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BUG: doing a class method lookup in __dealloc__ is dangerous #44879

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Merged
merged 1 commit into from
Dec 16, 2021
Merged

BUG: doing a class method lookup in __dealloc__ is dangerous #44879

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28 changes: 18 additions & 10 deletions pandas/_libs/parsers.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -558,18 +558,11 @@ cdef class TextReader:
pass

def __dealloc__(self):
self.close()
_close(self)
parser_del(self.parser)

def close(self) -> None:
# also preemptively free all allocated memory
parser_free(self.parser)
if self.true_set:
kh_destroy_str_starts(self.true_set)
self.true_set = NULL
if self.false_set:
kh_destroy_str_starts(self.false_set)
self.false_set = NULL
def close(self):
_close(self)

def _set_quoting(self, quote_char: str | bytes | None, quoting: int):
if not isinstance(quoting, int):
Expand Down Expand Up @@ -1292,6 +1285,21 @@ cdef class TextReader:
return None


# Factor out code common to TextReader.__dealloc__ and TextReader.close
# It cannot be a class method, since calling self.close() in __dealloc__
# which causes a class attribute lookup and violates best parctices
# https://cython.readthedocs.io/en/latest/src/userguide/special_methods.html#finalization-method-dealloc
cdef _close(TextReader reader):
# also preemptively free all allocated memory
parser_free(reader.parser)
if reader.true_set:
kh_destroy_str_starts(reader.true_set)
reader.true_set = NULL
if reader.false_set:
kh_destroy_str_starts(reader.false_set)
reader.false_set = NULL


cdef:
object _true_values = [b'True', b'TRUE', b'true']
object _false_values = [b'False', b'FALSE', b'false']
Expand Down