An unchecked shift of more than 64 bits on u64 values causes a shift
overflow panic. This may happen if a channel is penalized only once and
(1) is not successfully routed through and (2) after 64 or more half
life decays. Use a checked shift to prevent this from happening.
If a payment failed to route through a channel, a penalty is applied to
the channel in the future when finding a route. This penalty decays over
time. Immediately decay the penalty by one half life when a payment is
successfully routed through the channel.
Expand the Score trait with a payment_path_successful function for
scoring successful payment paths. Called by InvoicePayer's EventHandler
implementation when processing PaymentPathSuccessful events. May be used
by Score implementations to revert any channel penalties that were
applied by calls to payment_path_failed.
`scoring::Time` exists in part to make testing the passage of time
in `Scorer` practical. To allow no-std users to provide a time
source it was exposed as a trait as well. However, it seems
somewhat unlikely that a no-std user is going to have a use for
providing their own time source (otherwise they wouldn't be a
no-std user), and likely they won't have a graph in memory either.
`scoring::Time` as currently written is also exceptionally hard to
write C bindings for - the C bindings trait mappings relies on the
ability to construct trait implementations at runtime with function
pointers (i.e. `dyn Trait`s). `scoring::Time`, on the other hand,
is a supertrait of `core::ops::Sub` which requires a `sub` method
which takes a type parameter and returns a type parameter. Both of
which aren't practical in bindings, especially given the
`Sub::Output` associated type is not bound by any trait bounds at
all (implying we cannot simply map the `sub` function to return an
opaque trait object).
Thus, for simplicity, we here simply seal `scoring::Time` and make
it effectively-private, ensuring the bindings don't need to bother
with it.
Ultimately we likely need to wrap the locked `Score` in a struct
that exposes writeable somehow, but because all traits have to be
fully concretized for C bindings we'll still need `Writeable` on
all `Score` in order to expose `Writeable` on the locked score.
Otherwise, we'll only have a `LockedScore` with a `Score` visible
that only has the `Score` methods, never the original type.
Traits in top-level modules is somewhat confusing - generally
top-level modules are just organizational modules and don't contain
things themselves, instead placing traits and structs in
sub-modules. Further, its incredibly awkward to have a `scorer`
sub-module, but only have a single struct in it, with the relevant
trait it is the only implementation of somewhere else. Not having
`Score` in the `scorer` sub-module is further confusing because
it's the only module anywhere that references scoring at all.
2021-11-16 20:58:37 +00:00
Renamed from lightning/src/routing/scorer.rs (Browse further)
