Merge pull request #3719 from matrix-org/erikj/use_cache_fact

Use get_cache_factor_for function for `state_cache`

changelog.d/3719.bugfix

+Fix bug where `state_cache` cache factor ignored environment variables

synapse/state.py

@@ -29,7 +29,7 @@ from synapse.api.constants import EventTypes
 from synapse.api.errors import AuthError
 from synapse.events.snapshot import EventContext
 from synapse.util.async_helpers import Linearizer
-from synapse.util.caches import CACHE_SIZE_FACTOR
+from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logutils import log_function
 from synapse.util.metrics import Measure
@@ -40,7 +40,7 @@ logger = logging.getLogger(__name__)
 KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
 
 
-SIZE_OF_CACHE = int(100000 * CACHE_SIZE_FACTOR)
+SIZE_OF_CACHE = 100000 * get_cache_factor_for("state_cache")
 EVICTION_TIMEOUT_SECONDS = 60 * 60