252 lines
8.4 KiB
Python
252 lines
8.4 KiB
Python
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import os
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from binascii import hexlify
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from Crypto.Hash import keccak
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import random
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def to_hex(s):
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return hexlify(s).decode('utf-8')
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memo = {}
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def sha3(x):
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if x not in memo:
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memo[x] = keccak.new(digest_bits=256, data=x).digest()
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return memo[x]
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def hash_to_int(h):
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o = 0
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for c in h:
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o = (o << 8) + c
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return o
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NOTARIES = 20
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BASE_TS_DIFF = 1
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SKIP_TS_DIFF = 6
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SAMPLE = 8
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MIN_SAMPLE = lambda x: [6, 4, 3, 2, 2][x] if x < 5 else 1
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POWDIFF = 50 * NOTARIES
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SHARDS = 12
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# Not a full RANDAO; stub for now
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class Block():
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def __init__(self, parent, proposer, ts, sigs):
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self.contents = os.urandom(32)
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self.parent_hash = parent.hash if parent else (b'\x11' * 32)
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self.hash = sha3(self.parent_hash + self.contents)
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self.ts = ts
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self.sigs = sigs
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self.number = parent.number + 1 if parent else 0
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if parent:
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i = parent.child_proposers.index(proposer)
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assert self.ts >= parent.ts + BASE_TS_DIFF + i * SKIP_TS_DIFF
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assert len(sigs) >= parent.notary_req
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for sig in sigs:
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assert sig.target_hash == self.parent_hash
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# Calculate child proposers
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v = hash_to_int(sha3(self.contents))
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self.child_proposers = []
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while v > 0:
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self.child_proposers.append(v % NOTARIES)
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v //= NOTARIES
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# Calculate notaries
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if not parent:
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index = 0
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elif proposer in parent.child_proposers:
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index = parent.child_proposers.index(proposer)
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else:
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index = len(parent.child_proposers)
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self.notary_req = MIN_SAMPLE(index)
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v = hash_to_int(sha3(self.contents + b':n'))
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self.notaries = []
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for i in range(SAMPLE):
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self.notaries.append(v % NOTARIES)
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v //= NOTARIES
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# Calculate shard proposers
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v = hash_to_int(sha3(self.contents + b':s'))
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self.shard_proposers = []
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for i in range(SHARDS):
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self.shard_proposers.append(v % NOTARIES)
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v //= NOTARIES
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class Sig():
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def __init__(self, proposer, target):
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self.proposer = proposer
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self.target_hash = target.hash
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self.hash = os.urandom(32)
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assert self.proposer in target.notaries
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genesis = Block(None, 1, 0, [])
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class BlockMakingRequest():
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def __init__(self, parent, ts):
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self.parent = parent
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self.ts = ts
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self.hash = os.urandom(32)
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class Node():
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def __init__(self, _id, network, sleepy=False, careless=False, ts=0):
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self.blocks = {
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genesis.hash: genesis,
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}
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self.sigs = {}
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self.main_chain = [genesis.hash]
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self.timequeue = []
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self.parentqueue = {}
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self.children = {}
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self.ts = ts
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self.id = _id
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self.network = network
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self.used_parents = {}
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self.processed = {}
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self.sleepy = sleepy
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self.careless = careless
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self.first_round = True
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def broadcast(self, x):
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if self.sleepy and self.ts:
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return
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self.network.broadcast(self, x)
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self.on_receive(x)
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def log(self, words, lvl=3, all=False):
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#if "Tick:" != words[:5] or self.id == 0:
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if (self.id == 0 or all) and lvl >= 2:
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print(self.id, words)
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def on_receive(self, obj, reprocess=False):
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if obj.hash in self.processed and not reprocess:
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return
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self.processed[obj.hash] = obj
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if isinstance(obj, Block):
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return self.on_receive_beacon_block(obj)
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elif isinstance(obj, Sig):
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return self.on_receive_sig(obj)
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elif isinstance(obj, BlockMakingRequest):
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if self.main_chain[-1] == obj.parent:
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mc_ref = self.blocks[obj.parent]
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for i in range(2):
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if mc_ref.number == 0:
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break
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#mc_ref = self.blocks[mc_ref].parent_hash
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x = Block(self.blocks[obj.parent], self.id, self.ts,
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self.sigs[obj.parent] if obj.parent in self.sigs else [])
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self.log("Broadcasting block %s" % to_hex(x.hash[:4]))
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self.broadcast(x)
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def add_to_timequeue(self, obj):
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i = 0
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while i < len(self.timequeue) and self.timequeue[i].ts < obj.ts:
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i += 1
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self.timequeue.insert(i, obj)
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def add_to_multiset(self, _set, k, v):
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if k not in _set:
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_set[k] = []
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_set[k].append(v)
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def change_head(self, chain, new_head):
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chain.extend([None] * (new_head.number + 1 - len(chain)))
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i, c = new_head.number, new_head.hash
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while c != chain[i]:
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chain[i] = c
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c = self.blocks[c].parent_hash
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i -= 1
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for i in range(len(chain)):
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assert self.blocks[chain[i]].number == i
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def recalculate_head(self, chain, condition):
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while not condition(self.blocks[chain[-1]]):
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chain.pop()
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descendant_queue = [chain[-1]]
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new_head = chain[-1]
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while len(descendant_queue):
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first = descendant_queue.pop(0)
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if first in self.children:
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for c in self.children[first]:
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if condition(self.blocks[c]):
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descendant_queue.append(c)
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if self.blocks[first].number > self.blocks[new_head].number:
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new_head = first
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self.change_head(chain, self.blocks[new_head])
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for i in range(len(chain)):
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assert condition(self.blocks[chain[i]])
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def process_children(self, h):
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if h in self.parentqueue:
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for b in self.parentqueue[h]:
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self.on_receive(b, reprocess=True)
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del self.parentqueue[h]
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def is_descendant(self, a, b):
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a, b = self.blocks[a], self.blocks[b]
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while b.number > a.number:
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b = self.blocks[b.parent_hash]
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return a.hash == b.hash
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def have_ancestry(self, h):
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while h != genesis.hash:
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if h not in self.processed:
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return False
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h = self.processed[h].parent_hash
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return True
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def is_notarized(self, b):
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return len(self.sigs.get(b.hash, [])) >= b.notary_req
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def on_receive_beacon_block(self, block):
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# Parent not yet received
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if block.parent_hash not in self.blocks:
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self.add_to_multiset(self.parentqueue, block.parent_hash, block)
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return
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# Too early
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if block.ts > self.ts:
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self.add_to_timequeue(block)
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return
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# Add the block
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self.log("Processing beacon block %s" % to_hex(block.hash[:4]))
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self.blocks[block.hash] = block
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# Am I a notary, and is the block building on the head? Then broadcast a signature.
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if block.parent_hash == self.main_chain[-1] or self.careless:
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if self.id in block.notaries:
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self.broadcast(Sig(self.id, block))
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# Add child record
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self.add_to_multiset(self.children, block.parent_hash, block.hash)
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# Final steps
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self.process_children(block.hash)
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self.network.broadcast(self, block)
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def on_receive_sig(self, sig):
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if sig.target_hash not in self.blocks:
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self.add_to_multiset(self.parentqueue, sig.target_hash, sig)
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return
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# Add to head? Make a block?
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self.add_to_multiset(self.sigs, sig.target_hash, sig)
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if len(self.sigs[sig.target_hash]) == self.blocks[sig.target_hash].notary_req:
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block = self.blocks[sig.target_hash]
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if block.number > self.blocks[self.main_chain[-1]].number:
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self.change_head(self.main_chain, block)
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if self.id in block.child_proposers:
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my_index = block.child_proposers.index(self.id)
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target_ts = block.ts + BASE_TS_DIFF + my_index * SKIP_TS_DIFF
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self.log("Making block request for %.1f" % target_ts)
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self.add_to_timequeue(BlockMakingRequest(block.hash, target_ts))
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# Rebroadcast
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self.network.broadcast(self, sig)
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def tick(self):
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if self.first_round:
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if self.id in genesis.notaries:
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self.broadcast(Sig(self.id, genesis))
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self.first_round = False
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self.ts += 0.1
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self.log("Tick: %.1f" % self.ts, lvl=1)
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# Process time queue
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while len(self.timequeue) and self.timequeue[0].ts <= self.ts:
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self.on_receive(self.timequeue.pop(0), reprocess=True)
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