custom dispatcher pings/timeouts (#795)

* rel example

* tweaked rel example for linter

* added rel note to examples.rst

* slightly more compact example

* added example header

* matched wording

* _socket.recv(): _recv() except socket.error - changed or to and; added except TimeoutError - raise WebSocketTimeoutException

* _app - custom dispatcher check_callback() integration (and fixed pyevent compatibility): WrappedDispatcher (for use with generic event dispatchers such as pyevent and rel); create_dispatcher() accepts dispatcher kwarg (default None), and if it is specified, returns a WrappedDispatcher; use create_dispatcher() (passing specified dispatcher if any) every time (regardless of dispatcher specification)

* Add clarifying comment, rerun CI tests

* Add space to make linter happy

Co-authored-by: engn33r <engn33r@users.noreply.github.com>

websocket/_app.py

@@ -86,6 +86,20 @@ def select(self):
             return r[0][0]
 
 
+class WrappedDispatcher:
+    """
+    WrappedDispatcher
+    """
+    def __init__(self, app, ping_timeout, dispatcher):
+        self.app = app
+        self.ping_timeout = ping_timeout
+        self.dispatcher = dispatcher
+
+    def read(self, sock, read_callback, check_callback):
+        self.dispatcher.read(sock, read_callback)
+        self.ping_timeout and self.dispatcher.timeout(self.ping_timeout, check_callback)
+
+
 class WebSocketApp:
     """
     Higher level of APIs are provided. The interface is like JavaScript WebSocket object.
@@ -316,8 +330,7 @@ def teardown(close_frame=None):
                 http_proxy_auth=http_proxy_auth, subprotocols=self.subprotocols,
                 host=host, origin=origin, suppress_origin=suppress_origin,
                 proxy_type=proxy_type)
-            if not dispatcher:
-                dispatcher = self.create_dispatcher(ping_timeout)
+            dispatcher = self.create_dispatcher(ping_timeout, dispatcher)
 
             self._callback(self.on_open)
 
@@ -375,7 +388,9 @@ def check():
             teardown()
             return not isinstance(e, KeyboardInterrupt)
 
-    def create_dispatcher(self, ping_timeout):
+    def create_dispatcher(self, ping_timeout, dispatcher=None):
+        if dispatcher:  # If custom dispatcher is set, use WrappedDispatcher
+            return WrappedDispatcher(self, ping_timeout, dispatcher)
         timeout = ping_timeout or 10
         if self.sock.is_ssl():
             return SSLDispatcher(self, timeout)

websocket/_socket.py

@@ -92,9 +92,7 @@ def _recv():
             pass
         except socket.error as exc:
             error_code = extract_error_code(exc)
-            if error_code is None:
-                raise
-            if error_code != errno.EAGAIN or error_code != errno.EWOULDBLOCK:
+            if error_code != errno.EAGAIN and error_code != errno.EWOULDBLOCK:
                 raise
 
         sel = selectors.DefaultSelector()
@@ -111,6 +109,8 @@ def _recv():
             bytes_ = sock.recv(bufsize)
         else:
             bytes_ = _recv()
+    except TimeoutError:
+        raise WebSocketTimeoutException("Connection timed out")
     except socket.timeout as e:
         message = extract_err_message(e)
         raise WebSocketTimeoutException(message)