Allow configuration of Synapse's cache without using synctl or environment variables

changelog.d/6391.feature

@@ -0,0 +1 @@
+Synapse's cache factor can now be configured in `homeserver.yaml` by the `caches.global_factor` setting. Additionally, `caches.per_cache_factors` controls the cache factors for individual caches.

changelog.d/6446.misc

@@ -0,0 +1 @@
+Add benchmarks for LruCache.

synapse/api/auth.py

@@ -36,7 +36,7 @@
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.config.server import is_threepid_reserved
 from synapse.types import StateMap, UserID
-from synapse.util.caches import CACHE_SIZE_FACTOR, register_cache
+from synapse.util.caches import register_cache
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.metrics import Measure
 
@@ -72,7 +72,7 @@ def __init__(self, hs):
         self.store = hs.get_datastore()
         self.state = hs.get_state_handler()
 
-        self.token_cache = LruCache(CACHE_SIZE_FACTOR * 10000)
+        self.token_cache = LruCache(10000)
         register_cache("cache", "token_cache", self.token_cache)
 
         self._account_validity = hs.config.account_validity

synapse/app/homeserver.py

@@ -69,7 +69,6 @@
 from synapse.storage import DataStore
 from synapse.storage.engines import IncorrectDatabaseSetup
 from synapse.storage.prepare_database import UpgradeDatabaseException
-from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.module_loader import load_module
@@ -484,8 +483,8 @@ def phone_stats_home(hs, stats, stats_process=_stats_process):
 
     daily_sent_messages = yield hs.get_datastore().count_daily_sent_messages()
     stats["daily_sent_messages"] = daily_sent_messages
-    stats["cache_factor"] = CACHE_SIZE_FACTOR
-    stats["event_cache_size"] = hs.config.event_cache_size
+    stats["cache_factor"] = hs.config.caches.global_factor
+    stats["event_cache_size"] = hs.config.caches.event_cache_size
 
     #
     # Performance statistics

synapse/config/cache.py

@@ -0,0 +1,112 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 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 os
+from typing import Dict
+
+from ._base import Config, ConfigError
+
+_CACHES = {}
+_CACHE_PREFIX = "SYNAPSE_CACHE_FACTOR"
+DEFAULT_CACHE_SIZE_FACTOR = float(os.environ.get(_CACHE_PREFIX, 0.5))
+
+_DEFAULT_CONFIG = """\
+# Cache configuration
+#
+# 'global_factor' controls the global cache factor. This overrides the
+# "SYNAPSE_CACHE_FACTOR" environment variable.
+#
+# 'per_cache_factors' is a dictionary of cache name to cache factor for that
+# individual cache.
+#
+#caches:
+#  global_factor: 0.5
+#  per_cache_factors:
+#    get_users_who_share_room_with_user: 2
+#
+"""
+
+# Callback to ensure that all caches are the correct size, registered when the
+# configuration has been loaded.
+_ENSURE_CORRECT_CACHE_SIZING = None
+
+
+def add_resizable_cache(cache_name, cache_resize_callback):
+    _CACHES[cache_name.lower()] = cache_resize_callback
+    if _ENSURE_CORRECT_CACHE_SIZING:
+        _ENSURE_CORRECT_CACHE_SIZING()
+
+
+class CacheConfig(Config):
+    section = "caches"
+    _environ = os.environ
+
+    @staticmethod
+    def _reset():
+        global DEFAULT_CACHE_SIZE_FACTOR
+        global _ENSURE_CORRECT_CACHE_SIZING
+
+        DEFAULT_CACHE_SIZE_FACTOR = float(os.environ.get(_CACHE_PREFIX, 0.5))
+        _ENSURE_CORRECT_CACHE_SIZING = None
+        _CACHES.clear()
+
+    def read_config(self, config, **kwargs):
+        self.event_cache_size = self.parse_size(config.get("event_cache_size", "10K"))
+
+        global DEFAULT_CACHE_SIZE_FACTOR
+        global _ENSURE_CORRECT_CACHE_SIZING
+
+        cache_config = config.get("caches", {})
+
+        self.global_factor = cache_config.get(
+            "global_factor", DEFAULT_CACHE_SIZE_FACTOR
+        )
+        if not isinstance(self.global_factor, (int, float)):
+            raise ConfigError("caches.global_factor must be a number.")
+
+        # Set the global one so that it's reflected in new caches
+        DEFAULT_CACHE_SIZE_FACTOR = self.global_factor
+
+        # Load cache factors from the environment, but override them with the
+        # ones in the config file if they exist
+        individual_factors = {
+            key[len(_CACHE_PREFIX) + 1 :].lower(): float(val)
+            for key, val in self._environ.items()
+            if key.startswith(_CACHE_PREFIX + "_")
+        }
+
+        individual_factors_config = cache_config.get("per_cache_factors", {}) or {}
+        if not isinstance(individual_factors_config, dict):
+            raise ConfigError("caches.per_cache_factors must be a dictionary")
+
+        individual_factors.update(individual_factors_config)
+
+        self.cache_factors = dict()  # type: Dict[str, float]
+
+        for cache, factor in individual_factors.items():
+            if not isinstance(factor, (int, float)):
+                raise ConfigError(
+                    "caches.per_cache_factors.%s must be a number" % (cache.lower(),)
+                )
+            self.cache_factors[cache.lower()] = factor
+
+        # Register the global callback so that the individual cache sizes get set.
+        def ensure_cache_sizes():
+            for cache_name, callback in _CACHES.items():
+                new_factor = self.cache_factors.get(cache_name, self.global_factor)
+                callback(new_factor)
+
+        _ENSURE_CORRECT_CACHE_SIZING = ensure_cache_sizes
+        _ENSURE_CORRECT_CACHE_SIZING()

synapse/config/database.py

@@ -57,8 +57,6 @@ class DatabaseConfig(Config):
     section = "database"
 
     def read_config(self, config, **kwargs):
-        self.event_cache_size = self.parse_size(config.get("event_cache_size", "10K"))
-
         # We *experimentally* support specifying multiple databases via the
         # `databases` key. This is a map from a label to database config in the
         # same format as the `database` config option, plus an extra

synapse/config/homeserver.py

@@ -17,6 +17,7 @@
 from ._base import RootConfig
 from .api import ApiConfig
 from .appservice import AppServiceConfig
+from .cache import CacheConfig
 from .captcha import CaptchaConfig
 from .cas import CasConfig
 from .consent_config import ConsentConfig
@@ -80,4 +81,5 @@ class HomeServerConfig(RootConfig):
         RoomDirectoryConfig,
         ThirdPartyRulesConfig,
         TracerConfig,
+        CacheConfig,
     ]

synapse/http/client.py

@@ -49,7 +49,6 @@
 from synapse.logging.context import make_deferred_yieldable
 from synapse.logging.opentracing import set_tag, start_active_span, tags
 from synapse.util.async_helpers import timeout_deferred
-from synapse.util.caches import CACHE_SIZE_FACTOR
 
 logger = logging.getLogger(__name__)
 
@@ -241,7 +240,8 @@ def __getattr__(_self, attr):
         # tends to do so in batches, so we need to allow the pool to keep
         # lots of idle connections around.
         pool = HTTPConnectionPool(self.reactor)
-        pool.maxPersistentPerHost = max((100 * CACHE_SIZE_FACTOR, 5))
+        # XXX: Why does this use the cache factor????
+        pool.maxPersistentPerHost = max((100 * hs.config.caches.global_factor, 5))
         pool.cachedConnectionTimeout = 2 * 60
 
         # The default context factory in Twisted 14.0.0 (which we require) is

synapse/metrics/_exposition.py

@@ -33,6 +33,8 @@
 
 from twisted.web.resource import Resource
 
+from synapse.util import caches
+
 try:
     from prometheus_client.samples import Sample
 except ImportError:
@@ -103,13 +105,15 @@ def nameify_sample(sample):
 
 
 def generate_latest(registry, emit_help=False):
-    output = []
 
-    for metric in registry.collect():
+    # Trigger the cache metrics to be rescraped, which updates the common
+    # metrics but do not produce metrics themselves
+    for collector in caches.collectors_by_name.values():
+        collector.collect()
 
-        if metric.name.startswith("__unused"):
-            continue
+    output = []
 
+    for metric in registry.collect():
         if not metric.samples:
             # No samples, don't bother.
             continue

synapse/push/bulk_push_rule_evaluator.py

@@ -51,6 +51,7 @@
     "cache",
     "push_rules_delta_state_cache_metric",
     cache=[],  # Meaningless size, as this isn't a cache that stores values
+    resizable=False,
 )
 
 
@@ -67,7 +68,8 @@ def __init__(self, hs):
         self.room_push_rule_cache_metrics = register_cache(
             "cache",
             "room_push_rule_cache",
-            cache=[],  # Meaningless size, as this isn't a cache that stores values
+            cache=[],  # Meaningless size, as this isn't a cache that stores values,
+            resizable=False,
         )
 
     @defer.inlineCallbacks

synapse/push/push_rule_evaluator.py

@@ -20,7 +20,7 @@
 from six import string_types
 
 from synapse.types import UserID
-from synapse.util.caches import CACHE_SIZE_FACTOR, register_cache
+from synapse.util.caches import register_cache
 from synapse.util.caches.lrucache import LruCache
 
 logger = logging.getLogger(__name__)
@@ -149,7 +149,7 @@ def _get_value(self, dotted_key):
 
 
 # Caches (glob, word_boundary) -> regex for push. See _glob_matches
-regex_cache = LruCache(50000 * CACHE_SIZE_FACTOR)
+regex_cache = LruCache(50000)
 register_cache("cache", "regex_push_cache", regex_cache)
 
 

synapse/replication/slave/storage/client_ips.py

@@ -15,7 +15,6 @@
 
 from synapse.storage.data_stores.main.client_ips import LAST_SEEN_GRANULARITY
 from synapse.storage.database import Database
-from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.caches.descriptors import Cache
 
 from ._base import BaseSlavedStore
@@ -26,7 +25,7 @@ def __init__(self, database: Database, db_conn, hs):
         super(SlavedClientIpStore, self).__init__(database, db_conn, hs)
 
         self.client_ip_last_seen = Cache(
-            name="client_ip_last_seen", keylen=4, max_entries=50000 * CACHE_SIZE_FACTOR
+            name="client_ip_last_seen", keylen=4, max_entries=50000
         )
 
     def insert_client_ip(self, user_id, access_token, ip, user_agent, device_id):

synapse/state/__init__.py

@@ -35,7 +35,6 @@
 from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.types import StateMap
 from synapse.util.async_helpers import Linearizer
-from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.metrics import Measure, measure_func
 
@@ -53,7 +52,6 @@
 KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
 
 
-SIZE_OF_CACHE = 100000 * get_cache_factor_for("state_cache")
 EVICTION_TIMEOUT_SECONDS = 60 * 60
 
 
@@ -447,7 +445,7 @@ def __init__(self, hs):
         self._state_cache = ExpiringCache(
             cache_name="state_cache",
             clock=self.clock,
-            max_len=SIZE_OF_CACHE,
+            max_len=100000,
             expiry_ms=EVICTION_TIMEOUT_SECONDS * 1000,
             iterable=True,
             reset_expiry_on_get=True,

synapse/storage/data_stores/main/client_ips.py

@@ -22,7 +22,6 @@
 from synapse.metrics.background_process_metrics import wrap_as_background_process
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.database import Database
-from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.caches.descriptors import Cache
 
 logger = logging.getLogger(__name__)
@@ -367,7 +366,7 @@ class ClientIpStore(ClientIpBackgroundUpdateStore):
     def __init__(self, database: Database, db_conn, hs):
 
         self.client_ip_last_seen = Cache(
-            name="client_ip_last_seen", keylen=4, max_entries=50000 * CACHE_SIZE_FACTOR
+            name="client_ip_last_seen", keylen=4, max_entries=50000
         )
 
         super(ClientIpStore, self).__init__(database, db_conn, hs)

synapse/storage/data_stores/main/events_worker.py

@@ -72,7 +72,7 @@ def __init__(self, database: Database, db_conn, hs):
         super(EventsWorkerStore, self).__init__(database, db_conn, hs)
 
         self._get_event_cache = Cache(
-            "*getEvent*", keylen=3, max_entries=hs.config.event_cache_size
+            "*getEvent*", keylen=3, max_entries=hs.config.caches.event_cache_size
         )
 
         self._event_fetch_lock = threading.Condition()

synapse/storage/data_stores/main/relations.py

@@ -31,7 +31,7 @@
 
 
 class RelationsWorkerStore(SQLBaseStore):
-    @cached(tree=True)
+    @cached(tree=True, max_entries="event_cache_size")
     def get_relations_for_event(
         self,
         event_id,
@@ -133,7 +133,7 @@ def _get_recent_references_for_event_txn(txn):
             "get_recent_references_for_event", _get_recent_references_for_event_txn
         )
 
-    @cached(tree=True)
+    @cached(tree=True, max_entries="event_cache_size")
     def get_aggregation_groups_for_event(
         self,
         event_id,

synapse/storage/data_stores/state/store.py

@@ -28,7 +28,6 @@
 from synapse.storage.database import Database
 from synapse.storage.state import StateFilter
 from synapse.types import StateMap
-from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.descriptors import cached
 from synapse.util.caches.dictionary_cache import DictionaryCache
 
@@ -90,11 +89,10 @@ def __init__(self, database: Database, db_conn, hs):
         self._state_group_cache = DictionaryCache(
             "*stateGroupCache*",
             # TODO: this hasn't been tuned yet
-            50000 * get_cache_factor_for("stateGroupCache"),
+            50000,
         )
         self._state_group_members_cache = DictionaryCache(
-            "*stateGroupMembersCache*",
-            500000 * get_cache_factor_for("stateGroupMembersCache"),
+            "*stateGroupMembersCache*", 500000,
         )
 
     @cached(max_entries=10000, iterable=True)