def create_view_changer(node, vchCls=ViewChanger):
vc = vchCls(ViewChangerNodeDataProvider(node), node.timer)
if hasattr(node.config, 'PRE_VC_STRATEGY'):
vc.pre_vc_strategy = preVCStrategies.get(node.config.PRE_VC_STRATEGY)(vc, node)
return vc
def __init__(self, node):
self.node = node
self._view_no = 0 # type: int
HasActionQueue.__init__(self)
self.pre_vc_strategy = None
if hasattr(self.config, 'PRE_VC_STRATEGY'):
self.pre_vc_strategy = preVCStrategies.get(
self.config.PRE_VC_STRATEGY)(self)
self.inBox = deque()
self.outBox = deque()
self.inBoxRouter = Router(
(InstanceChange, self.process_instance_change_msg),
(ViewChangeDone, self.process_vchd_msg),
(FutureViewChangeDone, self.process_future_view_vchd_msg))
self.instanceChanges = InstanceChanges()
# The quorum of `ViewChangeDone` msgs is different depending on whether we're doing a real view change,
# or just propagating view_no and Primary from `CurrentState` messages sent to a newly joined Node.
# TODO: separate real view change and Propagation of Primary
# TODO: separate catch-up, view-change and primary selection so that
# they are really independent.
self.propagate_primary = False
# Tracks if other nodes are indicating that this node is in lower view
# than others. Keeps a map of view no to senders
# TODO: Consider if sufficient ViewChangeDone for 2 different (and
# higher views) are received, should one view change be interrupted in
# between.
self._next_view_indications = {}
self._view_change_in_progress = False
self.previous_master_primary = None
self.set_defaults()
self.initInsChngThrottling()
# Action for _schedule instanceChange messages
self.instance_change_action = None
# Count of instance change rounds
self.instance_change_rounds = 0
# Time for view_change_starting
self.start_view_change_ts = 0
# Last successful viewNo.
# In some cases view_change process can be uncompleted in time.
# In that case we want to know, which viewNo was successful (last completed view_change)
self.last_completed_view_no = 0
# Force periodic view change if enabled in config
force_view_change_freq = node.config.ForceViewChangeFreq
if force_view_change_freq > 0:
self.startRepeating(self.on_master_degradation,
force_view_change_freq)