Remove preserve_context_over_{fn, deferred}

Both of these functions ae known to leak logcontexts. Replace the remaining
calls to them and kill them off.

docs/log_contexts.rst

@@ -298,10 +298,6 @@ It can be used like this:
         # this will now be logged against the request context
         logger.debug("Request handling complete")
 
-XXX: I think ``preserve_context_over_fn`` is supposed to do the first option,
-but the fact that it does ``preserve_context_over_deferred`` on its results
-means that its use is fraught with difficulty.
-
 Passing synapse deferreds into third-party functions
 ----------------------------------------------------
 

synapse/federation/federation_client.py

@@ -25,7 +25,7 @@ from synapse.api.errors import (
 from synapse.util import unwrapFirstError, logcontext
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logutils import log_function
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 from synapse.events import FrozenEvent, builder
 import synapse.metrics
 
@@ -420,7 +420,7 @@ class FederationClient(FederationBase):
                 for e_id in batch
             ]
 
-            res = yield preserve_context_over_deferred(
+            res = yield make_deferred_yieldable(
                 defer.DeferredList(deferreds, consumeErrors=True)
             )
             for success, result in res:

synapse/handlers/appservice.py

@@ -17,7 +17,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import EventTypes
 from synapse.util.metrics import Measure
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 
 import logging
 
@@ -159,7 +159,7 @@ class ApplicationServicesHandler(object):
     def query_3pe(self, kind, protocol, fields):
         services = yield self._get_services_for_3pn(protocol)
 
-        results = yield preserve_context_over_deferred(defer.DeferredList([
+        results = yield make_deferred_yieldable(defer.DeferredList([
             preserve_fn(self.appservice_api.query_3pe)(service, kind, protocol, fields)
             for service in services
         ], consumeErrors=True))

synapse/handlers/initial_sync.py

@@ -27,7 +27,7 @@ from synapse.types import (
 from synapse.util import unwrapFirstError
 from synapse.util.async import concurrently_execute
 from synapse.util.caches.snapshot_cache import SnapshotCache
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
@@ -163,7 +163,7 @@ class InitialSyncHandler(BaseHandler):
                         lambda states: states[event.event_id]
                     )
 
-                (messages, token), current_state = yield preserve_context_over_deferred(
+                (messages, token), current_state = yield make_deferred_yieldable(
                     defer.gatherResults(
                         [
                             preserve_fn(self.store.get_recent_events_for_room)(

synapse/push/pusherpool.py

@@ -17,7 +17,7 @@
 from twisted.internet import defer
 
 from .pusher import PusherFactory
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 from synapse.util.async import run_on_reactor
 
 import logging
@@ -136,7 +136,7 @@ class PusherPool:
                             )
                         )
 
-            yield preserve_context_over_deferred(defer.gatherResults(deferreds))
+            yield make_deferred_yieldable(defer.gatherResults(deferreds))
         except Exception:
             logger.exception("Exception in pusher on_new_notifications")
 
@@ -161,7 +161,7 @@ class PusherPool:
                             preserve_fn(p.on_new_receipts)(min_stream_id, max_stream_id)
                         )
 
-            yield preserve_context_over_deferred(defer.gatherResults(deferreds))
+            yield make_deferred_yieldable(defer.gatherResults(deferreds))
         except Exception:
             logger.exception("Exception in pusher on_new_receipts")
 

synapse/storage/stream.py

@@ -39,7 +39,7 @@ from ._base import SQLBaseStore
 from synapse.util.caches.descriptors import cached
 from synapse.api.constants import EventTypes
 from synapse.types import RoomStreamToken
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 
 import logging
@@ -234,7 +234,7 @@ class StreamStore(SQLBaseStore):
         results = {}
         room_ids = list(room_ids)
         for rm_ids in (room_ids[i:i + 20] for i in xrange(0, len(room_ids), 20)):
-            res = yield preserve_context_over_deferred(defer.gatherResults([
+            res = yield make_deferred_yieldable(defer.gatherResults([
                 preserve_fn(self.get_room_events_stream_for_room)(
                     room_id, from_key, to_key, limit, order=order,
                 )

synapse/util/async.py

@@ -17,7 +17,7 @@
 from twisted.internet import defer, reactor
 
 from .logcontext import (
-    PreserveLoggingContext, preserve_fn, preserve_context_over_deferred,
+    PreserveLoggingContext, make_deferred_yieldable, preserve_fn
 )
 from synapse.util import logcontext, unwrapFirstError
 
@@ -351,7 +351,7 @@ class ReadWriteLock(object):
 
         # We wait for the latest writer to finish writing. We can safely ignore
         # any existing readers... as they're readers.
-        yield curr_writer
+        yield make_deferred_yieldable(curr_writer)
 
         @contextmanager
         def _ctx_manager():
@@ -380,7 +380,7 @@ class ReadWriteLock(object):
         curr_readers.clear()
         self.key_to_current_writer[key] = new_defer
 
-        yield preserve_context_over_deferred(defer.gatherResults(to_wait_on))
+        yield make_deferred_yieldable(defer.gatherResults(to_wait_on))
 
         @contextmanager
         def _ctx_manager():

synapse/util/distributor.py

@@ -13,32 +13,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from synapse.util.logcontext import (
-    PreserveLoggingContext, preserve_context_over_fn
-)
-
-from synapse.util import unwrapFirstError
-
 import logging
 
+from twisted.internet import defer
+
+from synapse.util import unwrapFirstError
+from synapse.util.logcontext import PreserveLoggingContext
 
 logger = logging.getLogger(__name__)
 
 
 def user_left_room(distributor, user, room_id):
-    return preserve_context_over_fn(
+    with PreserveLoggingContext():
-        distributor.fire,
+        distributor.fire("user_left_room", user=user, room_id=room_id)
-        "user_left_room", user=user, room_id=room_id
-    )
 
 
 def user_joined_room(distributor, user, room_id):
-    return preserve_context_over_fn(
+    with PreserveLoggingContext():
-        distributor.fire,
+        distributor.fire("user_joined_room", user=user, room_id=room_id)
-        "user_joined_room", user=user, room_id=room_id
-    )
 
 
 class Distributor(object):

synapse/util/logcontext.py

@@ -291,37 +291,6 @@ class _PreservingContextDeferred(defer.Deferred):
         return g
 
 
-def preserve_context_over_fn(fn, *args, **kwargs):
-    """Takes a function and invokes it with the given arguments, but removes
-    and restores the current logging context while doing so.
-
-    If the result is a deferred, call preserve_context_over_deferred before
-    returning it.
-    """
-    with PreserveLoggingContext():
-        res = fn(*args, **kwargs)
-
-    if isinstance(res, defer.Deferred):
-        return preserve_context_over_deferred(res)
-    else:
-        return res
-
-
-def preserve_context_over_deferred(deferred, context=None):
-    """Given a deferred wrap it such that any callbacks added later to it will
-    be invoked with the current context.
-
-    Deprecated: this almost certainly doesn't do want you want, ie make
-    the deferred follow the synapse logcontext rules: try
-    ``make_deferred_yieldable`` instead.
-    """
-    if context is None:
-        context = LoggingContext.current_context()
-    d = _PreservingContextDeferred(context)
-    deferred.chainDeferred(d)
-    return d
-
-
 def preserve_fn(f):
     """Wraps a function, to ensure that the current context is restored after
     return from the function, and that the sentinel context is set once the

synapse/visibility.py

@@ -17,7 +17,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import Membership, EventTypes
 
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 
 import logging
 
@@ -58,7 +58,7 @@ def filter_events_for_clients(store, user_tuples, events, event_id_to_state,
         always_include_ids (set(event_id)): set of event ids to specifically
             include (unless sender is ignored)
     """
-    forgotten = yield preserve_context_over_deferred(defer.gatherResults([
+    forgotten = yield make_deferred_yieldable(defer.gatherResults([
         defer.maybeDeferred(
             preserve_fn(store.who_forgot_in_room),
             room_id,