Issue #26404: Add context manager to socketserver, by Aviv Palivoda

Doc/library/http.server.rst

@@ -375,8 +375,7 @@ the current directory::
 
    Handler = http.server.SimpleHTTPRequestHandler
 
-   httpd = socketserver.TCPServer(("", PORT), Handler)
-
+   with socketserver.TCPServer(("", PORT), Handler) as httpd:
        print("serving at port", PORT)
        httpd.serve_forever()
 

Doc/library/socketserver.rst

@@ -52,11 +52,12 @@ handler class by subclassing the :class:`BaseRequestHandler` class and
 overriding its :meth:`~BaseRequestHandler.handle` method;
 this method will process incoming
 requests.  Second, you must instantiate one of the server classes, passing it
-the server's address and the request handler class.  Then call the
+the server's address and the request handler class. It is recommended to use
+the server in a :keyword:`with` statement. Then call the
 :meth:`~BaseServer.handle_request` or
 :meth:`~BaseServer.serve_forever` method of the server object to
 process one or many requests.  Finally, call :meth:`~BaseServer.server_close`
-to close the socket.
+to close the socket (unless you used a :keyword:`with` statement).
 
 When inheriting from :class:`ThreadingMixIn` for threaded connection behavior,
 you should explicitly declare how you want your threads to behave on an abrupt
@@ -353,6 +354,11 @@ Server Objects
       default implementation always returns :const:`True`.
 
 
+   .. versionchanged:: 3.6
+      Support for the :term:`context manager` protocol was added.  Exiting the
+      context manager is equivalent to calling :meth:`server_close`.
+
+
 Request Handler Objects
 -----------------------
 
@@ -433,8 +439,7 @@ This is the server side::
        HOST, PORT = "localhost", 9999
 
        # Create the server, binding to localhost on port 9999
-       server = socketserver.TCPServer((HOST, PORT), MyTCPHandler)
-
+       with socketserver.TCPServer((HOST, PORT), MyTCPHandler) as server:
            # Activate the server; this will keep running until you
            # interrupt the program with Ctrl-C
            server.serve_forever()
@@ -529,7 +534,7 @@ This is the server side::
 
    if __name__ == "__main__":
        HOST, PORT = "localhost", 9999
-       server = socketserver.UDPServer((HOST, PORT), MyUDPHandler)
+       with socketserver.UDPServer((HOST, PORT), MyUDPHandler) as server:
            server.serve_forever()
 
 This is the client side::
@@ -592,6 +597,7 @@ An example for the :class:`ThreadingMixIn` class::
        HOST, PORT = "localhost", 0
 
        server = ThreadedTCPServer((HOST, PORT), ThreadedTCPRequestHandler)
+       with server:
            ip, port = server.server_address
 
            # Start a thread with the server -- that thread will then start one
@@ -607,7 +613,6 @@ An example for the :class:`ThreadingMixIn` class::
            client(ip, port, "Hello World 3")
 
            server.shutdown()
-       server.server_close()
 
 
 The output of the example should look something like this::

Doc/library/wsgiref.rst

@@ -131,7 +131,7 @@ parameter expect a WSGI-compliant dictionary to be supplied; please see
                  for key, value in environ.items()]
           return ret
 
-      httpd = make_server('', 8000, simple_app)
+      with make_server('', 8000, simple_app) as httpd:
           print("Serving on port 8000...")
           httpd.serve_forever()
 
@@ -283,7 +283,7 @@ request.  (E.g., using the :func:`shift_path_info` function from
 
       from wsgiref.simple_server import make_server, demo_app
 
-      httpd = make_server('', 8000, demo_app)
+      with make_server('', 8000, demo_app) as httpd:
           print("Serving HTTP on port 8000...")
 
           # Respond to requests until process is killed
@@ -430,7 +430,7 @@ Paste" library.
       # This is the application wrapped in a validator
       validator_app = validator(simple_app)
 
-      httpd = make_server('', 8000, validator_app)
+      with make_server('', 8000, validator_app) as httpd:
           print("Listening on port 8000....")
           httpd.serve_forever()
 
@@ -769,7 +769,7 @@ This is a working "Hello World" WSGI application::
        # The returned object is going to be printed
        return [b"Hello World"]
 
-   httpd = make_server('', 8000, hello_world_app)
+   with make_server('', 8000, hello_world_app) as httpd:
        print("Serving on port 8000...")
 
        # Serve until process is killed

Doc/library/xmlrpc.server.rst

@@ -147,8 +147,8 @@ Server code::
        rpc_paths = ('/RPC2',)
 
    # Create server
-   server = SimpleXMLRPCServer(("localhost", 8000),
-                               requestHandler=RequestHandler)
+   with SimpleXMLRPCServer(("localhost", 8000),
+                           requestHandler=RequestHandler) as server:
        server.register_introspection_functions()
 
        # Register pow() function; this will use the value of
@@ -206,7 +206,7 @@ a server allowing dotted names and registering a multicall function.
             def getCurrentTime():
                 return datetime.datetime.now()
 
-    server = SimpleXMLRPCServer(("localhost", 8000))
+    with SimpleXMLRPCServer(("localhost", 8000)) as server:
         server.register_function(pow)
         server.register_function(lambda x,y: x+y, 'add')
         server.register_instance(ExampleService(), allow_dotted_names=True)
@@ -216,7 +216,6 @@ a server allowing dotted names and registering a multicall function.
             server.serve_forever()
         except KeyboardInterrupt:
             print("\nKeyboard interrupt received, exiting.")
-        server.server_close()
             sys.exit(0)
 
 This ExampleService demo can be invoked from the command line::

Doc/whatsnew/3.6.rst

@@ -259,6 +259,16 @@ you may now specify file paths on top of directories (e.g. zip files).
 (Contributed by Wolfgang Langner in :issue:`26587`).
 
 
+socketserver
+------------
+
+Servers based on the :mod:`socketserver` module, including those
+defined in :mod:`http.server`, :mod:`xmlrpc.server` and
+:mod:`wsgiref.simple_server`, now support the :term:`context manager`
+protocol.
+(Contributed by Aviv Palivoda in :issue:`26404`.)
+
+
 telnetlib
 ---------
 

Lib/http/server.py

@@ -1175,15 +1175,13 @@ def test(HandlerClass=BaseHTTPRequestHandler,
     server_address = (bind, port)
 
     HandlerClass.protocol_version = protocol
-    httpd = ServerClass(server_address, HandlerClass)
-
+    with ServerClass(server_address, HandlerClass) as httpd:
         sa = httpd.socket.getsockname()
         print("Serving HTTP on", sa[0], "port", sa[1], "...")
         try:
             httpd.serve_forever()
         except KeyboardInterrupt:
             print("\nKeyboard interrupt received, exiting.")
-        httpd.server_close()
             sys.exit(0)
 
 if __name__ == '__main__':

Lib/socketserver.py

@@ -378,6 +378,12 @@ class BaseServer:
         traceback.print_exc()
         print('-'*40, file=sys.stderr)
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        self.server_close()
+
 
 class TCPServer(BaseServer):
 

Lib/test/test_socketserver.py

@@ -104,7 +104,6 @@ class SocketServerTest(unittest.TestCase):
         class MyServer(svrcls):
             def handle_error(self, request, client_address):
                 self.close_request(request)
-                self.server_close()
                 raise
 
         class MyHandler(hdlrbase):
@@ -280,6 +279,12 @@ class SocketServerTest(unittest.TestCase):
                 socketserver.TCPServer((HOST, -1),
                                        socketserver.StreamRequestHandler)
 
+    def test_context_manager(self):
+        with socketserver.TCPServer((HOST, 0),
+                                    socketserver.StreamRequestHandler) as server:
+            pass
+        self.assertEqual(-1, server.socket.fileno())
+
 
 class ErrorHandlerTest(unittest.TestCase):
     """Test that the servers pass normal exceptions from the handler to

Lib/wsgiref/simple_server.py

@@ -156,10 +156,9 @@ def make_server(
 
 
 if __name__ == '__main__':
-    httpd = make_server('', 8000, demo_app)
+    with make_server('', 8000, demo_app) as httpd:
         sa = httpd.socket.getsockname()
         print("Serving HTTP on", sa[0], "port", sa[1], "...")
         import webbrowser
         webbrowser.open('http://localhost:8000/xyz?abc')
         httpd.handle_request()  # serve one request, then exit
-    httpd.server_close()

Lib/xmlrpc/server.py

@@ -971,7 +971,7 @@ if __name__ == '__main__':
             def getCurrentTime():
                 return datetime.datetime.now()
 
-    server = SimpleXMLRPCServer(("localhost", 8000))
+    with SimpleXMLRPCServer(("localhost", 8000)) as server:
         server.register_function(pow)
         server.register_function(lambda x,y: x+y, 'add')
         server.register_instance(ExampleService(), allow_dotted_names=True)
@@ -982,5 +982,4 @@ if __name__ == '__main__':
             server.serve_forever()
         except KeyboardInterrupt:
             print("\nKeyboard interrupt received, exiting.")
-        server.server_close()
             sys.exit(0)

Misc/NEWS

@@ -240,6 +240,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #26404: Add context manager to socketserver.  Patch by Aviv Palivoda.
+
 - Issue #26735: Fix :func:`os.urandom` on Solaris 11.3 and newer when reading
   more than 1,024 bytes: call ``getrandom()`` multiple times with a limit of
   1024 bytes per call.