From d1409f51ff40f6d0ca875c4fafc4189dbe258b37 Mon Sep 17 00:00:00 2001
From: Tim Park <timpark0807@gmail.com>
Date: Sat, 4 Jul 2020 20:49:36 -0700
Subject: [PATCH] Fixed #31732 -- Cached callables signatures in
 django.utils.inspect methods.

---
 django/utils/inspect.py | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/django/utils/inspect.py b/django/utils/inspect.py
index 293cbdffa1..9a7eb21647 100644
--- a/django/utils/inspect.py
+++ b/django/utils/inspect.py
@@ -1,8 +1,14 @@
+import functools
 import inspect
 
 
+@functools.lru_cache(maxsize=512)
+def _get_signature(func):
+    return inspect.signature(func)
+
+
 def get_func_args(func):
-    sig = inspect.signature(func)
+    sig = _get_signature(func)
     return [
         arg_name for arg_name, param in sig.parameters.items()
         if param.kind == inspect.Parameter.POSITIONAL_OR_KEYWORD
@@ -15,7 +21,7 @@ def get_func_full_args(func):
     does not have a default value, omit it in the tuple. Arguments such as
     *args and **kwargs are also included.
     """
-    sig = inspect.signature(func)
+    sig = _get_signature(func)
     args = []
     for arg_name, param in sig.parameters.items():
         name = arg_name
@@ -35,7 +41,7 @@ def get_func_full_args(func):
 
 def func_accepts_kwargs(func):
     return any(
-        p for p in inspect.signature(func).parameters.values()
+        p for p in _get_signature(func).parameters.values()
         if p.kind == p.VAR_KEYWORD
     )
 
@@ -45,7 +51,7 @@ def func_accepts_var_args(func):
     Return True if function 'func' accepts positional arguments *args.
     """
     return any(
-        p for p in inspect.signature(func).parameters.values()
+        p for p in _get_signature(func).parameters.values()
         if p.kind == p.VAR_POSITIONAL
     )
 
@@ -53,11 +59,11 @@ def func_accepts_var_args(func):
 def method_has_no_args(meth):
     """Return True if a method only accepts 'self'."""
     count = len([
-        p for p in inspect.signature(meth).parameters.values()
+        p for p in _get_signature(meth).parameters.values()
         if p.kind == p.POSITIONAL_OR_KEYWORD
     ])
     return count == 0 if inspect.ismethod(meth) else count == 1
 
 
 def func_supports_parameter(func, parameter):
-    return parameter in inspect.signature(func).parameters
+    return parameter in _get_signature(func).parameters