Cache the results of _choose_algorithm

flask_compress/flask_compress.py

@@ -5,6 +5,7 @@
 import functools
 import zlib
 from collections import defaultdict
+from functools import lru_cache
 from gzip import GzipFile
 from io import BytesIO
 
@@ -17,14 +18,15 @@
 from flask import after_this_request, current_app, request
 
 
+@lru_cache(maxsize=128)
 def _choose_algorithm(enabled_algorithms, accept_encoding):
     """
     Determine which compression algorithm we're going to use based on the
     client request. The `Accept-Encoding` header may list one or more desired
     algorithms, together with a "quality factor" for each one (higher quality
     means the client prefers that algorithm more).
 
-    :param enabled_algorithms: List of supported compression algorithms
+    :param enabled_algorithms: Tuple of supported compression algorithms
     :param accept_encoding: Content of the `Accept-Encoding` header
     :return: name of a compression algorithm (`gzip`, `deflate`, `br`, 'zstd')
         or `None` if the client and server don't agree on any.
@@ -167,9 +169,9 @@ def init_app(self, app):
 
         algo = app.config["COMPRESS_ALGORITHM"]
         if isinstance(algo, str):
-            self.enabled_algorithms = [i.strip() for i in algo.split(",")]
+            self.enabled_algorithms = tuple(i.strip() for i in algo.split(","))
         else:
-            self.enabled_algorithms = list(algo)
+            self.enabled_algorithms = tuple(algo)
 
         if app.config["COMPRESS_REGISTER"] and app.config["COMPRESS_MIMETYPES"]:
             app.after_request(self.after_request)

tests/test_flask_compress.py

@@ -260,19 +260,19 @@ def test_setting_compress_algorithm_simple_string(self):
         This is a backwards-compatibility test."""
         self.app.config["COMPRESS_ALGORITHM"] = "gzip"
         c = Compress(self.app)
-        self.assertListEqual(c.enabled_algorithms, ["gzip"])
+        self.assertTupleEqual(c.enabled_algorithms, ("gzip",))
 
     def test_setting_compress_algorithm_cs_string(self):
         """Test that `COMPRESS_ALGORITHM` can be a comma-separated string"""
         self.app.config["COMPRESS_ALGORITHM"] = "gzip, br, zstd"
         c = Compress(self.app)
-        self.assertListEqual(c.enabled_algorithms, ["gzip", "br", "zstd"])
+        self.assertTupleEqual(c.enabled_algorithms, ("gzip", "br", "zstd"))
 
     def test_setting_compress_algorithm_list(self):
         """Test that `COMPRESS_ALGORITHM` can be a list of strings"""
         self.app.config["COMPRESS_ALGORITHM"] = ["gzip", "br", "deflate"]
         c = Compress(self.app)
-        self.assertListEqual(c.enabled_algorithms, ["gzip", "br", "deflate"])
+        self.assertTupleEqual(c.enabled_algorithms, ("gzip", "br", "deflate"))
 
     def test_one_algo_supported(self):
         """Tests requesting a single supported compression algorithm"""