f - Add example to NetworkUpdateHandler docs

Author: jkczyz

lightning/src/routing/network_graph.rs

@@ -129,8 +129,46 @@ where C::Target: chain::Access, L::Target: Logger {
 /// Provides interface to help with initial routing sync by
 /// serving historical announcements.
 ///
-/// An [`EventHandler`] decorator for applying updates from [`Event::PaymentFailed`] to the
-/// [`NetworkGraph`].
+/// Serves as an [`EventHandler`] decorator for applying updates from [`Event::PaymentFailed`] to
+/// the [`NetworkGraph`].
+///
+/// # Example
+///
+/// ```
+/// # extern crate bitcoin;
+/// #
+/// # use bitcoin::blockdata::constants::genesis_block;
+/// # use bitcoin::blockdata::transaction::TxOut;
+/// # use bitcoin::hash_types::BlockHash;
+/// # use bitcoin::network::constants::Network;
+/// # use lightning::chain;
+/// # use lightning::routing::network_graph::{NetGraphMsgHandler, NetworkGraph};
+/// # use lightning::util::events::Event;
+/// # use lightning::util::logger::{Logger, Record};
+/// #
+///	# struct NullLogger;
+///	# impl Logger for NullLogger {
+///	#     fn log(&self, _record: &Record) {}
+///	# }
+///	# struct ChainSource;
+///	# impl chain::Access for ChainSource {
+///	#     fn get_utxo(&self, _: &BlockHash, _: u64) -> Result<TxOut, chain::AccessError> {
+///	#         unimplemented!()
+///	#     }
+///	# }
+/// let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
+/// let chain_source = ChainSource {};
+/// let logger = NullLogger {};
+/// let event_handler = |event: &Event| {
+///     // Handle event
+/// };
+/// let event_handler = NetGraphMsgHandler::new(network_graph, Some(&chain_source), &logger, event_handler);
+/// ```
+///
+/// Once `event_handler` has been decorated, use it with any implementation of [`EventsProvider`] as
+/// usual.
+///
+/// [`EventsProvider`]: crate::util::events::EventsProvider
 pub struct NetGraphMsgHandler<C: Deref, L: Deref, E: EventHandler>
 where C::Target: chain::Access, L::Target: Logger
 {