feat(zkos): Implement ZK OS Merkle tree #3625
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| /// Returns the new root hash of the tree on success. | ||
| pub fn verify( |
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AFAIU, the verification procedure implemented in the ZK OS repo uses separate Merkle paths for each of sorted_leaves, so the proof there is longer, but IIUC, the amount of hashing is the same (e.g., Merkle paths are not folded separately for each leaf; they are used almost in the same way as hashes here).
| 2025-02-19T11:07:06.144174Z INFO loadtest: Verified tree consistency in 41.126574667s | ||
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| I.e., latency is dominated by I/O (~30% for key–index lookup, ~30% for loading tree nodes, and ~20% for tree |
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Intuitively, there should be a way to optimize key–index lookup, but I haven't come up with anything functional yet. Stuff like reusing RocksDB iterators doesn't seem to provide efficiency boost.
| pub(crate) fn get(&self, depth_in_node: u8, index_on_level: u64) -> H256 { | ||
| let bit_shift = self.internal_node_depth - depth_in_node; |
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Does it make sense to validate depth_in_node and index_on_level? i.e add asserts
assert(depth_in_node < self.internal_node_depth)
assert(index_on_level < self.nodes.len() * (1 << bit_shift))
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It's possible, but I'm reasonably sure that both assertions hold by construction due to how get() is used in collect_hashes(). E.g., depth_in_node is defined as depth % P::INTERNAL_NODE_DEPTH, i.e., it's always valid.
What ❔
Implements a persistent Merkle tree for ZK OS using RocksDB and amortized design similar to Jellyfish Merkle tree used for Era.
Some stuff in the PR is preliminary:
Why ❔
ZK OS will need a persistent Merkle tree sooner or later. Amortized versioned design looks like a good choice (although not as good as for sparse Merkle trees, since internal nodes are almost guaranteed to be full in this case).
Is this a breaking change?
Operational changes
None.
Checklist
zkstack dev fmtandzkstack dev lint.