Remove concept of a non-limited stream. (#7011)

8 files changed, 71 insertions, 67 deletions

diff --git a/changelog.d/7011.misc b/changelog.d/7011.misc
new file mode 100644
index 0000000000..41c3b37574
--- /dev/null
+++ b/changelog.d/7011.misc
@@ -0,0 +1 @@
+Remove concept of a non-limited stream.
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 5526015ddb..6912165622 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -747,7 +747,7 @@ class PresenceHandler(object):
 
         return False
 
-    async def get_all_presence_updates(self, last_id, current_id):
+    async def get_all_presence_updates(self, last_id, current_id, limit):
         """
         Gets a list of presence update rows from between the given stream ids.
         Each row has:
@@ -762,7 +762,7 @@ class PresenceHandler(object):
         """
         # TODO(markjh): replicate the unpersisted changes.
         # This could use the in-memory stores for recent changes.
-        rows = await self.store.get_all_presence_updates(last_id, current_id)
+        rows = await self.store.get_all_presence_updates(last_id, current_id, limit)
         return rows
 
     def notify_new_event(self):
diff --git a/synapse/handlers/typing.py b/synapse/handlers/typing.py
index 391bceb0c4..c7bc14c623 100644
--- a/synapse/handlers/typing.py
+++ b/synapse/handlers/typing.py
@@ -15,6 +15,7 @@
 
 import logging
 from collections import namedtuple
+from typing import List
 
 from twisted.internet import defer
 
@@ -257,7 +258,13 @@ class TypingHandler(object):
             "typing_key", self._latest_room_serial, rooms=[member.room_id]
         )
 
-    async def get_all_typing_updates(self, last_id, current_id):
+    async def get_all_typing_updates(
+        self, last_id: int, current_id: int, limit: int
+    ) -> List[dict]:
+        """Get up to `limit` typing updates between the given tokens, earliest
+        updates first.
+        """
+
         if last_id == current_id:
             return []
 
@@ -275,7 +282,7 @@ class TypingHandler(object):
                 typing = self._room_typing[room_id]
                 rows.append((serial, room_id, list(typing)))
         rows.sort()
-        return rows
+        return rows[:limit]
 
     def get_current_token(self):
         return self._latest_room_serial
diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py
index ce9d1fae12..6e2ebaf614 100644
--- a/synapse/replication/tcp/resource.py
+++ b/synapse/replication/tcp/resource.py
@@ -166,11 +166,6 @@ class ReplicationStreamer(object):
                 self.pending_updates = False
 
                 with Measure(self.clock, "repl.stream.get_updates"):
-                    # First we tell the streams that they should update their
-                    # current tokens.
-                    for stream in self.streams:
-                        stream.advance_current_token()
-
                     all_streams = self.streams
 
                     if self._replication_torture_level is not None:
@@ -180,7 +175,7 @@ class ReplicationStreamer(object):
                         random.shuffle(all_streams)
 
                     for stream in all_streams:
-                        if stream.last_token == stream.upto_token:
+                        if stream.last_token == stream.current_token():
                             continue
 
                         if self._replication_torture_level:
@@ -192,7 +187,7 @@ class ReplicationStreamer(object):
                             "Getting stream: %s: %s -> %s",
                             stream.NAME,
                             stream.last_token,
-                            stream.upto_token,
+                            stream.current_token(),
                         )
                         try:
                             updates, current_token = await stream.get_updates()
diff --git a/synapse/replication/tcp/streams/_base.py b/synapse/replication/tcp/streams/_base.py
index 7a8b6e9df1..abf5c6c6a8 100644
--- a/synapse/replication/tcp/streams/_base.py
+++ b/synapse/replication/tcp/streams/_base.py
@@ -17,10 +17,12 @@
 import itertools
 import logging
 from collections import namedtuple
-from typing import Any, List, Optional
+from typing import Any, List, Optional, Tuple
 
 import attr
 
+from synapse.types import JsonDict
+
 logger = logging.getLogger(__name__)
 
 
@@ -119,13 +121,12 @@ class Stream(object):
     """Base class for the streams.
 
     Provides a `get_updates()` function that returns new updates since the last
-    time it was called up until the point `advance_current_token` was called.
+    time it was called.
     """
 
     NAME = None  # type: str  # The name of the stream
     # The type of the row. Used by the default impl of parse_row.
     ROW_TYPE = None  # type: Any
-    _LIMITED = True  # Whether the update function takes a limit
 
     @classmethod
     def parse_row(cls, row):
@@ -146,26 +147,15 @@ class Stream(object):
         # The token from which we last asked for updates
         self.last_token = self.current_token()
 
-        # The token that we will get updates up to
-        self.upto_token = self.current_token()
-
-    def advance_current_token(self):
-        """Updates `upto_token` to "now", which updates up until which point
-        get_updates[_since] will fetch rows till.
-        """
-        self.upto_token = self.current_token()
-
     def discard_updates_and_advance(self):
         """Called when the stream should advance but the updates would be discarded,
         e.g. when there are no currently connected workers.
         """
-        self.upto_token = self.current_token()
-        self.last_token = self.upto_token
+        self.last_token = self.current_token()
 
     async def get_updates(self):
         """Gets all updates since the last time this function was called (or
-        since the stream was constructed if it hadn't been called before),
-        until the `upto_token`
+        since the stream was constructed if it hadn't been called before).
 
         Returns:
             Deferred[Tuple[List[Tuple[int, Any]], int]:
@@ -178,44 +168,45 @@ class Stream(object):
 
         return updates, current_token
 
-    async def get_updates_since(self, from_token):
+    async def get_updates_since(
+        self, from_token: int
+    ) -> Tuple[List[Tuple[int, JsonDict]], int]:
         """Like get_updates except allows specifying from when we should
         stream updates
 
         Returns:
-            Deferred[Tuple[List[Tuple[int, Any]], int]:
-                Resolves to a pair ``(updates, current_token)``, where ``updates`` is a
-                list of ``(token, row)`` entries. ``row`` will be json-serialised and
-                sent over the replication steam.
+            Resolves to a pair `(updates, new_last_token)`, where `updates` is
+            a list of `(token, row)` entries and `new_last_token` is the new
+            position in stream.
         """
+
         if from_token in ("NOW", "now"):
-            return [], self.upto_token
+            return [], self.current_token()
 
-        current_token = self.upto_token
+        current_token = self.current_token()
 
         from_token = int(from_token)
 
         if from_token == current_token:
             return [], current_token
 
-        logger.info("get_updates_since: %s", self.__class__)
-        if self._LIMITED:
-            rows = await self.update_function(
-                from_token, current_token, limit=MAX_EVENTS_BEHIND + 1
-            )
+        rows = await self.update_function(
+            from_token, current_token, limit=MAX_EVENTS_BEHIND + 1
+        )
 
-            # never turn more than MAX_EVENTS_BEHIND + 1 into updates.
-            rows = itertools.islice(rows, MAX_EVENTS_BEHIND + 1)
-        else:
-            rows = await self.update_function(from_token, current_token)
+        # never turn more than MAX_EVENTS_BEHIND + 1 into updates.
+        rows = itertools.islice(rows, MAX_EVENTS_BEHIND + 1)
 
         updates = [(row[0], row[1:]) for row in rows]
 
         # check we didn't get more rows than the limit.
         # doing it like this allows the update_function to be a generator.
-        if self._LIMITED and len(updates) >= MAX_EVENTS_BEHIND:
+        if len(updates) >= MAX_EVENTS_BEHIND:
             raise Exception("stream %s has fallen behind" % (self.NAME))
 
+        # The update function didn't hit the limit, so we must have got all
+        # the updates to `current_token`, and can return that as our new
+        # stream position.
         return updates, current_token
 
     def current_token(self):
@@ -227,9 +218,8 @@ class Stream(object):
         """
         raise NotImplementedError()
 
-    def update_function(self, from_token, current_token, limit=None):
-        """Get updates between from_token and to_token. If Stream._LIMITED is
-        True then limit is provided, otherwise it's not.
+    def update_function(self, from_token, current_token, limit):
+        """Get updates between from_token and to_token.
 
         Returns:
             Deferred(list(tuple)): the first entry in the tuple is the token for
@@ -257,7 +247,6 @@ class BackfillStream(Stream):
 
 class PresenceStream(Stream):
     NAME = "presence"
-    _LIMITED = False
     ROW_TYPE = PresenceStreamRow
 
     def __init__(self, hs):
@@ -272,7 +261,6 @@ class PresenceStream(Stream):
 
 class TypingStream(Stream):
     NAME = "typing"
-    _LIMITED = False
     ROW_TYPE = TypingStreamRow
 
     def __init__(self, hs):
@@ -372,7 +360,6 @@ class DeviceListsStream(Stream):
     """
 
     NAME = "device_lists"
-    _LIMITED = False
     ROW_TYPE = DeviceListsStreamRow
 
     def __init__(self, hs):
@@ -462,7 +449,6 @@ class UserSignatureStream(Stream):
     """
 
     NAME = "user_signature"
-    _LIMITED = False
     ROW_TYPE = UserSignatureStreamRow
 
     def __init__(self, hs):
diff --git a/synapse/storage/data_stores/main/devices.py b/synapse/storage/data_stores/main/devices.py
index 4c19c02bbc..2d47cfd131 100644
--- a/synapse/storage/data_stores/main/devices.py
+++ b/synapse/storage/data_stores/main/devices.py
@@ -576,7 +576,7 @@ class DeviceWorkerStore(SQLBaseStore):
             return set()
 
     async def get_all_device_list_changes_for_remotes(
-        self, from_key: int, to_key: int
+        self, from_key: int, to_key: int, limit: int,
     ) -> List[Tuple[int, str]]:
         """Return a list of `(stream_id, entity)` which is the combined list of
         changes to devices and which destinations need to be poked. Entity is
@@ -592,10 +592,16 @@ class DeviceWorkerStore(SQLBaseStore):
                 SELECT stream_id, destination AS entity FROM device_lists_outbound_pokes
             ) AS e
             WHERE ? < stream_id AND stream_id <= ?
+            LIMIT ?
         """
 
         return await self.db.execute(
-            "get_all_device_list_changes_for_remotes", None, sql, from_key, to_key
+            "get_all_device_list_changes_for_remotes",
+            None,
+            sql,
+            from_key,
+            to_key,
+            limit,
         )
 
     @cached(max_entries=10000)
diff --git a/synapse/storage/data_stores/main/end_to_end_keys.py b/synapse/storage/data_stores/main/end_to_end_keys.py
index 001a53f9b4..bcf746b7ef 100644
--- a/synapse/storage/data_stores/main/end_to_end_keys.py
+++ b/synapse/storage/data_stores/main/end_to_end_keys.py
@@ -537,7 +537,7 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
 
         return result
 
-    def get_all_user_signature_changes_for_remotes(self, from_key, to_key):
+    def get_all_user_signature_changes_for_remotes(self, from_key, to_key, limit):
         """Return a list of changes from the user signature stream to notify remotes.
         Note that the user signature stream represents when a user signs their
         device with their user-signing key, which is not published to other
@@ -552,13 +552,19 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
             Deferred[list[(int,str)]] a list of `(stream_id, user_id)`
         """
         sql = """
-            SELECT MAX(stream_id) AS stream_id, from_user_id AS user_id
+            SELECT stream_id, from_user_id AS user_id
             FROM user_signature_stream
             WHERE ? < stream_id AND stream_id <= ?
-            GROUP BY user_id
+            ORDER BY stream_id ASC
+            LIMIT ?
         """
         return self.db.execute(
-            "get_all_user_signature_changes_for_remotes", None, sql, from_key, to_key
+            "get_all_user_signature_changes_for_remotes",
+            None,
+            sql,
+            from_key,
+            to_key,
+            limit,
         )
 
 
diff --git a/synapse/storage/data_stores/main/presence.py b/synapse/storage/data_stores/main/presence.py
index 604c8b7ddd..dab31e0c2d 100644
--- a/synapse/storage/data_stores/main/presence.py
+++ b/synapse/storage/data_stores/main/presence.py
@@ -60,7 +60,7 @@ class PresenceStore(SQLBaseStore):
                     "status_msg": state.status_msg,
                     "currently_active": state.currently_active,
                 }
-                for state in presence_states
+                for stream_id, state in zip(stream_orderings, presence_states)
             ],
         )
 
@@ -73,19 +73,22 @@ class PresenceStore(SQLBaseStore):
             )
             txn.execute(sql + clause, [stream_id] + list(args))
 
-    def get_all_presence_updates(self, last_id, current_id):
+    def get_all_presence_updates(self, last_id, current_id, limit):
         if last_id == current_id:
             return defer.succeed([])
 
         def get_all_presence_updates_txn(txn):
-            sql = (
-                "SELECT stream_id, user_id, state, last_active_ts,"
-                " last_federation_update_ts, last_user_sync_ts, status_msg,"
-                " currently_active"
-                " FROM presence_stream"
-                " WHERE ? < stream_id AND stream_id <= ?"
-            )
-            txn.execute(sql, (last_id, current_id))
+            sql = """
+                SELECT stream_id, user_id, state, last_active_ts,
+                    last_federation_update_ts, last_user_sync_ts,
+                    status_msg,
+                currently_active
+                FROM presence_stream
+                WHERE ? < stream_id AND stream_id <= ?
+                ORDER BY stream_id ASC
+                LIMIT ?
+            """
+            txn.execute(sql, (last_id, current_id, limit))
             return txn.fetchall()
 
         return self.db.runInteraction(