bpo-38615: Add timeout parameter for IMAP4 and IMAP4_SSL constructor (GH-17203)

imaplib.IMAP4 and imaplib.IMAP4_SSL now have an 
optional *timeout* parameter for their constructors.
Also, the imaplib.IMAP4.open() method now has an optional *timeout* parameter
with this change. The overridden methods of imaplib.IMAP4_SSL and
imaplib.IMAP4_stream were applied to this change.

1 files changed, 27 insertions, 10 deletions

diff --git a/Doc/library/imaplib.rst b/Doc/library/imaplib.rst
index df63d82..5b8ca7c 100644
--- a/Doc/library/imaplib.rst
+++ b/Doc/library/imaplib.rst
@@ -30,12 +30,14 @@ Three classes are provided by the :mod:`imaplib` module, :class:`IMAP4` is the
 base class:
 
 
-.. class:: IMAP4(host='', port=IMAP4_PORT)
+.. class:: IMAP4(host='', port=IMAP4_PORT, timeout=None)
 
    This class implements the actual IMAP4 protocol.  The connection is created and
    protocol version (IMAP4 or IMAP4rev1) is determined when the instance is
    initialized. If *host* is not specified, ``''`` (the local host) is used. If
-   *port* is omitted, the standard IMAP4 port (143) is used.
+   *port* is omitted, the standard IMAP4 port (143) is used. The optional *timeout*
+   parameter specifies a timeout in seconds for the connection attempt.
+   If timeout is not given or is None, the global default socket timeout is used.
 
    The :class:`IMAP4` class supports the :keyword:`with` statement.  When used
    like this, the IMAP4 ``LOGOUT`` command is issued automatically when the
@@ -50,6 +52,9 @@ base class:
    .. versionchanged:: 3.5
       Support for the :keyword:`with` statement was added.
 
+   .. versionchanged:: 3.9
+      The optional *timeout* parameter was added.
+
 Three exceptions are defined as attributes of the :class:`IMAP4` class:
 
 
@@ -78,7 +83,7 @@ There's also a subclass for secure connections:
 
 
 .. class:: IMAP4_SSL(host='', port=IMAP4_SSL_PORT, keyfile=None, \
-                     certfile=None, ssl_context=None)
+                     certfile=None, ssl_context=None, timeout=None)
 
    This is a subclass derived from :class:`IMAP4` that connects over an SSL
    encrypted socket (to use this class you need a socket module that was compiled
@@ -95,8 +100,12 @@ There's also a subclass for secure connections:
    mutually exclusive with *ssl_context*, a :class:`ValueError` is raised
    if *keyfile*/*certfile* is provided along with *ssl_context*.
 
+   The optional *timeout* parameter specifies a timeout in seconds for the
+   connection attempt. If timeout is not given or is None, the global default
+   socket timeout is used.
+
    .. versionchanged:: 3.3
-      *ssl_context* parameter added.
+      *ssl_context* parameter was added.
 
    .. versionchanged:: 3.4
       The class now supports hostname check with
@@ -110,6 +119,8 @@ There's also a subclass for secure connections:
        :func:`ssl.create_default_context` select the system's trusted CA
        certificates for you.
 
+   .. versionchanged:: 3.9
+      The optional *timeout* parameter was added.
 
 The second subclass allows for connections created by a child process:
 
@@ -353,16 +364,22 @@ An :class:`IMAP4` instance has the following methods:
    Send ``NOOP`` to server.
 
 
-.. method:: IMAP4.open(host, port)
+.. method:: IMAP4.open(host, port, timeout=None)
 
-   Opens socket to *port* at *host*.  This method is implicitly called by
-   the :class:`IMAP4` constructor.  The connection objects established by this
-   method will be used in the :meth:`IMAP4.read`, :meth:`IMAP4.readline`,
-   :meth:`IMAP4.send`, and :meth:`IMAP4.shutdown` methods.  You may override
-   this method.
+   Opens socket to *port* at *host*. The optional *timeout* parameter
+   specifies a timeout in seconds for the connection attempt.
+   If timeout is not given or is None, the global default socket timeout
+   is used. Also note that if the *timeout* parameter is set to be zero,
+   it will raise a :class:`ValueError` to reject creating a non-blocking socket.
+   This method is implicitly called by the :class:`IMAP4` constructor.
+   The connection objects established by this method will be used in
+   the :meth:`IMAP4.read`, :meth:`IMAP4.readline`, :meth:`IMAP4.send`,
+   and :meth:`IMAP4.shutdown` methods. You may override this method.
 
    .. audit-event:: imaplib.open self,host,port imaplib.IMAP4.open
 
+   .. versionchanged:: 3.9
+      The *timeout* parameter was added.
 
 .. method:: IMAP4.partial(message_num, message_part, start, length)