From 501994582899ad9d790029b3d7c48ba32f5720a9 Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Tue, 20 Aug 2019 11:20:10 +0100 Subject: [PATCH] Refactor the Appservice scheduler code Get rid of the labyrinthine `recoverer_fn` code, and clean up the startup code (it seemed to be previously inexplicably split between `ApplicationServiceScheduler.start` and `_Recoverer.start`). Add some docstrings too. --- changelog.d/5886.misc | 1 + synapse/appservice/scheduler.py | 110 +++++++++++++++++------------ tests/appservice/test_scheduler.py | 6 +- 3 files changed, 68 insertions(+), 49 deletions(-) create mode 100644 changelog.d/5886.misc diff --git a/changelog.d/5886.misc b/changelog.d/5886.misc new file mode 100644 index 0000000000..22adba3d85 --- /dev/null +++ b/changelog.d/5886.misc @@ -0,0 +1 @@ +Refactor the Appservice scheduler code. diff --git a/synapse/appservice/scheduler.py b/synapse/appservice/scheduler.py index 42a350bff8..03a14402c5 100644 --- a/synapse/appservice/scheduler.py +++ b/synapse/appservice/scheduler.py @@ -70,35 +70,37 @@ class ApplicationServiceScheduler(object): self.store = hs.get_datastore() self.as_api = hs.get_application_service_api() - def create_recoverer(service, callback): - return _Recoverer(self.clock, self.store, self.as_api, service, callback) - - self.txn_ctrl = _TransactionController( - self.clock, self.store, self.as_api, create_recoverer - ) + self.txn_ctrl = _TransactionController(self.clock, self.store, self.as_api) self.queuer = _ServiceQueuer(self.txn_ctrl, self.clock) @defer.inlineCallbacks def start(self): logger.info("Starting appservice scheduler") + # check for any DOWN ASes and start recoverers for them. - recoverers = yield _Recoverer.start( - self.clock, self.store, self.as_api, self.txn_ctrl.on_recovered + services = yield self.store.get_appservices_by_state( + ApplicationServiceState.DOWN ) - self.txn_ctrl.add_recoverers(recoverers) + + for service in services: + self.txn_ctrl.start_recoverer(service) def submit_event_for_as(self, service, event): self.queuer.enqueue(service, event) class _ServiceQueuer(object): - """Queues events for the same application service together, sending - transactions as soon as possible. Once a transaction is sent successfully, - this schedules any other events in the queue to run. + """Queue of events waiting to be sent to appservices. + + Groups events into transactions per-appservice, and sends them on to the + TransactionController. Makes sure that we only have one transaction in flight per + appservice at a given time. """ def __init__(self, txn_ctrl, clock): self.queued_events = {} # dict of {service_id: [events]} + + # the appservices which currently have a transaction in flight self.requests_in_flight = set() self.txn_ctrl = txn_ctrl self.clock = clock @@ -136,13 +138,29 @@ class _ServiceQueuer(object): class _TransactionController(object): - def __init__(self, clock, store, as_api, recoverer_fn): + """Transaction manager. + + Builds AppServiceTransactions and runs their lifecycle. Also starts a Recoverer + if a transaction fails. + + (Note we have only have one of these in the homeserver.) + + Args: + clock (synapse.util.Clock): + store (synapse.storage.DataStore): + as_api (synapse.appservice.api.ApplicationServiceApi): + """ + + def __init__(self, clock, store, as_api): self.clock = clock self.store = store self.as_api = as_api - self.recoverer_fn = recoverer_fn - # keep track of how many recoverers there are - self.recoverers = [] + + # map from service id to recoverer instance + self.recoverers = {} + + # for UTs + self.RECOVERER_CLASS = _Recoverer @defer.inlineCallbacks def send(self, service, events): @@ -154,42 +172,45 @@ class _TransactionController(object): if sent: yield txn.complete(self.store) else: - run_in_background(self._start_recoverer, service) + run_in_background(self._on_txn_fail, service) except Exception: logger.exception("Error creating appservice transaction") - run_in_background(self._start_recoverer, service) + run_in_background(self._on_txn_fail, service) @defer.inlineCallbacks def on_recovered(self, recoverer): - self.recoverers.remove(recoverer) logger.info( "Successfully recovered application service AS ID %s", recoverer.service.id ) + self.recoverers.pop(recoverer.service.id) logger.info("Remaining active recoverers: %s", len(self.recoverers)) yield self.store.set_appservice_state( recoverer.service, ApplicationServiceState.UP ) - def add_recoverers(self, recoverers): - for r in recoverers: - self.recoverers.append(r) - if len(recoverers) > 0: - logger.info("New active recoverers: %s", len(self.recoverers)) - @defer.inlineCallbacks - def _start_recoverer(self, service): + def _on_txn_fail(self, service): try: yield self.store.set_appservice_state(service, ApplicationServiceState.DOWN) - logger.info( - "Application service falling behind. Starting recoverer. AS ID %s", - service.id, - ) - recoverer = self.recoverer_fn(service, self.on_recovered) - self.add_recoverers([recoverer]) - recoverer.recover() + self.start_recoverer(service) except Exception: logger.exception("Error starting AS recoverer") + def start_recoverer(self, service): + """Start a Recoverer for the given service + + Args: + service (synapse.appservice.ApplicationService): + """ + logger.info("Starting recoverer for AS ID %s", service.id) + assert service.id not in self.recoverers + recoverer = self.RECOVERER_CLASS( + self.clock, self.store, self.as_api, service, self.on_recovered + ) + self.recoverers[service.id] = recoverer + recoverer.recover() + logger.info("Now %i active recoverers", len(self.recoverers)) + @defer.inlineCallbacks def _is_service_up(self, service): state = yield self.store.get_appservice_state(service) @@ -197,18 +218,17 @@ class _TransactionController(object): class _Recoverer(object): - @staticmethod - @defer.inlineCallbacks - def start(clock, store, as_api, callback): - services = yield store.get_appservices_by_state(ApplicationServiceState.DOWN) - recoverers = [_Recoverer(clock, store, as_api, s, callback) for s in services] - for r in recoverers: - logger.info( - "Starting recoverer for AS ID %s which was marked as " "DOWN", - r.service.id, - ) - r.recover() - return recoverers + """Manages retries and backoff for a DOWN appservice. + + We have one of these for each appservice which is currently considered DOWN. + + Args: + clock (synapse.util.Clock): + store (synapse.storage.DataStore): + as_api (synapse.appservice.api.ApplicationServiceApi): + service (synapse.appservice.ApplicationService): the service we are managing + callback (callable[_Recoverer]): called once the service recovers. + """ def __init__(self, clock, store, as_api, service, callback): self.clock = clock diff --git a/tests/appservice/test_scheduler.py b/tests/appservice/test_scheduler.py index 04b8c2c07c..52f89d3f83 100644 --- a/tests/appservice/test_scheduler.py +++ b/tests/appservice/test_scheduler.py @@ -37,11 +37,9 @@ class ApplicationServiceSchedulerTransactionCtrlTestCase(unittest.TestCase): self.recoverer = Mock() self.recoverer_fn = Mock(return_value=self.recoverer) self.txnctrl = _TransactionController( - clock=self.clock, - store=self.store, - as_api=self.as_api, - recoverer_fn=self.recoverer_fn, + clock=self.clock, store=self.store, as_api=self.as_api ) + self.txnctrl.RECOVERER_CLASS = self.recoverer_fn def test_single_service_up_txn_sent(self): # Test: The AS is up and the txn is successfully sent.