# -*- coding: utf-8 -*-
# Copyright 2014 - 2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from collections import namedtuple
from typing import (
Awaitable,
Callable,
Dict,
Iterable,
List,
Optional,
Set,
Tuple,
TypeVar,
Union,
)
import attr
from prometheus_client import Counter
from twisted.internet import defer
import synapse.server
from synapse.api.constants import EventTypes, HistoryVisibility, Membership
from synapse.api.errors import AuthError
from synapse.events import EventBase
from synapse.handlers.presence import format_user_presence_state
from synapse.logging.context import PreserveLoggingContext
from synapse.logging.utils import log_function
from synapse.metrics import LaterGauge
from synapse.streams.config import PaginationConfig
from synapse.types import (
Collection,
PersistedEventPosition,
RoomStreamToken,
StreamToken,
UserID,
)
from synapse.util.async_helpers import ObservableDeferred, timeout_deferred
from synapse.util.metrics import Measure
from synapse.visibility import filter_events_for_client
logger = logging.getLogger(__name__)
notified_events_counter = Counter("synapse_notifier_notified_events", "")
users_woken_by_stream_counter = Counter(
"synapse_notifier_users_woken_by_stream", "", ["stream"]
)
T = TypeVar("T")
# TODO(paul): Should be shared somewhere
def count(func: Callable[[T], bool], it: Iterable[T]) -> int:
"""Return the number of items in it for which func returns true."""
n = 0
for x in it:
if func(x):
n += 1
return n
class _NotificationListener:
"""This represents a single client connection to the events stream.
The events stream handler will have yielded to the deferred, so to
notify the handler it is sufficient to resolve the deferred.
"""
__slots__ = ["deferred"]
def __init__(self, deferred):
self.deferred = deferred
class _NotifierUserStream:
"""This represents a user connected to the event stream.
It tracks the most recent stream token for that user.
At a given point a user may have a number of streams listening for
events.
This listener will also keep track of which rooms it is listening in
so that it can remove itself from the indexes in the Notifier class.
"""
def __init__(
self,
user_id: str,
rooms: Collection[str],
current_token: StreamToken,
time_now_ms: int,
):
self.user_id = user_id
self.rooms = set(rooms)
self.current_token = current_token
# The last token for which we should wake up any streams that have a
# token that comes before it. This gets updated every time we get poked.
# We start it at the current token since if we get any streams
# that have a token from before we have no idea whether they should be
# woken up or not, so lets just wake them up.
self.last_notified_token = current_token
self.last_notified_ms = time_now_ms
with PreserveLoggingContext():
self.notify_deferred = ObservableDeferred(defer.Deferred())
def notify(
self,
stream_key: str,
stream_id: Union[int, RoomStreamToken],
time_now_ms: int,
):
"""Notify any listeners for this user of a new event from an
event source.
Args:
stream_key: The stream the event came from.
stream_id: The new id for the stream the event came from.
time_now_ms: The current time in milliseconds.
"""
self.current_token = self.current_token.copy_and_advance(stream_key, stream_id)
self.last_notified_token = self.current_token
self.last_notified_ms = time_now_ms
noify_deferred = self.notify_deferred
users_woken_by_stream_counter.labels(stream_key).inc()
with PreserveLoggingContext():
self.notify_deferred = ObservableDeferred(defer.Deferred())
noify_deferred.callback(self.current_token)
def remove(self, notifier: "Notifier"):
"""Remove this listener from all the indexes in the Notifier
it knows about.
"""
for room in self.rooms:
lst = notifier.room_to_user_streams.get(room, set())
lst.discard(self)
notifier.user_to_user_stream.pop(self.user_id)
def count_listeners(self) -> int:
return len(self.notify_deferred.observers())
def new_listener(self, token: StreamToken) -> _NotificationListener:
"""Returns a deferred that is resolved when there is a new token
greater than the given token.
Args:
token: The token from which we are streaming from, i.e. we shouldn't
notify for things that happened before this.
"""
# Immediately wake up stream if something has already since happened
# since their last token.
if self.last_notified_token != token:
return _NotificationListener(defer.succeed(self.current_token))
else:
return _NotificationListener(self.notify_deferred.observe())
class EventStreamResult(namedtuple("EventStreamResult", ("events", "tokens"))):
def __bool__(self):
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.
Primarily used from the /events stream.
"""
UNUSED_STREAM_EXPIRY_MS = 10 * 60 * 1000
def __init__(self, hs: "synapse.server.HomeServer"):
self.user_to_user_stream = {} # type: Dict[str, _NotifierUserStream]
self.room_to_user_streams = {} # type: Dict[str, Set[_NotifierUserStream]]
self.hs = hs
self.storage = hs.get_storage()
self.event_sources = hs.get_event_sources()
self.store = hs.get_datastore()
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]]
# Called when remote servers have come back online after having been
# down.
self.remote_server_up_callbacks = [] # type: List[Callable[[str], None]]
self.clock = hs.get_clock()
self.appservice_handler = hs.get_application_service_handler()
self._pusher_pool = hs.get_pusherpool()
self.federation_sender = None
if hs.should_send_federation():
self.federation_sender = hs.get_federation_sender()
self.state_handler = hs.get_state_handler()
self.clock.looping_call(
self.remove_expired_streams, self.UNUSED_STREAM_EXPIRY_MS
)
# This is not a very cheap test to perform, but it's only executed
# when rendering the metrics page, which is likely once per minute at
# most when scraping it.
def count_listeners():
all_user_streams = set() # type: Set[_NotifierUserStream]
for streams in list(self.room_to_user_streams.values()):
all_user_streams |= streams
for stream in list(self.user_to_user_stream.values()):
all_user_streams.add(stream)
return sum(stream.count_listeners() for stream in all_user_streams)
LaterGauge("synapse_notifier_listeners", "", [], count_listeners)
LaterGauge(
"synapse_notifier_rooms",
"",
[],
lambda: count(bool, list(self.room_to_user_streams.values())),
)
LaterGauge(
"synapse_notifier_users", "", [], lambda: len(self.user_to_user_stream)
)
def add_replication_callback(self, cb: Callable[[], None]):
"""Add a callback that will be called when some new data is available.
Callback is not given any arguments. It should *not* return a Deferred - if
it needs to do any asynchronous work, a background thread should be started and
wrapped with run_as_background_process.
"""
self.replication_callbacks.append(cb)
def on_new_room_event(
self,
event: EventBase,
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.
This triggers the notifier to wake up any listeners that are
listening to the room, and any listeners for the users in the
`extra_users` param.
The events can be peristed out of order. The notifier will wait
until all previous events have been persisted before notifying
the client streams.
"""
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()
def _notify_pending_new_room_events(self, max_room_stream_token: RoomStreamToken):
"""Notify for the room events that were queued waiting for a previous
event to be persisted.
Args:
max_room_stream_token: The highest stream_id below which all
events have been persisted.
"""
pending = self.pending_new_room_events
self.pending_new_room_events = []
users = set() # type: Set[UserID]
rooms = set() # type: Set[str]
for entry in pending:
if entry.event_pos.persisted_after(max_room_stream_token):
self.pending_new_room_events.append(entry)
else:
if (
entry.type == EventTypes.Member
and entry.membership == Membership.JOIN
and entry.state_key
):
self._user_joined_room(entry.state_key, entry.room_id)
users.update(entry.extra_users)
rooms.add(entry.room_id)
if users or rooms:
self.on_new_event(
"room_key",
max_room_stream_token,
users=users,
rooms=rooms,
)
self._on_updated_room_token(max_room_stream_token)
def _on_updated_room_token(self, max_room_stream_token: RoomStreamToken):
"""Poke services that might care that the room position has been
updated.
"""
# poke any interested application service.
self._notify_app_services(max_room_stream_token)
self._notify_pusher_pool(max_room_stream_token)
if self.federation_sender:
self.federation_sender.notify_new_events(max_room_stream_token)
def _notify_app_services(self, max_room_stream_token: RoomStreamToken):
try:
self.appservice_handler.notify_interested_services(max_room_stream_token)
except Exception:
logger.exception("Error notifying application services of event")
def _notify_app_services_ephemeral(
self,
stream_key: str,
new_token: Union[int, RoomStreamToken],
users: Collection[Union[str, UserID]] = [],
):
try:
stream_token = None
if isinstance(new_token, int):
stream_token = new_token
self.appservice_handler.notify_interested_services_ephemeral(
stream_key, stream_token, users
)
except Exception:
logger.exception("Error notifying application services of event")
def _notify_pusher_pool(self, max_room_stream_token: RoomStreamToken):
try:
self._pusher_pool.on_new_notifications(max_room_stream_token)
except Exception:
logger.exception("Error pusher pool of event")
def on_new_event(
self,
stream_key: str,
new_token: Union[int, RoomStreamToken],
users: Collection[Union[str, UserID]] = [],
rooms: Collection[str] = [],
):
"""Used to inform listeners that something has happened event wise.
Will wake up all listeners for the given users and rooms.
"""
with Measure(self.clock, "on_new_event"):
user_streams = set()
for user in users:
user_stream = self.user_to_user_stream.get(str(user))
if user_stream is not None:
user_streams.add(user_stream)
for room in rooms:
user_streams |= self.room_to_user_streams.get(room, set())
time_now_ms = self.clock.time_msec()
for user_stream in user_streams:
try:
user_stream.notify(stream_key, new_token, time_now_ms)
except Exception:
logger.exception("Failed to notify listener")
self.notify_replication()
# Notify appservices
self._notify_app_services_ephemeral(
stream_key,
new_token,
users,
)
def on_new_replication_data(self) -> None:
"""Used to inform replication listeners that something has happened
without waking up any of the normal user event streams"""
self.notify_replication()
async def wait_for_events(
self,
user_id: str,
timeout: int,
callback: Callable[[StreamToken, StreamToken], Awaitable[T]],
room_ids=None,
from_token=StreamToken.START,
) -> T:
"""Wait until the callback returns a non empty response or the
timeout fires.
"""
user_stream = self.user_to_user_stream.get(user_id)
if user_stream is None:
current_token = self.event_sources.get_current_token()
if room_ids is None:
room_ids = await self.store.get_rooms_for_user(user_id)
user_stream = _NotifierUserStream(
user_id=user_id,
rooms=room_ids,
current_token=current_token,
time_now_ms=self.clock.time_msec(),
)
self._register_with_keys(user_stream)
result = None
prev_token = from_token
if timeout:
end_time = self.clock.time_msec() + timeout
while not result:
try:
now = self.clock.time_msec()
if end_time <= now:
break
# Now we wait for the _NotifierUserStream to be told there
# is a new token.
listener = user_stream.new_listener(prev_token)
listener.deferred = timeout_deferred(
listener.deferred,
(end_time - now) / 1000.0,
self.hs.get_reactor(),
)
with PreserveLoggingContext():
await listener.deferred
current_token = user_stream.current_token
result = await callback(prev_token, current_token)
if result:
break
# Update the prev_token to the current_token since nothing
# has happened between the old prev_token and the current_token
prev_token = current_token
except defer.TimeoutError:
break
except defer.CancelledError:
break
if result is None:
# This happened if there was no timeout or if the timeout had
# already expired.
current_token = user_stream.current_token
result = await callback(prev_token, current_token)
return result
async def get_events_for(
self,
user: UserID,
pagination_config: PaginationConfig,
timeout: int,
is_guest: bool = False,
explicit_room_id: str = None,
) -> EventStreamResult:
"""For the given user and rooms, return any new events for them. If
there are no new events wait for up to `timeout` milliseconds for any
new events to happen before returning.
If explicit_room_id is not set, the user's joined rooms will be polled
for events.
If explicit_room_id is set, that room will be polled for events only if
it is world readable or the user has joined the room.
"""
if pagination_config.from_token:
from_token = pagination_config.from_token
else:
from_token = self.event_sources.get_current_token()
limit = pagination_config.limit
room_ids, is_joined = await self._get_room_ids(user, explicit_room_id)
is_peeking = not is_joined
async def check_for_updates(
before_token: StreamToken, after_token: StreamToken
) -> EventStreamResult:
if after_token == before_token:
return EventStreamResult([], (from_token, from_token))
events = [] # type: List[EventBase]
end_token = from_token
for name, source in self.event_sources.sources.items():
keyname = "%s_key" % name
before_id = getattr(before_token, keyname)
after_id = getattr(after_token, keyname)
if before_id == after_id:
continue
new_events, new_key = await source.get_new_events(
user=user,
from_key=getattr(from_token, keyname),
limit=limit,
is_guest=is_peeking,
room_ids=room_ids,
explicit_room_id=explicit_room_id,
)
if name == "room":
new_events = await filter_events_for_client(
self.storage,
user.to_string(),
new_events,
is_peeking=is_peeking,
)
elif name == "presence":
now = self.clock.time_msec()
new_events[:] = [
{
"type": "m.presence",
"content": format_user_presence_state(event, now),
}
for event in new_events
]
events.extend(new_events)
end_token = end_token.copy_and_replace(keyname, new_key)
return EventStreamResult(events, (from_token, end_token))
user_id_for_stream = user.to_string()
if is_peeking:
# Internally, the notifier keeps an event stream per user_id.
# This is used by both /sync and /events.
# We want /events to be used for peeking independently of /sync,
# without polluting its contents. So we invent an illegal user ID
# (which thus cannot clash with any real users) for keying peeking
# over /events.
#
# I am sorry for what I have done.
user_id_for_stream = "_PEEKING_%s_%s" % (
explicit_room_id,
user_id_for_stream,
)
result = await self.wait_for_events(
user_id_for_stream,
timeout,
check_for_updates,
room_ids=room_ids,
from_token=from_token,
)
return result
async def _get_room_ids(
self, user: UserID, explicit_room_id: Optional[str]
) -> Tuple[Collection[str], bool]:
joined_room_ids = await self.store.get_rooms_for_user(user.to_string())
if explicit_room_id:
if explicit_room_id in joined_room_ids:
return [explicit_room_id], True
if await self._is_world_readable(explicit_room_id):
return [explicit_room_id], False
raise AuthError(403, "Non-joined access not allowed")
return joined_room_ids, True
async def _is_world_readable(self, room_id: str) -> bool:
state = await self.state_handler.get_current_state(
room_id, EventTypes.RoomHistoryVisibility, ""
)
if state and "history_visibility" in state.content:
return (
state.content["history_visibility"] == HistoryVisibility.WORLD_READABLE
)
else:
return False
@log_function
def remove_expired_streams(self) -> None:
time_now_ms = self.clock.time_msec()
expired_streams = []
expire_before_ts = time_now_ms - self.UNUSED_STREAM_EXPIRY_MS
for stream in self.user_to_user_stream.values():
if stream.count_listeners():
continue
if stream.last_notified_ms < expire_before_ts:
expired_streams.append(stream)
for expired_stream in expired_streams:
expired_stream.remove(self)
@log_function
def _register_with_keys(self, user_stream: _NotifierUserStream):
self.user_to_user_stream[user_stream.user_id] = user_stream
for room in user_stream.rooms:
s = self.room_to_user_streams.setdefault(room, set())
s.add(user_stream)
def _user_joined_room(self, user_id: str, room_id: str):
new_user_stream = self.user_to_user_stream.get(user_id)
if new_user_stream is not None:
room_streams = self.room_to_user_streams.setdefault(room_id, set())
room_streams.add(new_user_stream)
new_user_stream.rooms.add(room_id)
def notify_replication(self) -> None:
"""Notify the any replication listeners that there's a new event"""
for cb in self.replication_callbacks:
cb()
def notify_remote_server_up(self, server: str):
"""Notify any replication that a remote server has come back up"""
# We call federation_sender directly rather than registering as a
# callback as a) we already have a reference to it and b) it introduces
# circular dependencies.
if self.federation_sender:
self.federation_sender.wake_destination(server)