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Implement pagination using chunks

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This commit is contained in:
Erik Johnston
2018-05-21 17:41:10 +01:00
parent bf599cdba1
commit b671e57759
3 changed files with 109 additions and 18 deletions
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2
synapse/handlers/message.py
View File

@@ -235,7 +235,7 @@ class MessageHandler(BaseHandler):
room_id, max_topo
)
events, next_key = yield self.store.paginate_room_events(
events, next_key, extremities = yield self.store.paginate_room_events(
room_id=room_id,
from_key=source_config.from_key,
to_key=source_config.to_key,

2
synapse/handlers/room.py
View File

@@ -534,7 +534,7 @@ class RoomEventSource(object):
@defer.inlineCallbacks
def get_pagination_rows(self, user, config, key):
events, next_key = yield self.store.paginate_room_events(
events, next_key, _ = yield self.store.paginate_room_events(
room_id=key,
from_key=config.from_key,
to_key=config.to_key,

123
synapse/storage/stream.py
View File

@@ -41,6 +41,7 @@ from synapse.storage.events import EventsWorkerStore
from synapse.types import RoomStreamToken
from synapse.util.caches.stream_change_cache import StreamChangeCache
from synapse.util.logcontext import make_deferred_yieldable, run_in_background
from synapse.storage.chunk_ordered_table import ChunkDBOrderedListStore
from synapse.storage.engines import PostgresEngine
import abc
@@ -394,7 +395,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
end_token = RoomStreamToken.parse(end_token)
rows, token = yield self.runInteraction(
rows, token, _ = yield self.runInteraction(
"get_recent_event_ids_for_room", self._paginate_room_events_txn,
room_id, from_token=end_token, limit=limit,
)
@@ -632,12 +633,12 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
results["stream_ordering"],
)
rows, start_token = self._paginate_room_events_txn(
rows, start_token, _ = self._paginate_room_events_txn(
txn, room_id, before_token, direction='b', limit=before_limit,
)
events_before = [r.event_id for r in rows]
rows, end_token = self._paginate_room_events_txn(
rows, end_token, _ = self._paginate_room_events_txn(
txn, room_id, after_token, direction='f', limit=after_limit,
)
events_after = [r.event_id for r in rows]
@@ -720,12 +721,19 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
those that match the filter.
Returns:
Deferred[tuple[list[_EventDictReturn], str]]: Returns the results
as a list of _EventDictReturn and a token that points to the end
of the result set.
Deferred[tuple[list[_EventDictReturn], str, list[int]]: Returns
the results as a list of _EventDictReturn, a token that points to
the end of the result set, and a list of chunks iterated over.
"""
assert int(limit) >= 0
limit = int(limit) # Sometimes we are passed a string from somewhere
assert limit >= 0
# There are two modes of fetching events: by stream order or by
# topological order. This is determined by whether the from_token is a
# stream or topological token. If stream then we can simply do a select
# ordered by stream_ordering column. If topological, then we need to
# fetch events from one chunk at a time until we hit the limit.
# Tokens really represent positions between elements, but we use
# the convention of pointing to the event before the gap. Hence
@@ -756,7 +764,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
bounds += " AND " + filter_clause
args.extend(filter_args)
args.append(int(limit))
args.append(limit)
sql = (
"SELECT event_id, chunk_id, topological_ordering, stream_ordering"
@@ -771,7 +779,65 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
txn.execute(sql, args)
rows = [_EventDictReturn(row[0], row[1], row[2]) for row in txn]
rows = [_EventDictReturn(row[0], row[1], row[2], row[3]) for row in txn]
# If we are paginating topologically and we haven't hit the limit on
# number of events then we need to fetch events from the previous or
# next chunk.
iterated_chunks = []
chunk_id = None
if from_token.chunk: # FIXME: may be topological but no chunk.
if rows:
chunk_id = rows[-1].chunk_id
iterated_chunks = [r.chunk_id for r in rows]
else:
chunk_id = from_token.chunk
iterated_chunks = [chunk_id]
table = ChunkDBOrderedListStore(
txn, room_id, self.clock,
)
if filter_clause:
filter_clause = "AND " + filter_clause
sql = (
"SELECT event_id, chunk_id, topological_ordering, stream_ordering"
" FROM events"
" WHERE outlier = ? AND room_id = ? %(filter_clause)s"
" ORDER BY topological_ordering %(order)s,"
" stream_ordering %(order)s LIMIT ?"
) % {
"filter_clause": filter_clause,
"order": order,
}
args = [False, room_id] + filter_args + [limit]
while chunk_id and (limit <= 0 or len(rows) < limit):
if chunk_id not in iterated_chunks:
iterated_chunks.append(chunk_id)
if direction == 'b':
chunk_id = table.get_prev(chunk_id)
else:
chunk_id = table.get_next(chunk_id)
if chunk_id is None:
break
txn.execute(sql, args)
new_rows = [_EventDictReturn(row[0], row[1], row[2], row[3]) for row in txn]
if not new_rows:
break
rows.extend(new_rows)
if limit > 0:
rows = rows[:limit]
if rows:
chunk = rows[-1].chunk_id
@@ -809,18 +875,43 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
those that match the filter.
Returns:
tuple[list[dict], str]: Returns the results as a list of dicts and
a token that points to the end of the result set. The dicts have
the keys "event_id", "topological_ordering" and "stream_orderign".
tuple[list[dict], str, list[str]]: Returns the results as a list of
dicts, a token that points to the end of the result set, and a list
of backwards extremities. The dicts have the keys "event_id",
"topological_ordering" and "stream_ordering".
"""
from_key = RoomStreamToken.parse(from_key)
if to_key:
to_key = RoomStreamToken.parse(to_key)
rows, token = yield self.runInteraction(
"paginate_room_events", self._paginate_room_events_txn,
room_id, from_key, to_key, direction, limit, event_filter,
def _do_paginate_room_events(txn):
rows, token, chunks = self._paginate_room_events_txn(
txn, room_id, from_key, to_key, direction, limit, event_filter,
)
# We now fetch the extremities by fetching the extremities for
# each chunk we iterated over.
extremities = []
seen = set()
for chunk_id in chunks:
if chunk_id in seen:
continue
seen.add(chunk_id)
event_ids = self._simple_select_onecol_txn(
txn,
table="chunk_backwards_extremities",
keyvalues={"chunk_id": chunk_id},
retcol="event_id"
)
extremities.extend(e for e in event_ids if e not in extremities)
return rows, token, extremities
rows, token, extremities = yield self.runInteraction(
"paginate_room_events", _do_paginate_room_events,
)
events = yield self._get_events(
@@ -830,7 +921,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
self._set_before_and_after(events, rows)
defer.returnValue((events, token))
defer.returnValue((events, token, extremities))
class StreamStore(StreamWorkerStore):