def advance_instance(self, new_instance_number, new_current_value, catchup=False):
self.master_attempt = False
if catchup:
super(DedicatedMasterStrategyMixin,self).advance_instance(new_instance_number, new_current_value)
self.paxos.prepare() # ensure we won't send any prepare messages with ID 1 (might conflict with the current master)
return
t = json.loads(new_current_value) # Returns a list: [master_uid, application_value]. Only one element will be valid
if t[0] is not None:
print ' Lease Granted: ', t[0]
self.update_lease( t[0] )
new_current_value = self.current_value
else:
print ' Application Value:', t[1]
new_current_value = t[1]
super(DedicatedMasterStrategyMixin,self).advance_instance(new_instance_number, new_current_value)
if self.master_uid:
master_pid = ProposalID(1,self.master_uid)
if self.master_uid == self.network_uid:
self.paxos.prepare()
for uid in self.peers:
self.paxos.receive_promise( Promise(uid, self.network_uid, master_pid, None, None) )
else:
self.paxos.receive_prepare( Prepare(self.master_uid, master_pid) )
self.paxos.observe_proposal( master_pid )
def receive_prepare(self, from_uid, instance_number, proposal_id):
# Only process messages for the current link in the multi-paxos chain
if instance_number != self.instance_number:
return
m = self.paxos.receive_prepare(Prepare(from_uid, proposal_id))
if isinstance(m, Promise):
self.save_state(self.instance_number, self.current_value,
m.proposal_id, m.last_accepted_id,
m.last_accepted_value)
self.messenger.send_promise(from_uid, self.instance_number,
m.proposal_id, m.last_accepted_id,
m.last_accepted_value)
else:
self.messenger.send_nack(from_uid, self.instance_number,
proposal_id, self.promised_id)