feat(trie): introduce TRIE_ACCOUNT_RLP_MAX_SIZE constant (#12638)

crates/trie/parallel/src/proof.rs

@@ -17,7 +17,7 @@ use reth_trie::{
     proof::StorageProof,
     trie_cursor::{InMemoryTrieCursorFactory, TrieCursorFactory},
     walker::TrieWalker,
-    HashBuilder, MultiProof, Nibbles, TrieAccount, TrieInput,
+    HashBuilder, MultiProof, Nibbles, TrieAccount, TrieInput, TRIE_ACCOUNT_RLP_MAX_SIZE,
 };
 use reth_trie_common::proof::ProofRetainer;
 use reth_trie_db::{DatabaseHashedCursorFactory, DatabaseTrieCursorFactory};
@@ -153,7 +153,7 @@ where
         let mut hash_builder = HashBuilder::default().with_proof_retainer(retainer);
 
         let mut storages = HashMap::default();
-        let mut account_rlp = Vec::with_capacity(128);
+        let mut account_rlp = Vec::with_capacity(TRIE_ACCOUNT_RLP_MAX_SIZE);
         let mut account_node_iter = TrieNodeIter::new(
             walker,
             hashed_cursor_factory.hashed_account_cursor().map_err(ProviderError::Database)?,

crates/trie/parallel/src/root.rs

@@ -14,7 +14,7 @@ use reth_trie::{
     trie_cursor::{InMemoryTrieCursorFactory, TrieCursorFactory},
     updates::TrieUpdates,
     walker::TrieWalker,
-    HashBuilder, Nibbles, StorageRoot, TrieAccount, TrieInput,
+    HashBuilder, Nibbles, StorageRoot, TrieAccount, TrieInput, TRIE_ACCOUNT_RLP_MAX_SIZE,
 };
 use reth_trie_db::{DatabaseHashedCursorFactory, DatabaseTrieCursorFactory};
 use std::{collections::HashMap, sync::Arc};
@@ -149,7 +149,7 @@ where
         );
 
         let mut hash_builder = HashBuilder::default().with_updates(retain_updates);
-        let mut account_rlp = Vec::with_capacity(128);
+        let mut account_rlp = Vec::with_capacity(TRIE_ACCOUNT_RLP_MAX_SIZE);
         while let Some(node) = account_node_iter.try_next().map_err(ProviderError::Database)? {
             match node {
                 TrieElement::Branch(node) => {

crates/trie/trie/src/constants.rs

@@ -0,0 +1,24 @@
+/// The maximum size of RLP encoded trie account in bytes.
+/// 2 (header) + 4 * 1 (field lens) + 8 (nonce) + 32 * 3 (balance, storage root, code hash)
+pub const TRIE_ACCOUNT_RLP_MAX_SIZE: usize = 110;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use alloy_primitives::{B256, U256};
+    use alloy_rlp::Encodable;
+    use reth_trie_common::TrieAccount;
+
+    #[test]
+    fn account_rlp_max_size() {
+        let account = TrieAccount {
+            nonce: u64::MAX,
+            balance: U256::MAX,
+            storage_root: B256::from_slice(&[u8::MAX; 32]),
+            code_hash: B256::from_slice(&[u8::MAX; 32]),
+        };
+        let mut encoded = Vec::new();
+        account.encode(&mut encoded);
+        assert_eq!(encoded.len(), TRIE_ACCOUNT_RLP_MAX_SIZE);
+    }
+}

crates/trie/trie/src/lib.rs

@@ -13,6 +13,10 @@
 )]
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 
+/// Constants related to the trie computation.
+mod constants;
+pub use constants::*;
+
 /// The implementation of a container for storing intermediate changes to a trie.
 /// The container indicates when the trie has been modified.
 pub mod prefix_set;

crates/trie/trie/src/proof.rs

@@ -4,7 +4,7 @@ use crate::{
     prefix_set::{PrefixSetMut, TriePrefixSetsMut},
     trie_cursor::TrieCursorFactory,
     walker::TrieWalker,
-    HashBuilder, Nibbles,
+    HashBuilder, Nibbles, TRIE_ACCOUNT_RLP_MAX_SIZE,
 };
 use alloy_primitives::{
     keccak256,
@@ -104,7 +104,7 @@ where
         let mut hash_builder = HashBuilder::default().with_proof_retainer(retainer);
 
         let mut storages = HashMap::default();
-        let mut account_rlp = Vec::with_capacity(128);
+        let mut account_rlp = Vec::with_capacity(TRIE_ACCOUNT_RLP_MAX_SIZE);
         let mut account_node_iter = TrieNodeIter::new(walker, hashed_account_cursor);
         while let Some(account_node) = account_node_iter.try_next()? {
             match account_node {

crates/trie/trie/src/trie.rs

@@ -7,7 +7,7 @@ use crate::{
     trie_cursor::TrieCursorFactory,
     updates::{StorageTrieUpdates, TrieUpdates},
     walker::TrieWalker,
-    HashBuilder, Nibbles, TrieAccount,
+    HashBuilder, Nibbles, TrieAccount, TRIE_ACCOUNT_RLP_MAX_SIZE,
 };
 use alloy_consensus::EMPTY_ROOT_HASH;
 use alloy_primitives::{keccak256, Address, B256};
@@ -178,7 +178,7 @@ where
             }
         };
 
-        let mut account_rlp = Vec::with_capacity(128);
+        let mut account_rlp = Vec::with_capacity(TRIE_ACCOUNT_RLP_MAX_SIZE);
         let mut hashed_entries_walked = 0;
         let mut updated_storage_nodes = 0;
         while let Some(node) = account_node_iter.try_next()? {

crates/trie/trie/src/witness.rs

@@ -3,7 +3,7 @@ use crate::{
     prefix_set::TriePrefixSetsMut,
     proof::{Proof, StorageProof},
     trie_cursor::TrieCursorFactory,
-    HashedPostState,
+    HashedPostState, TRIE_ACCOUNT_RLP_MAX_SIZE,
 };
 use alloy_consensus::EMPTY_ROOT_HASH;
 use alloy_primitives::{
@@ -97,7 +97,7 @@ where
 
         // Attempt to compute state root from proofs and gather additional
         // information for the witness.
-        let mut account_rlp = Vec::with_capacity(128);
+        let mut account_rlp = Vec::with_capacity(TRIE_ACCOUNT_RLP_MAX_SIZE);
         let mut account_trie_nodes = BTreeMap::default();
         for (hashed_address, hashed_slots) in proof_targets {
             let storage_multiproof = account_multiproof