Updated the RPJ algorithm
This commit is contained in:
Vitalik Buterin
parent
13a30dedf4
commit
82620d82de
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@ -19,9 +19,9 @@ def hash_to_int(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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NOTARIES = 60
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SLOT_SIZE = 6
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EPOCH_LENGTH = 5
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EPOCH_LENGTH = 20
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# Not a full RANDAO; stub for now
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class Block():
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@ -38,11 +38,12 @@ class Block():
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return SLOT_SIZE * self.slot
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class Sig():
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def __init__(self, proposer, targets, ts):
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def __init__(self, proposer, targets, slot, ts):
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self.proposer = proposer
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self.targets = targets
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self.hash = os.urandom(32)
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self.slot = slot
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self.ts = ts
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self.hash = os.urandom(32)
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genesis = Block(None, 0, 0)
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@ -58,6 +59,7 @@ class Node():
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self.parentqueue = {}
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self.children = {}
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self.scores = {}
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self.scores_at_height = {}
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self.justified = {}
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self.finalized = {}
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self.ts = ts
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@ -68,8 +70,8 @@ class Node():
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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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self.last_made_block = -1
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self.last_made_sig = -1
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self.last_made_block = 0
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self.last_made_sig = 0
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def broadcast(self, x):
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if self.sleepy and self.ts:
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@ -147,14 +149,6 @@ class Node():
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b = self.blocks[b.parent_hash]
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return a
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def get_ancestor_at_slot(self, a, slot, strict=True):
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while a.slot > slot and a.hash != genesis.hash:
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a = self.blocks[a.parent_hash]
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if a.slot == slot or strict is False:
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return a
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else:
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return None
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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.height > a.height:
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@ -198,22 +192,70 @@ class Node():
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max_score = max([0] + [self.scores.get(self.main_chain[i], 0) for i in range(anc.height + 1, len(self.main_chain))])
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# Process scoring
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max_newchain_score = 0
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for c in sig.targets:
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self.scores[c] = self.scores.get(c, 0) + 1
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if self.scores[c] == NOTARIES * 2 // 3:
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for i, c in list(enumerate(sig.targets))[::-1]:
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slot = sig.slot - 1 - i
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slot_key = slot.to_bytes(4, 'big')
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assert self.blocks[c].slot <= slot
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# If a parent and child block have non-consecutive slots, then the parent
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# block is also considered to be the canonical block at all of the intermediate
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# slot numbers. We store the scores for the block at each height separately
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self.scores_at_height[slot_key + c] = self.scores_at_height.get(slot_key + c, 0) + 1
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# For fork choice rule purposes, the score of a block is the highest score
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# that it has at any height
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self.scores[c] = max(self.scores.get(c, 0), self.scores_at_height[slot_key + c])
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# If 2/3 of notaries vote for a block, it is justified
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if self.scores_at_height[slot_key + c] == NOTARIES * 2 // 3:
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self.justified[c] = True
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c_minus_one_epoch = self.get_ancestor_at_slot(self.blocks[c], self.blocks[c].slot - EPOCH_LENGTH)
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if c_minus_one_epoch and c_minus_one_epoch.hash in self.justified:
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self.finalized[c_minus_one_epoch.hash] = True
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c2 = c
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self.log("Justified: %d %s" % (slot, hexlify(c).decode('utf-8')[:8]))
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# If EPOCH_LENGTH+1 blocks are justified in a row, the oldest is
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# considered finalized
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finalize = True
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for slot2 in range(slot - 1, max(slot - EPOCH_LENGTH, 0) - 1, -1):
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if slot2 < self.blocks[c2].slot:
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c2 = self.blocks[c2].parent_hash
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if self.scores_at_height.get(slot2.to_bytes(4, 'big') + c2, 0) < (NOTARIES * 2 // 3):
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finalize = False
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# self.log("Not quite finalized: stopped at %d needed %d" % (slot2, max(slot - EPOCH_LENGTH, 0)))
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break
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if finalize and c2 not in self.finalized:
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self.log("Finalized: %d %s" % (self.blocks[c2].slot, hexlify(c).decode('utf-8')[:8]))
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self.finalized[c2] = True
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# Find the maximum score of a block on the chain that this sig is weighing on
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if self.blocks[c].slot > anc.slot:
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max_newchain_score = max(max_newchain_score, self.scores[c])
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# If it's higher, switch over the canonical chain
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if max_newchain_score > max_score:
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self.main_chain = self.main_chain[:anc.height+1]
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self.recalculate_head()
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self.sigs[sig.hash] = sig
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# Rebroadcast
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self.network.broadcast(self, sig)
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# Get the portion of the main chain that is within the last EPOCH_LENGTH
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# slots, once again duplicating the parent in cases where the parent and
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# child's slots are not consecutive
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def get_sig_targets(self, start_slot):
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o = []
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i = len(self.main_chain) - 1
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for slot in range(start_slot - 1, max(start_slot - EPOCH_LENGTH, 0) - 1, -1):
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if slot < self.blocks[self.main_chain[i]].slot:
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i -= 1
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o.append(self.main_chain[i])
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for i, x in enumerate(o):
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assert self.blocks[x].slot <= start_slot - 1 - i
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assert len(o) == min(EPOCH_LENGTH, start_slot)
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return o
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def tick(self):
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self.ts += 0.1
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self.log("Tick: %.1f" % self.ts, lvl=1)
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@ -227,7 +269,9 @@ class Node():
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sig_from = len(self.main_chain) - 1
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while sig_from > 0 and self.blocks[self.main_chain[sig_from]].slot >= slot - EPOCH_LENGTH:
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sig_from -= 1
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self.broadcast(Sig(self.id, self.main_chain[sig_from:][::-1], self.ts))
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sig = Sig(self.id, self.get_sig_targets(slot), slot, self.ts)
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# self.log('Sig:', self.id, sig.slot, ' '.join([hexlify(t).decode('utf-8')[:4] for t in sig.targets]))
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self.broadcast(sig)
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self.last_made_sig = slot
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# Process time queue
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while len(self.timequeue) and self.timequeue[0].min_timestamp() <= self.ts:
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@ -2,11 +2,11 @@ from networksim import NetworkSimulator
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from ghost_node import Node, NOTARIES, Block, Sig, genesis, SLOT_SIZE
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from distributions import normal_distribution
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net = NetworkSimulator(latency=300)
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notaries = [Node(i, net, ts=max(normal_distribution(60, 60)(), 0) * 0.1, sleepy=i%4==0) for i in range(NOTARIES)]
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net = NetworkSimulator(latency=150)
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notaries = [Node(i, net, ts=max(normal_distribution(50, 50)(), 0) * 0.1, sleepy=False) for i in range(NOTARIES)]
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net.agents = notaries
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net.generate_peers()
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for i in range(10000):
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for i in range(15000):
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net.tick()
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for n in notaries:
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print("Local timestamp: %.1f, timequeue len %d" % (n.ts, len(n.timequeue)))
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@ -65,6 +65,8 @@ otheredges = [(u,v) for (u,v) in edges if G[u][v]['color'] == '0.75']
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nx.draw_networkx_edges(G, pos, edgelist=otheredges, width=1, edge_color='0.75')
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nx.draw_networkx_edges(G, pos, edgelist=blockedges, width=2, edge_color='b')
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print('Scores:', [n.scores.get(c, 0) for c in n.main_chain])
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plt.axis('off')
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# plt.savefig("degree.png", bbox_inches="tight")
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plt.show()
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