Fix(engine): Cache generation values to avoid repeated state reads (#438

)

engine-tests/src/tests/erc20.rs

@@ -107,8 +107,8 @@ fn profile_erc20_get_balance() {
         runner.profiled_view_call(test_utils::as_view_call(balance_tx, source_address));
     assert!(result.is_ok());
 
-    // call costs less than 4 Tgas
-    test_utils::assert_gas_bound(profile.all_gas(), 4);
+    // call costs less than 3 Tgas
+    test_utils::assert_gas_bound(profile.all_gas(), 3);
     // at least 70% of the cost is spent on wasm computation (as opposed to host functions)
     let wasm_fraction = (100 * profile.wasm_gas()) / profile.all_gas();
     assert!(

engine-tests/src/tests/one_inch.rs

@@ -23,11 +23,11 @@ fn test_1inch_liquidity_protocol() {
 
     let (result, profile, deployer_address) = helper.create_mooniswap_deployer();
     assert!(result.gas_used >= 5_100_000); // more than 5.1M EVM gas used
-    assert_gas_bound(profile.all_gas(), 20); // less than 20 NEAR Tgas used
+    assert_gas_bound(profile.all_gas(), 18); // less than 18 NEAR Tgas used
 
     let (result, profile, pool_factory) = helper.create_pool_factory(&deployer_address);
     assert!(result.gas_used >= 2_800_000); // more than 2.8M EVM gas used
-    assert_gas_bound(profile.all_gas(), 19); // less than 19 NEAR Tgas used
+    assert_gas_bound(profile.all_gas(), 18); // less than 18 NEAR Tgas used
 
     // create some ERC-20 tokens to have a liquidity pool for
     let signer_address = test_utils::address_from_secret_key(&helper.signer.secret_key);
@@ -39,7 +39,7 @@ fn test_1inch_liquidity_protocol() {
     let (result, profile, pool) =
         helper.create_pool(&pool_factory, token_a.0.address, token_b.0.address);
     assert!(result.gas_used >= 4_500_000); // more than 4.5M EVM gas used
-    assert_gas_bound(profile.all_gas(), 59); // less than 59 NEAR Tgas used
+    assert_gas_bound(profile.all_gas(), 48); // less than 48 NEAR Tgas used
 
     // Approve giving ERC-20 tokens to the pool
     helper.approve_erc20_tokens(&token_a, pool.address());
@@ -58,7 +58,7 @@ fn test_1inch_liquidity_protocol() {
         },
     );
     assert!(result.gas_used >= 302_000); // more than 302k EVM gas used
-    assert_gas_bound(profile.all_gas(), 89); // less than 89 NEAR Tgas used
+    assert_gas_bound(profile.all_gas(), 64); // less than 64 NEAR Tgas used
 
     // Same here
     helper.runner.context.block_timestamp += 10_000_000 * 1_000_000_000;
@@ -73,7 +73,7 @@ fn test_1inch_liquidity_protocol() {
         },
     );
     assert!(result.gas_used >= 210_000); // more than 210k EVM gas used
-    assert_gas_bound(profile.all_gas(), 91); // less than 91 NEAR Tgas used
+    assert_gas_bound(profile.all_gas(), 66); // less than 66 NEAR Tgas used
 
     let (result, profile) = helper.pool_withdraw(
         &pool,
@@ -84,7 +84,7 @@ fn test_1inch_liquidity_protocol() {
         },
     );
     assert!(result.gas_used >= 150_000); // more than 150k EVM gas used
-    assert_gas_bound(profile.all_gas(), 78); // less than 78 NEAR Tgas used
+    assert_gas_bound(profile.all_gas(), 57); // less than 57 NEAR Tgas used
 }
 
 #[test]
@@ -100,8 +100,8 @@ fn test_1_inch_limit_order_deploy() {
 
     // more than 3.5 million Ethereum gas used
     assert!(result.gas_used > 3_500_000);
-    // less than 20 NEAR Tgas used
-    assert_gas_bound(profile.all_gas(), 20);
+    // less than 17 NEAR Tgas used
+    assert_gas_bound(profile.all_gas(), 17);
     // at least 45% of which is from wasm execution
     let wasm_fraction = 100 * profile.wasm_gas() / profile.all_gas();
     assert!(

engine-tests/src/tests/sanity.rs

@@ -92,8 +92,8 @@ fn test_deploy_largest_contract() {
         result.gas_used,
     );
 
-    // Less than 20 NEAR Tgas
-    test_utils::assert_gas_bound(profile.all_gas(), 20);
+    // Less than 18 NEAR Tgas
+    test_utils::assert_gas_bound(profile.all_gas(), 18);
 }
 
 #[test]

engine-tests/src/tests/uniswap.rs

@@ -28,7 +28,7 @@ fn test_uniswap_input_multihop() {
     let mut context = UniswapTestContext::new("uniswap");
 
     // evm_gas = 970k
-    // near total gas = 410 Tgas
+    // near total gas = 302 Tgas
     // Wish: optimize so that this transaction costs less than 200 Tgas.
     // For now we just have to increase the burnt gas limit to make it run to completion.
     context.runner.wasm_config.limit_config.max_gas_burnt = 500_000_000_000_000;
@@ -54,17 +54,17 @@ fn test_uniswap_exact_output() {
 
     let (_result, profile) =
         context.add_equal_liquidity(LIQUIDITY_AMOUNT.into(), &token_a, &token_b);
-    test_utils::assert_gas_bound(profile.all_gas(), 126);
+    test_utils::assert_gas_bound(profile.all_gas(), 88);
     let wasm_fraction = 100 * profile.wasm_gas() / profile.all_gas();
     assert!(
-        15 <= wasm_fraction && wasm_fraction <= 20,
-        "{}% is not between 15% and 20%",
+        20 <= wasm_fraction && wasm_fraction <= 30,
+        "{}% is not between 20% and 30%",
         wasm_fraction
     );
 
     let (_amount_in, profile) =
         context.exact_output_single(&token_a, &token_b, OUTPUT_AMOUNT.into());
-    test_utils::assert_gas_bound(profile.all_gas(), 61);
+    test_utils::assert_gas_bound(profile.all_gas(), 48);
     let wasm_fraction = 100 * profile.wasm_gas() / profile.all_gas();
     assert!(
         20 <= wasm_fraction && wasm_fraction <= 30,

engine/src/engine.rs

@@ -16,10 +16,11 @@ use crate::prelude::precompiles::Precompiles;
 use crate::prelude::transactions::{EthTransactionKind, NormalizedEthTransaction};
 use crate::prelude::{
     address_to_key, bytes_to_key, sdk, storage_to_key, u256_to_arr, vec, AccountId, Address,
-    BorshDeserialize, BorshSerialize, KeyPrefix, PromiseArgs, PromiseCreateArgs, ToString, Vec,
-    Wei, ERC20_MINT_SELECTOR, H160, H256, U256,
+    BTreeMap, BorshDeserialize, BorshSerialize, KeyPrefix, PromiseArgs, PromiseCreateArgs,
+    ToString, Vec, Wei, ERC20_MINT_SELECTOR, H160, H256, U256,
 };
 use aurora_engine_precompiles::PrecompileConstructorContext;
+use core::cell::RefCell;
 
 /// Used as the first byte in the concatenation of data used to compute the blockhash.
 /// Could be useful in the future as a version byte, or to distinguish different types of blocks.
@@ -404,6 +405,7 @@ pub struct Engine<'env, I: IO, E: Env> {
     current_account_id: AccountId,
     io: I,
     env: &'env E,
+    generation_cache: RefCell<BTreeMap<Address, u32>>,
 }
 
 pub(crate) const CONFIG: &Config = &Config::london();
@@ -435,6 +437,7 @@ impl<'env, I: IO + Copy, E: Env> Engine<'env, I, E> {
             current_account_id,
             io,
             env,
+            generation_cache: RefCell::new(BTreeMap::new()),
         }
     }
 
@@ -1433,7 +1436,11 @@ impl<'env, I: IO + Copy, E: Env> evm::backend::Backend for Engine<'env, I, E> {
     /// Get storage value of address at index.
     fn storage(&self, address: H160, index: H256) -> H256 {
         let address = Address::new(address);
-        let generation = get_generation(&self.io, &address);
+        let generation = *self
+            .generation_cache
+            .borrow_mut()
+            .entry(address)
+            .or_insert_with(|| get_generation(&self.io, &address));
         get_storage(&self.io, &address, &index, generation)
     }