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dijkstra: fix heap ordering.

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We were always ordering heap by distance, not score (which are different
if we are routing by cheapest, not shortest!).

This simplifies our callbacks, too.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2020-10-20 14:28:06 +10:30
parent 4a1843a151
commit 1bf3eebbf6
6 changed files with 49 additions and 85 deletions
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47
common/route.c
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@@ -37,43 +37,28 @@ bool route_can_carry(const struct gossmap *map,
return route_can_carry_even_disabled(map, c, dir, amount, arg);
}
bool route_path_shorter(u32 old_distance, u32 new_distance,
struct amount_msat old_cost,
struct amount_msat new_cost,
struct amount_msat old_risk,
struct amount_msat new_risk,
void *unused)
/* Prioritize distance over costs */
u64 route_score_shorter(u32 distance,
struct amount_msat cost,
struct amount_msat risk)
{
if (new_distance > old_distance)
return false;
if (new_distance < old_distance)
return true;
u64 costs = cost.millisatoshis + risk.millisatoshis; /* Raw: score */
if (costs > 0xFFFFFFFF)
costs = 0xFFFFFFFF;
/* Tiebreak by cost */
if (!amount_msat_add(&old_cost, old_cost, old_risk)
|| !amount_msat_add(&new_cost, new_cost, new_risk))
return false;
return amount_msat_less(new_cost, old_cost);
return costs + ((u64)distance << 32);
}
bool route_path_cheaper(u32 old_distance, u32 new_distance,
struct amount_msat old_cost,
struct amount_msat new_cost,
struct amount_msat old_risk,
struct amount_msat new_risk,
void *unused)
/* Prioritize costs over distance */
u64 route_score_cheaper(u32 distance,
struct amount_msat cost,
struct amount_msat risk)
{
if (!amount_msat_add(&old_cost, old_cost, old_risk)
|| !amount_msat_add(&new_cost, new_cost, new_risk))
return false;
u64 costs = cost.millisatoshis + risk.millisatoshis; /* Raw: score */
if (costs > 0xFFFFFFFF)
costs = 0xFFFFFFFF;
if (amount_msat_greater(new_cost, old_cost))
return false;
if (amount_msat_less(new_cost, old_cost))
return true;
/* Tiebreak by distance */
return new_distance < old_distance;
return (costs << 32) + distance;
}
struct route **route_from_dijkstra(const struct gossmap *map,