1 files changed, 65 insertions, 0 deletions
diff --git a/python/olm/_finalize.py b/python/olm/_finalize.py
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+++ b/python/olm/_finalize.py
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+# The MIT License (MIT)
+# Copyright (c) 2010 Benjamin Peterson <benjamin@python.org>
+
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+# DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
+# OR OTHER DEALINGS IN THE SOFTWARE.
+
+"""Finalization with weakrefs
+
+This is designed for avoiding __del__.
+"""
+from __future__ import print_function
+
+import sys
+import traceback
+import weakref
+
+__author__ = "Benjamin Peterson <benjamin@python.org>"
+
+
+class OwnerRef(weakref.ref):
+    """A simple weakref.ref subclass, so attributes can be added."""
+    pass
+
+
+def _run_finalizer(ref):
+    """Internal weakref callback to run finalizers"""
+    del _finalize_refs[id(ref)]
+    finalizer = ref.finalizer
+    item = ref.item
+    try:
+        finalizer(item)
+    except Exception:  # pragma: no cover
+        print("Exception running {}:".format(finalizer), file=sys.stderr)
+        traceback.print_exc()
+
+
+_finalize_refs = {}
+
+
+def track_for_finalization(owner, item, finalizer):
+    """Register an object for finalization.
+
+    ``owner`` is the the object which is responsible for ``item``.
+    ``finalizer`` will be called with ``item`` as its only argument when
+    ``owner`` is destroyed by the garbage collector.
+    """
+    ref = OwnerRef(owner, _run_finalizer)
+    ref.item = item
+    ref.finalizer = finalizer
+    _finalize_refs[id(ref)] = ref