[3.6] Make exceptions pickleable. (#4095) (#4098)

Also change the repr of some exceptions..
(cherry picked from commit dd9db9a)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

CHANGES/4077.feature

@@ -0,0 +1 @@
+Made exceptions pickleable. Also changed the repr of some exceptions.

aiohttp/client_exceptions.py

@@ -72,9 +72,21 @@ def __init__(self, request_info: RequestInfo,
         self.message = message
         self.headers = headers
         self.history = history
+        self.args = (request_info, history)
 
-        super().__init__("%s, message='%s', url='%s" %
-                         (self.status, message, request_info.real_url))
+    def __str__(self) -> str:
+        return ("%s, message=%r, url=%r" %
+                (self.status, self.message, self.request_info.real_url))
+
+    def __repr__(self) -> str:
+        args = "%r, %r" % (self.request_info, self.history)
+        if self.status != 0:
+            args += ", status=%r" % (self.status,)
+        if self.message != '':
+            args += ", message=%r" % (self.message,)
+        if self.headers is not None:
+            args += ", headers=%r" % (self.headers,)
+        return "%s(%s)" % (type(self).__name__, args)
 
     @property
     def code(self) -> int:
@@ -131,6 +143,7 @@ def __init__(self, connection_key: ConnectionKey,
         self._conn_key = connection_key
         self._os_error = os_error
         super().__init__(os_error.errno, os_error.strerror)
+        self.args = (connection_key, os_error)
 
     @property
     def os_error(self) -> OSError:
@@ -152,6 +165,9 @@ def __str__(self) -> str:
         return ('Cannot connect to host {0.host}:{0.port} ssl:{0.ssl} [{1}]'
                 .format(self, self.strerror))
 
+    # OSError.__reduce__ does too much black magick
+    __reduce__ = BaseException.__reduce__
+
 
 class ClientProxyConnectionError(ClientConnectorError):
     """Proxy connection error.
@@ -170,6 +186,10 @@ class ServerDisconnectedError(ServerConnectionError):
 
     def __init__(self, message: Optional[str]=None) -> None:
         self.message = message
+        if message is None:
+            self.args = ()
+        else:
+            self.args = (message,)
 
 
 class ServerTimeoutError(ServerConnectionError, asyncio.TimeoutError):
@@ -185,9 +205,10 @@ def __init__(self, expected: bytes, got: bytes,
         self.got = got
         self.host = host
         self.port = port
+        self.args = (expected, got, host, port)
 
     def __repr__(self) -> str:
-        return '<{} expected={} got={} host={} port={}>'.format(
+        return '<{} expected={!r} got={!r} host={!r} port={!r}>'.format(
             self.__class__.__name__, self.expected, self.got,
             self.host, self.port)
 
@@ -246,6 +267,7 @@ def __init__(self, connection_key:
                  ConnectionKey, certificate_error: Exception) -> None:
         self._conn_key = connection_key
         self._certificate_error = certificate_error
+        self.args = (connection_key, certificate_error)
 
     @property
     def certificate_error(self) -> Exception:

aiohttp/http_exceptions.py

@@ -31,7 +31,11 @@ def __init__(self, *,
         self.headers = headers
         self.message = message
 
-        super().__init__("%s, message='%s'" % (self.code, message))
+    def __str__(self) -> str:
+        return "%s, message=%r" % (self.code, self.message)
+
+    def __repr__(self) -> str:
+        return "<%s: %s>" % (self.__class__.__name__, self)
 
 
 class BadHttpMessage(HttpProcessingError):
@@ -42,6 +46,7 @@ class BadHttpMessage(HttpProcessingError):
     def __init__(self, message: str, *,
                  headers: Optional[_CIMultiDict]=None) -> None:
         super().__init__(message=message, headers=headers)
+        self.args = (message,)
 
 
 class HttpBadRequest(BadHttpMessage):
@@ -74,6 +79,7 @@ def __init__(self, line: str,
         super().__init__(
             "Got more than %s bytes (%s) when reading %s." % (
                 limit, actual_size, line))
+        self.args = (line, limit, actual_size)
 
 
 class InvalidHeader(BadHttpMessage):
@@ -83,16 +89,20 @@ def __init__(self, hdr: Union[bytes, str]) -> None:
             hdr = hdr.decode('utf-8', 'surrogateescape')
         super().__init__('Invalid HTTP Header: {}'.format(hdr))
         self.hdr = hdr
+        self.args = (hdr,)
 
 
 class BadStatusLine(BadHttpMessage):
 
     def __init__(self, line: str='') -> None:
-        if not line:
+        if not isinstance(line, str):
             line = repr(line)
-        self.args = line,
+        self.args = (line,)
         self.line = line
 
+    __str__ = Exception.__str__
+    __repr__ = Exception.__repr__
+
 
 class InvalidURLError(BadHttpMessage):
     pass

aiohttp/http_websocket.py

@@ -100,7 +100,10 @@ class WebSocketError(Exception):
 
     def __init__(self, code: int, message: str) -> None:
         self.code = code
-        super().__init__(message)
+        super().__init__(code, message)
+
+    def __str__(self) -> str:
+        return self.args[1]
 
 
 class WSHandshakeError(Exception):