Properly paginate forward in the /relations API. (#13840)

This fixes a bug where the `/relations` API with `dir=f` would
skip the first item of each page (except the first page), causing
incomplete data to be returned to the client.
pull/13872/head
Patrick Cloke 2022-09-22 08:47:49 -04:00 committed by GitHub
parent 1a1abdda42
commit b7272b73aa
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4 changed files with 60 additions and 14 deletions

1
changelog.d/13840.bugfix Normal file
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@ -0,0 +1 @@
Fix a bug introduced in Synapse v1.53.0 where the experimental implementation of [MSC3715](https://github.com/matrix-org/matrix-spec-proposals/pull/3715) would give incorrect results when paginating forward.

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@ -51,6 +51,8 @@ class _RelatedEvent:
event_id: str
# The sender of the related event.
sender: str
topological_ordering: Optional[int]
stream_ordering: int
class RelationsWorkerStore(SQLBaseStore):
@ -91,6 +93,9 @@ class RelationsWorkerStore(SQLBaseStore):
# it. The `event_id` must match the `event.event_id`.
assert event.event_id == event_id
# Ensure bad limits aren't being passed in.
assert limit >= 0
where_clause = ["relates_to_id = ?", "room_id = ?"]
where_args: List[Union[str, int]] = [event.event_id, room_id]
is_redacted = event.internal_metadata.is_redacted()
@ -139,21 +144,34 @@ class RelationsWorkerStore(SQLBaseStore):
) -> Tuple[List[_RelatedEvent], Optional[StreamToken]]:
txn.execute(sql, where_args + [limit + 1])
last_topo_id = None
last_stream_id = None
events = []
for row in txn:
for event_id, relation_type, sender, topo_ordering, stream_ordering in txn:
# Do not include edits for redacted events as they leak event
# content.
if not is_redacted or row[1] != RelationTypes.REPLACE:
events.append(_RelatedEvent(row[0], row[2]))
last_topo_id = row[3]
last_stream_id = row[4]
if not is_redacted or relation_type != RelationTypes.REPLACE:
events.append(
_RelatedEvent(event_id, sender, topo_ordering, stream_ordering)
)
# If there are more events, generate the next pagination key.
# If there are more events, generate the next pagination key from the
# last event returned.
next_token = None
if len(events) > limit and last_topo_id and last_stream_id:
next_key = RoomStreamToken(last_topo_id, last_stream_id)
if len(events) > limit:
# Instead of using the last row (which tells us there is more
# data), use the last row to be returned.
events = events[:limit]
topo = events[-1].topological_ordering
token = events[-1].stream_ordering
if direction == "b":
# Tokens are positions between events.
# This token points *after* the last event in the chunk.
# We need it to point to the event before it in the chunk
# when we are going backwards so we subtract one from the
# stream part.
token -= 1
next_key = RoomStreamToken(topo, token)
if from_token:
next_token = from_token.copy_and_replace(
StreamKeyType.ROOM, next_key

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@ -1334,15 +1334,15 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
if rows:
topo = rows[-1].topological_ordering
toke = rows[-1].stream_ordering
token = rows[-1].stream_ordering
if direction == "b":
# Tokens are positions between events.
# This token points *after* the last event in the chunk.
# We need it to point to the event before it in the chunk
# when we are going backwards so we subtract one from the
# stream part.
toke -= 1
next_token = RoomStreamToken(topo, toke)
token -= 1
next_token = RoomStreamToken(topo, token)
else:
# TODO (erikj): We should work out what to do here instead.
next_token = to_token if to_token else from_token

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@ -788,6 +788,7 @@ class RelationPaginationTestCase(BaseRelationsTestCase):
channel.json_body["chunk"][0],
)
@unittest.override_config({"experimental_features": {"msc3715_enabled": True}})
def test_repeated_paginate_relations(self) -> None:
"""Test that if we paginate using a limit and tokens then we get the
expected events.
@ -809,7 +810,7 @@ class RelationPaginationTestCase(BaseRelationsTestCase):
channel = self.make_request(
"GET",
f"/_matrix/client/v1/rooms/{self.room}/relations/{self.parent_id}?limit=1{from_token}",
f"/_matrix/client/v1/rooms/{self.room}/relations/{self.parent_id}?limit=3{from_token}",
access_token=self.user_token,
)
self.assertEqual(200, channel.code, channel.json_body)
@ -827,6 +828,32 @@ class RelationPaginationTestCase(BaseRelationsTestCase):
found_event_ids.reverse()
self.assertEqual(found_event_ids, expected_event_ids)
# Test forward pagination.
prev_token = ""
found_event_ids = []
for _ in range(20):
from_token = ""
if prev_token:
from_token = "&from=" + prev_token
channel = self.make_request(
"GET",
f"/_matrix/client/v1/rooms/{self.room}/relations/{self.parent_id}?org.matrix.msc3715.dir=f&limit=3{from_token}",
access_token=self.user_token,
)
self.assertEqual(200, channel.code, channel.json_body)
found_event_ids.extend(e["event_id"] for e in channel.json_body["chunk"])
next_batch = channel.json_body.get("next_batch")
self.assertNotEqual(prev_token, next_batch)
prev_token = next_batch
if not prev_token:
break
self.assertEqual(found_event_ids, expected_event_ids)
def test_pagination_from_sync_and_messages(self) -> None:
"""Pagination tokens from /sync and /messages can be used to paginate /relations."""
channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "A")