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plugins/topology: remove unused fuzz factor.

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This breaks Dijkstra, which is presumably why it was actually
disabled.  Remove the code altoghether, instead.

Changelog-Fixed: JSON-RPC: `getroute` now documents that it ignores `fuzzpercent`.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2023-10-02 11:42:19 +10:30
parent 11df13e779
commit ddb16991ee
2 changed files with 4 additions and 40 deletions
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8
doc/lightning-getroute.7.md
View file

@ -34,12 +34,8 @@ If you didn't care about risk, *riskfactor* would be zero.
*fromid* is the node to start the route from: default is this node.
The *fuzzpercent* is a non-negative floating-point number, representing a
percentage of the actual fee. The *fuzzpercent* is used to distort
computed fees along each channel, to provide some randomization to the
route generated. 0.0 means the exact fee of that channel is used, while
100.0 means the fee used might be from 0 to twice the actual fee. The
default is 5.0, or up to 5% fee distortion.
*fuzzpercent* was used to distort fees to provide some randomization to the
route generated, but it was not properly implemented and is ignored.
*exclude* is a JSON array of short-channel-id/direction (e.g. [
"564334x877x1/0", "564195x1292x0/1" ]) or node-id which should be excluded

36
plugins/topology.c
View file

@ -28,30 +28,6 @@ static struct gossmap *get_gossmap(void)
return global_gossmap;
}
/* Convenience global since route_score_fuzz doesn't take args. 0 to 1. */
static double fuzz;
/* Prioritize costs over distance, but with fuzz. Cost must be
* the same when the same channel queried, so we base it on that. */
static u64 route_score_fuzz(u32 distance,
struct amount_msat cost,
struct amount_msat risk,
int dir UNUSED,
const struct gossmap_chan *c)
{
u64 costs = cost.millisatoshis + risk.millisatoshis; /* Raw: score */
/* Use the literal pointer, since it's stable. */
u64 h = siphash24(siphash_seed(), &c, sizeof(c));
/* Use distance as the tiebreaker */
costs += distance;
/* h / (UINT64_MAX / 2.0) is between 0 and 2. */
costs *= (h / (double)(UINT64_MAX / 2) - 1) * fuzz;
return costs;
}
static bool can_carry(const struct gossmap *map,
const struct gossmap_chan *c,
int dir,
@ -141,13 +117,6 @@ static struct command_result *json_getroute(struct command *cmd,
NULL))
return command_param_failed();
/* Convert from percentage */
fuzz = *fuzz_millionths / 100.0 / 1000000.0;
if (fuzz > 1.0)
return command_fail_badparam(cmd, "fuzzpercent",
buffer, params,
"should be <= 100");
gossmap = get_gossmap();
src = gossmap_find_node(gossmap, source);
if (!src)
@ -161,10 +130,9 @@ static struct command_result *json_getroute(struct command *cmd,
"%s: unknown destination node_id (no public channels?)",
type_to_string(tmpctx, struct node_id, destination));
fuzz = 0;
dij = dijkstra(tmpctx, gossmap, dst, *msat,
*riskfactor_millionths / 1000000.0,
can_carry, route_score_fuzz, excluded);
can_carry, route_score_cheaper, excluded);
route = route_from_dijkstra(dij, gossmap, dij, src, *msat, *cltv);
if (!route)
return command_fail(cmd, PAY_ROUTE_NOT_FOUND, "Could not find a route");
@ -637,7 +605,7 @@ static const struct plugin_command commands[] = {
"Primitive route command",
"Show route to {id} for {msatoshi}, using {riskfactor} and optional {cltv} (default 9). "
"If specified search from {fromid} otherwise use this node as source. "
"Randomize the route with up to {fuzzpercent} (default 5.0). "
"Randomize the route with up to {fuzzpercent} (ignored)). "
"{exclude} an array of short-channel-id/direction (e.g. [ '564334x877x1/0', '564195x1292x0/1' ]) "
"or node-id from consideration. "
"Set the {maxhops} the route can take (default 20).",