gh-113538: Revert "gh-113538: Add asycio.Server.{close,abort}_clients (#114432)" (#116632)

gvanrossum · web-flow · commit ba13215eb1ec · 2024-03-12T00:31:49.000Z
Revert "gh-113538: Add asycio.Server.{close,abort}_clients (#114432)" Reason: The new test doesn't always pass: #116423 (comment) This reverts commit 1d0d49a.
diff --git a/Doc/library/asyncio-eventloop.rst b/Doc/library/asyncio-eventloop.rst
@@ -1641,31 +1641,6 @@ Do not instantiate the :class:`Server` class directly.
       coroutine to wait until the server is closed (and no more
       connections are active).
 
-   .. method:: close_clients()
-
-      Close all existing incoming client connections.
-
-      Calls :meth:`~asyncio.BaseTransport.close` on all associated
-      transports.
-
-      :meth:`close` should be called before :meth:`close_clients` when
-      closing the server to avoid races with new clients connecting.
-
-      .. versionadded:: 3.13
-
-   .. method:: abort_clients()
-
-      Close all existing incoming client connections immediately,
-      without waiting for pending operations to complete.
-
-      Calls :meth:`~asyncio.WriteTransport.abort` on all associated
-      transports.
-
-      :meth:`close` should be called before :meth:`abort_clients` when
-      closing the server to avoid races with new clients connecting.
-
-      .. versionadded:: 3.13
-
    .. method:: get_loop()
 
       Return the event loop associated with the server object.
diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
@@ -270,11 +270,6 @@ asyncio
   the buffer size.
   (Contributed by Jamie Phan in :gh:`115199`.)
 
-* Add :meth:`asyncio.Server.close_clients` and
-  :meth:`asyncio.Server.abort_clients` methods which allow to more
-  forcefully close an asyncio server.
-  (Contributed by Pierre Ossman in :gh:`113538`.)
-
 base64
 ---
 
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
@@ -279,9 +279,7 @@ def __init__(self, loop, sockets, protocol_factory, ssl_context, backlog,
                  ssl_handshake_timeout, ssl_shutdown_timeout=None):
         self._loop = loop
         self._sockets = sockets
-        # Weak references so we don't break Transport's ability to
-        # detect abandoned transports
-        self._clients = weakref.WeakSet()
+        self._active_count = 0
         self._waiters = []
         self._protocol_factory = protocol_factory
         self._backlog = backlog
@@ -294,13 +292,14 @@ def __init__(self, loop, sockets, protocol_factory, ssl_context, backlog,
     def __repr__(self):
         return f'<{self.__class__.__name__} sockets={self.sockets!r}>'
 
-    def _attach(self, transport):
+    def _attach(self):
         assert self._sockets is not None
-        self._clients.add(transport)
+        self._active_count += 1
 
-    def _detach(self, transport):
-        self._clients.discard(transport)
-        if len(self._clients) == 0 and self._sockets is None:
+    def _detach(self):
+        assert self._active_count > 0
+        self._active_count -= 1
+        if self._active_count == 0 and self._sockets is None:
             self._wakeup()
 
     def _wakeup(self):
@@ -349,17 +348,9 @@ def close(self):
             self._serving_forever_fut.cancel()
             self._serving_forever_fut = None
 
-        if len(self._clients) == 0:
+        if self._active_count == 0:
             self._wakeup()
 
-    def close_clients(self):
-        for transport in self._clients.copy():
-            transport.close()
-
-    def abort_clients(self):
-        for transport in self._clients.copy():
-            transport.abort()
-
     async def start_serving(self):
         self._start_serving()
         # Skip one loop iteration so that all 'loop.add_reader'
diff --git a/Lib/asyncio/events.py b/Lib/asyncio/events.py
@@ -175,14 +175,6 @@ def close(self):
         """Stop serving.  This leaves existing connections open."""
         raise NotImplementedError
 
-    def close_clients(self):
-        """Close all active connections."""
-        raise NotImplementedError
-
-    def abort_clients(self):
-        """Close all active connections immediately."""
-        raise NotImplementedError
-
     def get_loop(self):
         """Get the event loop the Server object is attached to."""
         raise NotImplementedError
diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
@@ -63,7 +63,7 @@ def __init__(self, loop, sock, protocol, waiter=None,
         self._called_connection_lost = False
         self._eof_written = False
         if self._server is not None:
-            self._server._attach(self)
+            self._server._attach()
         self._loop.call_soon(self._protocol.connection_made, self)
         if waiter is not None:
             # only wake up the waiter when connection_made() has been called
@@ -167,7 +167,7 @@ def _call_connection_lost(self, exc):
             self._sock = None
             server = self._server
             if server is not None:
-                server._detach(self)
+                server._detach()
                 self._server = None
             self._called_connection_lost = True
 
diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
@@ -791,7 +791,7 @@ def __init__(self, loop, sock, protocol, extra=None, server=None):
         self._paused = False  # Set when pause_reading() called
 
         if self._server is not None:
-            self._server._attach(self)
+            self._server._attach()
         loop._transports[self._sock_fd] = self
 
     def __repr__(self):
@@ -868,8 +868,6 @@ def __del__(self, _warn=warnings.warn):
         if self._sock is not None:
             _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
             self._sock.close()
-            if self._server is not None:
-                self._server._detach(self)
 
     def _fatal_error(self, exc, message='Fatal error on transport'):
         # Should be called from exception handler only.
@@ -908,7 +906,7 @@ def _call_connection_lost(self, exc):
             self._loop = None
             server = self._server
             if server is not None:
-                server._detach(self)
+                server._detach()
                 self._server = None
 
     def get_write_buffer_size(self):
diff --git a/Lib/test/test_asyncio/test_server.py b/Lib/test/test_asyncio/test_server.py
@@ -125,12 +125,8 @@ async def main(srv):
 class TestServer2(unittest.IsolatedAsyncioTestCase):
 
     async def test_wait_closed_basic(self):
-        async def serve(rd, wr):
-            try:
-                await rd.read()
-            finally:
-                wr.close()
-                await wr.wait_closed()
+        async def serve(*args):
+            pass
 
         srv = await asyncio.start_server(serve, socket_helper.HOSTv4, 0)
         self.addCleanup(srv.close)
@@ -141,8 +137,7 @@ async def serve(rd, wr):
         self.assertFalse(task1.done())
 
         # active count != 0, not closed: should block
-        addr = srv.sockets[0].getsockname()
-        (rd, wr) = await asyncio.open_connection(addr[0], addr[1])
+        srv._attach()
         task2 = asyncio.create_task(srv.wait_closed())
         await asyncio.sleep(0)
         self.assertFalse(task1.done())
@@ -157,8 +152,7 @@ async def serve(rd, wr):
         self.assertFalse(task2.done())
         self.assertFalse(task3.done())
 
-        wr.close()
-        await wr.wait_closed()
+        srv._detach()
         # active count == 0, closed: should unblock
         await task1
         await task2
@@ -167,96 +161,22 @@ async def serve(rd, wr):
 
     async def test_wait_closed_race(self):
         # Test a regression in 3.12.0, should be fixed in 3.12.1
-        async def serve(rd, wr):
-            try:
-                await rd.read()
-            finally:
-                wr.close()
-                await wr.wait_closed()
+        async def serve(*args):
+            pass
 
         srv = await asyncio.start_server(serve, socket_helper.HOSTv4, 0)
         self.addCleanup(srv.close)
 
         task = asyncio.create_task(srv.wait_closed())
         await asyncio.sleep(0)
         self.assertFalse(task.done())
-        addr = srv.sockets[0].getsockname()
-        (rd, wr) = await asyncio.open_connection(addr[0], addr[1])
+        srv._attach()
         loop = asyncio.get_running_loop()
         loop.call_soon(srv.close)
-        loop.call_soon(wr.close)
+        loop.call_soon(srv._detach)
         await srv.wait_closed()
 
-    async def test_close_clients(self):
-        async def serve(rd, wr):
-            try:
-                await rd.read()
-            finally:
-                wr.close()
-                await wr.wait_closed()
-
-        srv = await asyncio.start_server(serve, socket_helper.HOSTv4, 0)
-        self.addCleanup(srv.close)
-
-        addr = srv.sockets[0].getsockname()
-        (rd, wr) = await asyncio.open_connection(addr[0], addr[1])
-        self.addCleanup(wr.close)
-
-        task = asyncio.create_task(srv.wait_closed())
-        await asyncio.sleep(0)
-        self.assertFalse(task.done())
-
-        srv.close()
-        srv.close_clients()
-        await asyncio.sleep(0)
-        await asyncio.sleep(0)
-        self.assertTrue(task.done())
-
-    async def test_abort_clients(self):
-        async def serve(rd, wr):
-            nonlocal s_rd, s_wr
-            s_rd = rd
-            s_wr = wr
-            await wr.wait_closed()
-
-        s_rd = s_wr = None
-        srv = await asyncio.start_server(serve, socket_helper.HOSTv4, 0)
-        self.addCleanup(srv.close)
-
-        addr = srv.sockets[0].getsockname()
-        (c_rd, c_wr) = await asyncio.open_connection(addr[0], addr[1], limit=4096)
-        self.addCleanup(c_wr.close)
-
-        # Limit the socket buffers so we can reliably overfill them
-        s_sock = s_wr.get_extra_info('socket')
-        s_sock.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 65536)
-        c_sock = c_wr.get_extra_info('socket')
-        c_sock.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 65536)
-
-        # Get the reader in to a paused state by sending more than twice
-        # the configured limit
-        s_wr.write(b'a' * 4096)
-        s_wr.write(b'a' * 4096)
-        s_wr.write(b'a' * 4096)
-        while c_wr.transport.is_reading():
-            await asyncio.sleep(0)
-
-        # Get the writer in a waiting state by sending data until the
-        # socket buffers are full on both server and client sockets and
-        # the kernel stops accepting more data
-        s_wr.write(b'a' * c_sock.getsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF))
-        s_wr.write(b'a' * s_sock.getsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF))
-        self.assertNotEqual(s_wr.transport.get_write_buffer_size(), 0)
-
-        task = asyncio.create_task(srv.wait_closed())
-        await asyncio.sleep(0)
-        self.assertFalse(task.done())
 
-        srv.close()
-        srv.abort_clients()
-        await asyncio.sleep(0)
-        await asyncio.sleep(0)
-        self.assertTrue(task.done())
 
 
 # Test the various corner cases of Unix server socket removal
diff --git a/Misc/NEWS.d/next/Library/2024-01-22-15-50-58.gh-issue-113538.v2wrwg.rst b/Misc/NEWS.d/next/Library/2024-01-22-15-50-58.gh-issue-113538.v2wrwg.rst
