Fix reply map value memory leak

[siavash119]

redis/hiredis-py#175

not sure why PyDict_SetItem is returning -1 even though the assignment seems to be successful. But it was skipping over the Py_DECREF calls causing a memory leak.

[mkmkme]

Hey,

Thanks for your contribution! Could you explain your message a bit though?

not sure why PyDict_SetItem is returning -1 even though the assignment seems to be successful

The assignment is not guaranteed to be successful. It will fail e.g. if self->pending object is of a type that can't be used as a dict key.

[siavash119]

You're right, my mistake; PyDict_SetItem is not returning -1 here normally. The leak, though, is it's returning 0 because the PyDict_SetItem is successful, but the Py_DECREF is only called if unsuccessful, therefore keeping an extra ref to the obj in memory. As per the c api docs, "(PyDict_SetItem) does not steal a reference to val." So a Py_DECREF is required even on successful completion.

libvalkey-py/src/reader.c

Lines 90 to 95 in a85254f

	if (PyDict_SetItem(parent, self->pendingObject, obj) < 0) {
	Py_DECREF(obj);
	Py_DECREF(self->pendingObject);
	self->pendingObject = NULL;
	return NULL;
	}

[mkmkme]

Thank you for a great catch! I was mistakenly thinking PyDict_SetItem would take ownership in case the call succeeds but this is indeed not the case.