Add server-side flag-based thread stopping with socket timeouts

server/handler.py

@@ -5,12 +5,12 @@ import socket
 import time
 import uuid
 from json import JSONDecodeError
-from typing import Any, List, Optional
+from typing import Any, Callable, List, Optional
 
 from shared import constants
 from shared import helpers
 # noinspection PyUnresolvedReferences
-from shared.exceptions import DataReceptionException
+from shared.exceptions import DataReceptionException, StopException
 from server import db
 from server.commands import CommandHandler
 
@@ -21,11 +21,14 @@ logger.setLevel(logging.DEBUG)
 class BaseClient(object):
     """A simple base class for the client containing basic client communication methods."""
 
-    def __init__(self, conn: socket.socket, all_clients: List['Client'], address) -> None:
+    def __init__(self, conn: socket.socket, all_clients: List['Client'], address, stop_flag: Callable[[], bool]) -> None:
-        self.conn, self.all_clients, self.address = conn, all_clients, address
+        self.conn, self.all_clients, self.address, self.stop_flag = conn, all_clients, address, stop_flag
         self.db: Optional[db.ServerDatabase] = None
 
+        self.conn.settimeout(0.5)
+
     def connect_database(self):
+        """"""
         if self.db is None:
             logger.debug('Connecting client to database.')
             self.db = db.ServerDatabase()
@@ -68,8 +71,8 @@ class Client(BaseClient):
     Client.run() should be ran in a thread alongside the other clients.
     """
 
-    def __init__(self, conn: socket.socket, address: Any, all_clients: List['Client']):
+    def __init__(self, conn: socket.socket, address: Any, all_clients: List['Client'], stop_flag: Callable[[], bool]):
-        super().__init__(conn, all_clients, address)
+        super().__init__(conn, all_clients, address, stop_flag)
 
         self.id = str(uuid.uuid4())
         self.short_id = self.id[:8]
@@ -126,12 +129,17 @@ class Client(BaseClient):
                 cur.close()
 
     def receive(self) -> Any:
+        while True:
             try:
+                self.check_stop()
                 length = int(self.conn.recv(constants.HEADER_LENGTH).decode('utf-8'))
+            except socket.timeout:
+                continue
             except ValueError:
                 raise DataReceptionException('The socket did not receive the expected header.')
             else:
                 logger.debug(f'Header received - Length {length}')
+                break
 
         try:
             data = self.conn.recv(length).decode('utf-8')
@@ -155,8 +163,14 @@ class Client(BaseClient):
         for client in self.all_clients:
             client.send_connections_list()
 
+    def check_stop(self) -> None:
+        """Raises a StopException if the stop flag is set to true by the commanding main thread."""
+        stop_flag: bool = self.stop_flag()
+        if stop_flag:
+            raise StopException()
+
     def close(self) -> None:
-        logger.info(f'Client {self.id} closed. ({self.nickname})')
+        logger.info(f'Shutting down Client {self.id}. ({self.nickname})')
         self.conn.close()  # Close socket connection
         self.all_clients.remove(self)  # Remove the user from the global client list
         self.broadcast_message(f'{self.nickname} left!')  # Now we can broadcast it's exit message
@@ -209,7 +223,11 @@ class Client(BaseClient):
                 self.close()
                 break
             except ConnectionResetError:
-                logger.critical('Lost connection to the client. Exiting.')
+                logger.critical('Lost connection to the client.')
+                self.close()
+                break
+            except StopException:
+                logger.info('Stop flag received from main thread.')
                 self.close()
                 break
             except Exception as e:

shared/exceptions.py

@@ -1,5 +1,11 @@
 class TCPChatException(BaseException):
     pass
 
+
 class DataReceptionException(TCPChatException):
     pass
+
+
+class StopException(TCPChatException):
+    """An exception that occurs when a thread finds a stop flag."""
+    pass