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# Protocol Buffers - Google's data interchange format
# Copyright 2008 Google Inc. All rights reserved.
#
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file or at
# https://developers.google.com/open-source/licenses/bsd
"""A subclass of unittest.TestCase which checks for reference leaks.
To use:
- Use testing_refleak.BaseTestCase instead of unittest.TestCase
- Configure and compile Python with --with-pydebug
If sys.gettotalrefcount() is not available (because Python was built without
the Py_DEBUG option), then this module is a no-op and tests will run normally.
"""
import copyreg
import gc
import sys
import unittest
class LocalTestResult(unittest.TestResult):
"""A TestResult which forwards events to a parent object, except for Skips."""
def __init__(self, parent_result):
unittest.TestResult.__init__(self)
self.parent_result = parent_result
def addError(self, test, error):
self.parent_result.addError(test, error)
def addFailure(self, test, error):
self.parent_result.addFailure(test, error)
def addSkip(self, test, reason):
pass
class ReferenceLeakCheckerMixin(object):
"""A mixin class for TestCase, which checks reference counts."""
NB_RUNS = 3
def run(self, result=None):
testMethod = getattr(self, self._testMethodName)
expecting_failure_method = getattr(testMethod, "__unittest_expecting_failure__", False)
expecting_failure_class = getattr(self, "__unittest_expecting_failure__", False)
if expecting_failure_class or expecting_failure_method:
return
# python_message.py registers all Message classes to some pickle global
# registry, which makes the classes immortal.
# We save a copy of this registry, and reset it before we could references.
self._saved_pickle_registry = copyreg.dispatch_table.copy()
# Run the test twice, to warm up the instance attributes.
super(ReferenceLeakCheckerMixin, self).run(result=result)
super(ReferenceLeakCheckerMixin, self).run(result=result)
oldrefcount = 0
local_result = LocalTestResult(result)
num_flakes = 0
refcount_deltas = []
while len(refcount_deltas) < self.NB_RUNS:
oldrefcount = self._getRefcounts()
super(ReferenceLeakCheckerMixin, self).run(result=local_result)
newrefcount = self._getRefcounts()
# If the GC was able to collect some objects after the call to run() that
# it could not collect before the call, then the counts won't match.
if newrefcount < oldrefcount and num_flakes < 2:
# This result is (probably) a flake -- garbage collectors aren't very
# predictable, but a lower ending refcount is the opposite of the
# failure we are testing for. If the result is repeatable, then we will
# eventually report it, but not after trying to eliminate it.
num_flakes += 1
continue
num_flakes = 0
refcount_deltas.append(newrefcount - oldrefcount)
print(refcount_deltas, self)
try:
self.assertEqual(refcount_deltas, [0] * self.NB_RUNS)
except Exception: # pylint: disable=broad-except
result.addError(self, sys.exc_info())
def _getRefcounts(self):
copyreg.dispatch_table.clear()
copyreg.dispatch_table.update(self._saved_pickle_registry)
# It is sometimes necessary to gc.collect() multiple times, to ensure
# that all objects can be collected.
gc.collect()
gc.collect()
gc.collect()
return sys.gettotalrefcount()
if hasattr(sys, 'gettotalrefcount'):
def TestCase(test_class):
new_bases = (ReferenceLeakCheckerMixin,) + test_class.__bases__
new_class = type(test_class)(
test_class.__name__, new_bases, dict(test_class.__dict__))
return new_class
SkipReferenceLeakChecker = unittest.skip
else:
# When PyDEBUG is not enabled, run the tests normally.
def TestCase(test_class):
return test_class
def SkipReferenceLeakChecker(reason):
del reason # Don't skip, so don't need a reason.
def Same(func):
return func
return Same
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