def run(self):
i = 1 # TODO pick i more intelligently?
b = self.nextballot(0) # TODO same?
v = None
self._rpcclient.set_timeout(self._timeout)
begin, retryphase1 = 1, 2
state = begin
while True:
if state == begin:
v = self._queue.get()
elif state == retryphase1:
state = begin
# Phase 1:
resps = self._rpcclient.prepare(i, b)
# We can only send our 'v' for acceptance if we have not already crossed
# the Rubicon: if any other v *possibly* has quorum, we can't submit.
# Each resp in resps is a ("promise", i, b, V, VB).
maj, res_val = _majority(len(self._peers), [resp[3:5] for resp in resps])
if not maj:
state = retryphase1
b = self.nextballot(b)
continue
# Instance is ready, proceed. Phase 2:
if res_val is not None:
v = res_val # Instance is reserved; we must choose this value.
resps = self._rpcclient.accept(i, b, v)
if not asyncrpc._is_majority(len(self._peers), resps):
state = retryphase1
b = self.nextballot(b)
continue
# Instance is closed. Convey "learn" messages to local learner.
self._learner.learn(i, v)
i += 1
def _majority(n_peers, values): """ Takes in a number of peers, and a list of at most n_peers (V, VB) pairs. Returns (True, None) if the instance is empty. Returns (True, v) if the instance is reserved. Returns (False, None) if a quorum of acceptors failed to reply. """ if not asyncrpc._is_majority(n_peers, values): return (False, None) empty = True maxVB = None maxV = None for (V, VB) in values: if VB is not None and (empty or VB > maxVB): maxV = V maxVB = VB empty = False if empty: return (True, None) return (True, maxV)
