fix(predicate): track resource UID to handle recreated resources

kube-runtime/src/utils/predicate.rs

@@ -1,14 +1,15 @@
-use crate::{reflector::ObjectRef, watcher::Error};
+use crate::watcher::Error;
 use core::{
     pin::Pin,
     task::{ready, Context, Poll},
 };
 use futures::Stream;
-use kube_client::Resource;
+use kube_client::{api::ObjectMeta, Resource};
 use pin_project::pin_project;
 use std::{
     collections::{hash_map::DefaultHasher, HashMap},
     hash::{Hash, Hasher},
+    marker::PhantomData,
 };
 
 fn hash<T: Hash + ?Sized>(t: &T) -> u64 {
@@ -17,6 +18,24 @@ fn hash<T: Hash + ?Sized>(t: &T) -> u64 {
     hasher.finish()
 }
 
+/// Private cache key that includes UID in equality for predicate filtering
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+struct PredicateCacheKey {
+    name: String,
+    namespace: Option<String>,
+    uid: Option<String>,
+}
+
+impl From<&ObjectMeta> for PredicateCacheKey {
+    fn from(meta: &ObjectMeta) -> Self {
+        Self {
+            name: meta.name.clone().unwrap_or_default(),
+            namespace: meta.namespace.clone(),
+            uid: meta.uid.clone(),
+        }
+    }
+}
+
 /// A predicate is a hasher of Kubernetes objects stream filtering
 pub trait Predicate<K> {
     /// A predicate only needs to implement optional hashing when keys exist
@@ -103,7 +122,9 @@ pub struct PredicateFilter<St, K: Resource, P: Predicate<K>> {
     #[pin]
     stream: St,
     predicate: P,
-    cache: HashMap<ObjectRef<K>, u64>,
+    cache: HashMap<PredicateCacheKey, u64>,
+    // K: Resource necessary to get .meta() of an object during polling
+    _phantom: PhantomData<K>,
 }
 impl<St, K, P> PredicateFilter<St, K, P>
 where
@@ -116,6 +137,7 @@ where
             stream,
             predicate,
             cache: HashMap::new(),
+            _phantom: PhantomData,
         }
     }
 }
@@ -134,17 +156,9 @@ where
             break match ready!(me.stream.as_mut().poll_next(cx)) {
                 Some(Ok(obj)) => {
                     if let Some(val) = me.predicate.hash_property(&obj) {
-                        let key = ObjectRef::from_obj(&obj);
-                        let changed = if let Some(old) = me.cache.get(&key) {
-                            *old != val
-                        } else {
-                            true
-                        };
-                        if let Some(old) = me.cache.get_mut(&key) {
-                            *old = val;
-                        } else {
-                            me.cache.insert(key, val);
-                        }
+                        let key = PredicateCacheKey::from(obj.meta());
+                        let changed = me.cache.get(&key) != Some(&val);
+                        me.cache.insert(key, val);
                         if changed {
                             Some(Ok(obj))
                         } else {
@@ -251,4 +265,58 @@ pub(crate) mod tests {
         assert_eq!(second.meta().generation, Some(2));
         assert!(matches!(poll!(rx.next()), Poll::Ready(None)));
     }
+
+    #[tokio::test]
+    async fn predicate_filtering_should_handle_recreated_resources_with_same_generation() {
+        use k8s_openapi::api::core::v1::Pod;
+
+        let mkobj = |g: i32, uid: &str| {
+            let p: Pod = serde_json::from_value(json!({
+                "apiVersion": "v1",
+                "kind": "Pod",
+                "metadata": {
+                    "name": "blog",
+                    "namespace": "default",
+                    "generation": Some(g),
+                    "uid": uid,
+                },
+                "spec": {
+                    "containers": [{
+                      "name": "blog",
+                      "image": "clux/blog:0.1.0"
+                    }],
+                }
+            }))
+            .unwrap();
+            p
+        };
+
+        // Simulate: create (gen=1, uid=1) -> update (gen=1, uid=1) -> delete ->
+        // create (gen=1, uid=2) -> delete -> create (gen=2, uid=3)
+        let data = stream::iter([
+            Ok(mkobj(1, "uid-1")),
+            Ok(mkobj(1, "uid-1")),
+            Ok(mkobj(1, "uid-2")),
+            Ok(mkobj(2, "uid-3")),
+        ]);
+        let mut rx = pin!(PredicateFilter::new(data, predicates::generation));
+
+        // mkobj(1, uid-1) passed through
+        let first = rx.next().now_or_never().unwrap().unwrap().unwrap();
+        assert_eq!(first.meta().generation, Some(1));
+        assert_eq!(first.meta().uid.as_deref(), Some("uid-1"));
+
+        // (no repeat mkobj(1, uid-1) - same UID and generation)
+        // mkobj(1, uid-2) next - different UID detected
+        let second = rx.next().now_or_never().unwrap().unwrap().unwrap();
+        assert_eq!(second.meta().generation, Some(1));
+        assert_eq!(second.meta().uid.as_deref(), Some("uid-2"));
+
+        // mkobj(2, uid-3) next
+        let third = rx.next().now_or_never().unwrap().unwrap().unwrap();
+        assert_eq!(third.meta().generation, Some(2));
+        assert_eq!(third.meta().uid.as_deref(), Some("uid-3"));
+
+        assert!(matches!(poll!(rx.next()), Poll::Ready(None)));
+    }
 }