From 18476614721db0769412b78716d49cd7cb276cb0 Mon Sep 17 00:00:00 2001
From: Aarni Koskela <akx@iki.fi>
Date: Tue, 7 Feb 2023 15:58:00 +0200
Subject: [PATCH 1/2] Replace babel.dates._pattern_cache with an LRU cache

Fixes #962
---
 babel/dates.py | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/babel/dates.py b/babel/dates.py
index ce439eecd..78c7facaf 100644
--- a/babel/dates.py
+++ b/babel/dates.py
@@ -19,6 +19,7 @@
 
 import re
 import warnings
+from functools import lru_cache
 from typing import TYPE_CHECKING, SupportsInt
 
 try:
@@ -1667,10 +1668,8 @@ def get_week_number(self, day_of_period: int, day_of_week: int | None = None) ->
 #: in order of decreasing magnitude.
 PATTERN_CHAR_ORDER = "GyYuUQqMLlwWdDFgEecabBChHKkjJmsSAzZOvVXx"
 
-_pattern_cache = {}
 
-
-def parse_pattern(pattern: str) -> DateTimePattern:
+def parse_pattern(pattern: str | DateTimePattern) -> DateTimePattern:
     """Parse date, time, and datetime format patterns.
 
     >>> parse_pattern("MMMMd").format
@@ -1693,10 +1692,11 @@ def parse_pattern(pattern: str) -> DateTimePattern:
     """
     if isinstance(pattern, DateTimePattern):
         return pattern
+    return _cached_parse_pattern(pattern)
 
-    if pattern in _pattern_cache:
-        return _pattern_cache[pattern]
 
+@lru_cache(maxsize=1024)
+def _cached_parse_pattern(pattern: str) -> DateTimePattern:
     result = []
 
     for tok_type, tok_value in tokenize_pattern(pattern):
@@ -1710,9 +1710,7 @@ def parse_pattern(pattern: str) -> DateTimePattern:
             result.append('%%(%s)s' % (fieldchar * fieldnum))
         else:
             raise NotImplementedError(f"Unknown token type: {tok_type}")
-
-    _pattern_cache[pattern] = pat = DateTimePattern(pattern, ''.join(result))
-    return pat
+    return DateTimePattern(pattern, ''.join(result))
 
 
 def tokenize_pattern(pattern: str) -> list[tuple[str, str | tuple[str, int]]]:

From 152a9e38339254afe12160eac16e945e05131a16 Mon Sep 17 00:00:00 2001
From: Aarni Koskela <akx@iki.fi>
Date: Tue, 7 Feb 2023 16:00:41 +0200
Subject: [PATCH 2/2] Replace babel.localedata.locale_identifiers cache with
 LRU cache

---
 babel/localedata.py      | 23 ++++++++++-------------
 tests/test_localedata.py | 13 +++++--------
 2 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/babel/localedata.py b/babel/localedata.py
index f765a1ea3..a9c7c75ec 100644
--- a/babel/localedata.py
+++ b/babel/localedata.py
@@ -20,6 +20,7 @@
 import threading
 from collections import abc
 from collections.abc import Iterator, Mapping, MutableMapping
+from functools import lru_cache
 from itertools import chain
 from typing import Any
 
@@ -74,28 +75,24 @@ def exists(name: str) -> bool:
     return True if file_found else bool(normalize_locale(name))
 
 
+@lru_cache(maxsize=None)
 def locale_identifiers() -> list[str]:
     """Return a list of all locale identifiers for which locale data is
     available.
 
-    This data is cached after the first invocation in `locale_identifiers.cache`.
-
-    Removing the `locale_identifiers.cache` attribute or setting it to `None`
-    will cause this function to re-read the list from disk.
+    This data is cached after the first invocation.
+    You can clear the cache by calling `locale_identifiers.cache_clear()`.
 
     .. versionadded:: 0.8.1
 
     :return: a list of locale identifiers (strings)
     """
-    data = getattr(locale_identifiers, 'cache', None)
-    if data is None:
-        locale_identifiers.cache = data = [
-            stem
-            for stem, extension in
-            (os.path.splitext(filename) for filename in os.listdir(_dirname))
-            if extension == '.dat' and stem != 'root'
-        ]
-    return data
+    return [
+        stem
+        for stem, extension in
+        (os.path.splitext(filename) for filename in os.listdir(_dirname))
+        if extension == '.dat' and stem != 'root'
+    ]
 
 
 def load(name: os.PathLike[str] | str, merge_inherited: bool = True) -> dict[str, Any]:
diff --git a/tests/test_localedata.py b/tests/test_localedata.py
index 913922ee4..75c34b19b 100644
--- a/tests/test_localedata.py
+++ b/tests/test_localedata.py
@@ -110,18 +110,15 @@ def listdir_spy(*args):
         rv = original_listdir(*args)
         listdir_calls.append((args, rv))
         return rv
-    monkeypatch.setattr(localedata.os, 'listdir', listdir_spy)
-
-    # In case we've already run some tests...
-    if hasattr(localedata.locale_identifiers, 'cache'):
-        del localedata.locale_identifiers.cache
 
+    monkeypatch.setattr(localedata.os, 'listdir', listdir_spy)
+    localedata.locale_identifiers.cache_clear()
     assert not listdir_calls
-    assert localedata.locale_identifiers()
+    l = localedata.locale_identifiers()
     assert len(listdir_calls) == 1
-    assert localedata.locale_identifiers() is localedata.locale_identifiers.cache
+    assert localedata.locale_identifiers() is l
     assert len(listdir_calls) == 1
-    localedata.locale_identifiers.cache = None
+    localedata.locale_identifiers.cache_clear()
     assert localedata.locale_identifiers()
     assert len(listdir_calls) == 2