Move event stream handling out of slave store. (#7491)

This allows us to have the logic on both master and workers, which is necessary to move event persistence off master.

We also combine the instantiation of ID generators from DataStore and slave stores to the base worker stores. This allows us to select which process writes events independently of the master/worker splits.

1 files changed, 11 insertions, 0 deletions

diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
index 86d04ea9ac..f89ce0bed2 100644
--- a/synapse/storage/util/id_generators.py
+++ b/synapse/storage/util/id_generators.py
@@ -166,6 +166,7 @@ class ChainedIdGenerator(object):
 
     def __init__(self, chained_generator, db_conn, table, column):
         self.chained_generator = chained_generator
+        self._table = table
         self._lock = threading.Lock()
         self._current_max = _load_current_id(db_conn, table, column)
         self._unfinished_ids = deque()  # type: Deque[Tuple[int, int]]
@@ -204,6 +205,16 @@ class ChainedIdGenerator(object):
 
             return self._current_max, self.chained_generator.get_current_token()
 
+    def advance(self, token: int):
+        """Stub implementation for advancing the token when receiving updates
+        over replication; raises an exception as this instance should be the
+        only source of updates.
+        """
+
+        raise Exception(
+            "Attempted to advance token on source for table %r", self._table
+        )
+
 
 class MultiWriterIdGenerator:
     """An ID generator that tracks a stream that can have multiple writers.