research/casper/voting_strategy.py

import random

# The voting strategy. Validators see what every other validator votes,
# and return their vote.
#
# Votes are log odds, ie. ln(p / (1-p))
#
# Remember, 0 and 1 are not probabilities!
# http://lesswrong.com/lw/mp/0_and_1_are_not_probabilities/ !)

def default_vote(scheduled_time, received_time, now, **kwargs):
    if received_time is None:
        time_delta = now - scheduled_time
        my_opinion_prob = 1 if time_delta < kwargs["blktime"] * 4 else 4.0 / (4 + time_delta * 1.0 / kwargs["blktime"])
        return 0 if random.random() < my_opinion_prob else -1
    else:
        time_delta = received_time * 0.9 + now * 0.1 - scheduled_time
        my_opinion_prob = 1 if abs(time_delta) < kwargs["blktime"] * 4 else 4.0 / (4 + abs(time_delta) * 1.0 / kwargs["blktime"])
        return 1 if random.random() < my_opinion_prob else -1
    

def vote(probs):
    if len(probs) == 0:
        return 0
    probs = sorted(probs)
    if probs[len(probs)/3] >= 1:
        return probs[len(probs)/3] + 1
    elif probs[len(probs)*2/3] <= -1:
        return probs[len(probs)*2/3] - 1
    else:
        return probs[len(probs)/2]