vclock.py

class vclock:

    def __init__(self, n, id):
        """
        Constructs a zeroed, *n* sized vector clock.
        """
        self.vclock = [0] * n
        self.id = id

    def merge(self, b):
        """
        Given two clocks, return a new clock with all
        values greater or equal to those of the merged
        clocks.
        """
        if self.id <= 4:
            if b.id <= 4:
                self.vclock = list(map(max, zip(self.vclock, b.vclock)))
            else:
                self.vclock[b.id] = max(self.vclock[b.id], b.vclock[b.id])
        else:
            self.vclock = list(map(max, zip(self.vclock, b.vclock)))


    def getTimestamp(self):
        return self.vclock[self.id]

    def increment(self):
        """
        Increment the clock at *index*.
        """
        self.vclock[self.id] = max(self.vclock) + 1
        return

    # def compare(self, b):
    #     """
    #     Compares two vector clocks, returns -1 if ``a < b``,
    #     1 if ``a > b`` else 0 for concurrent events
    #     or identical values.
    #     """
    #     gt = False
    #     lt = False
    #     for j, k in zip(self.vclock, b):
    #         gt |= j > k
    #         lt |= j < k
    #         if gt and lt:
    #             break
    #     return int(gt) - int(lt)
    #
    # def isConcurrent(self, b):
    #     """
    #     Returns whether the given clocks are concurrent.
    #     They must not be equal in value.
    #     """
    #
    #     return (self.vclock != b) and self.compare(b) == 0

'''
example code
import vclock  
a = vclock(3)
b = vclock(3)
a.increment()    
b.increment()
a.merge(b.vclock)
flag = vclock.is_concurrent(a, c)
print a
print c
print flag
'''