feat: basic persistent storage

.gitignore

@@ -13,13 +13,14 @@ Cargo.lock
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
 
+# Local state files.
+db/
+StateSnapshot.json
+
 # Direnv files.
 .direnv/
 .envrc
 
 # Nix files.
 flake.nix
 flake.lock
-
-# db
-db/

Cargo.toml

@@ -9,7 +9,8 @@ clap = { version = "4.4.0", features = ["string"] }
 ethers = "1"
 eyre = "0.6.8"
 hex = "0.4.3"
-indexmap = "2.0.1"
+indexmap = { version = "2.0.1", features = ["serde"] }
+serde = { version = "1.0.188", features = ["derive"] }
 serde_json = "1.0.107"
 thiserror = "1.0"
 tokio = { version = "1.32.0", features = ["macros"] }

src/lib.rs

@@ -1,7 +1,7 @@
 #![feature(array_chunks)]
 // #![warn(clippy::pedantic)]
 
-mod state;
+mod snapshot;
 mod tree;
 mod types;
 
@@ -15,6 +15,7 @@ use ethers::{
 use eyre::Result;
 
 pub const INITAL_STATE_PATH: &str = "InitialState.csv";
+pub const STATE_FILE_PATH: &str = "StateSnapshot.json";
 pub const ZK_SYNC_ADDR: &str = "0x32400084C286CF3E17e7B677ea9583e60a000324";
 pub const GENESIS_BLOCK: u64 = 16_627_460;
 pub const BLOCK_STEP: u64 = 128;
@@ -110,7 +111,7 @@ mod tests {
 
     use eyre::Result;
 
-    use crate::tree::TreeWrapper;
+    use crate::{snapshot::StateSnapshot, tree::TreeWrapper};
 
     use super::*;
 
@@ -119,14 +120,31 @@ mod tests {
     async fn it_works() -> Result<()> {
         // TODO: This should be an env variable / CLI argument.
         let db_dir = env::current_dir()?.join("db");
-        // TODO: Save / Load from existing db.
-        if db_dir.exists() {
-            std::fs::remove_dir_all(&db_dir)?;
-        }
-        let mut tree = TreeWrapper::new(db_dir.as_path())?;
+
+        // TODO: Implement graceful shutdown.
+        // If database directory already exists, we try to restore the latest state.
+        // The state contains the last processed block and a mapping of index to key
+        // values, if a state file does not exist, we simply use the defaults instead.
+        let should_restore_state = db_dir.exists();
+        let mut state_snapshot = if should_restore_state {
+            println!("Loading previous state file...");
+            StateSnapshot::read(STATE_FILE_PATH).expect("state file is malformed")
+        } else {
+            println!("No existing database found, starting from genesis...");
+            StateSnapshot::default()
+        };
+
+        // Extract fields from state snapshot.
+        let StateSnapshot {
+            mut current_l1_block_number,
+            mut latest_l2_block_number,
+            ref index_to_key_map,
+        } = state_snapshot;
+
+        let mut tree = TreeWrapper::new(db_dir.as_path(), index_to_key_map.clone())?;
 
         let (provider, contract) = init_eth_adapter("https://eth.llamarpc.com").await;
-        let latest_l1_block = provider
+        let latest_l1_block_number = provider
             .get_block(BlockNumber::Latest)
             .await?
             .unwrap()
@@ -136,26 +154,23 @@ mod tests {
         let event = contract.events_by_name("BlockCommit")?[0].clone();
         let function = contract.functions_by_name("commitBlocks")?[0].clone();
 
-        let mut current_block = GENESIS_BLOCK;
-        let mut latest_l2_block_number = U256::default();
-        while current_block <= latest_l1_block.0[0] {
+        println!("Starting from l1 block: {}", current_l1_block_number);
+        while current_l1_block_number <= latest_l1_block_number.0[0] {
             // Create a filter showing only `BlockCommit`s from the [`ZK_SYNC_ADDR`].
             // TODO: Filter by executed blocks too.
             let filter = Filter::new()
                 .address(ZK_SYNC_ADDR.parse::<Address>()?)
                 .topic0(event.signature())
-                .from_block(current_block)
-                .to_block(current_block + BLOCK_STEP);
+                .from_block(current_l1_block_number)
+                .to_block(current_l1_block_number + BLOCK_STEP);
 
             // Grab all relevant logs.
             let logs = provider.get_logs(&filter).await?;
             for log in logs {
-                println!("{:?}", log);
                 // log.topics:
                 // topics[1]: L2 block number.
                 // topics[2]: L2 block hash.
                 // topics[3]: L2 commitment.
-                // TODO: Check for already processed blocks.
 
                 let new_l2_block_number = U256::from_big_endian(log.topics[1].as_fixed_bytes());
                 if new_l2_block_number <= latest_l2_block_number {
@@ -171,13 +186,20 @@ mod tests {
                     println!("Parsed {} new blocks", num_blocks);
 
                     for block in blocks {
-                        latest_l2_block_number = tree.insert_block(block);
+                        latest_l2_block_number = tree.insert_block(&block);
+
+                        // Update snapshot values.
+                        state_snapshot.latest_l2_block_number = latest_l2_block_number;
+                        state_snapshot.index_to_key_map = tree.index_to_key.clone();
                     }
                 }
             }
-
             // Increment current block index.
-            current_block += BLOCK_STEP;
+            current_l1_block_number += BLOCK_STEP;
+
+            // Update snapshot values and write the current state to a file.
+            state_snapshot.current_l1_block_number = current_l1_block_number;
+            state_snapshot.write(STATE_FILE_PATH)?;
         }
 
         Ok(())

src/snapshot.rs

@@ -0,0 +1,57 @@
+#![allow(dead_code)]
+use std::{fs, io};
+
+use ethers::types::U256;
+use indexmap::IndexSet;
+use serde::{Deserialize, Serialize};
+
+use crate::GENESIS_BLOCK;
+
+/// Struct containing the fields used for restoring the tree state.
+#[derive(Serialize, Deserialize)]
+pub struct StateSnapshot {
+    /// The latest l1 block number that was processed.
+    pub current_l1_block_number: u64,
+    /// The latest l2 block number that was processed.
+    pub latest_l2_block_number: U256,
+    /// The mappings of index to key values.
+    pub index_to_key_map: IndexSet<U256>,
+}
+
+impl Default for StateSnapshot {
+    fn default() -> Self {
+        Self {
+            current_l1_block_number: GENESIS_BLOCK,
+            latest_l2_block_number: U256::default(),
+            index_to_key_map: IndexSet::default(),
+        }
+    }
+}
+
+impl StateSnapshot {
+    pub fn new(
+        latest_l1_block_number: u64,
+        latest_l2_block_number: U256,
+        index_to_key_map: IndexSet<U256>,
+    ) -> Self {
+        Self {
+            current_l1_block_number: latest_l1_block_number,
+            latest_l2_block_number,
+            index_to_key_map,
+        }
+    }
+
+    /// Reads and serializes the json file containing the index to key mappings.
+    pub fn read(path: &str) -> Result<StateSnapshot, io::Error> {
+        let contents = fs::read_to_string(path)?;
+        let state: StateSnapshot = serde_json::from_str(&contents)?;
+
+        Ok(state)
+    }
+
+    /// Writes the json file containing the index to key mappings.
+    pub fn write(&self, path: &str) -> Result<(), io::Error> {
+        let content = serde_json::to_string_pretty(&self)?;
+        fs::write(path, content)
+    }
+}

src/tree.rs

@@ -3,6 +3,7 @@
 use std::{fs, path::Path, str::FromStr};
 
 use ethers::types::{Address, H256, U256};
+use indexmap::IndexSet;
 use zk_evm::aux_structures::LogQuery;
 use zksync_merkle_tree::{Database, MerkleTree, RocksDBWrapper};
 
@@ -12,21 +13,27 @@ use crate::{types::CommitBlockInfoV1, INITAL_STATE_PATH};
 
 pub struct TreeWrapper<'a> {
     pub tree: MerkleTree<'a, RocksDBWrapper>,
-    // FIXME: How to save this for persistant storage?
-    pub index_to_key: Vec<U256>,
+    pub index_to_key: IndexSet<U256>,
 }
 
 impl TreeWrapper<'static> {
-    pub fn new(db_dir: &Path) -> Result<Self> {
+    /// Attempts to create a new [`TreeWrapper`].
+    pub fn new(db_dir: &Path, mut index_to_key: IndexSet<U256>) -> Result<Self> {
         let db = RocksDBWrapper::new(db_dir);
         let mut tree = MerkleTree::new(db);
-        let index_to_key = reconstruct_genesis_state(&mut tree, INITAL_STATE_PATH)?;
+
+        // If an existing `index_to_key` mapping was supplied, use that.
+        // Otherwise, reconstruct the genesis state.
+        if index_to_key.is_empty() {
+            println!("was empty!");
+            reconstruct_genesis_state(&mut tree, &mut index_to_key, INITAL_STATE_PATH)?;
+        }
 
         Ok(Self { tree, index_to_key })
     }
 
     /// Inserts a block into the tree and returns the new block number.
-    pub fn insert_block(&mut self, block: CommitBlockInfoV1) -> U256 {
+    pub fn insert_block(&mut self, block: &CommitBlockInfoV1) -> U256 {
         let new_l2_block_number = block.block_number;
         // INITIAL CALLDATA.
         let mut key_value_pairs: Vec<(U256, H256)> =
@@ -36,14 +43,14 @@ impl TreeWrapper<'static> {
             let value = H256::from(value);
 
             key_value_pairs.push((key, value));
-            self.index_to_key.push(key);
+            self.index_to_key.insert(key);
         }
 
         // REPEATED CALLDATA.
         for (index, value) in &block.repeated_storage_changes {
             let index = *index as usize;
             // Index is 1-based so we subtract 1.
-            let key = *self.index_to_key.get(index - 1).unwrap();
+            let key = *self.index_to_key.get_index(index - 1).unwrap();
             let value = H256::from(value);
 
             key_value_pairs.push((key, value));
@@ -66,8 +73,9 @@ impl TreeWrapper<'static> {
 /// Attempts to reconstruct the genesis state from a CSV file.
 fn reconstruct_genesis_state<D: Database>(
     tree: &mut MerkleTree<D>,
+    index_to_key: &mut IndexSet<U256>,
     path: &str,
-) -> Result<Vec<U256>> {
+) -> Result<()> {
     fn cleanup_encoding(input: &'_ str) -> &'_ str {
         input
             .strip_prefix("E'\\\\x")
@@ -139,7 +147,6 @@ fn reconstruct_genesis_state<D: Database>(
 
     println!("Have {} unique keys in the tree", key_set.len());
 
-    let mut index_to_key = Vec::with_capacity(batched.len());
     let mut key_value_pairs: Vec<(U256, H256)> = Vec::with_capacity(batched.len());
     for (address, key, value) in batched {
         let derived_key = LogQuery::derive_final_address_for_params(&address, &key);
@@ -159,12 +166,12 @@ fn reconstruct_genesis_state<D: Database>(
         let key = U256::from_little_endian(&derived_key);
         let value = H256::from(tmp);
         key_value_pairs.push((key, value));
-        index_to_key.push(key);
+        index_to_key.insert(key);
     }
 
     let output = tree.extend(key_value_pairs);
     dbg!(tree.latest_version());
     println!("Initial state root = {}", hex::encode(output.root_hash));
 
-    Ok(index_to_key)
+    Ok(())
 }