Fixed #33865 -- Optimized LimitedStream wrapper.

The current implementation of LimitedStream is slow because .read()
performs an extra copy into a buffer and .readline() performs two
extra copies. The stream being wrapped is already typically a BytesIO
object so this is unnecessary.

This implementation has largely been untouched for 12 years and,
inspired by a simpler implementation in werkzeug, it was possible to
achieve the following performance improvement:

LimitedStream.read() (single line):
  Mean +- std dev: [bench_limitedstream-main] 286 ns +- 6 ns
  -> [bench_limitedstream-patch] 227 ns +- 6 ns: 1.26x faster
LimitedStream.readline() (single line):
  Mean +- std dev: [bench_limitedstream-main] 507 ns +- 11 ns
  -> [bench_limitedstream-patch] 232 ns +- 8 ns: 2.18x faster
LimitedStream.read(8192) (single line):
  Mean +- std dev: [bench_limitedstream-main] 360 ns +- 8 ns
  -> [bench_limitedstream-patch] 297 ns +- 6 ns: 1.21x faster
LimitedStream.readline(8192) (single line):
  Mean +- std dev: [bench_limitedstream-main] 602 ns +- 10 ns
  -> [bench_limitedstream-patch] 305 ns +- 10 ns: 1.98x faster
LimitedStream.read() (multiple lines):
  Mean +- std dev: [bench_limitedstream-main] 290 ns +- 5 ns
  -> [bench_limitedstream-patch] 236 ns +- 6 ns: 1.23x faster
LimitedStream.readline() (multiple lines):
  Mean +- std dev: [bench_limitedstream-main] 517 ns +- 19 ns
  -> [bench_limitedstream-patch] 239 ns +- 7 ns: 2.16x faster
LimitedStream.read(8192) (multiple lines):
  Mean +- std dev: [bench_limitedstream-main] 363 ns +- 8 ns
  -> [bench_limitedstream-patch] 311 ns +- 11 ns: 1.17x faster
LimitedStream.readline(8192) (multiple lines):
  Mean +- std dev: [bench_limitedstream-main] 601 ns +- 12 ns
  -> [bench_limitedstream-patch] 308 ns +- 7 ns: 1.95x faster

Geometric mean: 1.59x faster

1 files changed, 4 insertions, 4 deletions

diff --git a/tests/builtin_server/tests.py b/tests/builtin_server/tests.py
index 2777db1e13..f654fdd92c 100644
--- a/tests/builtin_server/tests.py
+++ b/tests/builtin_server/tests.py
@@ -81,7 +81,7 @@ class WSGIFileWrapperTests(TestCase):
 
     def test_file_wrapper_uses_sendfile(self):
         env = {"SERVER_PROTOCOL": "HTTP/1.0"}
-        handler = FileWrapperHandler(None, BytesIO(), BytesIO(), env)
+        handler = FileWrapperHandler(BytesIO(), BytesIO(), BytesIO(), env)
         handler.run(wsgi_app_file_wrapper)
         self.assertTrue(handler._used_sendfile)
         self.assertEqual(handler.stdout.getvalue(), b"")
@@ -89,7 +89,7 @@ class WSGIFileWrapperTests(TestCase):
 
     def test_file_wrapper_no_sendfile(self):
         env = {"SERVER_PROTOCOL": "HTTP/1.0"}
-        handler = FileWrapperHandler(None, BytesIO(), BytesIO(), env)
+        handler = FileWrapperHandler(BytesIO(), BytesIO(), BytesIO(), env)
         handler.run(wsgi_app)
         self.assertFalse(handler._used_sendfile)
         self.assertEqual(handler.stdout.getvalue().splitlines()[-1], b"Hello World!")
@@ -102,7 +102,7 @@ class WSGIFileWrapperTests(TestCase):
         response when file_wrapper is used.
         """
         env = RequestFactory().get("/fileresponse/").environ
-        handler = FileWrapperHandler(None, BytesIO(), BytesIO(), env)
+        handler = FileWrapperHandler(BytesIO(), BytesIO(), BytesIO(), env)
         handler.run(get_internal_wsgi_application())
         # Sendfile is used only when file_wrapper has been used.
         self.assertTrue(handler._used_sendfile)
@@ -119,7 +119,7 @@ class WSGIFileWrapperTests(TestCase):
     @override_settings(ROOT_URLCONF="builtin_server.urls")
     def test_file_response_call_request_finished(self):
         env = RequestFactory().get("/fileresponse/").environ
-        handler = FileWrapperHandler(None, BytesIO(), BytesIO(), env)
+        handler = FileWrapperHandler(BytesIO(), BytesIO(), BytesIO(), env)
         with mock.MagicMock() as signal_handler:
             request_finished.connect(signal_handler)
             handler.run(get_internal_wsgi_application())