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# vim:fileencoding=utf-8:noet
from __future__ import (unicode_literals, division, absolute_import, print_function)
import gc
import sys
from types import FrameType
from itertools import chain
# From http://code.activestate.com/recipes/523004-find-cyclical-references/
def print_cycles(objects, outstream=sys.stdout, show_progress=False):
'''Find reference cycles
:param list objects:
A list of objects to find cycles in. It is often useful to pass in
gc.garbage to find the cycles that are preventing some objects from
being garbage collected.
:param file outstream:
The stream for output.
:param bool show_progress:
If True, print the number of objects reached as they are found.
'''
def print_path(path):
for i, step in enumerate(path):
# next “wraps around”
next = path[(i + 1) % len(path)]
outstream.write(' %s -- ' % str(type(step)))
written = False
if isinstance(step, dict):
for key, val in step.items():
if val is next:
outstream.write('[%s]' % repr(key))
written = True
break
if key is next:
outstream.write('[key] = %s' % repr(val))
written = True
break
elif isinstance(step, (list, tuple)):
for i, item in enumerate(step):
if item is next:
outstream.write('[%d]' % i)
written = True
elif getattr(type(step), '__getattribute__', None) in (object.__getattribute__, type.__getattribute__):
for attr in chain(dir(step), getattr(step, '__dict__', ())):
if getattr(step, attr, None) is next:
try:
outstream.write('%r.%s' % (step, attr))
except TypeError:
outstream.write('.%s' % (step, attr))
written = True
break
if not written:
outstream.write(repr(step))
outstream.write(' ->\n')
outstream.write('\n')
def recurse(obj, start, all, current_path):
if show_progress:
outstream.write('%d\r' % len(all))
all[id(obj)] = None
referents = gc.get_referents(obj)
for referent in referents:
# If we’ve found our way back to the start, this is
# a cycle, so print it out
if referent is start:
try:
outstream.write('Cyclic reference: %r\n' % referent)
except TypeError:
try:
outstream.write('Cyclic reference: %i (%r)\n' % (id(referent), type(referent)))
except TypeError:
outstream.write('Cyclic reference: %i\n' % id(referent))
print_path(current_path)
# Don’t go back through the original list of objects, or
# through temporary references to the object, since those
# are just an artifact of the cycle detector itself.
elif referent is objects or isinstance(referent, FrameType):
continue
# We haven’t seen this object before, so recurse
elif id(referent) not in all:
recurse(referent, start, all, current_path + (obj,))
for obj in objects:
# We are not interested in non-powerline cyclic references
try:
if not type(obj).__module__.startswith('powerline'):
continue
except AttributeError:
continue
recurse(obj, obj, {}, ())
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