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methanemethane
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bpo-29617: Remove Python 3.3 support from asyncio (GH-232)
1 parent f6448e5 commit 3e2ad8e

12 files changed

Lines changed: 65 additions & 223 deletions

‎Lib/asyncio/base_events.py‎

Lines changed: 6 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,6 @@
2929
import warnings
3030
import weakref
3131

32-
from . import compat
3332
from . import coroutines
3433
from . import events
3534
from . import futures
@@ -499,16 +498,12 @@ def is_closed(self):
499498
"""Returns True if the event loop was closed."""
500499
return self._closed
501500

502-
# On Python 3.3 and older, objects with a destructor part of a reference
503-
# cycle are never destroyed. It's not more the case on Python 3.4 thanks
504-
# to the PEP 442.
505-
if compat.PY34:
506-
def __del__(self):
507-
if not self.is_closed():
508-
warnings.warn("unclosed event loop %r" % self, ResourceWarning,
509-
source=self)
510-
if not self.is_running():
511-
self.close()
501+
def __del__(self):
502+
if not self.is_closed():
503+
warnings.warn("unclosed event loop %r" % self, ResourceWarning,
504+
source=self)
505+
if not self.is_running():
506+
self.close()
512507

513508
def is_running(self):
514509
"""Returns True if the event loop is running."""

‎Lib/asyncio/base_subprocess.py‎

Lines changed: 5 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,6 @@
22
import subprocess
33
import warnings
44

5-
from . import compat
65
from . import protocols
76
from . import transports
87
from .coroutines import coroutine
@@ -121,15 +120,11 @@ def close(self):
121120

122121
# Don't clear the _proc reference yet: _post_init() may still run
123122

124-
# On Python 3.3 and older, objects with a destructor part of a reference
125-
# cycle are never destroyed. It's not more the case on Python 3.4 thanks
126-
# to the PEP 442.
127-
if compat.PY34:
128-
def __del__(self):
129-
if not self._closed:
130-
warnings.warn("unclosed transport %r" % self, ResourceWarning,
131-
source=self)
132-
self.close()
123+
def __del__(self):
124+
if not self._closed:
125+
warnings.warn("unclosed transport %r" % self, ResourceWarning,
126+
source=self)
127+
self.close()
133128

134129
def get_pid(self):
135130
return self._pid

‎Lib/asyncio/compat.py‎

Lines changed: 0 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -2,17 +2,5 @@
22

33
import sys
44

5-
PY34 = sys.version_info >= (3, 4)
65
PY35 = sys.version_info >= (3, 5)
76
PY352 = sys.version_info >= (3, 5, 2)
8-
9-
10-
def flatten_list_bytes(list_of_data):
11-
"""Concatenate a sequence of bytes-like objects."""
12-
if not PY34:
13-
# On Python 3.3 and older, bytes.join() doesn't handle
14-
# memoryview.
15-
list_of_data = (
16-
bytes(data) if isinstance(data, memoryview) else data
17-
for data in list_of_data)
18-
return b''.join(list_of_data)

‎Lib/asyncio/events.py‎

Lines changed: 2 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -19,20 +19,15 @@
1919
import threading
2020
import traceback
2121

22-
from asyncio import compat
23-
2422

2523
def _get_function_source(func):
26-
if compat.PY34:
27-
func = inspect.unwrap(func)
28-
elif hasattr(func, '__wrapped__'):
29-
func = func.__wrapped__
24+
func = inspect.unwrap(func)
3025
if inspect.isfunction(func):
3126
code = func.__code__
3227
return (code.co_filename, code.co_firstlineno)
3328
if isinstance(func, functools.partial):
3429
return _get_function_source(func.func)
35-
if compat.PY34 and isinstance(func, functools.partialmethod):
30+
if isinstance(func, functools.partialmethod):
3631
return _get_function_source(func.func)
3732
return None
3833

‎Lib/asyncio/futures.py‎

Lines changed: 16 additions & 106 deletions
Original file line numberDiff line numberDiff line change
@@ -27,86 +27,6 @@
2727
STACK_DEBUG = logging.DEBUG - 1 # heavy-duty debugging
2828

2929

30-
class _TracebackLogger:
31-
"""Helper to log a traceback upon destruction if not cleared.
32-
33-
This solves a nasty problem with Futures and Tasks that have an
34-
exception set: if nobody asks for the exception, the exception is
35-
never logged. This violates the Zen of Python: 'Errors should
36-
never pass silently. Unless explicitly silenced.'
37-
38-
However, we don't want to log the exception as soon as
39-
set_exception() is called: if the calling code is written
40-
properly, it will get the exception and handle it properly. But
41-
we *do* want to log it if result() or exception() was never called
42-
-- otherwise developers waste a lot of time wondering why their
43-
buggy code fails silently.
44-
45-
An earlier attempt added a __del__() method to the Future class
46-
itself, but this backfired because the presence of __del__()
47-
prevents garbage collection from breaking cycles. A way out of
48-
this catch-22 is to avoid having a __del__() method on the Future
49-
class itself, but instead to have a reference to a helper object
50-
with a __del__() method that logs the traceback, where we ensure
51-
that the helper object doesn't participate in cycles, and only the
52-
Future has a reference to it.
53-
54-
The helper object is added when set_exception() is called. When
55-
the Future is collected, and the helper is present, the helper
56-
object is also collected, and its __del__() method will log the
57-
traceback. When the Future's result() or exception() method is
58-
called (and a helper object is present), it removes the helper
59-
object, after calling its clear() method to prevent it from
60-
logging.
61-
62-
One downside is that we do a fair amount of work to extract the
63-
traceback from the exception, even when it is never logged. It
64-
would seem cheaper to just store the exception object, but that
65-
references the traceback, which references stack frames, which may
66-
reference the Future, which references the _TracebackLogger, and
67-
then the _TracebackLogger would be included in a cycle, which is
68-
what we're trying to avoid! As an optimization, we don't
69-
immediately format the exception; we only do the work when
70-
activate() is called, which call is delayed until after all the
71-
Future's callbacks have run. Since usually a Future has at least
72-
one callback (typically set by 'yield from') and usually that
73-
callback extracts the callback, thereby removing the need to
74-
format the exception.
75-
76-
PS. I don't claim credit for this solution. I first heard of it
77-
in a discussion about closing files when they are collected.
78-
"""
79-
80-
__slots__ = ('loop', 'source_traceback', 'exc', 'tb')
81-
82-
def __init__(self, future, exc):
83-
self.loop = future._loop
84-
self.source_traceback = future._source_traceback
85-
self.exc = exc
86-
self.tb = None
87-
88-
def activate(self):
89-
exc = self.exc
90-
if exc is not None:
91-
self.exc = None
92-
self.tb = traceback.format_exception(exc.__class__, exc,
93-
exc.__traceback__)
94-
95-
def clear(self):
96-
self.exc = None
97-
self.tb = None
98-
99-
def __del__(self):
100-
if self.tb:
101-
msg = 'Future/Task exception was never retrieved\n'
102-
if self.source_traceback:
103-
src = ''.join(traceback.format_list(self.source_traceback))
104-
msg += 'Future/Task created at (most recent call last):\n'
105-
msg += '%s\n' % src.rstrip()
106-
msg += ''.join(self.tb).rstrip()
107-
self.loop.call_exception_handler({'message': msg})
108-
109-
11030
class Future:
11131
"""This class is *almost* compatible with concurrent.futures.Future.
11232
@@ -164,25 +84,21 @@ def __init__(self, *, loop=None):
16484
def __repr__(self):
16585
return '<%s %s>' % (self.__class__.__name__, ' '.join(self._repr_info()))
16686

167-
# On Python 3.3 and older, objects with a destructor part of a reference
168-
# cycle are never destroyed. It's not more the case on Python 3.4 thanks
169-
# to the PEP 442.
170-
if compat.PY34:
171-
def __del__(self):
172-
if not self._log_traceback:
173-
# set_exception() was not called, or result() or exception()
174-
# has consumed the exception
175-
return
176-
exc = self._exception
177-
context = {
178-
'message': ('%s exception was never retrieved'
179-
% self.__class__.__name__),
180-
'exception': exc,
181-
'future': self,
182-
}
183-
if self._source_traceback:
184-
context['source_traceback'] = self._source_traceback
185-
self._loop.call_exception_handler(context)
87+
def __del__(self):
88+
if not self._log_traceback:
89+
# set_exception() was not called, or result() or exception()
90+
# has consumed the exception
91+
return
92+
exc = self._exception
93+
context = {
94+
'message': ('%s exception was never retrieved'
95+
% self.__class__.__name__),
96+
'exception': exc,
97+
'future': self,
98+
}
99+
if self._source_traceback:
100+
context['source_traceback'] = self._source_traceback
101+
self._loop.call_exception_handler(context)
186102

187103
def cancel(self):
188104
"""Cancel the future and schedule callbacks.
@@ -317,13 +233,7 @@ def set_exception(self, exception):
317233
self._exception = exception
318234
self._state = _FINISHED
319235
self._schedule_callbacks()
320-
if compat.PY34:
321-
self._log_traceback = True
322-
else:
323-
self._tb_logger = _TracebackLogger(self, exception)
324-
# Arrange for the logger to be activated after all callbacks
325-
# have had a chance to call result() or exception().
326-
self._loop.call_soon(self._tb_logger.activate)
236+
self._log_traceback = True
327237

328238
def __iter__(self):
329239
if not self.done():

‎Lib/asyncio/proactor_events.py‎

Lines changed: 5 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,6 @@
1010
import warnings
1111

1212
from . import base_events
13-
from . import compat
1413
from . import constants
1514
from . import futures
1615
from . import sslproto
@@ -86,15 +85,11 @@ def close(self):
8685
self._read_fut.cancel()
8786
self._read_fut = None
8887

89-
# On Python 3.3 and older, objects with a destructor part of a reference
90-
# cycle are never destroyed. It's not more the case on Python 3.4 thanks
91-
# to the PEP 442.
92-
if compat.PY34:
93-
def __del__(self):
94-
if self._sock is not None:
95-
warnings.warn("unclosed transport %r" % self, ResourceWarning,
96-
source=self)
97-
self.close()
88+
def __del__(self):
89+
if self._sock is not None:
90+
warnings.warn("unclosed transport %r" % self, ResourceWarning,
91+
source=self)
92+
self.close()
9893

9994
def _fatal_error(self, exc, message='Fatal error on pipe transport'):
10095
if isinstance(exc, base_events._FATAL_ERROR_IGNORE):

‎Lib/asyncio/selector_events.py‎

Lines changed: 5 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -18,7 +18,6 @@
1818
ssl = None
1919

2020
from . import base_events
21-
from . import compat
2221
from . import constants
2322
from . import events
2423
from . import futures
@@ -621,15 +620,11 @@ def close(self):
621620
self._loop._remove_writer(self._sock_fd)
622621
self._loop.call_soon(self._call_connection_lost, None)
623622

624-
# On Python 3.3 and older, objects with a destructor part of a reference
625-
# cycle are never destroyed. It's not more the case on Python 3.4 thanks
626-
# to the PEP 442.
627-
if compat.PY34:
628-
def __del__(self):
629-
if self._sock is not None:
630-
warnings.warn("unclosed transport %r" % self, ResourceWarning,
631-
source=self)
632-
self._sock.close()
623+
def __del__(self):
624+
if self._sock is not None:
625+
warnings.warn("unclosed transport %r" % self, ResourceWarning,
626+
source=self)
627+
self._sock.close()
633628

634629
def _fatal_error(self, exc, message='Fatal error on transport'):
635630
# Should be called from exception handler only.

‎Lib/asyncio/sslproto.py‎

Lines changed: 5 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,6 @@
66
ssl = None
77

88
from . import base_events
9-
from . import compat
109
from . import protocols
1110
from . import transports
1211
from .log import logger
@@ -325,15 +324,11 @@ def close(self):
325324
self._closed = True
326325
self._ssl_protocol._start_shutdown()
327326

328-
# On Python 3.3 and older, objects with a destructor part of a reference
329-
# cycle are never destroyed. It's not more the case on Python 3.4 thanks
330-
# to the PEP 442.
331-
if compat.PY34:
332-
def __del__(self):
333-
if not self._closed:
334-
warnings.warn("unclosed transport %r" % self, ResourceWarning,
335-
source=self)
336-
self.close()
327+
def __del__(self):
328+
if not self._closed:
329+
warnings.warn("unclosed transport %r" % self, ResourceWarning,
330+
source=self)
331+
self.close()
337332

338333
def pause_reading(self):
339334
"""Pause the receiving end.

‎Lib/asyncio/tasks.py‎

Lines changed: 10 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -76,20 +76,16 @@ def __init__(self, coro, *, loop=None):
7676
self._loop.call_soon(self._step)
7777
self.__class__._all_tasks.add(self)
7878

79-
# On Python 3.3 or older, objects with a destructor that are part of a
80-
# reference cycle are never destroyed. That's not the case any more on
81-
# Python 3.4 thanks to the PEP 442.
82-
if compat.PY34:
83-
def __del__(self):
84-
if self._state == futures._PENDING and self._log_destroy_pending:
85-
context = {
86-
'task': self,
87-
'message': 'Task was destroyed but it is pending!',
88-
}
89-
if self._source_traceback:
90-
context['source_traceback'] = self._source_traceback
91-
self._loop.call_exception_handler(context)
92-
futures.Future.__del__(self)
79+
def __del__(self):
80+
if self._state == futures._PENDING and self._log_destroy_pending:
81+
context = {
82+
'task': self,
83+
'message': 'Task was destroyed but it is pending!',
84+
}
85+
if self._source_traceback:
86+
context['source_traceback'] = self._source_traceback
87+
self._loop.call_exception_handler(context)
88+
futures.Future.__del__(self)
9389

9490
def _repr_info(self):
9591
return base_tasks._task_repr_info(self)

‎Lib/asyncio/test_utils.py‎

Lines changed: 0 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -26,7 +26,6 @@
2626
ssl = None
2727

2828
from . import base_events
29-
from . import compat
3029
from . import events
3130
from . import futures
3231
from . import selectors
@@ -465,16 +464,6 @@ def tearDown(self):
465464
# in an except block of a generator
466465
self.assertEqual(sys.exc_info(), (None, None, None))
467466

468-
if not compat.PY34:
469-
# Python 3.3 compatibility
470-
def subTest(self, *args, **kwargs):
471-
class EmptyCM:
472-
def __enter__(self):
473-
pass
474-
def __exit__(self, *exc):
475-
pass
476-
return EmptyCM()
477-
478467

479468
@contextlib.contextmanager
480469
def disable_logger():

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