added : timed_cache sub-module

libp2p/timed_cache/basic_time_cache.py

@@ -0,0 +1,51 @@
+import threading
+import time
+
+
+class TimedCache:
+    """Base class for Timed Cache with cleanup mechanism."""
+
+    cache: dict[bytes, int]
+
+    SWEEP_INTERVAL = 60  # 1-minute interval between each sweep
+
+    def __init__(self, ttl: int) -> None:
+        """
+        Initialize a new TimedCache with a time-to-live for cache entries
+
+        :param ttl: no of seconds as time-to-live for each cache entry
+        """
+        self.ttl = ttl
+        self.lock = threading.Lock()
+        self.cache = {}
+        self._stop_event = threading.Event()
+        self._thread = threading.Thread(target=self._background_cleanup, daemon=True)
+        self._thread.start()
+
+    def _background_cleanup(self) -> None:
+        while not self._stop_event.wait(self.SWEEP_INTERVAL):
+            self._sweep()
+
+    def _sweep(self) -> None:
+        """Removes expired entries from the cache."""
+        now = time.time()
+        with self.lock:
+            keys_to_remove = [key for key, expiry in self.cache.items() if expiry < now]
+            for key in keys_to_remove:
+                del self.cache[key]
+
+    def stop(self) -> None:
+        """Stops the background cleanup thread."""
+        self._stop_event.set()
+        self._thread.join()
+
+    def length(self) -> int:
+        return len(self.cache)
+
+    def add(self, key: bytes) -> bool:
+        """To be implemented in subclasses."""
+        raise NotImplementedError
+
+    def has(self, key: bytes) -> bool:
+        """To be implemented in subclasses."""
+        raise NotImplementedError