Fixed #32565 -- Moved internal URLResolver view-strings mapping to admindocs.

Moved the functionality of URLResolver._is_callback(),
URLResolver._callback_strs, URLPattern.lookup_str() to
django.contrib.admindocs.

django/contrib/admindocs/apps.py

@@ -1,7 +1,15 @@
 from django.apps import AppConfig
+from django.urls import get_resolver, get_urlconf
 from django.utils.translation import gettext_lazy as _
 
+from .utils import _active, register_callback
+
 
 class AdminDocsConfig(AppConfig):
     name = "django.contrib.admindocs"
     verbose_name = _("Administrative Documentation")
+
+    def ready(self):
+        urlconf = get_urlconf()
+        urlresolver = get_resolver(urlconf)
+        register_callback(urlresolver, _active.local_value)

django/contrib/admindocs/utils.py

@@ -1,11 +1,15 @@
 "Misc. utility functions/classes for admin documentation generator."
 
+import functools
 import re
 from email.errors import HeaderParseError
 from email.parser import HeaderParser
 from inspect import cleandoc
 
+from asgiref.local import Local
+
 from django.urls import reverse
+from django.urls.resolvers import URLPattern
 from django.utils.regex_helper import _lazy_re_compile
 from django.utils.safestring import mark_safe
 
@@ -239,3 +243,43 @@ def remove_non_capturing_groups(pattern):
         final_pattern += pattern[prev_end:start]
         prev_end = end
     return final_pattern + pattern[prev_end:]
+
+
+# Callback strings are cached in a dictionary for every urlconf.
+# The active calback_strs are stored by thread id to make them thread local.
+_callback_strs = set()
+_active = Local()
+_active.local_value = _callback_strs
+
+
+def _is_callback(name, urlresolver=None):
+    if urlresolver and not urlresolver._populated:
+        register_callback(urlresolver, _active.local_value)
+    return name in _active.local_value
+
+
+@functools.lru_cache(maxsize=None)
+def lookup_str(urlpattern):
+    """
+    A string that identifies the view (e.g. 'path.to.view_function' or
+    'path.to.ClassBasedView').
+    """
+    callback = urlpattern.callback
+    if isinstance(callback, functools.partial):
+        callback = callback.func
+    if hasattr(callback, "view_class"):
+        callback = callback.view_class
+    elif not hasattr(callback, "__name__"):
+        return callback.__module__ + "." + callback.__class__.__name__
+    return callback.__module__ + "." + callback.__qualname__
+
+
+def register_callback(urlresolver, thread):
+    for url_pattern in reversed(urlresolver.url_patterns):
+        if isinstance(url_pattern, URLPattern):
+            thread.add(lookup_str(url_pattern))
+        else:  # url_pattern is a URLResolver.
+            _active.url_pattern_value = _callback_strs
+            register_callback(url_pattern, _active.url_pattern_value)
+            thread.update(_active.url_pattern_value)
+    urlresolver._populated = True

django/contrib/admindocs/views.py

@@ -30,7 +30,7 @@ from django.utils.inspect import (
 from django.utils.translation import gettext as _
 from django.views.generic import TemplateView
 
-from .utils import get_view_name
+from .utils import _is_callback, get_view_name
 
 # Exclude methods starting with these strings from documentation
 MODEL_METHODS_EXCLUDE = ("_", "add_", "delete", "save", "set_")
@@ -166,8 +166,7 @@ class ViewDetailView(BaseAdminDocsView):
 
     @staticmethod
     def _get_view_func(view):
-        urlconf = get_urlconf()
-        if get_resolver(urlconf)._is_callback(view):
+        if _is_callback(view):
             mod, func = get_mod_func(view)
             try:
                 # Separate the module and function, e.g.