[issue15903] Make rawiobase_read() read directly to bytes object
Richard Oudkerk
report at bugs.python.org
Tue Sep 18 20:19:43 CEST 2012
Richard Oudkerk added the comment:
I am rather confused about the ownership semantics when one uses PyMemoryView_FromBuffer().
It looks as though PyMemoryView_FromBuffer() "steals" ownership of the buffer since, when the associated _PyManagedBufferObject is garbage collected, PyBuffer_Release() is called on its copy of the buffer info. However, the _PyManagedBufferObject does not own a reference of the base object, so one still needs to decref the base object (at some time when it is safe to do so).
So am I right in thinking that
PyObject_GetBuffer(obj, &buf, ...);
view = PyMemoryView_FromBuffer(&buf); // view->master owns the buffer, but view->master->obj == NULL
...
Py_DECREF(view); // releases buffer (assuming no other exports)
Py_XDECREF(buf.obj);
has balanced refcounting and is more or less equivalent to
view = PyMemoryView_FromObject(obj);
...
Py_DECREF(view);
The documentation is not very helpful. It just says that calls to PyObject_GetBuffer() must be matched with calls to PyBuffer_Release().
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<http://bugs.python.org/issue15903>
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