Simulation script for ice age block times

iceage.py

# Date, blocknum, difficulty as of 2019-01-18
# Script by vbuterin, slightly modified by lrettig
import random
import datetime
import sys

def calc_bomb(i):
    period = i // 100000
    if (period > 0):
        # Subtract 2, this is the original formula
        # Subtract another 30, this is the Byzantium delay
        return 2**(period - 32)
    return 0

def calc_difficulty_byzantium(i, cur_time, prev_diff, prev_time):
    new_diff = prev_diff + prev_diff // 2048 * max(1 - (cur_time - prev_time) // 9, -99)
    new_diff += calc_bomb(i)
    return new_diff

first_block = 7_087_671
times = [1547823394]
#diffs = [3_033_556_249_786_083]
diffs = [2_580_831_000_000_000]
hashpower = diffs[0] / 14

for i in range(first_block, 10_000_000):
    blocktime = random.expovariate(hashpower / diffs[-1])
    new_time = times[-1] + blocktime
    new_diff = calc_difficulty_byzantium(i, new_time, diffs[-1], times[-1])
    times.append(new_time)
    diffs.append(new_diff)

    predicted_avg_blocktime = diffs[-1] / hashpower

    if i % 10000 == 0:
        print('Block %d, time %r blocktime %.2f diffratio %.4f' % (
            i,
            datetime.datetime.utcfromtimestamp(times[-1]).isoformat().replace('T',' '),
            predicted_avg_blocktime,
            calc_bomb(i) / diffs[-1],
            ))
    if predicted_avg_blocktime > 60:
        sys.exit('Predicted block time exceeded 60s')