Correctly count number of items in LRU (#8742) (#8754)

* Updated test to reflect counting issue

* Only increment and adjust size on Add

* Updated LRU count computation logic

Co-authored-by: Koen <koen@bpk.ltd>

src/Orleans.Core/Utils/LRU.cs

@@ -99,15 +99,15 @@ public TValue AddOrUpdate<TState>(TKey key, Func<TState, TKey, TValue> addFunc,
                 key,
                 static (key, state) =>
                 {
-                    var (outerState, addFunc, generation) = state;
+                    var (_, outerState, addFunc, generation) = state;
                     return new TimestampedValue(addFunc(outerState, key), generation);
                 },
                 static (key, existing, state) =>
                 {
-                    var (outerState, addFunc, generation) = state;
-                    return new TimestampedValue(addFunc(outerState, key), generation);
+                    var (self, outerState, addFunc, generation) = state;
+                    return new TimestampedValue(addFunc(outerState, key), self.GetNewGeneration());
                 },
-                (State: state, AddFunc: addFunc, Generation: generation));
+                (Self: this, State: state, AddFunc: addFunc, Generation: generation));
 
             var result = storedValue.Value;
 

test/NonSilo.Tests/General/LruTest.cs

@@ -23,6 +23,9 @@ public void LruCountTest()
 
             target.Add("2", "two");
             Assert.Equal(2, target.Count);  // "Count wrong after adding two items"
+
+            target.AddOrUpdate("2", "two");
+            Assert.Equal(2, target.Count);  // "Count wrong after updating existing item"
         }
 
         [Fact, TestCategory("BVT"), TestCategory("LRU")]