From fac8a38525387e344e3595a092578e0ffedd49ae Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Fri, 2 Dec 2022 10:28:41 -0500 Subject: [PATCH] Properly handle unknown results for the stream change cache. (#14592) StreamChangeCache.get_all_changed_entities can return None to signify it does not have information at the given stream position. Two callers (related to device lists and presence) were treating this response the same as an empty list (i.e. there being no updates). --- changelog.d/14592.bugfix | 1 + synapse/handlers/presence.py | 4 +-- synapse/storage/databases/main/devices.py | 33 +++++++++++++---------- 3 files changed, 22 insertions(+), 16 deletions(-) create mode 100644 changelog.d/14592.bugfix diff --git a/changelog.d/14592.bugfix b/changelog.d/14592.bugfix new file mode 100644 index 000000000000..149ee99dd716 --- /dev/null +++ b/changelog.d/14592.bugfix @@ -0,0 +1 @@ +Fix a long-standing bug where a device list update might not be sent to clients in certain circumstances. diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py index cf08737d115a..1799174c2f1a 100644 --- a/synapse/handlers/presence.py +++ b/synapse/handlers/presence.py @@ -1764,14 +1764,14 @@ async def _filter_all_presence_updates_for_user( Returns: A list of presence states for the given user to receive. """ + updated_users = None if from_key: # Only return updates since the last sync updated_users = self.store.presence_stream_cache.get_all_entities_changed( from_key ) - if not updated_users: - updated_users = [] + if updated_users is not None: # Get the actual presence update for each change users_to_state = await self.get_presence_handler().current_state_for_users( updated_users diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py index 534f7fc04a54..8ba995df3b61 100644 --- a/synapse/storage/databases/main/devices.py +++ b/synapse/storage/databases/main/devices.py @@ -842,12 +842,11 @@ async def get_users_whose_devices_changed( user_ids, from_key ) - if not user_ids_to_check: + # If an empty set was returned, there's nothing to do. + if user_ids_to_check is not None and not user_ids_to_check: return set() def _get_users_whose_devices_changed_txn(txn: LoggingTransaction) -> Set[str]: - changes: Set[str] = set() - stream_id_where_clause = "stream_id > ?" sql_args = [from_key] @@ -858,19 +857,25 @@ def _get_users_whose_devices_changed_txn(txn: LoggingTransaction) -> Set[str]: sql = f""" SELECT DISTINCT user_id FROM device_lists_stream WHERE {stream_id_where_clause} - AND """ - # Query device changes with a batch of users at a time - # Assertion for mypy's benefit; see also - # https://mypy.readthedocs.io/en/stable/common_issues.html#narrowing-and-inner-functions - assert user_ids_to_check is not None - for chunk in batch_iter(user_ids_to_check, 100): - clause, args = make_in_list_sql_clause( - txn.database_engine, "user_id", chunk - ) - txn.execute(sql + clause, sql_args + args) - changes.update(user_id for user_id, in txn) + # If the stream change cache gave us no information, fetch *all* + # users between the stream IDs. + if user_ids_to_check is None: + txn.execute(sql, sql_args) + return {user_id for user_id, in txn} + + # Otherwise, fetch changes for the given users. + else: + changes: Set[str] = set() + + # Query device changes with a batch of users at a time + for chunk in batch_iter(user_ids_to_check, 100): + clause, args = make_in_list_sql_clause( + txn.database_engine, "user_id", chunk + ) + txn.execute(sql + " AND " + clause, sql_args + args) + changes.update(user_id for user_id, in txn) return changes