From 3deff633c0e919b422a7a84ed603ed82eb8c869c Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Sat, 30 Mar 2019 10:51:39 +0200
Subject: [PATCH] Add the cachesreg module.

---
 Lib/_strptime.py                |  2 +
 Lib/cachesreg.py                |  8 +++
 Lib/ctypes/__init__.py          |  3 ++
 Lib/distutils/dir_util.py       |  2 +
 Lib/doctest.py                  |  6 +++
 Lib/filecmp.py                  |  3 ++
 Lib/functools.py                |  2 +
 Lib/linecache.py                |  2 +
 Lib/mimetypes.py                |  2 +
 Lib/re.py                       |  3 ++
 Lib/struct.py                   |  3 ++
 Lib/test/libregrtest/refleak.py | 89 +--------------------------------
 Lib/test/test_typing.py         |  3 +-
 Lib/typing.py                   |  7 +++
 Lib/urllib/parse.py             |  2 +
 Lib/urllib/request.py           |  3 ++
 Lib/warnings.py                 | 10 ++++
 Lib/xml/etree/ElementPath.py    |  2 +
 18 files changed, 63 insertions(+), 89 deletions(-)
 create mode 100644 Lib/cachesreg.py

diff --git a/Lib/_strptime.py b/Lib/_strptime.py
index f4f3c0b80c1d05..401a2857bdd0ad 100644
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -10,6 +10,7 @@
     strptime -- Calculates the time struct represented by the passed-in string
 
 """
+import cachesreg
 import time
 import locale
 import calendar
@@ -268,6 +269,7 @@ def compile(self, format):
 _TimeRE_cache = TimeRE()
 _CACHE_MAX_SIZE = 5 # Max number of regexes stored in _regex_cache
 _regex_cache = {}
+cachesreg.register(_regex_cache.clear)
 
 def _calc_julian_from_U_or_W(year, week_of_year, day_of_week, week_starts_Mon):
     """Calculate the Julian day based on the year, week of the year, and day of
diff --git a/Lib/cachesreg.py b/Lib/cachesreg.py
new file mode 100644
index 00000000000000..f31ce7d54de6d6
--- /dev/null
+++ b/Lib/cachesreg.py
@@ -0,0 +1,8 @@
+_clearers = []
+
+def register(callback):
+    _clearers.append(callback)
+
+def clear_caches():
+    for clear in _clearers[::-1]:
+        clear()
diff --git a/Lib/ctypes/__init__.py b/Lib/ctypes/__init__.py
index 4107db3e3972d7..8dae992833487c 100644
--- a/Lib/ctypes/__init__.py
+++ b/Lib/ctypes/__init__.py
@@ -12,6 +12,7 @@
 from _ctypes import ArgumentError
 
 from struct import calcsize as _calcsize
+import cachesreg as _cachesreg
 
 if __version__ != _ctypes_version:
     raise Exception("Version number mismatch", __version__, _ctypes_version)
@@ -267,6 +268,8 @@ def _reset_cache():
     POINTER(c_char).from_param = c_char_p.from_param
     _pointer_type_cache[None] = c_void_p
 
+_cachesreg.register(_reset_cache)
+
 def create_unicode_buffer(init, size=None):
     """create_unicode_buffer(aString) -> character array
     create_unicode_buffer(anInteger) -> character array
diff --git a/Lib/distutils/dir_util.py b/Lib/distutils/dir_util.py
index d5cd8e3e24f46a..303d7eb28d252f 100644
--- a/Lib/distutils/dir_util.py
+++ b/Lib/distutils/dir_util.py
@@ -3,6 +3,7 @@
 Utility functions for manipulating directories and directory trees."""
 
 import os
+import cachesreg as _cachesreg
 import errno
 from distutils.errors import DistutilsFileError, DistutilsInternalError
 from distutils import log
@@ -10,6 +11,7 @@
 # cache for by mkpath() -- in addition to cheapening redundant calls,
 # eliminates redundant "creating /foo/bar/baz" messages in dry-run mode
 _path_created = {}
+_cachesreg.register(_path_created.clear)
 
 # I don't use os.makedirs because a) it's new to Python 1.5.2, and
 # b) it blows up if the directory already exists (I want to silently
diff --git a/Lib/doctest.py b/Lib/doctest.py
index 79d91a040c2eee..972d3ef023b735 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -93,6 +93,7 @@ def _test():
 ]
 
 import __future__
+import cachesreg
 import difflib
 import inspect
 import linecache
@@ -1853,6 +1854,11 @@ def report_failure(self, out, test, example, got):
 # class, updated by testmod.
 master = None
 
+def _reset_master():
+    master = None
+
+cachesreg.register(_reset_master)
+
 def testmod(m=None, name=None, globs=None, verbose=None,
             report=True, optionflags=0, extraglobs=None,
             raise_on_error=False, exclude_empty=False):
diff --git a/Lib/filecmp.py b/Lib/filecmp.py
index e5ad8397e4c539..81801e03f6cdfb 100644
--- a/Lib/filecmp.py
+++ b/Lib/filecmp.py
@@ -10,6 +10,7 @@
 
 """
 
+import cachesreg
 import os
 import stat
 from itertools import filterfalse
@@ -26,6 +27,8 @@ def clear_cache():
     """Clear the filecmp cache."""
     _cache.clear()
 
+cachesreg.register(clear_cache)
+
 def cmp(f1, f2, shallow=True):
     """Compare two files.
 
diff --git a/Lib/functools.py b/Lib/functools.py
index 426653f13f6d1e..e9e162501f2cdd 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -14,6 +14,7 @@
            'partialmethod', 'singledispatch', 'singledispatchmethod']
 
 from abc import get_cache_token
+import cachesreg
 from collections import namedtuple
 # import types, weakref  # Deferred to single_dispatch()
 from reprlib import recursive_repr
@@ -630,6 +631,7 @@ def cache_clear():
 
     wrapper.cache_info = cache_info
     wrapper.cache_clear = cache_clear
+    cachesreg.register(cache_clear)
     return wrapper
 
 try:
diff --git a/Lib/linecache.py b/Lib/linecache.py
index 3afcce1f0a1456..4c24119e6ab7fa 100644
--- a/Lib/linecache.py
+++ b/Lib/linecache.py
@@ -5,6 +5,7 @@
 that name.
 """
 
+import cachesreg
 import functools
 import sys
 import os
@@ -33,6 +34,7 @@ def clearcache():
     global cache
     cache = {}
 
+cachesreg.register(clearcache)
 
 def getlines(filename, module_globals=None):
     """Get the lines for a Python source file from the cache.
diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 8861b75362dbd7..e8f45029612323 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -23,6 +23,7 @@
 read_mime_types(file) -- parse one file, return a dictionary or None
 """
 
+import cachesreg
 import os
 import sys
 import posixpath
@@ -548,6 +549,7 @@ def _default_mime_types():
         }
 
 
+cachesreg.register(_default_mime_types)
 _default_mime_types()
 
 
diff --git a/Lib/re.py b/Lib/re.py
index 68d62dc2a93b05..ffd835a7112bfc 100644
--- a/Lib/re.py
+++ b/Lib/re.py
@@ -119,6 +119,7 @@
 
 """
 
+import cachesreg
 import enum
 import sre_compile
 import sre_parse
@@ -238,6 +239,8 @@ def purge():
     _cache.clear()
     _compile_repl.cache_clear()
 
+cachesreg.register(purge)
+
 def template(pattern, flags=0):
     "Compile a template pattern, returning a Pattern object"
     return _compile(pattern, flags|T)
diff --git a/Lib/struct.py b/Lib/struct.py
index d6bba588636498..7dfe55a05c3695 100644
--- a/Lib/struct.py
+++ b/Lib/struct.py
@@ -13,3 +13,6 @@
 from _struct import *
 from _struct import _clearcache
 from _struct import __doc__
+import cachesreg
+
+cachesreg.register(_clearcache)
diff --git a/Lib/test/libregrtest/refleak.py b/Lib/test/libregrtest/refleak.py
index 6724488fcfb088..9d0a35a6af26f8 100644
--- a/Lib/test/libregrtest/refleak.py
+++ b/Lib/test/libregrtest/refleak.py
@@ -158,12 +158,7 @@ def dash_R_cleanup(fs, ps, pic, zdc, abcs):
 
 
 def clear_caches():
-    import gc
-
-    # Clear the warnings registry, so they can be displayed again
-    for mod in sys.modules.values():
-        if hasattr(mod, '__warningregistry__'):
-            del mod.__warningregistry__
+    import gc, cachesreg
 
     # Flush standard output, so that buffered data is sent to the OS and
     # associated Python objects are reclaimed.
@@ -171,87 +166,7 @@ def clear_caches():
         if stream is not None:
             stream.flush()
 
-    # Clear assorted module caches.
-    # Don't worry about resetting the cache if the module is not loaded
-    try:
-        distutils_dir_util = sys.modules['distutils.dir_util']
-    except KeyError:
-        pass
-    else:
-        distutils_dir_util._path_created.clear()
-    re.purge()
-
-    try:
-        _strptime = sys.modules['_strptime']
-    except KeyError:
-        pass
-    else:
-        _strptime._regex_cache.clear()
-
-    try:
-        urllib_parse = sys.modules['urllib.parse']
-    except KeyError:
-        pass
-    else:
-        urllib_parse.clear_cache()
-
-    try:
-        urllib_request = sys.modules['urllib.request']
-    except KeyError:
-        pass
-    else:
-        urllib_request.urlcleanup()
-
-    try:
-        linecache = sys.modules['linecache']
-    except KeyError:
-        pass
-    else:
-        linecache.clearcache()
-
-    try:
-        mimetypes = sys.modules['mimetypes']
-    except KeyError:
-        pass
-    else:
-        mimetypes._default_mime_types()
-
-    try:
-        filecmp = sys.modules['filecmp']
-    except KeyError:
-        pass
-    else:
-        filecmp._cache.clear()
-
-    try:
-        struct = sys.modules['struct']
-    except KeyError:
-        pass
-    else:
-        struct._clearcache()
-
-    try:
-        doctest = sys.modules['doctest']
-    except KeyError:
-        pass
-    else:
-        doctest.master = None
-
-    try:
-        ctypes = sys.modules['ctypes']
-    except KeyError:
-        pass
-    else:
-        ctypes._reset_cache()
-
-    try:
-        typing = sys.modules['typing']
-    except KeyError:
-        pass
-    else:
-        for f in typing._cleanups:
-            f()
-
+    cachesreg.clear_caches()
     gc.collect()
 
 
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 0d66ebbd18456e..c5322527c3c19f 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -45,8 +45,7 @@ def assertNotIsSubclass(self, cls, class_or_tuple, msg=None):
             raise self.failureException(message)
 
     def clear_caches(self):
-        for f in typing._cleanups:
-            f()
+        typing._clear_caches()
 
 
 class Employee:
diff --git a/Lib/typing.py b/Lib/typing.py
index 530d4633fe4c22..2a62cdf7866d17 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -19,6 +19,7 @@
 """
 
 from abc import abstractmethod, abstractproperty
+import cachesreg
 import collections
 import collections.abc
 import contextlib
@@ -233,6 +234,12 @@ def _remove_dups_flatten(parameters):
 
 _cleanups = []
 
+def _clear_caches():
+    for f in _cleanups:
+        f()
+
+cachesreg.register(_clear_caches)
+
 
 def _tp_cache(func):
     """Internal wrapper caching __getitem__ of generic types with a fallback to
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 8b6c9b10609152..bc752659b2ae56 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -27,6 +27,7 @@
 test_urlparse.py provides a good indicator of parsing behavior.
 """
 
+import cachesreg
 import re
 import sys
 import collections
@@ -86,6 +87,7 @@ def clear_cache():
     _parse_cache.clear()
     _safe_quoters.clear()
 
+cachesreg.register(clear_cache)
 
 # Helpers for bytes handling
 # For 3.2, we deliberately require applications that
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index df2ff06f0fc9a2..73d6db2bb2f0a8 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -83,6 +83,7 @@
 
 import base64
 import bisect
+import cachesreg
 import email
 import hashlib
 import http.client
@@ -302,6 +303,8 @@ def urlcleanup():
     if _opener:
         _opener = None
 
+cachesreg.register(urlcleanup)
+
 # copied from cookielib.py
 _cut_port_re = re.compile(r":\d+$", re.ASCII)
 def request_host(request):
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 00f740ca3a95ba..2a62213ebf4714 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -1,6 +1,7 @@
 """Python part of the warnings subsystem."""
 
 import sys
+import cachesreg
 
 
 __all__ = ["warn", "warn_explicit", "showwarning",
@@ -538,6 +539,15 @@ def _filters_mutated():
     _warnings_defaults = False
 
 
+
+def _clear_warning_registry():
+    # Clear the warnings registry, so they can be displayed again
+    for mod in sys.modules.values():
+        if hasattr(mod, '__warningregistry__'):
+            del mod.__warningregistry__
+
+cachesreg.register(_clear_warning_registry)
+
 # Module initialization
 _processoptions(sys.warnoptions)
 if not _warnings_defaults:
diff --git a/Lib/xml/etree/ElementPath.py b/Lib/xml/etree/ElementPath.py
index ef32917b14d41e..cec7a7326d4644 100644
--- a/Lib/xml/etree/ElementPath.py
+++ b/Lib/xml/etree/ElementPath.py
@@ -56,6 +56,7 @@
 # you, if needed.
 ##
 
+import cachesreg as _cachesreg
 import re
 
 xpath_tokenizer_re = re.compile(
@@ -251,6 +252,7 @@ def select(context, result):
     }
 
 _cache = {}
+_cachesreg.register(_cache.clear)
 
 class _SelectorContext:
     parent_map = None