The "path_score" callback was supposed to evaluate the *entire path*,
but that was counter-intuitive and opened the door to a cost function
bug which caused this path cost to be less than the closer path.
In particular, the capacity bias code didn't understand this at all.
1. Rename the function to `channel_score` and remove the "distance"
parameter (always "1" since you're supposed to be evaluating a
single hop).
2. Rename "cost" to the more specific "fee": "score" is our
actual cost function result (we avoid the word "cost" as it
may get confused with satoshi amounts).
3. For capacity biassing, we do want to know the amount, but
explicitly hand that as a separate parameter "total".
4. Fix a minor bug where total handed to scoring function previously
included channel fee (this is wrong: fee is paid before sending into
channel).
5. Remove the now-unused total_delay member from the dijkstra
struct.
Here are the results of our test now (routing 4194303 msat, which
didn't crash the old code, so we could compare). In both cases
we could find routes to 615 nodes:
Linear success probability (when found): min-max(mean +/- stddev)
Before: 0.484764-0.999750(0.9781+/-0.049)
After: 0.487040-0.999543(0.952548+/-0.075)
Hops:
Before: 1-5(2.13821+/-0.66)
After: 1-5(2.98374+/-0.77)
Fees:
Before: 0-50041(2173.75+/-5.3e+03)
After: 0-50848(922.457+/-2.7e+03)
Delay (blocks):
Before: 0-294(83.1642+/-68)
After: 0-196(65.8081+/-60)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: https://github.com/ElementsProject/lightning/issues/7092
Changelog-Fixed: Plugins: `pay` would occasionally crash on routing.
Changelog-Fixed: Plugins: `pay` route algorithm fixed and refined to balance fees and capacity far better.
The only way you'll see private channel_updates is if you put them
there yourself with localmods.
I also renamed the confusing gossmap_chan_capacity to gossmap_chan_has_capacity.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
As side-effect, getroute(0) is special too.
Reported-by: MiddleW4y in Discord
Fixes: #6577
Changelog-Fixed: `pay` will still use an invoice routehint if path to it doesn't take 1-msat payments.
Don't shoehorn it into onion_nonfinal_hop() and onion_final_hop(), but
provide an explicit routine "blinded_onion_hops" and an onion helper
"onion_blinded_hop()" for it to call.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This likely lead to a number of false errors when attempting to
route. We deemed a channel to be unusable as soon as either direction
isn't usable. This is bad since it excludes not only zeroconf
channels (which have different scids for the two directions), but it
also excludes any channel that we haven't seen an update from
yet. This was likely introduced when attemting to exclude nodes that
haven't sent a disable, but their peer has, but this is not necessary
as the unresponsive node would be marked as isolated by all its peers,
so we don't need to artificially mark a channel direction as disabled
when really we can't even enter the node to traverse the channel in
that direction.
Changelog-Fixed: routing: Fixed an issue where we would exclude the entire channel if either direction was disabled, or we hadn't seen an update yet.
As per proposal in https://github.com/lightning/bolts/pull/962
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Removed: protocol: support for legacy onion format removed, since everyone supports the new one.
Before:
Ten builds, laptop -j5, no ccache:
```
real 0m36.686000-38.956000(38.608+/-0.65)s
user 2m32.864000-42.253000(40.7545+/-2.7)s
sys 0m16.618000-18.316000(17.8531+/-0.48)s
```
Ten builds, laptop -j5, ccache (warm):
```
real 0m8.212000-8.577000(8.39989+/-0.13)s
user 0m12.731000-13.212000(12.9751+/-0.17)s
sys 0m3.697000-3.902000(3.83722+/-0.064)s
```
After:
Ten builds, laptop -j5, no ccache: 8% faster
```
real 0m33.802000-35.773000(35.468+/-0.54)s
user 2m19.073000-27.754000(26.2542+/-2.3)s
sys 0m15.784000-17.173000(16.7165+/-0.37)s
```
Ten builds, laptop -j5, ccache (warm): 1% faster
```
real 0m8.200000-8.485000(8.30138+/-0.097)s
user 0m12.485000-13.100000(12.7344+/-0.19)s
sys 0m3.702000-3.889000(3.78787+/-0.056)s
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is in preparation for removing support (next release?).
Changelog-Changed: Protocol: We now assume nodes support TLV onions (non-legacy) unless we have a node_announcement which says they don't.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We should actually be including this (as it may define _GNU_SOURCE
etc) before any system headers. But where we include <assert.h> we
often didn't, because check-includes would complain that the headers
included it too.
Weaken that check, and include config.h in C files before assert.h.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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>
