[FSSDK-11157] update: added remove method in LRU Cache for CMAB service (#454)

* Add remove method and tests in LRUCache for cmab service

* refactor: simplify remove method in LRUCache and update related tests

* refactor: remove redundant assertion in test_remove_existing_key

Author: FarhanAnjum-opti

optimizely/odp/lru_cache.py

@@ -91,6 +91,11 @@ def peek(self, key: K) -> Optional[V]:
             element = self.map.get(key)
         return element.value if element is not None else None
 
+    def remove(self, key: K) -> None:
+        """Remove the element associated with the provided key from the cache."""
+        with self.lock:
+            self.map.pop(key, None)
+
 
 @dataclass
 class CacheElement(Generic[V]):

tests/test_lru_cache.py

@@ -130,6 +130,82 @@ def test_reset(self):
         cache.save('cow', 'crate')
         self.assertEqual(cache.lookup('cow'), 'crate')
 
+    def test_remove_non_existent_key(self):
+        cache = LRUCache(3, 1000)
+        cache.save("1", 100)
+        cache.save("2", 200)
+
+        cache.remove("3")  # Doesn't exist
+
+        self.assertEqual(cache.lookup("1"), 100)
+        self.assertEqual(cache.lookup("2"), 200)
+
+    def test_remove_existing_key(self):
+        cache = LRUCache(3, 1000)
+
+        cache.save("1", 100)
+        cache.save("2", 200)
+        cache.save("3", 300)
+
+        self.assertEqual(cache.lookup("1"), 100)
+        self.assertEqual(cache.lookup("2"), 200)
+        self.assertEqual(cache.lookup("3"), 300)
+
+        cache.remove("2")
+
+        self.assertEqual(cache.lookup("1"), 100)
+        self.assertIsNone(cache.lookup("2"))
+        self.assertEqual(cache.lookup("3"), 300)
+
+    def test_remove_from_zero_sized_cache(self):
+        cache = LRUCache(0, 1000)
+        cache.save("1", 100)
+        cache.remove("1")
+
+        self.assertIsNone(cache.lookup("1"))
+
+    def test_remove_and_add_back(self):
+        cache = LRUCache(3, 1000)
+        cache.save("1", 100)
+        cache.save("2", 200)
+        cache.save("3", 300)
+
+        cache.remove("2")
+        cache.save("2", 201)
+
+        self.assertEqual(cache.lookup("1"), 100)
+        self.assertEqual(cache.lookup("2"), 201)
+        self.assertEqual(cache.lookup("3"), 300)
+
+    def test_thread_safety(self):
+        import threading
+
+        max_size = 100
+        cache = LRUCache(max_size, 1000)
+
+        for i in range(1, max_size + 1):
+            cache.save(str(i), i * 100)
+
+        def remove_key(k):
+            cache.remove(str(k))
+
+        threads = []
+        for i in range(1, (max_size // 2) + 1):
+            thread = threading.Thread(target=remove_key, args=(i,))
+            threads.append(thread)
+            thread.start()
+
+        for thread in threads:
+            thread.join()
+
+        for i in range(1, max_size + 1):
+            if i <= max_size // 2:
+                self.assertIsNone(cache.lookup(str(i)))
+            else:
+                self.assertEqual(cache.lookup(str(i)), i * 100)
+
+        self.assertEqual(len(cache.map), max_size // 2)
+
     # type checker test
     # confirm that LRUCache matches OptimizelySegmentsCache protocol
     _: OptimizelySegmentsCache = LRUCache(0, 0)