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# Time between successful PoW solutions
POW_SOLUTION_TIME = 12
# Time for a block to traverse the network
TRANSIT_TIME = 8
# Max uncle depth
UNCLE_DEPTH = 4
# Uncle block reward (normal block reward = 1)
UNCLE_REWARD_COEFF = 32/32.
UNCLE_DEPTH_PENALTY = 4/32.
# Reward for including uncles
NEPHEW_REWARD_COEFF = 1/32.
# Rounds to test
ROUNDS = 1000000
import random
all_miners = {}
class Miner():
def __init__(self, p, backward=0):
# Miner hashpower
self.hashpower = p
# Miner mines a few blocks behind the head?
self.backward = backward
self.id = random.randrange(10000000)
# Set up a few genesis blocks (since the algo is grandpa-dependent,
# we need two genesis blocks plus some genesis uncles)
self.blocks = {}
self.children = {}
for i in range(UNCLE_DEPTH + 2):
self.blocks[i] = \
{"parent": i-1, "uncles": {}, "miner": -1, "height": i,
"score": i, "id": i}
self.children[i-1] = {i: True}
# ID of "latest block"
self.head = UNCLE_DEPTH + 1
# Hear about a block
def recv(self, block):
# Add the block to the set if it's valid
addme = True
if block["id"] in self.blocks:
addme = False
if block["parent"] not in self.blocks:
addme = False
if addme:
self.blocks[block["id"]] = block
if block["parent"] not in self.children:
self.children[block["parent"]] = {}
if block["id"] not in self.children[block["parent"]]:
self.children[block["parent"]][block["id"]] = block["id"]
if block["score"] > self.blocks[self.head]["score"]:
self.head = block["id"]
# Mine a block
def mine(self):
HEAD = self.blocks[self.head]
for i in range(self.backward):
HEAD = self.blocks[HEAD["parent"]]
H = HEAD
h = self.blocks[self.blocks[self.head]["parent"]]
# Select the uncles. The valid set of uncles for a block consists
# of the children of the 2nd to N+1th order grandparents minus
# the parent and said grandparents themselves and blocks that were
# uncles of those previous blocks
u = {}
notu = {}
for i in range(UNCLE_DEPTH - self.backward):
for c in self.children.get(h["id"], {}):
u[c] = True
notu[H["id"]] = True
for c in H["uncles"]:
notu[c] = True
H = h
h = self.blocks[h["parent"]]
for i in notu:
if i in u:
del u[i]
block = {"parent": self.head, "uncles": u, "miner": self.id,
"height": HEAD["height"] + 1, "score": HEAD["score"]+1+len(u),
"id": random.randrange(1000000000000)}
self.recv(block)
global all_miners
all_miners[block["id"]] = block
return block
# If b1 is the n-th degree grandchild and b2 is the m-th degree grandchild
# of nearest common ancestor C, returns min(m, n)
def cousin_degree(miner, b1, b2):
while miner.blocks[b1]["height"] > miner.blocks[b2]["height"]:
b1 = miner.blocks[b1]["parent"]
while miner.blocks[b2]["height"] > miner.blocks[b1]["height"]:
b2 = miner.blocks[b2]["parent"]
t = 0
while b1 != b2:
b1 = miner.blocks[b1]["parent"]
b2 = miner.blocks[b2]["parent"]
t += 1
return t
# Set hashpower percentages and strategies
# Strategy = how many blocks behind head you mine
profiles = [
# (hashpower, strategy, count)
(1, 0, 20),
(1, 1, 4), # cheaters, mine 1/2/4 blocks back to reduce
(1, 2, 3), # chance of being in a two-block fork
(1, 4, 3),
(5, 0, 1),
(10, 0, 1),
(15, 0, 1),
(25, 0, 1),
]
total_pct = 0
miners = []
for p, b, c in profiles:
for i in range(c):
miners.append(Miner(p, b))
total_pct += p
miner_dict = {}
for m in miners:
miner_dict[m.id] = m
listen_queue = []
for t in range(ROUNDS):
if t % 5000 == 0:
print t
for m in miners:
R = random.randrange(POW_SOLUTION_TIME * total_pct)
if R < m.hashpower and t < ROUNDS - TRANSIT_TIME * 3:
b = m.mine()
listen_queue.append([t + TRANSIT_TIME, b])
while len(listen_queue) and listen_queue[0][0] <= t:
t, b = listen_queue.pop(0)
for m in miners:
m.recv(b)
h = miners[0].blocks[miners[0].head]
profit = {}
total_blocks_in_chain = 0
length_of_chain = 0
ZORO = {}
print "### PRINTING BLOCKCHAIN ###"
while h["id"] > UNCLE_DEPTH + 2:
# print h["id"], h["miner"], h["height"], h["score"]
# print "Uncles: ", list(h["uncles"])
total_blocks_in_chain += 1 + len(h["uncles"])
ZORO[h["id"]] = True
length_of_chain += 1
profit[h["miner"]] = profit.get(h["miner"], 0) + \
1 + NEPHEW_REWARD_COEFF * len(h["uncles"])
for u in h["uncles"]:
ZORO[u] = True
u2 = miners[0].blocks[u]
profit[u2["miner"]] \
= profit.get(u2["miner"], 0) + UNCLE_REWARD_COEFF - UNCLE_DEPTH_PENALTY * (h["height"] - u2["height"])
h = miners[0].blocks[h["parent"]]
print "### PRINTING HEADS ###"
for m in miners:
print m.head
print "### PRINTING PROFITS ###"
for p in profit:
print miner_dict.get(p, Miner(0)).hashpower, profit.get(p, 0)
print "### PRINTING RESULTS ###"
groupings = {}
counts = {}
for p in profit:
m = miner_dict.get(p, None)
if m:
h = str(m.hashpower)+','+str(m.backward)
counts[h] = counts.get(h, 0) + 1
groupings[h] = groupings.get(h, 0) + profit[p]
for c in counts:
print c, groupings[c] / counts[c] / (groupings['1,0'] / counts['1,0'])
print " "
print "Total blocks produced: ", len(all_miners) - UNCLE_DEPTH
print "Total blocks in chain: ", total_blocks_in_chain
print "Efficiency: ", \
total_blocks_in_chain * 1.0 / (len(all_miners) - UNCLE_DEPTH)
print "Average uncles: ", total_blocks_in_chain * 1.0 / length_of_chain - 1
print "Length of chain: ", length_of_chain
print "Block time: ", ROUNDS * 1.0 / length_of_chain