fix(l2): regenerate head state in node initialization

cmd/ethrex/initializers.rs

@@ -504,22 +504,44 @@ pub async fn init_l1(
     ))
 }
 
-async fn regenerate_head_state(store: &Store, blockchain: &Arc<Blockchain>) -> eyre::Result<()> {
+/// Regenerates the state up to the head block by re-applying blocks from the
+/// last known state root.
+///
+/// Since the path-based feature was added, the database stores the state 128
+/// blocks behind the head block while the state of the blocks in between are
+/// kept in in-memory-diff-layers.
+/// 
+/// After the node is shutdown, those in-memory layers are lost, and the database
+/// won't have the state for those blocks. It will have the blocks though.
+/// 
+/// When the node is started again, the state needs to be regenerated by
+/// re-applying the blocks from the last known state root up to the head block.
+/// 
+/// This function performs that regeneration.
+pub async fn regenerate_head_state(
+    store: &Store,
+    blockchain: &Arc<Blockchain>,
+) -> eyre::Result<()> {
     let head_block_number = store.get_latest_block_number().await?;
+
     let Some(last_header) = store.get_block_header(head_block_number)? else {
         unreachable!("Database is empty, genesis block should be present");
     };
 
     let mut current_last_header = last_header;
 
+    // Find the last block with a known state root
     while !store.has_state_root(current_last_header.state_root)? {
         let parent_number = current_last_header.number - 1;
+
         debug!("Need to regenerate state for block {parent_number}");
+
         let Some(parent_header) = store.get_block_header(parent_number)? else {
             return Err(eyre::eyre!(
                 "Parent header for block {parent_number} not found"
             ));
         };
+
         current_last_header = parent_header;
     }
 
@@ -529,17 +551,22 @@ async fn regenerate_head_state(store: &Store, blockchain: &Arc<Blockchain>) -> e
         debug!("State is already up to date");
         return Ok(());
     }
+
     info!("Regenerating state from block {last_state_number} to {head_block_number}");
 
+    // Re-apply blocks from the last known state root to the head block
     for i in (last_state_number + 1)..=head_block_number {
         debug!("Re-applying block {i} to regenerate state");
 
         let block = store
             .get_block_by_number(i)
             .await?
             .ok_or_else(|| eyre::eyre!("Block {i} not found"))?;
+
         blockchain.add_block(block).await?;
     }
+
     info!("Finished regenerating state");
+
     Ok(())
 }

cmd/ethrex/l2/initializers.rs

@@ -1,7 +1,7 @@
 use crate::cli::Options as L1Options;
 use crate::initializers::{
     self, get_authrpc_socket_addr, get_http_socket_addr, get_local_node_record, get_local_p2p_node,
-    get_network, get_signer, init_blockchain, init_network, init_store,
+    get_network, get_signer, init_blockchain, init_network, init_store, regenerate_head_state,
 };
 use crate::l2::L2Options;
 use crate::utils::{
@@ -169,6 +169,8 @@ pub async fn init_l2(
 
     let blockchain = init_blockchain(store.clone(), blockchain_opts);
 
+    regenerate_head_state(&store, &blockchain).await?;
+
     let signer = get_signer(&datadir);
 
     let local_p2p_node = get_local_p2p_node(&opts.node_opts, &signer);