Allow configuration of Synapse's cache without using synctl or environment variables (#6391)

1 files changed, 127 insertions, 0 deletions

diff --git a/tests/config/test_cache.py b/tests/config/test_cache.py
new file mode 100644
index 0000000000..2920279125
--- /dev/null
+++ b/tests/config/test_cache.py
@@ -0,0 +1,127 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from synapse.config._base import Config, RootConfig
+from synapse.config.cache import CacheConfig, add_resizable_cache
+from synapse.util.caches.lrucache import LruCache
+
+from tests.unittest import TestCase
+
+
+class FakeServer(Config):
+    section = "server"
+
+
+class TestConfig(RootConfig):
+    config_classes = [FakeServer, CacheConfig]
+
+
+class CacheConfigTests(TestCase):
+    def setUp(self):
+        # Reset caches before each test
+        TestConfig().caches.reset()
+
+    def test_individual_caches_from_environ(self):
+        """
+        Individual cache factors will be loaded from the environment.
+        """
+        config = {}
+        t = TestConfig()
+        t.caches._environ = {
+            "SYNAPSE_CACHE_FACTOR_SOMETHING_OR_OTHER": "2",
+            "SYNAPSE_NOT_CACHE": "BLAH",
+        }
+        t.read_config(config, config_dir_path="", data_dir_path="")
+
+        self.assertEqual(dict(t.caches.cache_factors), {"something_or_other": 2.0})
+
+    def test_config_overrides_environ(self):
+        """
+        Individual cache factors defined in the environment will take precedence
+        over those in the config.
+        """
+        config = {"caches": {"per_cache_factors": {"foo": 2, "bar": 3}}}
+        t = TestConfig()
+        t.caches._environ = {
+            "SYNAPSE_CACHE_FACTOR_SOMETHING_OR_OTHER": "2",
+            "SYNAPSE_CACHE_FACTOR_FOO": 1,
+        }
+        t.read_config(config, config_dir_path="", data_dir_path="")
+
+        self.assertEqual(
+            dict(t.caches.cache_factors),
+            {"foo": 1.0, "bar": 3.0, "something_or_other": 2.0},
+        )
+
+    def test_individual_instantiated_before_config_load(self):
+        """
+        If a cache is instantiated before the config is read, it will be given
+        the default cache size in the interim, and then resized once the config
+        is loaded.
+        """
+        cache = LruCache(100)
+
+        add_resizable_cache("foo", cache_resize_callback=cache.set_cache_factor)
+        self.assertEqual(cache.max_size, 50)
+
+        config = {"caches": {"per_cache_factors": {"foo": 3}}}
+        t = TestConfig()
+        t.read_config(config, config_dir_path="", data_dir_path="")
+
+        self.assertEqual(cache.max_size, 300)
+
+    def test_individual_instantiated_after_config_load(self):
+        """
+        If a cache is instantiated after the config is read, it will be
+        immediately resized to the correct size given the per_cache_factor if
+        there is one.
+        """
+        config = {"caches": {"per_cache_factors": {"foo": 2}}}
+        t = TestConfig()
+        t.read_config(config, config_dir_path="", data_dir_path="")
+
+        cache = LruCache(100)
+        add_resizable_cache("foo", cache_resize_callback=cache.set_cache_factor)
+        self.assertEqual(cache.max_size, 200)
+
+    def test_global_instantiated_before_config_load(self):
+        """
+        If a cache is instantiated before the config is read, it will be given
+        the default cache size in the interim, and then resized to the new
+        default cache size once the config is loaded.
+        """
+        cache = LruCache(100)
+        add_resizable_cache("foo", cache_resize_callback=cache.set_cache_factor)
+        self.assertEqual(cache.max_size, 50)
+
+        config = {"caches": {"global_factor": 4}}
+        t = TestConfig()
+        t.read_config(config, config_dir_path="", data_dir_path="")
+
+        self.assertEqual(cache.max_size, 400)
+
+    def test_global_instantiated_after_config_load(self):
+        """
+        If a cache is instantiated after the config is read, it will be
+        immediately resized to the correct size given the global factor if there
+        is no per-cache factor.
+        """
+        config = {"caches": {"global_factor": 1.5}}
+        t = TestConfig()
+        t.read_config(config, config_dir_path="", data_dir_path="")
+
+        cache = LruCache(100)
+        add_resizable_cache("foo", cache_resize_callback=cache.set_cache_factor)
+        self.assertEqual(cache.max_size, 150)