Catch up after Federation Outage (split, 2): Track last successful stream ordering after transmission (#8247)

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

synapse/storage/databases/main/transactions.py

@@ -333,3 +333,41 @@ class TransactionStore(SQLBaseStore):
             ["stream_ordering"],
             [(stream_ordering,)] * len(rows),
         )
+
+    async def get_destination_last_successful_stream_ordering(
+        self, destination: str
+    ) -> Optional[int]:
+        """
+        Gets the stream ordering of the PDU most-recently successfully sent
+        to the specified destination, or None if this information has not been
+        tracked yet.
+
+        Args:
+            destination: the destination to query
+        """
+        return await self.db_pool.simple_select_one_onecol(
+            "destinations",
+            {"destination": destination},
+            "last_successful_stream_ordering",
+            allow_none=True,
+            desc="get_last_successful_stream_ordering",
+        )
+
+    async def set_destination_last_successful_stream_ordering(
+        self, destination: str, last_successful_stream_ordering: int
+    ) -> None:
+        """
+        Marks that we have successfully sent the PDUs up to and including the
+        one specified.
+
+        Args:
+            destination: the destination we have successfully sent to
+            last_successful_stream_ordering: the stream_ordering of the most
+                recent successfully-sent PDU
+        """
+        return await self.db_pool.simple_upsert(
+            "destinations",
+            keyvalues={"destination": destination},
+            values={"last_successful_stream_ordering": last_successful_stream_ordering},
+            desc="set_last_successful_stream_ordering",
+        )