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https://git.anonymousland.org/anonymousland/synapse-product.git
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379 lines
14 KiB
Python
379 lines
14 KiB
Python
# Copyright 2015, 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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This module controls the reliability for application service transactions.
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The nominal flow through this module looks like:
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__________
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1---ASa[e]-->| Service |--> Queue ASa[f]
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2----ASb[e]->| Queuer |
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3--ASa[f]--->|__________|-----------+ ASa[e], ASb[e]
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V
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-````````- +------------+
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|````````|<--StoreTxn-|Transaction |
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|Database| | Controller |---> SEND TO AS
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`--------` +------------+
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What happens on SEND TO AS depends on the state of the Application Service:
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- If the AS is marked as DOWN, do nothing.
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- If the AS is marked as UP, send the transaction.
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* SUCCESS : Increment where the AS is up to txn-wise and nuke the txn
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contents from the db.
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* FAILURE : Marked AS as DOWN and start Recoverer.
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Recoverer attempts to recover ASes who have died. The flow for this looks like:
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,--------------------- backoff++ --------------.
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V |
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START ---> Wait exp ------> Get oldest txn ID from ----> FAILURE
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backoff DB and try to send it
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^ |___________
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Mark AS as | V
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UP & quit +---------- YES SUCCESS
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NO <--- Have more txns? <------ Mark txn success & nuke <-+
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from db; incr AS pos.
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Reset backoff.
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This is all tied together by the AppServiceScheduler which DIs the required
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components.
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"""
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import logging
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from typing import (
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TYPE_CHECKING,
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Awaitable,
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Callable,
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Collection,
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Dict,
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List,
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Optional,
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Set,
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)
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from synapse.appservice import ApplicationService, ApplicationServiceState
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from synapse.appservice.api import ApplicationServiceApi
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from synapse.events import EventBase
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from synapse.logging.context import run_in_background
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from synapse.metrics.background_process_metrics import run_as_background_process
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from synapse.storage.databases.main import DataStore
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from synapse.types import JsonDict
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from synapse.util import Clock
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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# Maximum number of events to provide in an AS transaction.
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MAX_PERSISTENT_EVENTS_PER_TRANSACTION = 100
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# Maximum number of ephemeral events to provide in an AS transaction.
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MAX_EPHEMERAL_EVENTS_PER_TRANSACTION = 100
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# Maximum number of to-device messages to provide in an AS transaction.
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MAX_TO_DEVICE_MESSAGES_PER_TRANSACTION = 100
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class ApplicationServiceScheduler:
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"""Public facing API for this module. Does the required DI to tie the
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components together. This also serves as the "event_pool", which in this
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case is a simple array.
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"""
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def __init__(self, hs: "HomeServer"):
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self.clock = hs.get_clock()
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self.store = hs.get_datastore()
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self.as_api = hs.get_application_service_api()
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self.txn_ctrl = _TransactionController(self.clock, self.store, self.as_api)
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self.queuer = _ServiceQueuer(self.txn_ctrl, self.clock)
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async def start(self) -> None:
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logger.info("Starting appservice scheduler")
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# check for any DOWN ASes and start recoverers for them.
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services = await self.store.get_appservices_by_state(
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ApplicationServiceState.DOWN
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)
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for service in services:
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self.txn_ctrl.start_recoverer(service)
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def enqueue_for_appservice(
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self,
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appservice: ApplicationService,
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events: Optional[Collection[EventBase]] = None,
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ephemeral: Optional[Collection[JsonDict]] = None,
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to_device_messages: Optional[Collection[JsonDict]] = None,
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) -> None:
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"""
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Enqueue some data to be sent off to an application service.
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Args:
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appservice: The application service to create and send a transaction to.
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events: The persistent room events to send.
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ephemeral: The ephemeral events to send.
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to_device_messages: The to-device messages to send. These differ from normal
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to-device messages sent to clients, as they have 'to_device_id' and
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'to_user_id' fields.
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"""
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# We purposefully allow this method to run with empty events/ephemeral
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# collections, so that callers do not need to check iterable size themselves.
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if not events and not ephemeral and not to_device_messages:
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return
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if events:
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self.queuer.queued_events.setdefault(appservice.id, []).extend(events)
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if ephemeral:
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self.queuer.queued_ephemeral.setdefault(appservice.id, []).extend(ephemeral)
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if to_device_messages:
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self.queuer.queued_to_device_messages.setdefault(appservice.id, []).extend(
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to_device_messages
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)
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# Kick off a new application service transaction
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self.queuer.start_background_request(appservice)
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class _ServiceQueuer:
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"""Queue of events waiting to be sent to appservices.
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Groups events into transactions per-appservice, and sends them on to the
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TransactionController. Makes sure that we only have one transaction in flight per
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appservice at a given time.
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"""
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def __init__(self, txn_ctrl: "_TransactionController", clock: Clock):
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# dict of {service_id: [events]}
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self.queued_events: Dict[str, List[EventBase]] = {}
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# dict of {service_id: [events]}
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self.queued_ephemeral: Dict[str, List[JsonDict]] = {}
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# dict of {service_id: [to_device_message_json]}
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self.queued_to_device_messages: Dict[str, List[JsonDict]] = {}
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# the appservices which currently have a transaction in flight
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self.requests_in_flight: Set[str] = set()
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self.txn_ctrl = txn_ctrl
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self.clock = clock
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def start_background_request(self, service: ApplicationService) -> None:
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# start a sender for this appservice if we don't already have one
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if service.id in self.requests_in_flight:
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return
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run_as_background_process(
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"as-sender-%s" % (service.id,), self._send_request, service
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)
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async def _send_request(self, service: ApplicationService) -> None:
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# sanity-check: we shouldn't get here if this service already has a sender
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# running.
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assert service.id not in self.requests_in_flight
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self.requests_in_flight.add(service.id)
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try:
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while True:
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all_events = self.queued_events.get(service.id, [])
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events = all_events[:MAX_PERSISTENT_EVENTS_PER_TRANSACTION]
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del all_events[:MAX_PERSISTENT_EVENTS_PER_TRANSACTION]
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all_events_ephemeral = self.queued_ephemeral.get(service.id, [])
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ephemeral = all_events_ephemeral[:MAX_EPHEMERAL_EVENTS_PER_TRANSACTION]
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del all_events_ephemeral[:MAX_EPHEMERAL_EVENTS_PER_TRANSACTION]
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all_to_device_messages = self.queued_to_device_messages.get(
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service.id, []
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)
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to_device_messages_to_send = all_to_device_messages[
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:MAX_TO_DEVICE_MESSAGES_PER_TRANSACTION
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]
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del all_to_device_messages[:MAX_TO_DEVICE_MESSAGES_PER_TRANSACTION]
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if not events and not ephemeral and not to_device_messages_to_send:
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return
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try:
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await self.txn_ctrl.send(
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service, events, ephemeral, to_device_messages_to_send
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)
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except Exception:
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logger.exception("AS request failed")
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finally:
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self.requests_in_flight.discard(service.id)
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class _TransactionController:
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"""Transaction manager.
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Builds AppServiceTransactions and runs their lifecycle. Also starts a Recoverer
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if a transaction fails.
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(Note we have only have one of these in the homeserver.)
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"""
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def __init__(self, clock: Clock, store: DataStore, as_api: ApplicationServiceApi):
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self.clock = clock
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self.store = store
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self.as_api = as_api
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# map from service id to recoverer instance
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self.recoverers: Dict[str, "_Recoverer"] = {}
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# for UTs
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self.RECOVERER_CLASS = _Recoverer
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async def send(
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self,
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service: ApplicationService,
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events: List[EventBase],
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ephemeral: Optional[List[JsonDict]] = None,
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to_device_messages: Optional[List[JsonDict]] = None,
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) -> None:
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"""
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Create a transaction with the given data and send to the provided
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application service.
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Args:
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service: The application service to send the transaction to.
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events: The persistent events to include in the transaction.
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ephemeral: The ephemeral events to include in the transaction.
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to_device_messages: The to-device messages to include in the transaction.
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"""
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try:
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txn = await self.store.create_appservice_txn(
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service=service,
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events=events,
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ephemeral=ephemeral or [],
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to_device_messages=to_device_messages or [],
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)
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service_is_up = await self._is_service_up(service)
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if service_is_up:
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sent = await txn.send(self.as_api)
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if sent:
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await txn.complete(self.store)
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else:
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run_in_background(self._on_txn_fail, service)
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except Exception:
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logger.exception("Error creating appservice transaction")
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run_in_background(self._on_txn_fail, service)
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async def on_recovered(self, recoverer: "_Recoverer") -> None:
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logger.info(
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"Successfully recovered application service AS ID %s", recoverer.service.id
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)
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self.recoverers.pop(recoverer.service.id)
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logger.info("Remaining active recoverers: %s", len(self.recoverers))
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await self.store.set_appservice_state(
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recoverer.service, ApplicationServiceState.UP
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)
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async def _on_txn_fail(self, service: ApplicationService) -> None:
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try:
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await self.store.set_appservice_state(service, ApplicationServiceState.DOWN)
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self.start_recoverer(service)
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except Exception:
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logger.exception("Error starting AS recoverer")
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def start_recoverer(self, service: ApplicationService) -> None:
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"""Start a Recoverer for the given service
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Args:
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service:
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"""
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logger.info("Starting recoverer for AS ID %s", service.id)
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assert service.id not in self.recoverers
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recoverer = self.RECOVERER_CLASS(
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self.clock, self.store, self.as_api, service, self.on_recovered
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)
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self.recoverers[service.id] = recoverer
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recoverer.recover()
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logger.info("Now %i active recoverers", len(self.recoverers))
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async def _is_service_up(self, service: ApplicationService) -> bool:
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state = await self.store.get_appservice_state(service)
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return state == ApplicationServiceState.UP or state is None
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class _Recoverer:
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"""Manages retries and backoff for a DOWN appservice.
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We have one of these for each appservice which is currently considered DOWN.
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Args:
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clock (synapse.util.Clock):
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store (synapse.storage.DataStore):
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as_api (synapse.appservice.api.ApplicationServiceApi):
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service (synapse.appservice.ApplicationService): the service we are managing
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callback (callable[_Recoverer]): called once the service recovers.
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"""
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def __init__(
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self,
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clock: Clock,
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store: DataStore,
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as_api: ApplicationServiceApi,
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service: ApplicationService,
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callback: Callable[["_Recoverer"], Awaitable[None]],
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):
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self.clock = clock
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self.store = store
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self.as_api = as_api
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self.service = service
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self.callback = callback
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self.backoff_counter = 1
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def recover(self) -> None:
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def _retry() -> None:
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run_as_background_process(
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"as-recoverer-%s" % (self.service.id,), self.retry
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)
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delay = 2 ** self.backoff_counter
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logger.info("Scheduling retries on %s in %fs", self.service.id, delay)
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self.clock.call_later(delay, _retry)
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def _backoff(self) -> None:
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# cap the backoff to be around 8.5min => (2^9) = 512 secs
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if self.backoff_counter < 9:
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self.backoff_counter += 1
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self.recover()
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async def retry(self) -> None:
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logger.info("Starting retries on %s", self.service.id)
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try:
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while True:
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txn = await self.store.get_oldest_unsent_txn(self.service)
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if not txn:
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# nothing left: we're done!
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await self.callback(self)
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return
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logger.info(
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"Retrying transaction %s for AS ID %s", txn.id, txn.service.id
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)
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sent = await txn.send(self.as_api)
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if not sent:
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break
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await txn.complete(self.store)
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# reset the backoff counter and then process the next transaction
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self.backoff_counter = 1
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except Exception:
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logger.exception("Unexpected error running retries")
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# we didn't manage to send all of the transactions before we got an error of
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# some flavour: reschedule the next retry.
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self._backoff()
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