gh-72719: Remove asyncore and asynchat modules (#96580)

Remove modules asyncore and asynchat, which were deprecated by PEP 594.

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

6 files changed, 9 insertions, 588 deletions

diff --git a/Doc/library/asynchat.rst b/Doc/library/asynchat.rst
deleted file mode 100644
index 32e04ad..0000000
--- a/Doc/library/asynchat.rst
+++ /dev/null
@@ -1,217 +0,0 @@
-:mod:`asynchat` --- Asynchronous socket command/response handler
-================================================================
-
-.. module:: asynchat
-   :synopsis: Support for asynchronous command/response protocols.
-   :deprecated:
-
-.. moduleauthor:: Sam Rushing <rushing@nightmare.com>
-.. sectionauthor:: Steve Holden <sholden@holdenweb.com>
-
-**Source code:** :source:`Lib/asynchat.py`
-
-.. deprecated-removed:: 3.6 3.12
-   The :mod:`asynchat` module is deprecated
-   (see :pep:`PEP 594 <594#asynchat>` for details).
-   Please use :mod:`asyncio` instead.
-
---------------
-
-.. note::
-
-   This module exists for backwards compatibility only.  For new code we
-   recommend using :mod:`asyncio`.
-
-This module builds on the :mod:`asyncore` infrastructure, simplifying
-asynchronous clients and servers and making it easier to handle protocols
-whose elements are terminated by arbitrary strings, or are of variable length.
-:mod:`asynchat` defines the abstract class :class:`async_chat` that you
-subclass, providing implementations of the :meth:`collect_incoming_data` and
-:meth:`found_terminator` methods. It uses the same asynchronous loop as
-:mod:`asyncore`, and the two types of channel, :class:`asyncore.dispatcher`
-and :class:`asynchat.async_chat`, can freely be mixed in the channel map.
-Typically an :class:`asyncore.dispatcher` server channel generates new
-:class:`asynchat.async_chat` channel objects as it receives incoming
-connection requests.
-
-.. include:: ../includes/wasm-notavail.rst
-
-.. class:: async_chat()
-
-   This class is an abstract subclass of :class:`asyncore.dispatcher`. To make
-   practical use of the code you must subclass :class:`async_chat`, providing
-   meaningful :meth:`collect_incoming_data` and :meth:`found_terminator`
-   methods.
-   The :class:`asyncore.dispatcher` methods can be used, although not all make
-   sense in a message/response context.
-
-   Like :class:`asyncore.dispatcher`, :class:`async_chat` defines a set of
-   events that are generated by an analysis of socket conditions after a
-   :c:func:`select` call. Once the polling loop has been started the
-   :class:`async_chat` object's methods are called by the event-processing
-   framework with no action on the part of the programmer.
-
-   Two class attributes can be modified, to improve performance, or possibly
-   even to conserve memory.
-
-
-   .. data:: ac_in_buffer_size
-
-      The asynchronous input buffer size (default ``4096``).
-
-
-   .. data:: ac_out_buffer_size
-
-      The asynchronous output buffer size (default ``4096``).
-
-   Unlike :class:`asyncore.dispatcher`, :class:`async_chat` allows you to
-   define a :abbr:`FIFO (first-in, first-out)` queue of *producers*. A producer need
-   have only one method, :meth:`more`, which should return data to be
-   transmitted on the channel.
-   The producer indicates exhaustion (*i.e.* that it contains no more data) by
-   having its :meth:`more` method return the empty bytes object. At this point
-   the :class:`async_chat` object removes the producer from the queue and starts
-   using the next producer, if any. When the producer queue is empty the
-   :meth:`handle_write` method does nothing. You use the channel object's
-   :meth:`set_terminator` method to describe how to recognize the end of, or
-   an important breakpoint in, an incoming transmission from the remote
-   endpoint.
-
-   To build a functioning :class:`async_chat` subclass your  input methods
-   :meth:`collect_incoming_data` and :meth:`found_terminator` must handle the
-   data that the channel receives asynchronously. The methods are described
-   below.
-
-
-.. method:: async_chat.close_when_done()
-
-   Pushes a ``None`` on to the producer queue. When this producer is popped off
-   the queue it causes the channel to be closed.
-
-
-.. method:: async_chat.collect_incoming_data(data)
-
-   Called with *data* holding an arbitrary amount of received data.  The
-   default method, which must be overridden, raises a
-   :exc:`NotImplementedError` exception.
-
-
-.. method:: async_chat.discard_buffers()
-
-   In emergencies this method will discard any data held in the input and/or
-   output buffers and the producer queue.
-
-
-.. method:: async_chat.found_terminator()
-
-   Called when the incoming data stream  matches the termination condition set
-   by :meth:`set_terminator`. The default method, which must be overridden,
-   raises a :exc:`NotImplementedError` exception. The buffered input data
-   should be available via an instance attribute.
-
-
-.. method:: async_chat.get_terminator()
-
-   Returns the current terminator for the channel.
-
-
-.. method:: async_chat.push(data)
-
-   Pushes data on to the channel's queue to ensure its transmission.
-   This is all you need to do to have the channel write the data out to the
-   network, although it is possible to use your own producers in more complex
-   schemes to implement encryption and chunking, for example.
-
-
-.. method:: async_chat.push_with_producer(producer)
-
-   Takes a producer object and adds it to the producer queue associated with
-   the channel.  When all currently pushed producers have been exhausted the
-   channel will consume this producer's data by calling its :meth:`more`
-   method and send the data to the remote endpoint.
-
-
-.. method:: async_chat.set_terminator(term)
-
-   Sets the terminating condition to be recognized on the channel.  ``term``
-   may be any of three types of value, corresponding to three different ways
-   to handle incoming protocol data.
-
-   +-----------+---------------------------------------------+
-   | term      | Description                                 |
-   +===========+=============================================+
-   | *string*  | Will call :meth:`found_terminator` when the |
-   |           | string is found in the input stream         |
-   +-----------+---------------------------------------------+
-   | *integer* | Will call :meth:`found_terminator` when the |
-   |           | indicated number of characters have been    |
-   |           | received                                    |
-   +-----------+---------------------------------------------+
-   | ``None``  | The channel continues to collect data       |
-   |           | forever                                     |
-   +-----------+---------------------------------------------+
-
-   Note that any data following the terminator will be available for reading
-   by the channel after :meth:`found_terminator` is called.
-
-
-.. _asynchat-example:
-
-asynchat Example
-----------------
-
-The following partial example shows how HTTP requests can be read with
-:class:`async_chat`.  A web server might create an
-:class:`http_request_handler` object for each incoming client connection.
-Notice that initially the channel terminator is set to match the blank line at
-the end of the HTTP headers, and a flag indicates that the headers are being
-read.
-
-Once the headers have been read, if the request is of type POST (indicating
-that further data are present in the input stream) then the
-``Content-Length:`` header is used to set a numeric terminator to read the
-right amount of data from the channel.
-
-The :meth:`handle_request` method is called once all relevant input has been
-marshalled, after setting the channel terminator to ``None`` to ensure that
-any extraneous data sent by the web client are ignored. ::
-
-
-   import asynchat
-
-   class http_request_handler(asynchat.async_chat):
-
-       def __init__(self, sock, addr, sessions, log):
-           asynchat.async_chat.__init__(self, sock=sock)
-           self.addr = addr
-           self.sessions = sessions
-           self.ibuffer = []
-           self.obuffer = b""
-           self.set_terminator(b"\r\n\r\n")
-           self.reading_headers = True
-           self.handling = False
-           self.cgi_data = None
-           self.log = log
-
-       def collect_incoming_data(self, data):
-           """Buffer the data"""
-           self.ibuffer.append(data)
-
-       def found_terminator(self):
-           if self.reading_headers:
-               self.reading_headers = False
-               self.parse_headers(b"".join(self.ibuffer))
-               self.ibuffer = []
-               if self.op.upper() == b"POST":
-                   clen = self.headers.getheader("content-length")
-                   self.set_terminator(int(clen))
-               else:
-                   self.handling = True
-                   self.set_terminator(None)
-                   self.handle_request()
-           elif not self.handling:
-               self.set_terminator(None)  # browsers sometimes over-send
-               self.cgi_data = parse(self.headers, b"".join(self.ibuffer))
-               self.handling = True
-               self.ibuffer = []
-               self.handle_request()
diff --git a/Doc/library/asyncore.rst b/Doc/library/asyncore.rst
deleted file mode 100644
index a3a4e90..0000000
--- a/Doc/library/asyncore.rst
+++ /dev/null
@@ -1,365 +0,0 @@
-:mod:`asyncore` --- Asynchronous socket handler
-===============================================
-
-.. module:: asyncore
-   :synopsis: A base class for developing asynchronous socket handling
-              services.
-   :deprecated:
-
-.. moduleauthor:: Sam Rushing <rushing@nightmare.com>
-.. sectionauthor:: Christopher Petrilli <petrilli@amber.org>
-.. sectionauthor:: Steve Holden <sholden@holdenweb.com>
-.. heavily adapted from original documentation by Sam Rushing
-
-**Source code:** :source:`Lib/asyncore.py`
-
-.. deprecated-removed:: 3.6 3.12
-   The :mod:`asyncore` module is deprecated
-   (see :pep:`PEP 594 <594#asyncore>` for details).
-   Please use :mod:`asyncio` instead.
-
---------------
-
-.. note::
-
-   This module exists for backwards compatibility only.  For new code we
-   recommend using :mod:`asyncio`.
-
-This module provides the basic infrastructure for writing asynchronous  socket
-service clients and servers.
-
-.. include:: ../includes/wasm-notavail.rst
-
-There are only two ways to have a program on a single processor do  "more than
-one thing at a time." Multi-threaded programming is the  simplest and most
-popular way to do it, but there is another very different technique, that lets
-you have nearly all the advantages of  multi-threading, without actually using
-multiple threads.  It's really  only practical if your program is largely I/O
-bound.  If your program is processor bound, then pre-emptive scheduled threads
-are probably what you really need.  Network servers are rarely processor
-bound, however.
-
-If your operating system supports the :c:func:`select` system call in its I/O
-library (and nearly all do), then you can use it to juggle multiple
-communication channels at once; doing other work while your I/O is taking
-place in the "background."  Although this strategy can seem strange and
-complex, especially at first, it is in many ways easier to understand and
-control than multi-threaded programming.  The :mod:`asyncore` module solves
-many of the difficult problems for you, making the task of building
-sophisticated high-performance network servers and clients a snap.  For
-"conversational" applications and protocols the companion :mod:`asynchat`
-module is invaluable.
-
-The basic idea behind both modules is to create one or more network
-*channels*, instances of class :class:`asyncore.dispatcher` and
-:class:`asynchat.async_chat`.  Creating the channels adds them to a global
-map, used by the :func:`loop` function if you do not provide it with your own
-*map*.
-
-Once the initial channel(s) is(are) created, calling the :func:`loop` function
-activates channel service, which continues until the last channel (including
-any that have been added to the map during asynchronous service) is closed.
-
-
-.. function:: loop([timeout[, use_poll[, map[,count]]]])
-
-   Enter a polling loop that terminates after count passes or all open
-   channels have been closed.  All arguments are optional.  The *count*
-   parameter defaults to ``None``, resulting in the loop terminating only when all
-   channels have been closed.  The *timeout* argument sets the timeout
-   parameter for the appropriate :func:`~select.select` or :func:`~select.poll`
-   call, measured in seconds; the default is 30 seconds.  The *use_poll*
-   parameter, if true, indicates that :func:`~select.poll` should be used in
-   preference to :func:`~select.select` (the default is ``False``).
-
-   The *map* parameter is a dictionary whose items are the channels to watch.
-   As channels are closed they are deleted from their map.  If *map* is
-   omitted, a global map is used. Channels (instances of
-   :class:`asyncore.dispatcher`, :class:`asynchat.async_chat` and subclasses
-   thereof) can freely be mixed in the map.
-
-
-.. class:: dispatcher()
-
-   The :class:`dispatcher` class is a thin wrapper around a low-level socket
-   object. To make it more useful, it has a few methods for event-handling
-   which are called from the asynchronous loop.   Otherwise, it can be treated
-   as a normal non-blocking socket object.
-
-   The firing of low-level events at certain times or in certain connection
-   states tells the asynchronous loop that certain higher-level events have
-   taken place.  For example, if we have asked for a socket to connect to
-   another host, we know that the connection has been made when the socket
-   becomes writable for the first time (at this point you know that you may
-   write to it with the expectation of success).  The implied higher-level
-   events are:
-
-   +----------------------+----------------------------------------+
-   | Event                | Description                            |
-   +======================+========================================+
-   | ``handle_connect()`` | Implied by the first read or write     |
-   |                      | event                                  |
-   +----------------------+----------------------------------------+
-   | ``handle_close()``   | Implied by a read event with no data   |
-   |                      | available                              |
-   +----------------------+----------------------------------------+
-   | ``handle_accepted()``| Implied by a read event on a listening |
-   |                      | socket                                 |
-   +----------------------+----------------------------------------+
-
-   During asynchronous processing, each mapped channel's :meth:`readable` and
-   :meth:`writable` methods are used to determine whether the channel's socket
-   should be added to the list of channels :c:func:`select`\ ed or
-   :c:func:`poll`\ ed for read and write events.
-
-   Thus, the set of channel events is larger than the basic socket events.  The
-   full set of methods that can be overridden in your subclass follows:
-
-
-   .. method:: handle_read()
-
-      Called when the asynchronous loop detects that a :meth:`read` call on the
-      channel's socket will succeed.
-
-
-   .. method:: handle_write()
-
-      Called when the asynchronous loop detects that a writable socket can be
-      written.  Often this method will implement the necessary buffering for
-      performance.  For example::
-
-         def handle_write(self):
-             sent = self.send(self.buffer)
-             self.buffer = self.buffer[sent:]
-
-
-   .. method:: handle_expt()
-
-      Called when there is out of band (OOB) data for a socket connection.  This
-      will almost never happen, as OOB is tenuously supported and rarely used.
-
-
-   .. method:: handle_connect()
-
-      Called when the active opener's socket actually makes a connection.  Might
-      send a "welcome" banner, or initiate a protocol negotiation with the
-      remote endpoint, for example.
-
-
-   .. method:: handle_close()
-
-      Called when the socket is closed.
-
-
-   .. method:: handle_error()
-
-      Called when an exception is raised and not otherwise handled.  The default
-      version prints a condensed traceback.
-
-
-   .. method:: handle_accept()
-
-      Called on listening channels (passive openers) when a connection can be
-      established with a new remote endpoint that has issued a :meth:`connect`
-      call for the local endpoint. Deprecated in version 3.2; use
-      :meth:`handle_accepted` instead.
-
-      .. deprecated:: 3.2
-
-
-   .. method:: handle_accepted(sock, addr)
-
-      Called on listening channels (passive openers) when a connection has been
-      established with a new remote endpoint that has issued a :meth:`connect`
-      call for the local endpoint.  *sock* is a *new* socket object usable to
-      send and receive data on the connection, and *addr* is the address
-      bound to the socket on the other end of the connection.
-
-      .. versionadded:: 3.2
-
-
-   .. method:: readable()
-
-      Called each time around the asynchronous loop to determine whether a
-      channel's socket should be added to the list on which read events can
-      occur.  The default method simply returns ``True``, indicating that by
-      default, all channels will be interested in read events.
-
-
-   .. method:: writable()
-
-      Called each time around the asynchronous loop to determine whether a
-      channel's socket should be added to the list on which write events can
-      occur.  The default method simply returns ``True``, indicating that by
-      default, all channels will be interested in write events.
-
-
-   In addition, each channel delegates or extends many of the socket methods.
-   Most of these are nearly identical to their socket partners.
-
-
-   .. method:: create_socket(family=socket.AF_INET, type=socket.SOCK_STREAM)
-
-      This is identical to the creation of a normal socket, and will use the
-      same options for creation.  Refer to the :mod:`socket` documentation for
-      information on creating sockets.
-
-      .. versionchanged:: 3.3
-         *family* and *type* arguments can be omitted.
-
-
-   .. method:: connect(address)
-
-      As with the normal socket object, *address* is a tuple with the first
-      element the host to connect to, and the second the port number.
-
-
-   .. method:: send(data)
-
-      Send *data* to the remote end-point of the socket.
-
-
-   .. method:: recv(buffer_size)
-
-      Read at most *buffer_size* bytes from the socket's remote end-point.  An
-      empty bytes object implies that the channel has been closed from the
-      other end.
-
-      Note that :meth:`recv` may raise :exc:`BlockingIOError` , even though
-      :func:`select.select` or :func:`select.poll` has reported the socket
-      ready for reading.
-
-
-   .. method:: listen(backlog)
-
-      Listen for connections made to the socket.  The *backlog* argument
-      specifies the maximum number of queued connections and should be at least
-      1; the maximum value is system-dependent (usually 5).
-
-
-   .. method:: bind(address)
-
-      Bind the socket to *address*.  The socket must not already be bound.  (The
-      format of *address* depends on the address family --- refer to the
-      :mod:`socket` documentation for more information.)  To mark
-      the socket as re-usable (setting the :const:`SO_REUSEADDR` option), call
-      the :class:`dispatcher` object's :meth:`set_reuse_addr` method.
-
-
-   .. method:: accept()
-
-      Accept a connection.  The socket must be bound to an address and listening
-      for connections.  The return value can be either ``None`` or a pair
-      ``(conn, address)`` where *conn* is a *new* socket object usable to send
-      and receive data on the connection, and *address* is the address bound to
-      the socket on the other end of the connection.
-      When ``None`` is returned it means the connection didn't take place, in
-      which case the server should just ignore this event and keep listening
-      for further incoming connections.
-
-
-   .. method:: close()
-
-      Close the socket.  All future operations on the socket object will fail.
-      The remote end-point will receive no more data (after queued data is
-      flushed).  Sockets are automatically closed when they are
-      garbage-collected.
-
-
-.. class:: dispatcher_with_send()
-
-   A :class:`dispatcher` subclass which adds simple buffered output capability,
-   useful for simple clients. For more sophisticated usage use
-   :class:`asynchat.async_chat`.
-
-.. class:: file_dispatcher()
-
-   A file_dispatcher takes a file descriptor or :term:`file object` along
-   with an optional map argument and wraps it for use with the :c:func:`poll`
-   or :c:func:`loop` functions.  If provided a file object or anything with a
-   :c:func:`fileno` method, that method will be called and passed to the
-   :class:`file_wrapper` constructor.
-
-   .. availability:: Unix.
-
-.. class:: file_wrapper()
-
-   A file_wrapper takes an integer file descriptor and calls :func:`os.dup` to
-   duplicate the handle so that the original handle may be closed independently
-   of the file_wrapper.  This class implements sufficient methods to emulate a
-   socket for use by the :class:`file_dispatcher` class.
-
-   .. availability:: Unix.
-
-
-.. _asyncore-example-1:
-
-asyncore Example basic HTTP client
-----------------------------------
-
-Here is a very basic HTTP client that uses the :class:`dispatcher` class to
-implement its socket handling::
-
-   import asyncore
-
-   class HTTPClient(asyncore.dispatcher):
-
-       def __init__(self, host, path):
-           asyncore.dispatcher.__init__(self)
-           self.create_socket()
-           self.connect( (host, 80) )
-           self.buffer = bytes('GET %s HTTP/1.0\r\nHost: %s\r\n\r\n' %
-                               (path, host), 'ascii')
-
-       def handle_connect(self):
-           pass
-
-       def handle_close(self):
-           self.close()
-
-       def handle_read(self):
-           print(self.recv(8192))
-
-       def writable(self):
-           return (len(self.buffer) > 0)
-
-       def handle_write(self):
-           sent = self.send(self.buffer)
-           self.buffer = self.buffer[sent:]
-
-
-   client = HTTPClient('www.python.org', '/')
-   asyncore.loop()
-
-.. _asyncore-example-2:
-
-asyncore Example basic echo server
-----------------------------------
-
-Here is a basic echo server that uses the :class:`dispatcher` class to accept
-connections and dispatches the incoming connections to a handler::
-
-    import asyncore
-
-    class EchoHandler(asyncore.dispatcher_with_send):
-
-        def handle_read(self):
-            data = self.recv(8192)
-            if data:
-                self.send(data)
-
-    class EchoServer(asyncore.dispatcher):
-
-        def __init__(self, host, port):
-            asyncore.dispatcher.__init__(self)
-            self.create_socket()
-            self.set_reuse_addr()
-            self.bind((host, port))
-            self.listen(5)
-
-        def handle_accepted(self, sock, addr):
-            print('Incoming connection from %s' % repr(addr))
-            handler = EchoHandler(sock)
-
-    server = EchoServer('localhost', 8080)
-    asyncore.loop()
diff --git a/Doc/library/socketserver.rst b/Doc/library/socketserver.rst
index 70d56a1..2678539 100644
--- a/Doc/library/socketserver.rst
+++ b/Doc/library/socketserver.rst
@@ -177,8 +177,7 @@ expensive or inappropriate for the service) is to maintain an explicit table of
 partially finished requests and to use :mod:`selectors` to decide which
 request to work on next (or whether to handle a new incoming request).  This is
 particularly important for stream services where each client can potentially be
-connected for a long time (if threads or subprocesses cannot be used).  See
-:mod:`asyncore` for another way to manage this.
+connected for a long time (if threads or subprocesses cannot be used).
 
 .. XXX should data and methods be intermingled, or separate?
    how should the distinction between class and instance variables be drawn?
diff --git a/Doc/library/superseded.rst b/Doc/library/superseded.rst
index 57ef963..8786e22 100644
--- a/Doc/library/superseded.rst
+++ b/Doc/library/superseded.rst
@@ -11,8 +11,6 @@ backwards compatibility. They have been superseded by other modules.
 .. toctree::
 
    aifc.rst
-   asynchat.rst
-   asyncore.rst
    audioop.rst
    cgi.rst
    cgitb.rst
diff --git a/Doc/license.rst b/Doc/license.rst
index 92059b9..4c2b52e 100644
--- a/Doc/license.rst
+++ b/Doc/license.rst
@@ -383,11 +383,11 @@ Project, https://www.wide.ad.jp/. ::
    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    SUCH DAMAGE.
 
-
 Asynchronous socket services
 ----------------------------
 
-The :mod:`asynchat` and :mod:`asyncore` modules contain the following notice::
+The :mod:`test.support.asynchat` and :mod:`test.support.asyncore`
+modules contain the following notice::
 
    Copyright 1996 by Sam Rushing
 
diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst
index 5e8d971..cf71aab 100644
--- a/Doc/whatsnew/3.12.rst
+++ b/Doc/whatsnew/3.12.rst
@@ -522,6 +522,12 @@ Removed
 
 .. _aiosmtpd: https://pypi.org/project/aiosmtpd/
 
+* ``asynchat`` and ``asyncore`` have been removed
+  according to the schedule in :pep:`594`,
+  having been deprecated in Python 3.6.
+  Use :mod:`asyncio` instead.
+  (Contributed by Nikita Sobolev in :gh:`96580`.)
+
 * Remove ``io.OpenWrapper`` and ``_pyio.OpenWrapper``, deprecated in Python
   3.10: just use :func:`open` instead. The :func:`open` (:func:`io.open`)
   function is a built-in function. Since Python 3.10, :func:`_pyio.open` is