perf: remove empty HashMap instances from TrieUpdates and HashedPostState

[kien-rise]

This is the simplified version of #13929.

Checklist

Checklist

• Do benchmarks
• Improve PR description

Problem

In our benchmarks, we discovered that TrieUpdates::insert_storage_updates and HashedPostState::from_bundle_state are adding hundreds of thousands of empty HashMap instances. Since an empty HashMap does nothing, they can be safely removed without affecting correctness. By removing these empty HashMaps, we can reduce both memory usage (particularly heap allocation) and computation time.

---

To help visualize this better, here's an example of a state update from an ERC20 transaction:

{
  0x420000000000000000000000000000000000001b: Account { info: AccountInfo { balance: 0, nonce: 0, code_hash: 0xfa8c9db6c6cab7108dea276f4cd09d575674eb0852c0fa3187e59e98ef977998 }, storage: {}, status: AccountStatus(Touched) }, 
  0x420000000000000000000000000000000000001a: Account { info: AccountInfo { balance: 87755350474236426, nonce: 0, code_hash: 0xfa8c9db6c6cab7108dea276f4cd09d575674eb0852c0fa3187e59e98ef977998 }, storage: {}, status: AccountStatus(Touched) }, 
  0xd0f350b13465b5251bb03e4bbf9fa1dbc4a378f3: Account { info: AccountInfo { balance: 0, nonce: 1, code_hash: 0x9a412367fa4e1b709d142ec5c1cb547e716dd3368a69c5ecb373ac619d954cda }, storage: {6003198035184720553317537415064026399565423954743751102363488919614904056574: EvmStorageSlot { original_value: 300, present_value: 299, is_cold: false }, 81223867398230462435007348759598610405472546022605592074303692128879761985171: EvmStorageSlot { original_value: 300, present_value: 301, is_cold: false }}, status: AccountStatus(Touched) }, 
  0x4200000000000000000000000000000000000019: Account { info: AccountInfo { balance: 117754043519, nonce: 0, code_hash: 0xfa8c9db6c6cab7108dea276f4cd09d575674eb0852c0fa3187e59e98ef977998 }, storage: {}, status: AccountStatus(Touched) }, 
  0x4200000000000000000000000000000000000011: Account { info: AccountInfo { balance: 16822006217, nonce: 0, code_hash: 0xfa8c9db6c6cab7108dea276f4cd09d575674eb0852c0fa3187e59e98ef977998 }, storage: {}, status: AccountStatus(Touched) }, 
  0x31c8e9e5e7f5ecb0dbadd2c611d6c90d85a522a0: Account { info: AccountInfo { balance: 299999458782401680, nonce: 10, code_hash: 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 }, storage: {}, status: AccountStatus(Touched) }
}

In the example above, even though 6 accounts are involved, only one (the ERC20 contract) actually has storage changes. The issue is that the other 5 accounts contribute 5 empty HashMaps, which are no-ops and unnecessary.

Solution

Eliminate empty HashMaps by simply not adding them.

Notable changes

# crates/trie/common/src/updates.rs

impl TrieUpdates {

    /// Insert storage updates for a given hashed address.
    pub fn insert_storage_updates(
        &mut self,
        hashed_address: B256,
        storage_updates: StorageTrieUpdates,
    ) {
+        if storage_updates.is_empty() {
+            return;
+        }
         let existing = self.storage_tries.insert(hashed_address, storage_updates);
         debug_assert!(existing.is_none());
     }

# crates/trie/trie/src/state.rs

impl HashedPostState {

    pub fn from_bundle_state<'a, KH: KeyHasher>(
        state: impl IntoParallelIterator<Item = (&'a Address, &'a BundleAccount)>,
    ) -> Self {

         let mut storages = HashMap::with_capacity_and_hasher(hashed.len(), Default::default());
         for (address, (account, storage)) in hashed {
             accounts.insert(address, account);
-            storages.insert(address, storage);
+            if !storage.is_empty() {
+                storages.insert(address, storage);
+            }
         }
         Self { accounts, storages }
     }

Results

Run time analysis

We benchmarked the "before" and "after" under the same condition (same machine, test, TPS, config). The results show a significant improvement across all three of our playbooks:

(unit: μs)	Before	After	Ratio
ERC20	585111076	406979612	0.6955595761
Raw Transfer	323457659	179755982	0.55573265
Uniswap	1254878698	1114317335	0.8879880874

---

Branch statistics

For each added if statement, we tracked how often the condition evaluates to true or false. Here’s the summary:

Condition	ERC20	Raw Transfer	Uniswap
storage_updates.is_empty() == true	1.7058%	1.8344%	1.7931%
storage.is_empty() == true	99.9846%	99.9960%	99.5428%

The data above shows that while if storage_updates.is_empty() does not lead to significant changes, the if !storage.is_empty() { ... } in HashedPostState::from_bundle_state is highly effective.

E2E Benchmarks

"785bc168-8538d2e7-erc20-30600"
{"tps": 30601.0, "gps": 1056921700.4938775, "is_chain_lagged": false, "chain_lag_distance": 0}
[406979612, 441650528]
"785bc168-8538d2e7-erc20-35000"
{"tps": 35001.0, "gps": 1208892408.0443406, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-erc20-36000"
{"tps": 36001.0, "gps": 1243434143.3961585, "is_chain_lagged": false, "chain_lag_distance": 0}
"785bc168-8538d2e7-erc20-36400"
{"tps": 36401.0, "gps": 1257247094.8883495, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-erc20-36500"
{"tps": 36501.0, "gps": 1260693706.9232643, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-erc20-36600"
{"tps": 36601.0, "gps": 1264152458.967033, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-erc20-36700"
{"tps": 36701.0, "gps": 1267609469.7209303, "is_chain_lagged": true, "chain_lag_distance": 3}
"785bc168-8538d2e7-erc20-36800"
{"tps": 36801.0, "gps": 1271062700.5061426, "is_chain_lagged": true, "chain_lag_distance": 3}
"785bc168-8538d2e7-erc20-37200"
{"tps": 37201.0, "gps": 1284879652.7344913, "is_chain_lagged": true, "chain_lag_distance": 4}
"785bc168-8538d2e7-erc20-37600"
{"tps": 37601.0, "gps": 1298689498.6323714, "is_chain_lagged": true, "chain_lag_distance": 4}
"785bc168-8538d2e7-erc20-38000"
{"tps": 38001.0, "gps": 1312505549.7563453, "is_chain_lagged": true, "chain_lag_distance": 6}
"785bc168-8538d2e7-erc20-44000"
{"tps": 44001.0, "gps": 1519733106.229075, "is_chain_lagged": true, "chain_lag_distance": 40}
"785bc168-8538d2e7-raw-transfer-100000"
{"tps": 70917.98574821853, "gps": 1489301229.0783849, "is_chain_lagged": true, "chain_lag_distance": 2}
"785bc168-8538d2e7-raw-transfer-54600"
{"tps": 54512.001818181816, "gps": 1144775549.149091, "is_chain_lagged": false, "chain_lag_distance": 0}
[179755982, 194221704]
"785bc168-8538d2e7-raw-transfer-62000"
{"tps": 61380.149590163935, "gps": 1289006639.2868853, "is_chain_lagged": true, "chain_lag_distance": 2}
"785bc168-8538d2e7-raw-transfer-63000"
{"tps": 62550.83054393306, "gps": 1313590953.6401675, "is_chain_lagged": false, "chain_lag_distance": 0}
"785bc168-8538d2e7-raw-transfer-65000"
{"tps": 64196.991416309014, "gps": 1348160328.695279, "is_chain_lagged": false, "chain_lag_distance": 0}
"785bc168-8538d2e7-raw-transfer-69000"
{"tps": 68050.51818181819, "gps": 1429084397.3454545, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-raw-transfer-70000"
{"tps": 67990.69772727272, "gps": 1427828167.1454546, "is_chain_lagged": false, "chain_lag_distance": 0}
"785bc168-8538d2e7-raw-transfer-72000"
{"tps": 69915.03971962616, "gps": 1468239350.3831775, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-raw-transfer-76000"
{"tps": 68643.54377880185, "gps": 1441537944.4147465, "is_chain_lagged": true, "chain_lag_distance": 2}
"785bc168-8538d2e7-raw-transfer-78000"
{"tps": 69454.44755244756, "gps": 1458566913.5244756, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-raw-transfer-80000"
{"tps": 70477.3905882353, "gps": 1480048723.2705882, "is_chain_lagged": true, "chain_lag_distance": 3}
"785bc168-8538d2e7-raw-transfer-82000"
{"tps": 71027.36255924171, "gps": 1491598139.0331755, "is_chain_lagged": true, "chain_lag_distance": 3}
"785bc168-8538d2e7-raw-transfer-84000"
{"tps": 69952.23696682464, "gps": 1469020502.3033175, "is_chain_lagged": true, "chain_lag_distance": 3}
"785bc168-8538d2e7-uniswap-6330"
{"tps": 6331.0, "gps": 882453837.7864077, "is_chain_lagged": false, "chain_lag_distance": 1}
[1114317335, 1141570733]
"785bc168-8538d2e7-uniswap-6580"
{"tps": 6581.0, "gps": 917313166.4229926, "is_chain_lagged": false, "chain_lag_distance": 0}
"785bc168-8538d2e7-uniswap-6590"
{"tps": 6591.0, "gps": 918700006.3924413, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-uniswap-6600"
{"tps": 6601.0, "gps": 920100031.6195819, "is_chain_lagged": false, "chain_lag_distance": 1}
"785bc168-8538d2e7-uniswap-6610"
{"tps": 6611.0, "gps": 921483410.1694952, "is_chain_lagged": true, "chain_lag_distance": 3}
"785bc168-8538d2e7-uniswap-6620"
{"tps": 6621.0, "gps": 922882071.8124034, "is_chain_lagged": true, "chain_lag_distance": 2}
"785bc168-8538d2e7-uniswap-6700"
{"tps": 6701.0, "gps": 934018761.980563, "is_chain_lagged": true, "chain_lag_distance": 7}
"785bc168-8538d2e7-uniswap-6860"
{"tps": 6861.0, "gps": 956326845.1132205, "is_chain_lagged": true, "chain_lag_distance": 17}

[rkrasiuk]

lgtm!

[mattsse]

lgtm