Return latest state root in Transaction.commit

src/database.rs

@@ -451,13 +451,16 @@ mod tests {
         let file_path = tmp_dir.path().join("test.db");
         let db = Database::create_new(&file_path).unwrap();
 
+        let tx = db.begin_rw().unwrap();
+        assert_eq!(tx.commit().unwrap(), EMPTY_ROOT_HASH);
+
         let address1 = address!("0xd8da6bf26964af9d7eed9e03e53415d37aa96045");
         let account1 = Account::new(1, U256::from(100), EMPTY_ROOT_HASH, KECCAK_EMPTY);
 
         let mut tx = db.begin_rw().unwrap();
         tx.set_account(AddressPath::for_address(address1), Some(account1.clone())).unwrap();
 
-        tx.commit().unwrap();
+        assert_ne!(tx.commit().unwrap(), EMPTY_ROOT_HASH);
         db.close().unwrap();
 
         let db = Database::open(&file_path).unwrap();

src/meta/mod.rs

@@ -69,6 +69,7 @@ use crate::{
     snapshot::SnapshotId,
 };
 use alloy_primitives::B256;
+use alloy_trie::EMPTY_ROOT_HASH;
 use memmap2::MmapMut;
 use std::{
     cmp::Ordering,
@@ -142,7 +143,11 @@ impl MetadataSlot {
     #[inline]
     #[must_use]
     pub fn root_node_hash(&self) -> B256 {
-        self.root_node_hash.into()
+        if self.root_node_hash == [0; 32] {
+            EMPTY_ROOT_HASH
+        } else {
+            self.root_node_hash.into()
+        }
     }
 
     /// Returns the ID of the page containing the root node.

src/transaction.rs

@@ -170,7 +170,7 @@ impl<DB: Deref<Target = Database>> Transaction<DB, RW> {
         Ok(())
     }
 
-    pub fn commit(mut self) -> Result<(), TransactionError> {
+    pub fn commit(mut self) -> Result<B256, TransactionError> {
         let mut changes = self.pending_changes.drain().collect::<Vec<_>>();
         if !changes.is_empty() {
             self.database.storage_engine.set_values(&mut self.context, changes.as_mut()).unwrap();
@@ -184,7 +184,7 @@ impl<DB: Deref<Target = Database>> Transaction<DB, RW> {
         transaction_manager.remove_tx(self.context.snapshot_id, true);
 
         self.committed = true;
-        Ok(())
+        Ok(self.context.root_node_hash)
     }
 
     pub fn rollback(mut self) -> Result<(), TransactionError> {
@@ -197,12 +197,12 @@ impl<DB: Deref<Target = Database>> Transaction<DB, RW> {
 }
 
 impl<DB: Deref<Target = Database>> Transaction<DB, RO> {
-    pub fn commit(mut self) -> Result<(), TransactionError> {
+    pub fn commit(mut self) -> Result<B256, TransactionError> {
         let mut transaction_manager = self.database.transaction_manager.lock();
         transaction_manager.remove_tx(self.context.snapshot_id, false);
 
         self.committed = true;
-        Ok(())
+        Ok(self.context.root_node_hash)
     }
 }