Fix some instances of ExpiringCache not expiring cache items

ExpiringCache required that `start()` be called before it would actually
start expiring entries. A number of places didn't do that.

This PR removes `start` from ExpiringCache, and automatically starts
backround reaping process on creation instead.

synapse/app/appservice.py

@@ -172,7 +172,6 @@ def start(config_options):
 
     def start():
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 

synapse/app/client_reader.py

@@ -181,7 +181,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)

synapse/app/event_creator.py

@@ -199,7 +199,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)

synapse/app/federation_reader.py

@@ -168,7 +168,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)

synapse/app/federation_sender.py

@@ -201,7 +201,6 @@ def start(config_options):
 
     def start():
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
     _base.start_worker_reactor("synapse-federation-sender", config)

synapse/app/frontend_proxy.py

@@ -258,7 +258,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)

synapse/app/homeserver.py

@@ -384,7 +384,6 @@ def setup(config_options):
 
     def start():
         hs.get_pusherpool().start()
-        hs.get_state_handler().start_caching()
         hs.get_datastore().start_profiling()
         hs.get_datastore().start_doing_background_updates()
         hs.get_federation_client().start_get_pdu_cache()

synapse/app/media_repository.py

@@ -168,7 +168,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)

synapse/app/pusher.py

@@ -228,7 +228,6 @@ def start(config_options):
     def start():
         ps.get_pusherpool().start()
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 

synapse/app/synchrotron.py

@@ -435,7 +435,6 @@ def start(config_options):
 
     def start():
         ss.get_datastore().start_profiling()
-        ss.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 

synapse/app/user_dir.py

@@ -229,7 +229,6 @@ def start(config_options):
 
     def start():
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 

synapse/federation/federation_client.py

@@ -66,6 +66,14 @@ class FederationClient(FederationBase):
         self.state = hs.get_state_handler()
         self.transport_layer = hs.get_federation_transport_client()
 
+        self._get_pdu_cache = ExpiringCache(
+            cache_name="get_pdu_cache",
+            clock=self._clock,
+            max_len=1000,
+            expiry_ms=120 * 1000,
+            reset_expiry_on_get=False,
+        )
+
     def _clear_tried_cache(self):
         """Clear pdu_destination_tried cache"""
         now = self._clock.time_msec()
@@ -82,17 +90,6 @@ class FederationClient(FederationBase):
             if destination_dict:
                 self.pdu_destination_tried[event_id] = destination_dict
 
-    def start_get_pdu_cache(self):
-        self._get_pdu_cache = ExpiringCache(
-            cache_name="get_pdu_cache",
-            clock=self._clock,
-            max_len=1000,
-            expiry_ms=120 * 1000,
-            reset_expiry_on_get=False,
-        )
-
-        self._get_pdu_cache.start()
-
     @log_function
     def make_query(self, destination, query_type, args,
                    retry_on_dns_fail=False, ignore_backoff=False):
@@ -229,7 +226,6 @@ class FederationClient(FederationBase):
 
         # TODO: Rate limit the number of times we try and get the same event.
 
-        if self._get_pdu_cache:
         ev = self._get_pdu_cache.get(event_id)
         if ev:
             defer.returnValue(ev)
@@ -285,7 +281,7 @@ class FederationClient(FederationBase):
                 )
                 continue
 
-        if self._get_pdu_cache is not None and signed_pdu:
+        if signed_pdu:
             self._get_pdu_cache[event_id] = signed_pdu
 
         defer.returnValue(signed_pdu)

synapse/rest/media/v1/preview_url_resource.py

@@ -79,7 +79,6 @@ class PreviewUrlResource(Resource):
             # don't spider URLs more often than once an hour
             expiry_ms=60 * 60 * 1000,
         )
-        self._cache.start()
 
         self._cleaner_loop = self.clock.looping_call(
             self._start_expire_url_cache_data, 10 * 1000,

synapse/state/__init__.py

@@ -95,10 +95,6 @@ class StateHandler(object):
         self.hs = hs
         self._state_resolution_handler = hs.get_state_resolution_handler()
 
-    def start_caching(self):
-        # TODO: remove this shim
-        self._state_resolution_handler.start_caching()
-
     @defer.inlineCallbacks
     def get_current_state(self, room_id, event_type=None, state_key="",
                           latest_event_ids=None):
@@ -428,9 +424,6 @@ class StateResolutionHandler(object):
         self._state_cache = None
         self.resolve_linearizer = Linearizer(name="state_resolve_lock")
 
-    def start_caching(self):
-        logger.debug("start_caching")
-
         self._state_cache = ExpiringCache(
             cache_name="state_cache",
             clock=self.clock,
@@ -440,8 +433,6 @@ class StateResolutionHandler(object):
             reset_expiry_on_get=True,
         )
 
-        self._state_cache.start()
-
     @defer.inlineCallbacks
     @log_function
     def resolve_state_groups(

synapse/util/caches/expiringcache.py

@@ -58,7 +58,6 @@ class ExpiringCache(object):
 
         self.metrics = register_cache("expiring", cache_name, self)
 
-    def start(self):
         if not self._expiry_ms:
             # Don't bother starting the loop if things never expire
             return

tests/util/test_expiring_cache.py

@@ -65,7 +65,6 @@ class ExpiringCacheTestCase(unittest.TestCase):
     def test_time_eviction(self):
         clock = MockClock()
         cache = ExpiringCache("test", clock, expiry_ms=1000)
-        cache.start()
 
         cache["key"] = 1
         clock.advance_time(0.5)