Break Circular References #43

telnetlib3/server.py

@@ -14,6 +14,7 @@
 import asyncio
 import logging
 import signal
+from weakref import proxy
 
 # local
 from . import server_base
@@ -111,7 +112,7 @@ def check_negotiation(self, final=False):
         encoding = self.encoding(outgoing=True, incoming=True)
         if not self.waiter_encoding.done() and result:
             self.log.debug('encoding complete: {0!r}'.format(encoding))
-            self.waiter_encoding.set_result(self)
+            self.waiter_encoding.set_result(proxy(self))
 
         elif (not self.waiter_encoding.done() and
               self.writer.remote_option.get(TTYPE) is False):
@@ -120,13 +121,13 @@ def check_negotiation(self, final=False):
             # the distant end would not support it, declaring encoding failed.
             self.log.debug('encoding failed after {0:1.2f}s: {1}'
                            .format(self.duration, encoding))
-            self.waiter_encoding.set_result(self)
+            self.waiter_encoding.set_result(proxy(self))
             return parent
 
         elif not self.waiter_encoding.done() and final:
             self.log.debug('encoding failed after {0:1.2f}s: {1}'
                            .format(self.duration, encoding))
-            self.waiter_encoding.set_result(self)
+            self.waiter_encoding.set_result(proxy(self))
             return parent
 
         return parent and result

telnetlib3/server_base.py

@@ -4,6 +4,7 @@
 import logging
 import datetime
 import sys
+from weakref import proxy
 
 from .stream_writer import (TelnetWriter, TelnetWriterUnicode)
 from .stream_reader import (TelnetReader, TelnetReaderUnicode)
@@ -85,7 +86,11 @@ def connection_lost(self, exc):
         self._transport.close()
         self._waiter_connected.cancel()
         if self.shell is None:
-            self._waiter_closed.set_result(self)
+            self._waiter_closed.set_result(proxy(self))
+
+        # break circular refrences.
+        self._transport = None
+        self.reader.fn_encoding = None
 
     def connection_made(self, transport):
         """
@@ -134,7 +139,7 @@ def begin_shell(self, result):
             if asyncio.iscoroutine(coro):
                 fut = self._loop.create_task(coro)
                 fut.add_done_callback(
-                    lambda fut_obj: self._waiter_closed.set_result(self))
+                    lambda fut_obj: self._waiter_closed.set_result(proxy(self)))
 
     def data_received(self, data):
         """Process bytes received by transport."""
@@ -277,11 +282,11 @@ def _check_negotiation_timer(self):
         if self.check_negotiation(final=final):
             self.log.debug('negotiation complete after {:1.2f}s.'
                            .format(self.duration))
-            self._waiter_connected.set_result(self)
+            self._waiter_connected.set_result(proxy(self))
         elif final:
             self.log.debug('negotiation failed after {:1.2f}s.'
                            .format(self.duration))
-            self._waiter_connected.set_result(self)
+            self._waiter_connected.set_result(proxy(self))
         else:
             # keep re-queuing until complete
             self._check_later = self._loop.call_later(

telnetlib3/stream_writer.py

@@ -182,6 +182,17 @@ def __init__(self, transport, protocol, *, client=False, server=False,
 
     # Base protocol methods
 
+    def close(self):
+        super().close()
+        # break circular refs
+        self._ext_callback.clear()
+        self._ext_send_callback.clear()
+        self._slc_callback.clear()
+        self._iac_callback.clear()
+        self.fn_encoding = None
+        self._protocol = None
+        self._transport = None
+
     def __repr__(self):
         """Description of stream encoding state."""
         info = ['TelnetWriter']

telnetlib3/tests/test_shell.py

@@ -1,6 +1,7 @@
 """Test the server's shell(reader, writer) callback."""
 # std imports
 import asyncio
+import weakref
 
 # local imports
 import telnetlib3
@@ -22,6 +23,7 @@ async def test_telnet_server_shell_as_coroutine(event_loop, bind_host,
     from telnetlib3.telopt import IAC, DO, WONT, TTYPE
     # given,
     _waiter = asyncio.Future()
+    _saved = weakref.WeakSet()
     send_input = 'Alpha'
     expect_output = 'Beta'
     expect_hello = IAC + DO + TTYPE
@@ -33,6 +35,10 @@ def shell(reader, writer):
         inp = yield from reader.readexactly(len(send_input))
         assert inp == send_input
         writer.write(expect_output)
+        _saved.add(writer)
+        _saved.add(writer._protocol)
+        yield from writer.drain()
+        writer.close()
 
     # exercise,
     await telnetlib3.create_server(
@@ -61,6 +67,9 @@ def shell(reader, writer):
 
     # verify,
     assert server_output.decode('ascii') == expect_output
+
+    # no leaks
+    assert len(_saved) == 0
 
 
 @pytest.mark.asyncio