feat(kad): perform lazy cleanup for expired provider records

Pull-Request: #5980.

Author: lla-dane

protocols/kad/CHANGELOG.md

@@ -14,6 +14,8 @@
   See [PR 5715](https://github.com/libp2p/rust-libp2p/pull/5715).
 - Remove deprecated default constructor for `ProtocolConfig`.
   See [PR 5774](https://github.com/libp2p/rust-libp2p/pull/5774).
+- Add lazy cleanup for expired provider records in `Behavior::get_providers` and `Behavior::provider_peers`.
+  See [PR 5980](https://github.com/libp2p/rust-libp2p/pull/5980)
 
 <!-- Update to libp2p-core v0.43.0 -->
 

protocols/kad/src/behaviour.rs

@@ -1053,7 +1053,14 @@ where
             .store
             .providers(&key)
             .into_iter()
-            .filter(|p| !p.is_expired(Instant::now()))
+            .filter(|p| {
+                if p.is_expired(Instant::now()) {
+                    self.store.remove_provider(&key, &p.provider);
+                    false
+                } else {
+                    true
+                }
+            })
             .map(|p| p.provider)
             .collect();
 
@@ -1220,19 +1227,19 @@ where
 
     /// Collects all peers who are known to be providers of the value for a given `Multihash`.
     fn provider_peers(&mut self, key: &record::Key, source: &PeerId) -> Vec<KadPeer> {
-        let kbuckets = &mut self.kbuckets;
-        let connected = &mut self.connected_peers;
-        let listen_addresses = &self.listen_addresses;
-        let external_addresses = &self.external_addresses;
-
         self.store
             .providers(key)
             .into_iter()
-            .filter_map(move |p| {
+            .filter_map(|p| {
+                if p.is_expired(Instant::now()) {
+                    self.store.remove_provider(key, &p.provider);
+                    return None;
+                }
+
                 if &p.provider != source {
                     let node_id = p.provider;
                     let multiaddrs = p.addresses;
-                    let connection_ty = if connected.contains(&node_id) {
+                    let connection_ty = if self.connected_peers.contains(&node_id) {
                         ConnectionType::Connected
                     } else {
                         ConnectionType::NotConnected
@@ -1244,17 +1251,17 @@ where
                         // try to find addresses in the routing table, as was
                         // done before provider records were stored along with
                         // their addresses.
-                        if &node_id == kbuckets.local_key().preimage() {
+                        if &node_id == self.kbuckets.local_key().preimage() {
                             Some(
-                                listen_addresses
+                                self.listen_addresses
                                     .iter()
-                                    .chain(external_addresses.iter())
+                                    .chain(self.external_addresses.iter())
                                     .cloned()
                                     .collect::<Vec<_>>(),
                             )
                         } else {
                             let key = kbucket::Key::from(node_id);
-                            kbuckets
+                            self.kbuckets
                                 .entry(&key)
                                 .as_mut()
                                 .and_then(|e| e.view())