Python weakref.finalize() Examples

def __init__(self, suffix="", prefix=None, dir=None):
        if "RAM_DISK" in os.environ:
            import uuid

            name = uuid.uuid4().hex
            dir_name = os.path.join(os.environ["RAM_DISK"].strip(), name)
            os.mkdir(dir_name)
            self.name = dir_name
        else:
            suffix = suffix if suffix else ""
            if not prefix:
                self.name = mkdtemp(suffix=suffix, dir=dir)
            else:
                self.name = mkdtemp(suffix, prefix, dir)
        self._finalizer = finalize(
            self,
            self._cleanup,
            self.name,
            warn_message="Implicitly cleaning up {!r}".format(self),
        ) 

def __init__(self, session=None, soup_config={'features': 'lxml'},
                 requests_adapters=None,
                 raise_on_404=False, user_agent=None):

        self.raise_on_404 = raise_on_404
        self.session = session or requests.Session()

        if hasattr(weakref, 'finalize'):
            self._finalize = weakref.finalize(self.session, self.close)
        else:   # pragma: no cover
            # Python < 3 does not have weakref.finalize, but these
            # versions accept calling session.close() within __del__
            self._finalize = self.close

        self.set_user_agent(user_agent)

        if requests_adapters is not None:
            for adaptee, adapter in requests_adapters.items():
                self.session.mount(adaptee, adapter)

        self.soup_config = soup_config or dict() 

def assertCalled(test, times=None):
    def decorator(fn):
        fn._called = 0

        def finalize(fn):
            if times is not None:
                test.assertEqual(fn._called, times, "Function '{}' was not called the correct number of times".format(fn.__name__))
            else:
                test.assertTrue(fn._called, "Function '{}' was never called".format(fn.__name__))

        weakref.finalize(fn, finalize, fn)

        @wraps(fn)
        def wrapper(*args, **kwargs):
            fn._called += 1
            fn(*args, **kwargs)

        return wrapper
    return decorator 

def __init__(self, url, engine_kwargs=None, skip_compatibility_check=False):
        # type: (str, Optional[Dict[str, Any]], bool) -> None

        self.engine_kwargs = engine_kwargs or {}
        self.url = self._fill_storage_url_template(url)
        self.skip_compatibility_check = skip_compatibility_check

        self._set_default_engine_kwargs_for_mysql(url, self.engine_kwargs)

        try:
            self.engine = create_engine(self.url, **self.engine_kwargs)
        except ImportError as e:
            raise ImportError(
                "Failed to import DB access module for the specified storage URL. "
                "Please install appropriate one. (The actual import error is: " + str(e) + ".)"
            )

        self.scoped_session = orm.scoped_session(orm.sessionmaker(bind=self.engine))
        models.BaseModel.metadata.create_all(self.engine)

        self._version_manager = _VersionManager(self.url, self.engine, self.scoped_session)
        if not skip_compatibility_check:
            self._version_manager.check_table_schema_compatibility()

        weakref.finalize(self, self._finalize) 

def run(self, **options):
        self.shutdown()
        import threading
        options = combine_dicts(self.run_options, options)
        memo = os.environ.get("WERKZEUG_RUN_MAIN")
        try:
            os.environ["WERKZEUG_RUN_MAIN"] = "true"
            threading.Thread(
                target=run_server,
                args=(self.app(), self.get_port(**options))
            ).start()
            # noinspection PyArgumentList
            self.shutdown = weakref.finalize(self, self.shutdown_site, self.url)
            self.wait_server()
        finally:
            if memo is None:
                os.environ.pop("WERKZEUG_RUN_MAIN")
            else:
                os.environ["WERKZEUG_RUN_MAIN"] = memo

        return self 

def test_all_freed(self):
        # we want a weakrefable subclass of weakref.finalize
        class MyFinalizer(weakref.finalize):
            pass

        a = self.A()
        res = []
        def callback():
            res.append(123)
        f = MyFinalizer(a, callback)

        wr_callback = weakref.ref(callback)
        wr_f = weakref.ref(f)
        del callback, f

        self.assertIsNotNone(wr_callback())
        self.assertIsNotNone(wr_f())

        del a
        self._collect_if_necessary()

        self.assertIsNone(wr_callback())
        self.assertIsNone(wr_f())
        self.assertEqual(res, [123]) 

def run_in_child(cls):
        def error():
            # Create an atexit finalizer from inside a finalizer called
            # at exit.  This should be the next to be run.
            g1 = weakref.finalize(cls, print, 'g1')
            print('f3 error')
            1/0

        # cls should stay alive till atexit callbacks run
        f1 = weakref.finalize(cls, print, 'f1', _global_var)
        f2 = weakref.finalize(cls, print, 'f2', _global_var)
        f3 = weakref.finalize(cls, error)
        f4 = weakref.finalize(cls, print, 'f4', _global_var)

        assert f1.atexit == True
        f2.atexit = False
        assert f3.atexit == True
        assert f4.atexit == True 

def __new__(cls, dir=False, **kwargs):
        """
        Create a tempfile, return pathlib.Path reference to it.
        """
        if dir:
            name = tempfile.mkdtemp(**kwargs)
        else:
            fd, name = tempfile.mkstemp(**kwargs)
            # fd is now assigned to our process table, but we don't need to do
            # anything with the file. We will call `open` on the `name` later
            # producing a different file descriptor, so close this one to
            # prevent a resource leak.
            os.close(fd)
        obj = super().__new__(cls, name)
        obj._destructor = weakref.finalize(obj, cls._destruct, str(obj))
        return obj 

def __init__(self, value_ref: executor_pb2.ValueRef, type_spec, executor):
    """Creates the value.

    Args:
      value_ref: An instance of `executor_pb2.ValueRef` returned by the remote
        executor service.
      type_spec: An instance of `computation_types.Type`.
      executor: The executor that created this value.
    """
    py_typecheck.check_type(value_ref, executor_pb2.ValueRef)
    py_typecheck.check_type(type_spec, computation_types.Type)
    py_typecheck.check_type(executor, RemoteExecutor)
    self._value_ref = value_ref
    self._type_signature = type_spec
    self._executor = executor

    # Clean up the value and the memory associated with it on the remote
    # worker when no references to it remain.
    def finalizer(value_ref, executor):
      executor._dispose(value_ref)  # pylint: disable=protected-access

    weakref.finalize(self, finalizer, value_ref, executor) 

def __init__(self, suffix="", prefix=None, dir=None):
        if "RAM_DISK" in os.environ:
            import uuid

            name = uuid.uuid4().hex
            dir_name = os.path.join(os.environ["RAM_DISK"].strip(), name)
            os.mkdir(dir_name)
            self.name = dir_name
        else:
            suffix = suffix if suffix else ""
            if not prefix:
                self.name = mkdtemp(suffix=suffix, dir=dir)
            else:
                self.name = mkdtemp(suffix, prefix, dir)
        self._finalizer = finalize(
            self,
            self._cleanup,
            self.name,
            warn_message="Implicitly cleaning up {!r}".format(self),
        ) 

def test_all_freed(self):
        # we want a weakrefable subclass of weakref.finalize
        class MyFinalizer(weakref.finalize):
            pass

        a = self.A()
        res = []
        def callback():
            res.append(123)
        f = MyFinalizer(a, callback)

        wr_callback = weakref.ref(callback)
        wr_f = weakref.ref(f)
        del callback, f

        self.assertIsNotNone(wr_callback())
        self.assertIsNotNone(wr_f())

        del a
        self._collect_if_necessary()

        self.assertIsNone(wr_callback())
        self.assertIsNone(wr_f())
        self.assertEqual(res, [123]) 

def run_in_child(cls):
        def error():
            # Create an atexit finalizer from inside a finalizer called
            # at exit.  This should be the next to be run.
            g1 = weakref.finalize(cls, print, 'g1')
            print('f3 error')
            1/0

        # cls should stay alive till atexit callbacks run
        f1 = weakref.finalize(cls, print, 'f1', _global_var)
        f2 = weakref.finalize(cls, print, 'f2', _global_var)
        f3 = weakref.finalize(cls, error)
        f4 = weakref.finalize(cls, print, 'f4', _global_var)

        assert f1.atexit == True
        f2.atexit = False
        assert f3.atexit == True
        assert f4.atexit == True 

def test_all_freed(self):
        # we want a weakrefable subclass of weakref.finalize
        class MyFinalizer(weakref.finalize):
            pass

        a = self.A()
        res = []
        def callback():
            res.append(123)
        f = MyFinalizer(a, callback)

        wr_callback = weakref.ref(callback)
        wr_f = weakref.ref(f)
        del callback, f

        self.assertIsNotNone(wr_callback())
        self.assertIsNotNone(wr_f())

        del a
        self._collect_if_necessary()

        self.assertIsNone(wr_callback())
        self.assertIsNone(wr_f())
        self.assertEqual(res, [123]) 

def run_in_child(cls):
        def error():
            # Create an atexit finalizer from inside a finalizer called
            # at exit.  This should be the next to be run.
            g1 = weakref.finalize(cls, print, 'g1')
            print('f3 error')
            1/0

        # cls should stay alive till atexit callbacks run
        f1 = weakref.finalize(cls, print, 'f1', _global_var)
        f2 = weakref.finalize(cls, print, 'f2', _global_var)
        f3 = weakref.finalize(cls, error)
        f4 = weakref.finalize(cls, print, 'f4', _global_var)

        assert f1.atexit == True
        f2.atexit = False
        assert f3.atexit == True
        assert f4.atexit == True 

def test_no_linger(self):
        """Test that deleted animations are garbage-collected"""
        anim1_alivelist = ['animation 1 alive']
        anim2_alivelist = ['animation 2 alive']
        obj_alivelist = ['object alive']
        # cannot use SimpleNamespace because it doesn't support weakref
        obj = TestObject()
        obj.attribute = 0
        anim1 = animate(obj, attribute=1, duration=5)
        anim2 = animate(obj, attribute=2, duration=1)
        weakref.finalize(anim1, anim1_alivelist.clear)
        weakref.finalize(anim2, anim2_alivelist.clear)
        weakref.finalize(obj, obj_alivelist.clear)

        del anim1
        del anim2
        del obj
        gc.collect()
        self.assertEqual(anim1_alivelist, [])

        clock.tick(3)
        gc.collect()
        self.assertEqual(anim2_alivelist, [])
        self.assertEqual(obj_alivelist, []) 

def __init__(self):
        super().__init__()

        self._state = MediaState.Null
        self._elements = []
        self._old_pipe = ''
        self._loop_count = 0

        self._gst_pipe = Gst.Pipeline()
        self._gst_state = Gst.State.NULL
        self._time_query = Gst.Query.new_position(Gst.Format.TIME)

        bus = self._gst_pipe.get_bus()
        bus.add_signal_watch()

        # Use a weakref instead of the method or the object will not be
        # garbage-collected
        on_message = weakref.WeakMethod(self.__on_message)
        handler = bus.connect('message', lambda *args: on_message()(*args))
        weakref.finalize(self, self.__finalizer, self._gst_pipe, handler,
                         self._elements)

        self.changed('loop').connect(self.__prepare_loops)
        self.changed('pipe').connect(self.__prepare_pipe) 

def _create_cluster(self):
        if not self._fargate_scheduler or not self._fargate_workers:
            raise RuntimeError("You must specify a cluster when not using Fargate.")
        if self._worker_gpu:
            raise RuntimeError(
                "It is not possible to use GPUs with Fargate. "
                "Please provide an existing cluster with GPU instances available. "
            )
        self.cluster_name = dask.config.expand_environment_variables(
            self._cluster_name_template
        )
        self.cluster_name = self.cluster_name.format(uuid=str(uuid.uuid4())[:10])
        async with self._client("ecs") as ecs:
            response = await ecs.create_cluster(
                clusterName=self.cluster_name, tags=dict_to_aws(self.tags)
            )
        weakref.finalize(self, self.sync, self._delete_cluster)
        return response["cluster"]["clusterArn"] 

def __init__(self, session=None, soup_config={'features': 'lxml'},
                 requests_adapters=None,
                 raise_on_404=False, user_agent=None):

        self.raise_on_404 = raise_on_404
        self.session = session or requests.Session()

        if hasattr(weakref, 'finalize'):
            self._finalize = weakref.finalize(self.session, self.close)
        else:   # pragma: no cover
            # Python < 3 does not have weakref.finalize, but these
            # versions accept calling session.close() within __del__
            self._finalize = self.close

        self.set_user_agent(user_agent)

        if requests_adapters is not None:
            for adaptee, adapter in requests_adapters.items():
                self.session.mount(adaptee, adapter)

        self.soup_config = soup_config or dict() 

def finalize(self):
            """Finalizes the object if not already done."""
            self._finalizer() 

def _do_finalize_object_ref(obj_ref):
        """Helper function for weakref.finalize() that dereferences a weakref
        to an object and calls its _do_finalize_object() method if the object
        is still alive. Does nothing otherwise.

        Returns: None (implicit)

        Arguments:
        * obj_ref -- weakref to an object
        """
        obj = obj_ref()
        if obj is not None:
            # else object disappeared
            obj._do_finalize_object() 

def _do_finalize_object_ref(obj_ref):
        """Helper function for weakref.finalize() that dereferences a weakref
        to an object and calls its _do_finalize_object() method if the object
        is still alive. Does nothing otherwise.

        Returns: None (implicit)

        Arguments:
        * obj_ref -- weakref to an object
        """
        obj = obj_ref()
        if obj is not None:
            # else object disappeared
            obj._do_finalize_object() 

def __del__(self):
        self.finalize() 

def at_exit(workers_pool: QThreadPool, logging_worker: LoggingWorker, name: str):
        """
        The instance deconstruction handler is meant to be used with weakref.finalize() conforming with the requirement
        to have no reference to the target object (so it doesn't contain any instance reference and also is decorated as
        'staticmethod')
        """
        # Wait forever for all the jobs to complete. Currently, we cannot abort them gracefully
        workers_pool.waitForDone(msecs=-1)
        logging_worker.stopped.set()  # post the event in the logging worker to inform it...
        logging_worker.thread.wait()  # ...and wait for it to exit, too
        module_logger.info(f"destroyed {name} ProjectListItem") 

def finalize(self):
        """Finalizes the object if not already done.

        Returns: None
        """
        # this is the "public" finalize method
        raise NotImplementedError(
            "finalize() must be implemented by AutoFinalizedObject."
        ) 

def finalize(*args, **kwargs):
        pass 

def __init__(self, suffix=None, prefix=None, dir=None):
        self.name = tempfile.mkdtemp(suffix, prefix, dir)
        self._finalizer = _weakref.finalize(
            self, self._cleanup, self.name,
            warn_message="Implicitly cleaning up {!r}".format(self)) 

def test_order(self):
        a = self.A()
        res = []

        f1 = weakref.finalize(a, res.append, 'f1')
        f2 = weakref.finalize(a, res.append, 'f2')
        f3 = weakref.finalize(a, res.append, 'f3')
        f4 = weakref.finalize(a, res.append, 'f4')
        f5 = weakref.finalize(a, res.append, 'f5')

        # make sure finalizers can keep themselves alive
        del f1, f4

        self.assertTrue(f2.alive)
        self.assertTrue(f3.alive)
        self.assertTrue(f5.alive)

        self.assertTrue(f5.detach())
        self.assertFalse(f5.alive)

        f5()                       # nothing because previously unregistered
        res.append('A')
        f3()                       # => res.append('f3')
        self.assertFalse(f3.alive)
        res.append('B')
        f3()                       # nothing because previously called
        res.append('C')
        del a
        self._collect_if_necessary()
                                   # => res.append('f4')
                                   # => res.append('f2')
                                   # => res.append('f1')
        self.assertFalse(f2.alive)
        res.append('D')
        f2()                       # nothing because previously called by gc

        expected = ['A', 'f3', 'B', 'C', 'f4', 'f2', 'f1', 'D']
        self.assertEqual(res, expected) 

def test_finalize(self):
        def add(x,y,z):
            res.append(x + y + z)
            return x + y + z

        a = self.A()

        res = []
        f = weakref.finalize(a, add, 67, 43, z=89)
        self.assertEqual(f.alive, True)
        self.assertEqual(f.peek(), (a, add, (67,43), {'z':89}))
        self.assertEqual(f(), 199)
        self.assertEqual(f(), None)
        self.assertEqual(f(), None)
        self.assertEqual(f.peek(), None)
        self.assertEqual(f.detach(), None)
        self.assertEqual(f.alive, False)
        self.assertEqual(res, [199])

        res = []
        f = weakref.finalize(a, add, 67, 43, 89)
        self.assertEqual(f.peek(), (a, add, (67,43,89), {}))
        self.assertEqual(f.detach(), (a, add, (67,43,89), {}))
        self.assertEqual(f(), None)
        self.assertEqual(f(), None)
        self.assertEqual(f.peek(), None)
        self.assertEqual(f.detach(), None)
        self.assertEqual(f.alive, False)
        self.assertEqual(res, [])

        res = []
        f = weakref.finalize(a, add, x=67, y=43, z=89)
        del a
        self._collect_if_necessary()
        self.assertEqual(f(), None)
        self.assertEqual(f(), None)
        self.assertEqual(f.peek(), None)
        self.assertEqual(f.detach(), None)
        self.assertEqual(f.alive, False)
        self.assertEqual(res, [199]) 

def __init__(self, suffix=None, prefix=None, dir=None):
        self.name = mkdtemp(suffix, prefix, dir)
        self._finalizer = _weakref.finalize(
            self, self._cleanup, self.name,
            warn_message="Implicitly cleaning up {!r}".format(self)) 

def finalize(self):
            """Finalizes the object if not already done."""
            self._finalizer()