Rejig structure given the appservice_handler already filters the correct ASes to use.
Kegan Dougal
parent
0c838f9f5e
commit
d516d68b29
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@ -16,17 +16,11 @@
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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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\O/ --- event -->| | +--------------+
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| - event ---->| event_pool|<-- poll 1/s for events ---| EventSorter |
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/ \ ---- event ->|___________| +--------------+
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USERS ____________________________|
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| | |
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V V V
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ASa ASb ASc
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[e,e] [e] [e,e,e]
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V
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_________
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---ASa[e]-->| Event |
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----ASb[e]->| Grouper |<-poll 1/s--+
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--ASa[e]--->|_________| | ASa[e,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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@ -43,11 +37,11 @@ Recoverer attempts to recover ASes who have died. The flow for this looks like:
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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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^ |___________
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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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@ -62,24 +56,28 @@ class AppServiceScheduler(object):
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case is a simple array.
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"""
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def __init__(self, store, as_api, services):
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self.app_services = services
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self.event_pool = []
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def __init__(self, clock, store, as_api):
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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.event_grouper = _EventGrouper()
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def create_recoverer(service):
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return _Recoverer(store, as_api, service)
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self.txn_ctrl = _TransactionController(store, as_api, create_recoverer)
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def create_recoverer(service, callback):
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return _Recoverer(clock, store, as_api, service, callback)
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self.event_sorter = _EventSorter(self, self.txn_ctrl, services)
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self.txn_ctrl = _TransactionController(
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clock, store, as_api, self.event_grouper, create_recoverer
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)
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def start(self):
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self.event_sorter.start_polling()
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# check for any DOWN ASes and start recoverers for them.
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_Recoverer.start(
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self.clock, self.store, self.as_api, self.txn_ctrl.on_recovered
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)
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self.txn_ctrl.start_polling()
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def store_event(self, event): # event_pool
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self.event_pool.append(event)
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def drain_events(self): # event_pool
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return self.event_pool
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def submit_event_for_as(self, service, event):
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self.event_grouper.on_receive(service, event)
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class AppServiceTransaction(object):
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@ -99,71 +97,99 @@ class AppServiceTransaction(object):
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pass
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class _EventSorter(object):
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class _EventGrouper(object):
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"""Groups events for the same application service together.
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"""
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def __init__(self, event_pool, txn_ctrl, services):
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self.event_pool = event_pool
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self.txn_ctrl = txn_ctrl
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self.services = services
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def __init__(self):
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self.groups = {} # dict of {service: [events]}
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def start_polling(self):
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events = self.event_pool.drain_events()
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if events:
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self._process(events)
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# TODO repoll later on
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def _process(self, events):
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# TODO sort events
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# TODO fe (AS, events) => poke transaction controller on_receive_events
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def on_receive(self, service, event):
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# TODO group this
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pass
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def drain_groups(self):
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return self.groups
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class _TransactionController(object):
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def __init__(self, store, as_api, recoverer_fn):
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def __init__(self, clock, store, as_api, event_grouper, recoverer_fn):
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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.event_grouper = event_grouper
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self.recoverer_fn = recoverer_fn
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def on_receive_events(self, service, events):
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txn = self._store_txn(service, events)
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if txn.send(self.as_api):
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txn.complete(self.store)
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else:
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self._start_recoverer(service)
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def start_polling(self):
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groups = self.event_grouper.drain_groups()
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for service in groups:
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txn_id = self._get_next_txn_id(service)
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txn = AppServiceTransaction(service, txn_id, groups[service])
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self._store_txn(txn)
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if self._is_service_up(service):
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if txn.send(self.as_api):
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txn.complete(self.store)
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else:
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# TODO mark AS as down
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self._start_recoverer(service)
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self.clock.call_later(1000, self.start_polling)
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def on_recovered(self, service):
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# TODO mark AS as UP
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pass
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def _start_recoverer(self, service):
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recoverer = self.recoverer_fn(service)
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recoverer = self.recoverer_fn(service, self.on_recovered)
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recoverer.recover()
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def _store_txn(self, service, events):
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pass # returns AppServiceTransaction
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def _is_service_up(self, service):
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pass
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def _get_next_txn_id(self, service):
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pass # TODO work out the next txn_id for this service
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def _store_txn(self, txn):
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pass
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class _Recoverer(object):
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def __init__(self, store, as_api, service):
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@staticmethod
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def start(clock, store, as_api, callback):
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# TODO check for DOWN ASes and init recoverers
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pass
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def __init__(self, clock, store, as_api, service, callback):
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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):
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# TODO wait a bit
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self.clock.call_later(2000 ** self.backoff_counter, self.retry)
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def retry(self):
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txn = self._get_oldest_txn()
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if txn:
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if txn.send(self.as_api):
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txn.complete(self.store)
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# reset the backoff counter and retry immediately
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self.backoff_counter = 1
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self.retry()
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return
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else:
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self.backoff_counter += 1
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self.recover(self.service)
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self.recover()
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return
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else:
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self._set_service_recovered(self.service)
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self._set_service_recovered()
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def _set_service_recovered(self, service):
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pass
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def _set_service_recovered(self):
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self.callback(self.service)
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def _get_oldest_txn(self):
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pass # returns AppServiceTransaction
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