def _(self, message, channel, create_reply=Promise.create):
"""Promise Phase.
If an acceptor receives a prepare request with number n greater than
that of any prepare request to which it has already responded then it
responds to the request with a promise not to accept any more
proposals numbered less than n and with the highest-numbered proposal
(if any) that it has accepted.
"""
LOG.debug("RECEIVED message {0}".format(message))
if message.proposal >= self.state.read(Role.PROMISED):
self.state.write(Role.PROMISED, message.proposal)
reply = create_reply(
sender=message.receiver,
receiver=message.sender,
proposal=message.proposal,
accepted_proposal=self.state.read(Role.ACCEPTED),
value=self.state.read(Role.VALUE))
channel.unicast(reply)
else:
reply = Nack.create(sender=message.receiver,
receiver=message.sender)
channel.unicast(reply)
def _(self, message, channel, create_reply=Accepted.create):
"""Accepted Phase.
If an acceptor receives an accept request for a proposal numbered n,
it accepts the proposal unless it has already responded to a prepare
request having a number greater than n.
"""
LOG.debug("RECEIVED message {0}".format(message))
if message.proposal >= self.state.read(Role.PROMISED):
if message.proposal > self.state.read(Role.ACCEPTED):
self.state.write(Role.ACCEPTED, message.proposal)
self.state.write(Role.VALUE, message.value)
reply = create_reply(sender=message.receiver,
value=self.state.read(Role.VALUE),
proposal=message.proposal)
channel.broadcast(reply)
else:
reply = Nack.create(sender=message.receiver,
receiver=message.sender,
value=self.state.read(Role.VALUE),
proposal=message.proposal)
channel.unicast(reply)