0])
splits = mpp_split.suggest_splits(1_000_000_000, self.channels_with_funds, exclude_single_part_payments=False, exclude_multinode_payments=True)
for split in splits:
assert mpp_split.number_nonzero_nodes(split[0]) == 1
assert mpp_split.number_nonzero_nodes(split.config) == 1
def test_saturation(self):
"""Split configurations which spend the full amount in a channel should be avoided."""
channels_with_funds = {(0, 0): 159_799_733_076, (1, 1): 499_986_152_000}
splits = mpp_split.suggest_splits(600_000_000_000, channels_with_funds, exclude_single_parts=True)
splits = mpp_split.suggest_splits(600_000_000_000, channels_with_funds, exclude_single_part_payments=True)
uses_full_amount = False
for c, a in splits[0][0].items():
for c, a in splits[0].config.items():
if a == channels_with_funds[c]:
uses_full_amount |= True
self.assertFalse(uses_full_amount)
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)
amount = mpp_split.MIN_PART_SIZE_MSAT // 2
splits = mpp_split.suggest_splits(amount, self.channels_with_funds, exclude_single_part_payments=False)
# we only get four configurations that end up spending the full amount
# in a single channel
self.assertEqual(4, len(splits))
@@ -77,25 +92,33 @@ class TestMppSplit(ElectrumTestCase):
with self.subTest(msg="split payments with intermediate part penalty"):
mpp_split.PART_PENALTY = 1.0
splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds)
self.assertEqual(2, mpp_split.number_nonzero_parts(splits[0][0]))
self.assertEqual(2, mpp_split.number_parts(splits[0].config))
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(3, mpp_split.number_nonzero_parts(splits[0][0]))
self.assertEqual(4, mpp_split.number_parts(splits[0].config))
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(4, mpp_split.number_nonzero_parts(splits[0][0]))
self.assertEqual(5, mpp_split.number_parts(splits[0].config))
def test_suggest_splits_single_channel(self):
channels_with_funds = {
0: 1_000_000_000,
(0, 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])
splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_part_payments=False)
self.assertEqual({(0, 0): [1_000_000_000]}, splits[0].config)
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))
with self.subTest(msg="test sending a large amount over a single channel in chunks"):
mpp_split.PART_PENALTY = 0.5
splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_part_payments=False)
self.assertEqual(2, len(splits[0].config[(0, 0)]))
with self.subTest(msg="test sending a large amount over a single channel in chunks"):
mpp_split.PART_PENALTY = 0.3
splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_part_payments=False)
self.assertEqual(3, len(splits[0].config[(0, 0)]))