dpp-acceptor.py

Accepted = namedtuple('Accepted', ['n', 'val'])
class Variable:
    def __init__(self, nodes, q):
        self.q = q
        self.nodes = nodes
        self.promise = 0
        self.accepted = Accepted(0,None)
        self.mem = Mem()     # we don't persist self.mem and keep it in memory
        self.mem.era = 0     # current era
        self.mem.ops = 0     # number of active _read_write_read started in current era
        self.mem.old_ops = 0 # number of active _read_write_read started in previous era
        self.mem.lock = Condition() # serializes access to self.mem
    @synchronized
    def prepare(self, n):
        if self.promise.n < n:
            self.promise = n
            return self.accepted
        return Conflict(promise=self.promise)
    @synchronized
    def accept(self, n, val):
        if self.promise == n:
            self.accepted = Accepted(n, val)
            return OK()
        return Conflict(promise=self.promise)