Fix public room list pagination.

We incorrectly used `room_id` as to bound the result set, even though we
order by `joined_members, room_id`, leading to incorrect results after
pagination.
This commit is contained in:
Erik Johnston 2019-10-02 15:09:10 +01:00
parent baf12bc02a
commit 03cf4385e0
2 changed files with 59 additions and 27 deletions

View File

@ -142,12 +142,12 @@ class RoomListHandler(BaseHandler):
if since_token:
batch_token = RoomListNextBatch.from_token(since_token)
last_room_id = batch_token.last_room_id
bounds = (batch_token.last_joined_members, batch_token.last_room_id)
forwards = batch_token.direction_is_forward
else:
batch_token = None
bounds = None
last_room_id = None
forwards = True
# we request one more than wanted to see if there are more pages to come
@ -157,7 +157,7 @@ class RoomListHandler(BaseHandler):
network_tuple,
search_filter,
probing_limit,
last_room_id=last_room_id,
bounds=bounds,
forwards=forwards,
ignore_non_federatable=from_federation,
)
@ -193,30 +193,38 @@ class RoomListHandler(BaseHandler):
more_to_come = False
if num_results > 0:
final_room_id = results[-1]["room_id"]
initial_room_id = results[0]["room_id"]
final_entry = results[-1]
initial_entry = results[0]
if forwards:
if batch_token:
# If there was a token given then we assume that there
# must be previous results.
response["prev_batch"] = RoomListNextBatch(
last_room_id=initial_room_id, direction_is_forward=False
last_joined_members=initial_entry["num_joined_members"],
last_room_id=initial_entry["room_id"],
direction_is_forward=False,
).to_token()
if more_to_come:
response["next_batch"] = RoomListNextBatch(
last_room_id=final_room_id, direction_is_forward=True
last_joined_members=final_entry["num_joined_members"],
last_room_id=final_entry["room_id"],
direction_is_forward=True,
).to_token()
else:
if batch_token:
response["next_batch"] = RoomListNextBatch(
last_room_id=final_room_id, direction_is_forward=True
last_joined_members=final_entry["num_joined_members"],
last_room_id=final_entry["room_id"],
direction_is_forward=True,
).to_token()
if more_to_come:
response["prev_batch"] = RoomListNextBatch(
last_room_id=initial_room_id, direction_is_forward=False
last_joined_members=initial_entry["num_joined_members"],
last_room_id=initial_entry["room_id"],
direction_is_forward=False,
).to_token()
for room in results:
@ -449,12 +457,17 @@ class RoomListNextBatch(
namedtuple(
"RoomListNextBatch",
(
"last_joined_members", # The count to get rooms after/before
"last_room_id", # The room_id to get rooms after/before
"direction_is_forward", # Bool if this is a next_batch, false if prev_batch
),
)
):
KEY_DICT = {"last_room_id": "r", "direction_is_forward": "d"}
KEY_DICT = {
"last_joined_members": "m",
"last_room_id": "r",
"direction_is_forward": "d",
}
REVERSE_KEY_DICT = {v: k for k, v in KEY_DICT.items()}

View File

@ -17,6 +17,7 @@
import collections
import logging
import re
from typing import Optional, Tuple
from canonicaljson import json
@ -25,6 +26,7 @@ from twisted.internet import defer
from synapse.api.errors import StoreError
from synapse.storage._base import SQLBaseStore
from synapse.storage.search import SearchStore
from synapse.types import ThirdPartyInstanceID
from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
logger = logging.getLogger(__name__)
@ -119,24 +121,25 @@ class RoomWorkerStore(SQLBaseStore):
@defer.inlineCallbacks
def get_largest_public_rooms(
self,
network_tuple,
search_filter,
limit,
last_room_id,
forwards,
ignore_non_federatable=False,
network_tuple: Optional[ThirdPartyInstanceID],
search_filter: Optional[dict],
limit: Optional[int],
bounds: Optional[Tuple[int, str]],
forwards: bool,
ignore_non_federatable: bool = False,
):
"""Gets the largest public rooms (where largest is in terms of joined
members, as tracked in the statistics table).
Args:
network_tuple (ThirdPartyInstanceID|None):
search_filter (dict|None):
limit (int|None): Maxmimum number of rows to return, unlimited otherwise.
last_room_id (str|None): if present, a room ID which bounds the
result set, and is always *excluded* from the result set.
forwards (bool): true iff going forwards, going backwards otherwise
ignore_non_federatable (bool): If true filters out non-federatable rooms.
network_tuple
search_filter
limit: Maxmimum number of rows to return, unlimited otherwise.
bounds: An uppoer or lower bound to apply to result set if given,
consists of a joined member count and room_id (these are
excluded from result set).
forwards: true iff going forwards, going backwards otherwise
ignore_non_federatable: If true filters out non-federatable rooms.
Returns:
Rooms in order: biggest number of joined users first.
@ -147,13 +150,29 @@ class RoomWorkerStore(SQLBaseStore):
where_clauses = []
query_args = []
if last_room_id:
# Work out the bounds if we're given them, these bounds look slightly
# odd, but are designed to help query planner use indices by pulling
# out a common bound.
if bounds:
last_joined_members, last_room_id = bounds
if forwards:
where_clauses.append("room_id < ?")
where_clauses.append(
"""
joined_members <= ? AND (
joined_members < ? OR room_id < ?
)
"""
)
else:
where_clauses.append("? < room_id")
where_clauses.append(
"""
joined_members >= ? AND (
joined_members > ? OR room_id > ?
)
"""
)
query_args += [last_room_id]
query_args += [last_joined_members, last_joined_members, last_room_id]
if search_filter and search_filter.get("generic_search_term", None):
search_term = "%" + search_filter["generic_search_term"] + "%"