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lightningd: fix/refactor select_inchan for invoice route-hint, use fractional excess as weight

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Refactored the weighted-reservoir-sampling algo to make it more straightforward.
It now uses the excess as fraction of capacity as weight. This favors channels that
are more _relatively_ unbalanced to be used for incoming payment.

Now passes test_invoice_routeboost_private() when using max fundamount=16777215.
This commit is contained in:
Simon Vrouwe
2019-04-09 18:35:28 +03:00
committed by Rusty Russell
parent 06a062f36b
commit c053dc9a6a
3 changed files with 128 additions and 58 deletions
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76
lightningd/test/run-invoice-select-inchan.c
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@@ -618,6 +618,7 @@ static void add_peer(struct lightningd *ld, int n, enum channel_state state,
c->funding.satoshis = n+1;
c->our_msat = AMOUNT_MSAT(1);
c->our_config.channel_reserve = AMOUNT_SAT(1);
c->channel_info.their_config.channel_reserve = AMOUNT_SAT(0);
list_add_tail(&peer->channels, &c->list);
}
@@ -647,71 +648,59 @@ int main(void)
list_head_init(&ld->peers);
inchans = tal_arr(tmpctx, struct route_info, 0);
/* Nothing to choose from -> NULL result. */
/* 1. Nothing to choose from -> NULL result. */
assert(select_inchan(tmpctx, ld, AMOUNT_MSAT(0), inchans, &any_offline) == NULL);
assert(any_offline == false);
/* inchan but no peer -> NULL result. */
/* 2. inchan but no corresponding peer -> NULL result. */
add_inchan(&inchans, 0);
assert(select_inchan(tmpctx, ld, AMOUNT_MSAT(0), inchans, &any_offline) == NULL);
assert(any_offline == false);
/* connected peer but no inchan -> NULL result. */
add_peer(ld, 1, CHANNELD_NORMAL, false);
assert(select_inchan(tmpctx, ld, AMOUNT_MSAT(0), inchans, &any_offline) == NULL);
assert(any_offline == false);
/* inchan but peer awaiting lockin -> NULL result. */
/* 3. inchan but its peer in awaiting lockin -> NULL result. */
add_peer(ld, 0, CHANNELD_AWAITING_LOCKIN, true);
assert(select_inchan(tmpctx, ld, AMOUNT_MSAT(0), inchans, &any_offline) == NULL);
assert(any_offline == false);
/* inchan but peer not connected -> NULL result. */
/* 4. connected peer but no corresponding inchan -> NULL result. */
add_peer(ld, 1, CHANNELD_NORMAL, true);
assert(select_inchan(tmpctx, ld, AMOUNT_MSAT(0), inchans, &any_offline) == NULL);
assert(any_offline == false);
/* 5. inchan but its peer (replaced with one) offline -> NULL result. */
list_del_from(&ld->peers, &list_tail(&ld->peers, struct peer, list)->list);
add_peer(ld, 1, CHANNELD_NORMAL, false);
add_inchan(&inchans, 1);
assert(select_inchan(tmpctx, ld, AMOUNT_MSAT(0), inchans, &any_offline) == NULL);
assert(any_offline == true);
/* Finally, a correct peer! */
/* 6. Finally, a correct peer! */
add_inchan(&inchans, 2);
add_peer(ld, 2, CHANNELD_NORMAL, true);
ret = select_inchan(tmpctx, ld, AMOUNT_MSAT(0), inchans, &any_offline);
assert(tal_count(ret) == 1);
assert(tal_count(ret[0]) == 1);
assert(any_offline == true);
assert(any_offline == true); /* Peer 1 is offline */
assert(route_info_eq(ret[0], &inchans[2]));
/* Not if we ask for too much! Reserve is 1 satoshi */
/* 7. Correct peer with just enough capacity_to_pay_us */
ret = select_inchan(tmpctx, ld, AMOUNT_MSAT(1999), inchans, &any_offline);
assert(tal_count(ret) == 1);
assert(tal_count(ret[0]) == 1);
assert(any_offline == false); /* Other candidate insufficient funds. */
assert(route_info_eq(ret[0], &inchans[2]));
/* 8. Not if we ask for too much! Our balance is 1msat. */
ret = select_inchan(tmpctx, ld, AMOUNT_MSAT(2000), inchans, &any_offline);
assert(ret == NULL);
assert(any_offline == false); /* Other candidate insufficient funds. */
/* Add another candidate, with twice as much excess. */
/* 9. Add another peer */
add_inchan(&inchans, 3);
add_peer(ld, 3, CHANNELD_NORMAL, true);
for (size_t i = n = 0; i < 1000; i++) {
ret = select_inchan(tmpctx, ld, AMOUNT_MSAT(1000), inchans, &any_offline);
assert(tal_count(ret) == 1);
assert(tal_count(ret[0]) == 1);
assert(any_offline == false); /* Other candidate insufficient funds. */
assert(route_info_eq(ret[0], &inchans[2])
|| route_info_eq(ret[0], &inchans[3]));
n += route_info_eq(ret[0], &inchans[2]);
}
/* Handwave over probability of this happening! Within 20% */
assert(n > 333 - 66 && n < 333 + 66);
printf("Number of selections with 999 excess: %zu\n"
"Number of selections with 1999 excess: %zu\n",
n, 1000 - n);
/* Simulate selection ratios between excesses 25% and 50% of capacity*/
for (size_t i = n = 0; i < 1000; i++) {
ret = select_inchan(tmpctx, ld, AMOUNT_MSAT(1499), inchans, &any_offline);
assert(tal_count(ret) == 1);
@@ -722,10 +711,33 @@ int main(void)
n += route_info_eq(ret[0], &inchans[2]);
}
assert(n > 250 - 50 && n < 250 + 50);
printf("Number of selections with 500 excess: %zu\n"
"Number of selections with 1500 excess: %zu\n",
/* Handwave over probability of this happening! Within 20% */
printf("Number of selections with excess 25 percent of capacity: %zu\n"
"Number of selections with excess 50 percent of capacity: %zu\n",
n, 1000 - n);
assert(n > 333 - 66 && n < 333 + 66);
/* 10. Last peer's capacity goes from 3 to 2 sat*/
list_tail(&list_tail(&ld->peers, struct peer, list)->channels, struct channel, list)->
channel_info.their_config.channel_reserve = AMOUNT_SAT(1);
ret = select_inchan(tmpctx, ld, AMOUNT_MSAT(1499), inchans, &any_offline);
/* Simulate selection ratios between excesses 25% and 75% of capacity*/
for (size_t i = n = 0; i < 1000; i++) {
ret = select_inchan(tmpctx, ld, AMOUNT_MSAT(1499), inchans, &any_offline);
assert(tal_count(ret) == 1);
assert(tal_count(ret[0]) == 1);
assert(any_offline == false); /* Other candidate insufficient funds. */
assert(route_info_eq(ret[0], &inchans[2])
|| route_info_eq(ret[0], &inchans[3]));
n += route_info_eq(ret[0], &inchans[2]);
}
/* Handwave over probability of this happening! Within 20% */
printf("Number of selections with excess 25 percent of capacity: %zu\n"
"Number of selections with excess 75 percent of capacity: %zu\n",
n, 1000 - n);
assert(n > 250 - 50 && n < 250 + 50);
/* No memory leaks please */
secp256k1_context_destroy(secp256k1_ctx);