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synapse/synapse/push/emailpusher.py
Richard van der Hoff 9255a6cb17 Improve exception handling for background processes
There were a bunch of places where we fire off a process to happen in the
background, but don't have any exception handling on it - instead relying on
the unhandled error being logged when the relevent deferred gets
garbage-collected.

This is unsatisfactory for a number of reasons:
 - logging on garbage collection is best-effort and may happen some time after
   the error, if at all
 - it can be hard to figure out where the error actually happened.
 - it is logged as a scary CRITICAL error which (a) I always forget to grep for
   and (b) it's not really CRITICAL if a background process we don't care about
   fails.

So this is an attempt to add exception handling to everything we fire off into
the background.
2018-04-27 11:07:40 +01:00

289 lines
11 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 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.
from twisted.internet import defer, reactor
from twisted.internet.error import AlreadyCalled, AlreadyCancelled
import logging
from synapse.util.metrics import Measure
from synapse.util.logcontext import LoggingContext
logger = logging.getLogger(__name__)
# The amount of time we always wait before ever emailing about a notification
# (to give the user a chance to respond to other push or notice the window)
DELAY_BEFORE_MAIL_MS = 10 * 60 * 1000
# THROTTLE is the minimum time between mail notifications sent for a given room.
# Each room maintains its own throttle counter, but each new mail notification
# sends the pending notifications for all rooms.
THROTTLE_START_MS = 10 * 60 * 1000
THROTTLE_MAX_MS = 24 * 60 * 60 * 1000 # 24h
# THROTTLE_MULTIPLIER = 6 # 10 mins, 1 hour, 6 hours, 24 hours
THROTTLE_MULTIPLIER = 144 # 10 mins, 24 hours - i.e. jump straight to 1 day
# If no event triggers a notification for this long after the previous,
# the throttle is released.
# 12 hours - a gap of 12 hours in conversation is surely enough to merit a new
# notification when things get going again...
THROTTLE_RESET_AFTER_MS = (12 * 60 * 60 * 1000)
# does each email include all unread notifs, or just the ones which have happened
# since the last mail?
# XXX: this is currently broken as it includes ones from parted rooms(!)
INCLUDE_ALL_UNREAD_NOTIFS = False
class EmailPusher(object):
"""
A pusher that sends email notifications about events (approximately)
when they happen.
This shares quite a bit of code with httpusher: it would be good to
factor out the common parts
"""
def __init__(self, hs, pusherdict, mailer):
self.hs = hs
self.mailer = mailer
self.store = self.hs.get_datastore()
self.clock = self.hs.get_clock()
self.pusher_id = pusherdict['id']
self.user_id = pusherdict['user_name']
self.app_id = pusherdict['app_id']
self.email = pusherdict['pushkey']
self.last_stream_ordering = pusherdict['last_stream_ordering']
self.timed_call = None
self.throttle_params = None
# See httppusher
self.max_stream_ordering = None
self.processing = False
@defer.inlineCallbacks
def on_started(self):
if self.mailer is not None:
try:
self.throttle_params = yield self.store.get_throttle_params_by_room(
self.pusher_id
)
yield self._process()
except Exception:
logger.exception("Error starting email pusher")
def on_stop(self):
if self.timed_call:
try:
self.timed_call.cancel()
except (AlreadyCalled, AlreadyCancelled):
pass
self.timed_call = None
@defer.inlineCallbacks
def on_new_notifications(self, min_stream_ordering, max_stream_ordering):
self.max_stream_ordering = max(max_stream_ordering, self.max_stream_ordering)
yield self._process()
def on_new_receipts(self, min_stream_id, max_stream_id):
# We could wake up and cancel the timer but there tend to be quite a
# lot of read receipts so it's probably less work to just let the
# timer fire
return defer.succeed(None)
@defer.inlineCallbacks
def on_timer(self):
self.timed_call = None
yield self._process()
@defer.inlineCallbacks
def _process(self):
if self.processing:
return
with LoggingContext("emailpush._process"):
with Measure(self.clock, "emailpush._process"):
try:
self.processing = True
# if the max ordering changes while we're running _unsafe_process,
# call it again, and so on until we've caught up.
while True:
starting_max_ordering = self.max_stream_ordering
try:
yield self._unsafe_process()
except Exception:
logger.exception("Exception processing notifs")
if self.max_stream_ordering == starting_max_ordering:
break
finally:
self.processing = False
@defer.inlineCallbacks
def _unsafe_process(self):
"""
Main logic of the push loop without the wrapper function that sets
up logging, measures and guards against multiple instances of it
being run.
"""
start = 0 if INCLUDE_ALL_UNREAD_NOTIFS else self.last_stream_ordering
fn = self.store.get_unread_push_actions_for_user_in_range_for_email
unprocessed = yield fn(self.user_id, start, self.max_stream_ordering)
soonest_due_at = None
if not unprocessed:
yield self.save_last_stream_ordering_and_success(self.max_stream_ordering)
return
for push_action in unprocessed:
received_at = push_action['received_ts']
if received_at is None:
received_at = 0
notif_ready_at = received_at + DELAY_BEFORE_MAIL_MS
room_ready_at = self.room_ready_to_notify_at(
push_action['room_id']
)
should_notify_at = max(notif_ready_at, room_ready_at)
if should_notify_at < self.clock.time_msec():
# one of our notifications is ready for sending, so we send
# *one* email updating the user on their notifications,
# we then consider all previously outstanding notifications
# to be delivered.
reason = {
'room_id': push_action['room_id'],
'now': self.clock.time_msec(),
'received_at': received_at,
'delay_before_mail_ms': DELAY_BEFORE_MAIL_MS,
'last_sent_ts': self.get_room_last_sent_ts(push_action['room_id']),
'throttle_ms': self.get_room_throttle_ms(push_action['room_id']),
}
yield self.send_notification(unprocessed, reason)
yield self.save_last_stream_ordering_and_success(max([
ea['stream_ordering'] for ea in unprocessed
]))
# we update the throttle on all the possible unprocessed push actions
for ea in unprocessed:
yield self.sent_notif_update_throttle(
ea['room_id'], ea
)
break
else:
if soonest_due_at is None or should_notify_at < soonest_due_at:
soonest_due_at = should_notify_at
if self.timed_call is not None:
try:
self.timed_call.cancel()
except (AlreadyCalled, AlreadyCancelled):
pass
self.timed_call = None
if soonest_due_at is not None:
self.timed_call = reactor.callLater(
self.seconds_until(soonest_due_at), self.on_timer
)
@defer.inlineCallbacks
def save_last_stream_ordering_and_success(self, last_stream_ordering):
self.last_stream_ordering = last_stream_ordering
yield self.store.update_pusher_last_stream_ordering_and_success(
self.app_id, self.email, self.user_id,
last_stream_ordering, self.clock.time_msec()
)
def seconds_until(self, ts_msec):
secs = (ts_msec - self.clock.time_msec()) / 1000
return max(secs, 0)
def get_room_throttle_ms(self, room_id):
if room_id in self.throttle_params:
return self.throttle_params[room_id]["throttle_ms"]
else:
return 0
def get_room_last_sent_ts(self, room_id):
if room_id in self.throttle_params:
return self.throttle_params[room_id]["last_sent_ts"]
else:
return 0
def room_ready_to_notify_at(self, room_id):
"""
Determines whether throttling should prevent us from sending an email
for the given room
Returns: The timestamp when we are next allowed to send an email notif
for this room
"""
last_sent_ts = self.get_room_last_sent_ts(room_id)
throttle_ms = self.get_room_throttle_ms(room_id)
may_send_at = last_sent_ts + throttle_ms
return may_send_at
@defer.inlineCallbacks
def sent_notif_update_throttle(self, room_id, notified_push_action):
# We have sent a notification, so update the throttle accordingly.
# If the event that triggered the notif happened more than
# THROTTLE_RESET_AFTER_MS after the previous one that triggered a
# notif, we release the throttle. Otherwise, the throttle is increased.
time_of_previous_notifs = yield self.store.get_time_of_last_push_action_before(
notified_push_action['stream_ordering']
)
time_of_this_notifs = notified_push_action['received_ts']
if time_of_previous_notifs is not None and time_of_this_notifs is not None:
gap = time_of_this_notifs - time_of_previous_notifs
else:
# if we don't know the arrival time of one of the notifs (it was not
# stored prior to email notification code) then assume a gap of
# zero which will just not reset the throttle
gap = 0
current_throttle_ms = self.get_room_throttle_ms(room_id)
if gap > THROTTLE_RESET_AFTER_MS:
new_throttle_ms = THROTTLE_START_MS
else:
if current_throttle_ms == 0:
new_throttle_ms = THROTTLE_START_MS
else:
new_throttle_ms = min(
current_throttle_ms * THROTTLE_MULTIPLIER,
THROTTLE_MAX_MS
)
self.throttle_params[room_id] = {
"last_sent_ts": self.clock.time_msec(),
"throttle_ms": new_throttle_ms
}
yield self.store.set_throttle_params(
self.pusher_id, room_id, self.throttle_params[room_id]
)
@defer.inlineCallbacks
def send_notification(self, push_actions, reason):
logger.info("Sending notif email for user %r", self.user_id)
yield self.mailer.send_notification_mail(
self.app_id, self.user_id, self.email, push_actions, reason
)