Sliding Sync: Make `PerConnectionState` immutable (#17600)

This is so that we can cache it.

We also move the sliding sync types to
`synapse/types/handlers/sliding_sync.py`. This is mainly in-prep for
#17599 to avoid circular imports.

The only change in behaviour is that
`RoomSyncConfig.combine_sync_config(..)` now returns a new room sync
config rather than mutating in-place.

Reviewable commit-by-commit.

---------

Co-authored-by: Eric Eastwood <eric.eastwood@beta.gouv.fr>

1 files changed, 8 insertions, 6 deletions

diff --git a/synapse/handlers/sliding_sync/extensions.py b/synapse/handlers/sliding_sync/extensions.py

index a2d4f24f9c..d9f4c56e6e 100644
--- a/synapse/handlers/sliding_sync/extensions.py
+++ b/synapse/handlers/sliding_sync/extensions.py
@@ -20,11 +20,6 @@ from typing_extensions import assert_never
 
 from synapse.api.constants import AccountDataTypes, EduTypes
 from synapse.handlers.receipts import ReceiptEventSource
-from synapse.handlers.sliding_sync.types import (
-    HaveSentRoomFlag,
-    MutablePerConnectionState,
-    PerConnectionState,
-)
 from synapse.logging.opentracing import trace
 from synapse.storage.databases.main.receipts import ReceiptInRoom
 from synapse.types import (
@@ -35,7 +30,14 @@ from synapse.types import (
     StrCollection,
     StreamToken,
 )
-from synapse.types.handlers import OperationType, SlidingSyncConfig, SlidingSyncResult
+from synapse.types.handlers.sliding_sync import (
+    HaveSentRoomFlag,
+    MutablePerConnectionState,
+    OperationType,
+    PerConnectionState,
+    SlidingSyncConfig,
+    SlidingSyncResult,
+)
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer