Remove references to self when creating device finalizers #132
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This is necessary so open devices don't leak, later crashing hid_exit().
From the documentation: > It is important to ensure that func, args and kwargs do not own any references to obj, either directly or indirectly, since otherwise obj will never be garbage collected. In particular, func should not be a bound method of obj. The issue wasn't observed during testing, but it may be implementation-defined (as with __del__) and depend on specific combinations of interpreter and Cython versions. Instead of relying on unspecified behavior, only keep the hid_device pointer. This requires a wrapper because weakref.finalize() cannot be passed cdef functions or C pointers. Alternatives were attempted---__dealloc__, weakref.ref(self)---but they only worked in some cases (respectively: only for `del <device>` and except for `del <device>`). Reported-by: @bearsh Related: trezor#130
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@bearsh, do you think this solves the problem? |
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according to the doc it should. I didn't try this PR yet but I suppose you did 😉 and looking at the code it seems to be sane. at the end it's up to the maintainer to decide... |
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Thanks! |
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Reported-by @bearsh in #130 (comment).
From the documentation:
The issue wasn't observed during testing, but it may be implementation-defined (as with
__del__) and depend on specificcombinations of interpreter and Cython versions.
Instead of relying on unspecified behavior, only keep the
hid_devicepointer. This requires a wrapper becauseweakref.finalize()cannot be passedcdeffunctions or C pointers.Alternatives were attempted—
__dealloc__,weakref.ref(self)—but they only worked in some cases (respectively: only fordel <device>and except fordel <device>).Besides removing references to
selffrom the finalizers, also fix another problem in #130: raise aRuntimeErrorifopen()/open_path()are called on an already opendevice(), preventing the oldhid_device *to leak, which would later crashhid_exit().