# SPDX-FileCopyrightText: 2024 geisserml <geisserml@gmail.com>
# SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
__all__ = ("AutoCastable", "AutoCloseable", "DEBUG_AUTOCLOSE", "LIBRARY_AVAILABLE")
import os
import sys
import ctypes
import weakref
import logging
import uuid
logger = logging.getLogger(__name__)
# mutable bools
DEBUG_AUTOCLOSE = ctypes.c_bool(False)
LIBRARY_AVAILABLE = ctypes.c_bool(False) # set to true on library init
STATE_INVALID = -1
STATE_AUTO = 0
STATE_EXPLICIT = 1
STATE_BYPARENT = 2
[docs]
class AutoCastable:
@property
def _as_parameter_(self):
return self.raw
def _close_template(close_func, raw, obj_repr, state, parent, *args, **kwargs):
if DEBUG_AUTOCLOSE:
desc = {STATE_AUTO: "auto", STATE_EXPLICIT: "explicit", STATE_BYPARENT: "by parent"}[state.value]
# use os.write() rather than print() to avoid "reentrant call" exceptions on shutdown (see https://stackoverflow.com/q/75367828/15547292)
os.write(sys.stderr.fileno(), f"Close ({desc}) {obj_repr}\n".encode())
if not LIBRARY_AVAILABLE:
os.write(sys.stderr.fileno(), f"-> Cannot close object, library is destroyed. This may cause a memory leak!\n".encode())
return
assert (parent is None) or not parent._tree_closed()
close_func(raw, *args, **kwargs)
[docs]
class AutoCloseable (AutoCastable):
def __init__(self, close_func, *args, obj=None, needs_free=True, **kwargs):
# NOTE proactively prevent accidental double initialization
assert not hasattr(self, "_finalizer")
self._close_func = close_func
self._obj = self if obj is None else obj
self._uuid = uuid.uuid4()
self._ex_args = args
self._ex_kwargs = kwargs
self._autoclose_state = ctypes.c_int8(STATE_AUTO) # mutable int
self._finalizer = None
self._kids = []
if needs_free:
self._attach_finalizer()
def __repr__(self):
return f"<{type(self).__name__} uuid:{str(self._uuid)[:8]}>"
def _attach_finalizer(self):
# NOTE this function captures the value of the `parent` property at finalizer installation time - if it changes, detach the old finalizer and create a new one
assert self._finalizer is None
self._finalizer = weakref.finalize(self._obj, _close_template, self._close_func, self.raw, repr(self), self._autoclose_state, self.parent, *self._ex_args, **self._ex_kwargs)
def _detach_finalizer(self):
self._finalizer.detach()
self._finalizer = None
def _tree_closed(self):
if self.raw is None:
return True
if (self.parent is not None) and self.parent._tree_closed():
return True
return False
def _add_kid(self, k):
self._kids.append( weakref.ref(k) )
[docs]
def close(self, _by_parent=False):
if not self.raw or not self._finalizer:
return False
for k_ref in self._kids:
k = k_ref()
if k and k.raw:
k.close(_by_parent=True)
self._autoclose_state.value = STATE_BYPARENT if _by_parent else STATE_EXPLICIT
self._finalizer()
self._autoclose_state.value = STATE_INVALID
self.raw = None
self._finalizer = None
self._kids.clear()
return True