Don't pull event from DB when handling replication traffic. (#8669)

I was trying to make it so that we didn't have to start a background task when handling RDATA, but that is a bigger job (due to all the code in `generic_worker`). However I still think not pulling the event from the DB may help reduce some DB usage due to replication, even if most workers will simply go and pull that event from the DB later anyway.

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>
This commit is contained in:
Erik Johnston 2020-10-28 12:11:45 +00:00 committed by GitHub
parent aff1eb7c67
commit a6ea1a957e
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5 changed files with 87 additions and 31 deletions

1
changelog.d/8669.misc Normal file
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@ -0,0 +1 @@
Don't pull event from DB when handling replication traffic.

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@ -28,6 +28,7 @@ from typing import (
Union,
)
import attr
from prometheus_client import Counter
from twisted.internet import defer
@ -173,6 +174,17 @@ class EventStreamResult(namedtuple("EventStreamResult", ("events", "tokens"))):
return bool(self.events)
@attr.s(slots=True, frozen=True)
class _PendingRoomEventEntry:
event_pos = attr.ib(type=PersistedEventPosition)
extra_users = attr.ib(type=Collection[UserID])
room_id = attr.ib(type=str)
type = attr.ib(type=str)
state_key = attr.ib(type=Optional[str])
membership = attr.ib(type=Optional[str])
class Notifier:
""" This class is responsible for notifying any listeners when there are
new events available for it.
@ -190,9 +202,7 @@ class Notifier:
self.storage = hs.get_storage()
self.event_sources = hs.get_event_sources()
self.store = hs.get_datastore()
self.pending_new_room_events = (
[]
) # type: List[Tuple[PersistedEventPosition, EventBase, Collection[UserID]]]
self.pending_new_room_events = [] # type: List[_PendingRoomEventEntry]
# Called when there are new things to stream over replication
self.replication_callbacks = [] # type: List[Callable[[], None]]
@ -254,6 +264,28 @@ class Notifier:
event_pos: PersistedEventPosition,
max_room_stream_token: RoomStreamToken,
extra_users: Collection[UserID] = [],
):
"""Unwraps event and calls `on_new_room_event_args`.
"""
self.on_new_room_event_args(
event_pos=event_pos,
room_id=event.room_id,
event_type=event.type,
state_key=event.get("state_key"),
membership=event.content.get("membership"),
max_room_stream_token=max_room_stream_token,
extra_users=extra_users,
)
def on_new_room_event_args(
self,
room_id: str,
event_type: str,
state_key: Optional[str],
membership: Optional[str],
event_pos: PersistedEventPosition,
max_room_stream_token: RoomStreamToken,
extra_users: Collection[UserID] = [],
):
"""Used by handlers to inform the notifier something has happened
in the room, room event wise.
@ -266,7 +298,16 @@ class Notifier:
until all previous events have been persisted before notifying
the client streams.
"""
self.pending_new_room_events.append((event_pos, event, extra_users))
self.pending_new_room_events.append(
_PendingRoomEventEntry(
event_pos=event_pos,
extra_users=extra_users,
room_id=room_id,
type=event_type,
state_key=state_key,
membership=membership,
)
)
self._notify_pending_new_room_events(max_room_stream_token)
self.notify_replication()
@ -284,18 +325,19 @@ class Notifier:
users = set() # type: Set[UserID]
rooms = set() # type: Set[str]
for event_pos, event, extra_users in pending:
if event_pos.persisted_after(max_room_stream_token):
self.pending_new_room_events.append((event_pos, event, extra_users))
for entry in pending:
if entry.event_pos.persisted_after(max_room_stream_token):
self.pending_new_room_events.append(entry)
else:
if (
event.type == EventTypes.Member
and event.membership == Membership.JOIN
entry.type == EventTypes.Member
and entry.membership == Membership.JOIN
and entry.state_key
):
self._user_joined_room(event.state_key, event.room_id)
self._user_joined_room(entry.state_key, entry.room_id)
users.update(extra_users)
rooms.add(event.room_id)
users.update(entry.extra_users)
rooms.add(entry.room_id)
if users or rooms:
self.on_new_event(

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@ -141,21 +141,25 @@ class ReplicationDataHandler:
if row.type != EventsStreamEventRow.TypeId:
continue
assert isinstance(row, EventsStreamRow)
assert isinstance(row.data, EventsStreamEventRow)
event = await self.store.get_event(
row.data.event_id, allow_rejected=True
)
if event.rejected_reason:
if row.data.rejected:
continue
extra_users = () # type: Tuple[UserID, ...]
if event.type == EventTypes.Member:
extra_users = (UserID.from_string(event.state_key),)
if row.data.type == EventTypes.Member and row.data.state_key:
extra_users = (UserID.from_string(row.data.state_key),)
max_token = self.store.get_room_max_token()
event_pos = PersistedEventPosition(instance_name, token)
self.notifier.on_new_room_event(
event, event_pos, max_token, extra_users
self.notifier.on_new_room_event_args(
event_pos=event_pos,
max_room_stream_token=max_token,
extra_users=extra_users,
room_id=row.data.room_id,
event_type=row.data.type,
state_key=row.data.state_key,
membership=row.data.membership,
)
# Notify any waiting deferreds. The list is ordered by position so we

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@ -15,12 +15,15 @@
# limitations under the License.
import heapq
from collections.abc import Iterable
from typing import List, Tuple, Type
from typing import TYPE_CHECKING, List, Optional, Tuple, Type
import attr
from ._base import Stream, StreamUpdateResult, Token
if TYPE_CHECKING:
from synapse.server import HomeServer
"""Handling of the 'events' replication stream
This stream contains rows of various types. Each row therefore contains a 'type'
@ -81,12 +84,14 @@ class BaseEventsStreamRow:
class EventsStreamEventRow(BaseEventsStreamRow):
TypeId = "ev"
event_id = attr.ib() # str
room_id = attr.ib() # str
type = attr.ib() # str
state_key = attr.ib() # str, optional
redacts = attr.ib() # str, optional
relates_to = attr.ib() # str, optional
event_id = attr.ib(type=str)
room_id = attr.ib(type=str)
type = attr.ib(type=str)
state_key = attr.ib(type=Optional[str])
redacts = attr.ib(type=Optional[str])
relates_to = attr.ib(type=Optional[str])
membership = attr.ib(type=Optional[str])
rejected = attr.ib(type=bool)
@attr.s(slots=True, frozen=True)
@ -113,7 +118,7 @@ class EventsStream(Stream):
NAME = "events"
def __init__(self, hs):
def __init__(self, hs: "HomeServer"):
self._store = hs.get_datastore()
super().__init__(
hs.get_instance_name(),

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@ -1117,11 +1117,13 @@ class EventsWorkerStore(SQLBaseStore):
def get_all_new_forward_event_rows(txn):
sql = (
"SELECT e.stream_ordering, e.event_id, e.room_id, e.type,"
" state_key, redacts, relates_to_id"
" state_key, redacts, relates_to_id, membership, rejections.reason IS NOT NULL"
" FROM events AS e"
" LEFT JOIN redactions USING (event_id)"
" LEFT JOIN state_events USING (event_id)"
" LEFT JOIN event_relations USING (event_id)"
" LEFT JOIN room_memberships USING (event_id)"
" LEFT JOIN rejections USING (event_id)"
" WHERE ? < stream_ordering AND stream_ordering <= ?"
" AND instance_name = ?"
" ORDER BY stream_ordering ASC"
@ -1152,12 +1154,14 @@ class EventsWorkerStore(SQLBaseStore):
def get_ex_outlier_stream_rows_txn(txn):
sql = (
"SELECT event_stream_ordering, e.event_id, e.room_id, e.type,"
" state_key, redacts, relates_to_id"
" state_key, redacts, relates_to_id, membership, rejections.reason IS NOT NULL"
" FROM events AS e"
" INNER JOIN ex_outlier_stream AS out USING (event_id)"
" LEFT JOIN redactions USING (event_id)"
" LEFT JOIN state_events USING (event_id)"
" LEFT JOIN event_relations USING (event_id)"
" LEFT JOIN room_memberships USING (event_id)"
" LEFT JOIN rejections USING (event_id)"
" WHERE ? < event_stream_ordering"
" AND event_stream_ordering <= ?"
" AND out.instance_name = ?"