Issue 7846: fnmatch cache can grow without bound
Updated to solution to use the functools.lru_cache(). Restores the API so that purge() is not needed (because the cache never gets big).
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@ -84,13 +84,6 @@ patterns.
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<_sre.SRE_Match object at 0x...>
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.. function:: purge()
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Clear the internal pattern cache.
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.. versionadded:: 3.2
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.. seealso::
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Module :mod:`glob`
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@ -12,19 +12,9 @@ corresponding to PATTERN. (It does not compile it.)
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import os
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import posixpath
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import re
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import functools
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__all__ = ["filter", "fnmatch", "fnmatchcase", "purge", "translate"]
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_cache = {} # Maps text patterns to compiled regexen.
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_cacheb = {} # Ditto for bytes patterns.
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_MAXCACHE = 100 # Maximum size of caches.
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def purge():
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"""Clear the pattern cache."""
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_cache.clear()
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_cacheb.clear()
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__all__ = ["filter", "fnmatch", "fnmatchcase", "translate"]
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def fnmatch(name, pat):
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"""Test whether FILENAME matches PATTERN.
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@ -45,28 +35,21 @@ def fnmatch(name, pat):
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pat = os.path.normcase(pat)
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return fnmatchcase(name, pat)
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def _compile_pattern(pat):
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cache = _cacheb if isinstance(pat, bytes) else _cache
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regex = cache.get(pat)
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if regex is None:
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if isinstance(pat, bytes):
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pat_str = str(pat, 'ISO-8859-1')
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res_str = translate(pat_str)
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res = bytes(res_str, 'ISO-8859-1')
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else:
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res = translate(pat)
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if len(cache) >= _MAXCACHE:
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cache.clear()
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cache[pat] = regex = re.compile(res)
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return regex.match
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@functools.lru_cache(maxsize=250)
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def _compile_pattern(pat, is_bytes=False):
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if is_bytes:
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pat_str = str(pat, 'ISO-8859-1')
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res_str = translate(pat_str)
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res = bytes(res_str, 'ISO-8859-1')
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else:
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res = translate(pat)
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return re.compile(res).match
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def filter(names, pat):
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"""Return the subset of the list NAMES that match PAT."""
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result = []
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pat = os.path.normcase(pat)
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match = _compile_pattern(pat)
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match = _compile_pattern(pat, isinstance(pat, bytes))
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if os.path is posixpath:
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# normcase on posix is NOP. Optimize it away from the loop.
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for name in names:
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@ -78,14 +61,13 @@ def filter(names, pat):
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result.append(name)
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return result
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def fnmatchcase(name, pat):
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"""Test whether FILENAME matches PATTERN, including case.
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This is a version of fnmatch() which doesn't case-normalize
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its arguments.
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"""
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match = _compile_pattern(pat)
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match = _compile_pattern(pat, isinstance(pat, bytes))
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return match(name) is not None
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@ -3,15 +3,10 @@
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from test import support
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import unittest
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from fnmatch import (fnmatch, fnmatchcase, _MAXCACHE, _cache, _cacheb, purge,
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translate, filter)
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from fnmatch import fnmatch, fnmatchcase, translate, filter
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class FnmatchTestCase(unittest.TestCase):
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def tearDown(self):
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purge()
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def check_match(self, filename, pattern, should_match=1, fn=fnmatch):
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if should_match:
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self.assertTrue(fn(filename, pattern),
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@ -65,22 +60,6 @@ class FnmatchTestCase(unittest.TestCase):
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self.check_match(b'test\xff', b'te*\xff')
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self.check_match(b'foo\nbar', b'foo*')
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def test_cache_clearing(self):
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# check that caches do not grow too large
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# http://bugs.python.org/issue7846
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# string pattern cache
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for i in range(_MAXCACHE + 1):
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fnmatch('foo', '?' * i)
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self.assertLessEqual(len(_cache), _MAXCACHE)
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# bytes pattern cache
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for i in range(_MAXCACHE + 1):
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fnmatch(b'foo', b'?' * i)
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self.assertLessEqual(len(_cacheb), _MAXCACHE)
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class TranslateTestCase(unittest.TestCase):
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def test_translate(self):
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