Merge pull request #1806 from arik-so/2022-10-background-processor-deparametrization

[rust-lightning] / lightning / src / routing / router.rs

diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs
index cd75654be5239885329517d01054bc36a5fab7ee..cffd9ddb0a581ea2e26a53ee3f305a8c7f81bbf7 100644 (file)
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@ -29,6 +29,49 @@ use alloc::collections::BinaryHeap;
 use core::cmp;
 use core::ops::Deref;
 
+/// A trait defining behavior for routing a payment.
+pub trait Router {
+       /// Finds a [`Route`] between `payer` and `payee` for a payment with the given values.
+       fn find_route(
+               &self, payer: &PublicKey, route_params: &RouteParameters,
+               first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: InFlightHtlcs
+       ) -> Result<Route, LightningError>;
+}
+
+/// A map with liquidity value (in msat) keyed by a short channel id and the direction the HTLC
+/// is traveling in. The direction boolean is determined by checking if the HTLC source's public
+/// key is less than its destination. See [`InFlightHtlcs::used_liquidity_msat`] for more
+/// details.
+#[cfg(not(any(test, feature = "_test_utils")))]
+pub struct InFlightHtlcs(HashMap<(u64, bool), u64>);
+#[cfg(any(test, feature = "_test_utils"))]
+pub struct InFlightHtlcs(pub HashMap<(u64, bool), u64>);
+
+impl InFlightHtlcs {
+       /// Create a new `InFlightHtlcs` via a mapping from:
+       /// (short_channel_id, source_pubkey < target_pubkey) -> used_liquidity_msat
+       pub fn new(inflight_map: HashMap<(u64, bool), u64>) -> Self {
+               InFlightHtlcs(inflight_map)
+       }
+
+       /// Returns liquidity in msat given the public key of the HTLC source, target, and short channel
+       /// id.
+       pub fn used_liquidity_msat(&self, source: &NodeId, target: &NodeId, channel_scid: u64) -> Option<u64> {
+               self.0.get(&(channel_scid, source < target)).map(|v| *v)
+       }
+}
+
+impl Writeable for InFlightHtlcs {
+       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> { self.0.write(writer) }
+}
+
+impl Readable for InFlightHtlcs {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+               let infight_map: HashMap<(u64, bool), u64> = Readable::read(reader)?;
+               Ok(Self(infight_map))
+       }
+}
+
 /// A hop in a route
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub struct RouteHop {
@@ -185,8 +228,7 @@ pub const DEFAULT_MAX_PATH_COUNT: u8 = 10;
 const MEDIAN_HOP_CLTV_EXPIRY_DELTA: u32 = 40;
 
 // During routing, we only consider paths shorter than our maximum length estimate.
-// In the legacy onion format, the maximum number of hops used to be a fixed value of 20.
-// However, in the TLV onion format, there is no fixed maximum length, but the `hop_payloads`
+// In the TLV onion format, there is no fixed maximum length, but the `hop_payloads`
 // field is always 1300 bytes. As the `tlv_payload` for each hop may vary in length, we have to
 // estimate how many hops the route may have so that it actually fits the `hop_payloads` field.
 //