Add fork choice rule #58
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| def chain_density(chain: Chain, slot: Slot) -> int: | ||
| return count(block for block in chain.blocks if block.slot < slot) | ||
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| def maxvalid_bg(local_chain: Chain, forks: List[Chain], k: int, s: int) -> Chain: |
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Could we add a note for what k and s are?
davidrusu
reviewed
Jan 29, 2024
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| if m <= k: | ||
| # Classic longest chain rule with parameter k | ||
| if cmax.length() < chain.length(): | ||
| cmax = chain | ||
| else: | ||
| # The chain is forking too much, we need to pay a bit more attention | ||
| # In particular, select the chain that is the densest after the fork | ||
| forking_slot = Slot( | ||
| cmax.blocks[lowest_common_ancestor].slot.absolute_slot + s | ||
| ) | ||
| cmax_density = chain_density(cmax, forking_slot) | ||
| candidate_density = chain_density(chain, forking_slot) | ||
| if cmax_density < candidate_density: | ||
| cmax = chain |
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thinking out loud: If the second forking rule is so great, why do we need the first one? performance? 🤔
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I guess 's' can't be to small to avoid tails in the distribution of slot leaders, so you would need to wait a bit every time to observe the distribution after a fork. Also, if you were to propose a block after a slot with duplicate leaders you can't use a rule that needs information about future slots
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Add the fork choice rule as described in 'Ouroboros Genesis: Composable Proof-of-Stake Blockchains with Dynamic Availability'
Tests still missing