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test ledger state is properly updated on re-org

This commit is contained in:
David Rusu 2024-02-01 21:33:37 +04:00
parent 62ea40ba5e
commit 9345af0614
3 changed files with 103 additions and 45 deletions
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43
cryptarchia/cryptarchia.py
View File

@ -26,8 +26,13 @@ class TimeConfig:
@dataclass
class Config:
k: int
active_slot_coeff: float # 'f', the rate of occupied slots
time: TimeConfig
@property
def s(self):
return int(3 * self.k / self.active_slot_coeff)
# An absolute unique indentifier of a slot, counting incrementally from 0
@dataclass
@ -158,6 +163,15 @@ class LedgerState:
commitments: set[Id] = field(default_factory=set) # set of commitments
nullifiers: set[Id] = field(default_factory=set) # set of nullified
def copy(self):
return LedgerState(
block=self.block,
nonce=self.nonce,
total_stake=self.total_stake,
commitments=self.commitments.copy(),
nullifiers=self.nullifiers.copy(),
)
def verify_committed(self, commitment: Id) -> bool:
return commitment in self.commitments
@ -180,7 +194,7 @@ class Follower:
nonce_snapshot=genesis_state,
)
self.genesis_state = genesis_state
self.ledger_state = genesis_state
self.ledger_state = genesis_state.copy()
def validate_header(self, block: BlockHeader) -> bool:
# TODO: this is not the full block validation spec, only slot leader is verified
@ -201,16 +215,20 @@ class Follower:
return True
for chain in self.forks:
if chain.tip().id() == block.parent():
if chain.tip().id() == block.parent:
chain.blocks.append(block)
return True
return False
def try_create_fork(self, block: BlockHeader) -> Optional[Chain]:
if self.genesis_state.block == block.parent:
# this block is forking off the genesis state
return Chain(blocks=[block])
chains = self.forks + [self.local_chain]
for chain in chains:
if self.chain.contains_block(block):
if chain.contains_block(block):
block_position = chain.block_position(block)
return Chain(blocks=chain.blocks[:block_position] + [block])
@ -234,7 +252,7 @@ class Follower:
return
# We may need to switch forks, lets run the fork choice rule to check.
new_chain = Follower.fork_choice(self.local_chain, self.forks)
new_chain = self.fork_choice()
if new_chain == self.local_chain:
# we have not re-org'd therefore we can simply update our ledger state
@ -252,14 +270,14 @@ class Follower:
self.local_chain = new_chain
# Evaluate the fork choice rule and return the block header of the block that should be the head of the chain
@staticmethod
def fork_choice(local_chain: Chain, forks: List[Chain]) -> Chain:
# TODO: define k and s
return maxvalid_bg(local_chain, forks, 0, 0)
def fork_choice(self) -> Chain:
return maxvalid_bg(
self.local_chain, self.forks, k=self.config.k, s=self.config.s
)
def tip_id(self) -> Id:
if self.local_chain.length() > 0:
return self.local_chain.tip().id
return self.local_chain.tip().id()
else:
return self.ledger_state.block
@ -286,11 +304,6 @@ class EpochState:
return self.nonce_snapshot.nonce
@dataclass
class LeaderConfig:
active_slot_coeff: float = 0.05 # 'f', the rate of occupied slots
def phi(f: float, alpha: float) -> float:
"""
params:
@ -322,7 +335,7 @@ class MOCK_LEADER_VRF:
@dataclass
class Leader:
config: LeaderConfig
config: Config
coin: Coin
def try_prove_slot_leader(

10
cryptarchia/test_leader.py
View File

@ -2,7 +2,7 @@ from unittest import TestCase
import numpy as np
from .cryptarchia import Leader, LeaderConfig, EpochState, LedgerState, Coin, phi
from .cryptarchia import Leader, Config, EpochState, LedgerState, Coin, phi, TimeConfig
class TestLeader(TestCase):
@ -15,8 +15,12 @@ class TestLeader(TestCase):
)
f = 0.05
leader_config = LeaderConfig(active_slot_coeff=f)
l = Leader(config=leader_config, coin=Coin(pk=0, value=10))
config = Config(
k=10,
active_slot_coeff=f,
time=TimeConfig(slots_per_epoch=1000, slot_duration=1, chain_start_time=0),
)
l = Leader(config=config, coin=Coin(pk=0, value=10))
# We'll use the Margin of Error equation to decide how many samples we need.
# https://en.wikipedia.org/wiki/Margin_of_error

95
cryptarchia/test_ledger_state_update.py
View File

@ -11,36 +11,48 @@ from .cryptarchia import (
LedgerState,
MockLeaderProof,
Slot,
Id,
)
def mk_genesis_state(initial_stake_distribution: list[Coin]) -> LedgerState:
return LedgerState(
block=bytes(32),
nonce=bytes(32),
total_stake=sum(c.value for c in initial_stake_distribution),
commitments={c.commitment() for c in initial_stake_distribution},
nullifiers=set(),
)
def mk_block(parent: Id, slot: int, coin: Coin, content=bytes(32)) -> BlockHeader:
from hashlib import sha256
return BlockHeader(
slot=Slot(slot),
parent=parent,
content_size=len(content),
content_id=sha256(content).digest(),
leader_proof=MockLeaderProof.from_coin(coin),
)
def config() -> Config:
return Config(
k=10, time=TimeConfig(slots_per_epoch=1000, slot_duration=1, chain_start_time=0)
k=10,
active_slot_coeff=0.05,
time=TimeConfig(slots_per_epoch=1000, slot_duration=1, chain_start_time=0),
)
class TestLedgerStateUpdate(TestCase):
def test_ledger_state_prevents_coin_reuse(self):
leader_coin = Coin(pk=0, value=100)
genesis_state = LedgerState(
block=bytes(32),
nonce=bytes(32),
total_stake=leader_coin.value,
commitments={leader_coin.commitment()},
nullifiers=set(),
)
genesis = mk_genesis_state([leader_coin])
follower = Follower(genesis_state, config())
block = BlockHeader(
slot=Slot(0),
parent=genesis_state.block,
content_size=1,
content_id=bytes(32),
leader_proof=MockLeaderProof.from_coin(leader_coin),
)
follower = Follower(genesis, config())
block = mk_block(slot=0, parent=genesis.block, coin=leader_coin)
follower.on_block(block)
# Follower should have accepted the block
@ -50,18 +62,47 @@ class TestLedgerStateUpdate(TestCase):
# Follower should have updated their ledger state to mark the leader coin as spent
assert follower.ledger_state.verify_unspent(leader_coin.nullifier()) == False
reuse_coin_block = BlockHeader(
slot=Slot(0),
parent=block.id(),
content_size=1,
content_id=bytes(32),
leader_proof=MockLeaderProof(
commitment=leader_coin.commitment(),
nullifier=leader_coin.nullifier(),
),
)
reuse_coin_block = mk_block(slot=1, parent=block.id, coin=leader_coin)
follower.on_block(block)
# Follower should *not* have accepted the block
assert follower.local_chain.length() == 1
assert follower.local_chain.tip() == block
def test_ledger_state_is_properly_updated_on_reorg(self):
coin_1 = Coin(pk=0, value=100)
coin_2 = Coin(pk=1, value=100)
coin_3 = Coin(pk=1, value=100)
genesis = mk_genesis_state([coin_1, coin_2, coin_3])
follower = Follower(genesis, config())
# 1) coin_1 & coin_2 both concurrently win slot 0
block_1 = mk_block(parent=genesis.block, slot=0, coin=coin_1)
block_2 = mk_block(parent=genesis.block, slot=0, coin=coin_2)
# 2) follower sees block 1 first
follower.on_block(block_1)
assert follower.tip_id() == block_1.id()
assert not follower.ledger_state.verify_unspent(coin_1.nullifier())
# 3) then sees block 2, but sticks with block_1 as the tip
follower.on_block(block_2)
assert follower.tip_id() == block_1.id()
assert len(follower.forks) == 1, f"{len(follower.forks)}"
# 4) then coin_3 wins slot 1 and chooses to extend from block_2
block_3 = mk_block(parent=block_2.id(), slot=0, coin=coin_3)
follower.on_block(block_3)
# the follower should have switched over to the block_2 fork
assert follower.tip_id() == block_3.id()
# and the original coin_1 should now be removed from the spent pool
assert follower.ledger_state.verify_unspent(coin_1.nullifier())