Add drop funtions to storage implementations

lightrag/kg/json_kv_impl.py

@@ -127,3 +127,26 @@ class JsonKVStorage(BaseKVStorage):
                 self._data.pop(doc_id, None)
             await set_all_update_flags(self.namespace)
         await self.index_done_callback()
+
+    async def drop(self) -> dict[str, str]:
+        """Drop all data from storage and clean up resources
+        
+        This method will:
+        1. Clear all data from memory
+        2. Update flags to notify other processes
+        3. Trigger index_done_callback to save the empty state
+        
+        Returns:
+            dict[str, str]: Operation status and message
+            - On success: {"status": "success", "message": "data dropped"}
+            - On failure: {"status": "error", "message": "<error details>"}
+        """
+        try:
+            async with self._storage_lock:
+                self._data.update({})
+            await self.index_done_callback()
+            logger.info(f"Process {os.getpid()} drop {self.namespace}")
+            return {"status": "success", "message": "data dropped"}
+        except Exception as e:
+            logger.error(f"Error dropping {self.namespace}: {e}")
+            return {"status": "error", "message": str(e)}