Add config settings for background update parameters (#11980)

9 files changed, 430 insertions, 34 deletions

diff --git a/changelog.d/11980.misc b/changelog.d/11980.misc
new file mode 100644
index 0000000000..36e992e645
--- /dev/null
+++ b/changelog.d/11980.misc
@@ -0,0 +1 @@
+Add config settings for background update parameters.
\ No newline at end of file
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index d634fd8ff5..36c6c56e58 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -2735,3 +2735,35 @@ redis:
   # Optional password if configured on the Redis instance
   #
   #password: <secret_password>
+
+
+## Background Updates ##
+
+# Background updates are database updates that are run in the background in batches.
+# The duration, minimum batch size, default batch size, whether to sleep between batches and if so, how long to
+# sleep can all be configured. This is helpful to speed up or slow down the updates.
+#
+background_updates:
+    # How long in milliseconds to run a batch of background updates for. Defaults to 100. Uncomment and set
+    # a time to change the default.
+    #
+    #background_update_duration_ms: 500
+
+    # Whether to sleep between updates. Defaults to True. Uncomment to change the default.
+    #
+    #sleep_enabled: false
+
+    # If sleeping between updates, how long in milliseconds to sleep for. Defaults to 1000. Uncomment
+    # and set a duration to change the default.
+    #
+    #sleep_duration_ms: 300
+
+    # Minimum size a batch of background updates can be. Must be greater than 0. Defaults to 1. Uncomment and
+    # set a size to change the default.
+    #
+    #min_batch_size: 10
+
+    # The batch size to use for the first iteration of a new background update. The default is 100.
+    # Uncomment and set a size to change the default.
+    #
+    #default_batch_size: 50
diff --git a/synapse/config/_base.pyi b/synapse/config/_base.pyi
index 1eb5f5a68c..363d8b4554 100644
--- a/synapse/config/_base.pyi
+++ b/synapse/config/_base.pyi
@@ -19,6 +19,7 @@ from synapse.config import (
     api,
     appservice,
     auth,
+    background_updates,
     cache,
     captcha,
     cas,
@@ -113,6 +114,7 @@ class RootConfig:
     caches: cache.CacheConfig
     federation: federation.FederationConfig
     retention: retention.RetentionConfig
+    background_updates: background_updates.BackgroundUpdateConfig
 
     config_classes: List[Type["Config"]] = ...
     def __init__(self) -> None: ...
diff --git a/synapse/config/background_updates.py b/synapse/config/background_updates.py
new file mode 100644
index 0000000000..f6cdeacc4b
--- /dev/null
+++ b/synapse/config/background_updates.py
@@ -0,0 +1,68 @@
+# Copyright 2022 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 ._base import Config
+
+
+class BackgroundUpdateConfig(Config):
+    section = "background_updates"
+
+    def generate_config_section(self, **kwargs) -> str:
+        return """\
+        ## Background Updates ##
+
+        # Background updates are database updates that are run in the background in batches.
+        # The duration, minimum batch size, default batch size, whether to sleep between batches and if so, how long to
+        # sleep can all be configured. This is helpful to speed up or slow down the updates.
+        #
+        background_updates:
+            # How long in milliseconds to run a batch of background updates for. Defaults to 100. Uncomment and set
+            # a time to change the default.
+            #
+            #background_update_duration_ms: 500
+
+            # Whether to sleep between updates. Defaults to True. Uncomment to change the default.
+            #
+            #sleep_enabled: false
+
+            # If sleeping between updates, how long in milliseconds to sleep for. Defaults to 1000. Uncomment
+            # and set a duration to change the default.
+            #
+            #sleep_duration_ms: 300
+
+            # Minimum size a batch of background updates can be. Must be greater than 0. Defaults to 1. Uncomment and
+            # set a size to change the default.
+            #
+            #min_batch_size: 10
+
+            # The batch size to use for the first iteration of a new background update. The default is 100.
+            # Uncomment and set a size to change the default.
+            #
+            #default_batch_size: 50
+        """
+
+    def read_config(self, config, **kwargs) -> None:
+        bg_update_config = config.get("background_updates") or {}
+
+        self.update_duration_ms = bg_update_config.get(
+            "background_update_duration_ms", 100
+        )
+
+        self.sleep_enabled = bg_update_config.get("sleep_enabled", True)
+
+        self.sleep_duration_ms = bg_update_config.get("sleep_duration_ms", 1000)
+
+        self.min_batch_size = bg_update_config.get("min_batch_size", 1)
+
+        self.default_batch_size = bg_update_config.get("default_batch_size", 100)
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 001605c265..a4ec706908 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -16,6 +16,7 @@ from .account_validity import AccountValidityConfig
 from .api import ApiConfig
 from .appservice import AppServiceConfig
 from .auth import AuthConfig
+from .background_updates import BackgroundUpdateConfig
 from .cache import CacheConfig
 from .captcha import CaptchaConfig
 from .cas import CasConfig
@@ -99,4 +100,5 @@ class HomeServerConfig(RootConfig):
         WorkerConfig,
         RedisConfig,
         ExperimentalConfig,
+        BackgroundUpdateConfig,
     ]
diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index 4acc2c997d..08c6eabc6d 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -60,18 +60,19 @@ class _BackgroundUpdateHandler:
 
 
 class _BackgroundUpdateContextManager:
-    BACKGROUND_UPDATE_INTERVAL_MS = 1000
-    BACKGROUND_UPDATE_DURATION_MS = 100
-
-    def __init__(self, sleep: bool, clock: Clock):
+    def __init__(
+        self, sleep: bool, clock: Clock, sleep_duration_ms: int, update_duration: int
+    ):
         self._sleep = sleep
         self._clock = clock
+        self._sleep_duration_ms = sleep_duration_ms
+        self._update_duration_ms = update_duration
 
     async def __aenter__(self) -> int:
         if self._sleep:
-            await self._clock.sleep(self.BACKGROUND_UPDATE_INTERVAL_MS / 1000)
+            await self._clock.sleep(self._sleep_duration_ms / 1000)
 
-        return self.BACKGROUND_UPDATE_DURATION_MS
+        return self._update_duration_ms
 
     async def __aexit__(self, *exc) -> None:
         pass
@@ -133,9 +134,6 @@ class BackgroundUpdater:
     process and autotuning the batch size.
     """
 
-    MINIMUM_BACKGROUND_BATCH_SIZE = 1
-    DEFAULT_BACKGROUND_BATCH_SIZE = 100
-
     def __init__(self, hs: "HomeServer", database: "DatabasePool"):
         self._clock = hs.get_clock()
         self.db_pool = database
@@ -160,6 +158,14 @@ class BackgroundUpdater:
         # enable/disable background updates via the admin API.
         self.enabled = True
 
+        self.minimum_background_batch_size = hs.config.background_updates.min_batch_size
+        self.default_background_batch_size = (
+            hs.config.background_updates.default_batch_size
+        )
+        self.update_duration_ms = hs.config.background_updates.update_duration_ms
+        self.sleep_duration_ms = hs.config.background_updates.sleep_duration_ms
+        self.sleep_enabled = hs.config.background_updates.sleep_enabled
+
     def register_update_controller_callbacks(
         self,
         on_update: ON_UPDATE_CALLBACK,
@@ -216,7 +222,9 @@ class BackgroundUpdater:
         if self._on_update_callback is not None:
             return self._on_update_callback(update_name, database_name, oneshot)
 
-        return _BackgroundUpdateContextManager(sleep, self._clock)
+        return _BackgroundUpdateContextManager(
+            sleep, self._clock, self.sleep_duration_ms, self.update_duration_ms
+        )
 
     async def _default_batch_size(self, update_name: str, database_name: str) -> int:
         """The batch size to use for the first iteration of a new background
@@ -225,7 +233,7 @@ class BackgroundUpdater:
         if self._default_batch_size_callback is not None:
             return await self._default_batch_size_callback(update_name, database_name)
 
-        return self.DEFAULT_BACKGROUND_BATCH_SIZE
+        return self.default_background_batch_size
 
     async def _min_batch_size(self, update_name: str, database_name: str) -> int:
         """A lower bound on the batch size of a new background update.
@@ -235,7 +243,7 @@ class BackgroundUpdater:
         if self._min_batch_size_callback is not None:
             return await self._min_batch_size_callback(update_name, database_name)
 
-        return self.MINIMUM_BACKGROUND_BATCH_SIZE
+        return self.minimum_background_batch_size
 
     def get_current_update(self) -> Optional[BackgroundUpdatePerformance]:
         """Returns the current background update, if any."""
@@ -254,9 +262,12 @@ class BackgroundUpdater:
         if self.enabled:
             # if we start a new background update, not all updates are done.
             self._all_done = False
-            run_as_background_process("background_updates", self.run_background_updates)
+            sleep = self.sleep_enabled
+            run_as_background_process(
+                "background_updates", self.run_background_updates, sleep
+            )
 
-    async def run_background_updates(self, sleep: bool = True) -> None:
+    async def run_background_updates(self, sleep: bool) -> None:
         if self._running or not self.enabled:
             return
 
diff --git a/tests/config/test_background_update.py b/tests/config/test_background_update.py
new file mode 100644
index 0000000000..0c32c1ca29
--- /dev/null
+++ b/tests/config/test_background_update.py
@@ -0,0 +1,58 @@
+# Copyright 2022 The 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.
+import yaml
+
+from synapse.storage.background_updates import BackgroundUpdater
+
+from tests.unittest import HomeserverTestCase, override_config
+
+
+class BackgroundUpdateConfigTestCase(HomeserverTestCase):
+    # Tests that the default values in the config are correctly loaded. Note that the default
+    # values are loaded when the corresponding config options are commented out, which is why there isn't
+    # a config specified here.
+    def test_default_configuration(self):
+        background_updater = BackgroundUpdater(
+            self.hs, self.hs.get_datastores().main.db_pool
+        )
+
+        self.assertEqual(background_updater.minimum_background_batch_size, 1)
+        self.assertEqual(background_updater.default_background_batch_size, 100)
+        self.assertEqual(background_updater.sleep_enabled, True)
+        self.assertEqual(background_updater.sleep_duration_ms, 1000)
+        self.assertEqual(background_updater.update_duration_ms, 100)
+
+    # Tests that non-default values for the config options are properly picked up and passed on.
+    @override_config(
+        yaml.safe_load(
+            """
+            background_updates:
+                background_update_duration_ms: 1000
+                sleep_enabled: false
+                sleep_duration_ms: 600
+                min_batch_size: 5
+                default_batch_size: 50
+            """
+        )
+    )
+    def test_custom_configuration(self):
+        background_updater = BackgroundUpdater(
+            self.hs, self.hs.get_datastores().main.db_pool
+        )
+
+        self.assertEqual(background_updater.minimum_background_batch_size, 5)
+        self.assertEqual(background_updater.default_background_batch_size, 50)
+        self.assertEqual(background_updater.sleep_enabled, False)
+        self.assertEqual(background_updater.sleep_duration_ms, 600)
+        self.assertEqual(background_updater.update_duration_ms, 1000)
diff --git a/tests/rest/admin/test_background_updates.py b/tests/rest/admin/test_background_updates.py
index becec84524..6cf56b1e35 100644
--- a/tests/rest/admin/test_background_updates.py
+++ b/tests/rest/admin/test_background_updates.py
@@ -39,6 +39,7 @@ class BackgroundUpdatesTestCase(unittest.HomeserverTestCase):
         self.store = hs.get_datastores().main
         self.admin_user = self.register_user("admin", "pass", admin=True)
         self.admin_user_tok = self.login("admin", "pass")
+        self.updater = BackgroundUpdater(hs, self.store.db_pool)
 
     @parameterized.expand(
         [
@@ -135,10 +136,10 @@ class BackgroundUpdatesTestCase(unittest.HomeserverTestCase):
         """Test the status API works with a background update."""
 
         # Create a new background update
-
         self._register_bg_update()
 
         self.store.db_pool.updates.start_doing_background_updates()
+
         self.reactor.pump([1.0, 1.0, 1.0])
 
         channel = self.make_request(
@@ -158,7 +159,7 @@ class BackgroundUpdatesTestCase(unittest.HomeserverTestCase):
                         "average_items_per_ms": 0.1,
                         "total_duration_ms": 1000.0,
                         "total_item_count": (
-                            BackgroundUpdater.DEFAULT_BACKGROUND_BATCH_SIZE
+                            self.updater.default_background_batch_size
                         ),
                     }
                 },
@@ -213,7 +214,7 @@ class BackgroundUpdatesTestCase(unittest.HomeserverTestCase):
                         "average_items_per_ms": 0.1,
                         "total_duration_ms": 1000.0,
                         "total_item_count": (
-                            BackgroundUpdater.DEFAULT_BACKGROUND_BATCH_SIZE
+                            self.updater.default_background_batch_size
                         ),
                     }
                 },
@@ -242,7 +243,7 @@ class BackgroundUpdatesTestCase(unittest.HomeserverTestCase):
                         "average_items_per_ms": 0.1,
                         "total_duration_ms": 1000.0,
                         "total_item_count": (
-                            BackgroundUpdater.DEFAULT_BACKGROUND_BATCH_SIZE
+                            self.updater.default_background_batch_size
                         ),
                     }
                 },
diff --git a/tests/storage/test_background_update.py b/tests/storage/test_background_update.py
index 9fdf54ea31..5cf18b690e 100644
--- a/tests/storage/test_background_update.py
+++ b/tests/storage/test_background_update.py
@@ -14,12 +14,15 @@
 
 from unittest.mock import Mock
 
+import yaml
+
 from twisted.internet.defer import Deferred, ensureDeferred
 
 from synapse.storage.background_updates import BackgroundUpdater
 
 from tests import unittest
 from tests.test_utils import make_awaitable, simple_async_mock
+from tests.unittest import override_config
 
 
 class BackgroundUpdateTestCase(unittest.HomeserverTestCase):
@@ -34,6 +37,19 @@ class BackgroundUpdateTestCase(unittest.HomeserverTestCase):
         self.updates.register_background_update_handler(
             "test_update", self.update_handler
         )
+        self.store = self.hs.get_datastores().main
+
+    async def update(self, progress, count):
+        duration_ms = 10
+        await self.clock.sleep((count * duration_ms) / 1000)
+        progress = {"my_key": progress["my_key"] + 1}
+        await self.store.db_pool.runInteraction(
+            "update_progress",
+            self.updates._background_update_progress_txn,
+            "test_update",
+            progress,
+        )
+        return count
 
     def test_do_background_update(self):
         # the time we claim it takes to update one item when running the update
@@ -42,27 +58,14 @@ class BackgroundUpdateTestCase(unittest.HomeserverTestCase):
         # the target runtime for each bg update
         target_background_update_duration_ms = 100
 
-        store = self.hs.get_datastores().main
         self.get_success(
-            store.db_pool.simple_insert(
+            self.store.db_pool.simple_insert(
                 "background_updates",
                 values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
             )
         )
 
-        # first step: make a bit of progress
-        async def update(progress, count):
-            await self.clock.sleep((count * duration_ms) / 1000)
-            progress = {"my_key": progress["my_key"] + 1}
-            await store.db_pool.runInteraction(
-                "update_progress",
-                self.updates._background_update_progress_txn,
-                "test_update",
-                progress,
-            )
-            return count
-
-        self.update_handler.side_effect = update
+        self.update_handler.side_effect = self.update
         self.update_handler.reset_mock()
         res = self.get_success(
             self.updates.do_next_background_update(False),
@@ -72,7 +75,7 @@ class BackgroundUpdateTestCase(unittest.HomeserverTestCase):
 
         # on the first call, we should get run with the default background update size
         self.update_handler.assert_called_once_with(
-            {"my_key": 1}, self.updates.DEFAULT_BACKGROUND_BATCH_SIZE
+            {"my_key": 1}, self.updates.default_background_batch_size
         )
 
         # second step: complete the update
@@ -99,6 +102,224 @@ class BackgroundUpdateTestCase(unittest.HomeserverTestCase):
         self.assertTrue(result)
         self.assertFalse(self.update_handler.called)
 
+    @override_config(
+        yaml.safe_load(
+            """
+            background_updates:
+                default_batch_size: 20
+            """
+        )
+    )
+    def test_background_update_default_batch_set_by_config(self):
+        """
+        Test that the background update is run with the default_batch_size set by the config
+        """
+
+        self.get_success(
+            self.store.db_pool.simple_insert(
+                "background_updates",
+                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
+            )
+        )
+
+        self.update_handler.side_effect = self.update
+        self.update_handler.reset_mock()
+        res = self.get_success(
+            self.updates.do_next_background_update(False),
+            by=0.01,
+        )
+        self.assertFalse(res)
+
+        # on the first call, we should get run with the default background update size specified in the config
+        self.update_handler.assert_called_once_with({"my_key": 1}, 20)
+
+    def test_background_update_default_sleep_behavior(self):
+        """
+        Test default background update behavior, which is to sleep
+        """
+
+        self.get_success(
+            self.store.db_pool.simple_insert(
+                "background_updates",
+                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
+            )
+        )
+
+        self.update_handler.side_effect = self.update
+        self.update_handler.reset_mock()
+        self.updates.start_doing_background_updates(),
+
+        # 2: advance the reactor less than the default sleep duration (1000ms)
+        self.reactor.pump([0.5])
+        # check that an update has not been run
+        self.update_handler.assert_not_called()
+
+        # advance reactor past default sleep duration
+        self.reactor.pump([1])
+        # check that update has been run
+        self.update_handler.assert_called()
+
+    @override_config(
+        yaml.safe_load(
+            """
+            background_updates:
+                sleep_duration_ms: 500
+            """
+        )
+    )
+    def test_background_update_sleep_set_in_config(self):
+        """
+        Test that changing the sleep time in the config changes how long it sleeps
+        """
+
+        self.get_success(
+            self.store.db_pool.simple_insert(
+                "background_updates",
+                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
+            )
+        )
+
+        self.update_handler.side_effect = self.update
+        self.update_handler.reset_mock()
+        self.updates.start_doing_background_updates(),
+
+        # 2: advance the reactor less than the configured sleep duration (500ms)
+        self.reactor.pump([0.45])
+        # check that an update has not been run
+        self.update_handler.assert_not_called()
+
+        # advance reactor past config sleep duration but less than default duration
+        self.reactor.pump([0.75])
+        # check that update has been run
+        self.update_handler.assert_called()
+
+    @override_config(
+        yaml.safe_load(
+            """
+            background_updates:
+                sleep_enabled: false
+            """
+        )
+    )
+    def test_disabling_background_update_sleep(self):
+        """
+        Test that disabling sleep in the config results in bg update not sleeping
+        """
+
+        self.get_success(
+            self.store.db_pool.simple_insert(
+                "background_updates",
+                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
+            )
+        )
+
+        self.update_handler.side_effect = self.update
+        self.update_handler.reset_mock()
+        self.updates.start_doing_background_updates(),
+
+        # 2: advance the reactor very little
+        self.reactor.pump([0.025])
+        # check that an update has run
+        self.update_handler.assert_called()
+
+    @override_config(
+        yaml.safe_load(
+            """
+            background_updates:
+                background_update_duration_ms: 500
+            """
+        )
+    )
+    def test_background_update_duration_set_in_config(self):
+        """
+        Test that the desired duration set in the config is used in determining batch size
+        """
+        # Duration of one background update item
+        duration_ms = 10
+
+        self.get_success(
+            self.store.db_pool.simple_insert(
+                "background_updates",
+                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
+            )
+        )
+
+        self.update_handler.side_effect = self.update
+        self.update_handler.reset_mock()
+        res = self.get_success(
+            self.updates.do_next_background_update(False),
+            by=0.02,
+        )
+        self.assertFalse(res)
+
+        # the first update was run with the default batch size, this should be run with 500ms as the
+        # desired duration
+        async def update(progress, count):
+            self.assertEqual(progress, {"my_key": 2})
+            self.assertAlmostEqual(
+                count,
+                500 / duration_ms,
+                places=0,
+            )
+            await self.updates._end_background_update("test_update")
+            return count
+
+        self.update_handler.side_effect = update
+        self.get_success(self.updates.do_next_background_update(False))
+
+    @override_config(
+        yaml.safe_load(
+            """
+            background_updates:
+                min_batch_size: 5
+            """
+        )
+    )
+    def test_background_update_min_batch_set_in_config(self):
+        """
+        Test that the minimum batch size set in the config is used
+        """
+        # a very long-running individual update
+        duration_ms = 50
+
+        self.get_success(
+            self.store.db_pool.simple_insert(
+                "background_updates",
+                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
+            )
+        )
+
+        # Run the update with the long-running update item
+        async def update(progress, count):
+            await self.clock.sleep((count * duration_ms) / 1000)
+            progress = {"my_key": progress["my_key"] + 1}
+            await self.store.db_pool.runInteraction(
+                "update_progress",
+                self.updates._background_update_progress_txn,
+                "test_update",
+                progress,
+            )
+            return count
+
+        self.update_handler.side_effect = update
+        self.update_handler.reset_mock()
+        res = self.get_success(
+            self.updates.do_next_background_update(False),
+            by=1,
+        )
+        self.assertFalse(res)
+
+        # the first update was run with the default batch size, this should be run with minimum batch size
+        # as the first items took a very long time
+        async def update(progress, count):
+            self.assertEqual(progress, {"my_key": 2})
+            self.assertEqual(count, 5)
+            await self.updates._end_background_update("test_update")
+            return count
+
+        self.update_handler.side_effect = update
+        self.get_success(self.updates.do_next_background_update(False))
+
 
 class BackgroundUpdateControllerTestCase(unittest.HomeserverTestCase):
     def prepare(self, reactor, clock, homeserver):