class TimerModel(SimModel, TimerService):
TimerEvent = NamedTuple('TimerEvent', [('name', str),
('callback', Callable)])
def __init__(self, name):
self._name = name
self._ts = 0
self._outbox = ListEventStream()
def process(self, draw, event: SimEvent):
self._ts = event.timestamp
if isinstance(event.payload, self.TimerEvent):
if event.payload.name == self._name:
event.payload.callback()
def outbox(self):
return self._outbox
def error_status(self) -> Optional[str]:
pass
def get_current_time(self) -> float:
return self._ts
def schedule(self, delay: float, callback: Callable):
# TODO: Some classes (like ViewChanger) sometimes try to schedule None events o_O
if callback is None:
return
self._outbox.add(
SimEvent(timestamp=self._ts + delay,
payload=self.create_timer_event(callback)))
def cancel(self, callback: Callable):
self._outbox.remove_all(
lambda ev: isinstance(ev.payload, self.TimerEvent) and ev.payload
== self.create_timer_event(callback))
def create_timer_event(self, callback: Callable):
return self.TimerEvent(name=self._name, callback=callback)
class NodeModel:
def __init__(self, name: str, node_names: List[str], connections: PoolConnections):
self._name = name
self._node_names = node_names
self._quorum = Quorums(len(node_names))
self._ts = 0
self._corrupted_name = None
self._timer = TimerModel(name)
self._connections = connections
self._view_changer = create_view_changer(self)
self._internal_outbox = ListEventStream()
self.outbox = CompositeEventStream(self._internal_outbox, self._timer.outbox())
self._check_performance_timer = RepeatingTimer(self._timer, 30, self._check_performance)
@property
def name(self):
return self._name
@property
def view_no(self):
return self._view_changer.view_no
@property
def is_participating(self):
return not self._view_changer.view_change_in_progress and not self.is_corrupted
@property
def primary_name(self):
return self._primary_name(self._view_changer.view_no)
@property
def next_primary_name(self):
view_no = self._view_changer.view_no
if not self._view_changer.view_change_in_progress:
view_no += 1
return self._primary_name(view_no)
@property
def current_primary_name(self):
view_no = self._view_changer.view_no - 1
if not self._view_changer.view_change_in_progress:
view_no += 1
return self._primary_name(view_no)
@property
def is_primary(self):
return self.name == self.primary_name
@property
def is_primary_disconnected(self):
return self._connections.are_connected(self._ts, (self.name, self.primary_name))
@property
def is_corrupted(self):
return self._corrupted_name == self.name
@property
def connected_nodes(self) -> List[int]:
result = []
for name in self._node_names:
if name == self.name:
continue
if self._connections.are_connected(self._ts, (self.name, name)):
result.append(name)
return result
def restart(self):
pass
def outage(self, node: str):
if node == self.primary_name:
self._view_changer.on_primary_loss()
self._flush_viewchanger_outbox()
def corrupt(self, node: str):
self._corrupted_name = node
if self.name == node:
self._check_performance_timer.stop()
def process(self, draw, event: SimEvent):
self._ts = event.timestamp
self._timer.process(draw, event)
if isinstance(event.payload, CatchupDoneEvent):
if event.payload.node == self.name:
self._view_changer.on_catchup_complete()
if isinstance(event.payload, NetworkEvent):
self.process_network(event.payload)
self._flush_viewchanger_outbox()
def process_network(self, message: NetworkEvent):
if self.name == self._corrupted_name:
return
if message.dst != self.name:
return
self._view_changer.inBoxRouter.handleSync((message.payload, message.src))
def _flush_viewchanger_outbox(self):
if self.name == self._corrupted_name:
return
for msg in self._view_changer.outBox:
self._broadcast(msg)
self._view_changer.outBox.clear()
def _send(self, message, delay=1):
self._internal_outbox.add(SimEvent(timestamp=self._ts + delay, payload=message))
self.outbox.sort()
def _broadcast(self, payload):
for name in self._node_names:
if name == self.name:
continue
self._send(NetworkEvent(src=self.name,
dst=name,
payload=payload))
def _check_performance(self):
if self.primary_name == self._corrupted_name:
self._view_changer.on_master_degradation()
self._flush_viewchanger_outbox()
def _primary_name(self, view_no):
return self._node_names[view_no % len(self._node_names)]