///
/// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
/// called from inside the library in response to chain events, P2P events, or timer events).
+///
+/// LDK may generate a substantial number of fee-estimation calls in some cases. You should
+/// pre-calculate and cache the fee estimate results to ensure you don't substantially slow HTLC
+/// handling.
pub trait FeeEstimator {
/// Gets estimated satoshis of fee required per 1000 Weight-Units.
///