Refactor: pull out fee payer balance check (#25519)

(cherry picked from commit 7b98ff1)

runtime/src/accounts.rs

@@ -348,51 +348,15 @@ impl Accounts {
                 if payer_index != 0 {
                     warn!("Payer index should be 0! {:?}", tx);
                 }
-                let (ref payer_address, ref mut payer_account) = accounts[payer_index];
-                if payer_account.lamports() == 0 {
-                    error_counters.account_not_found += 1;
-                    return Err(TransactionError::AccountNotFound);
-                }
-                let min_balance = match get_system_account_kind(payer_account).ok_or_else(|| {
-                    error_counters.invalid_account_for_fee += 1;
-                    TransactionError::InvalidAccountForFee
-                })? {
-                    SystemAccountKind::System => 0,
-                    SystemAccountKind::Nonce => {
-                        // Should we ever allow a fees charge to zero a nonce account's
-                        // balance. The state MUST be set to uninitialized in that case
-                        rent_collector.rent.minimum_balance(NonceState::size())
-                    }
-                };
 
-                if payer_account.lamports() < fee + min_balance {
-                    error_counters.insufficient_funds += 1;
-                    return Err(TransactionError::InsufficientFundsForFee);
-                }
-                let payer_pre_rent_state =
-                    RentState::from_account(payer_account, &rent_collector.rent);
-                payer_account
-                    .checked_sub_lamports(fee)
-                    .map_err(|_| TransactionError::InsufficientFundsForFee)?;
-
-                let payer_post_rent_state =
-                    RentState::from_account(payer_account, &rent_collector.rent);
-                let rent_state_result = check_rent_state_with_account(
-                    &payer_pre_rent_state,
-                    &payer_post_rent_state,
-                    payer_address,
-                    payer_account,
-                    feature_set.is_active(&feature_set::do_support_realloc::id()),
-                    feature_set
-                        .is_active(&feature_set::include_account_index_in_rent_error::ID)
-                        .then(|| payer_index),
-                );
-                // Feature gate only wraps the actual error return so that the metrics and debug
-                // logging generated by `check_rent_state_with_account()` can be examined before
-                // feature activation
-                if feature_set.is_active(&feature_set::require_rent_exempt_accounts::id()) {
-                    rent_state_result?;
-                }
+                Self::check_fee_payer_balance(
+                    &mut accounts,
+                    payer_index,
+                    error_counters,
+                    rent_collector,
+                    feature_set,
+                    fee,
+                )?;
 
                 let program_indices = message
                     .instructions()
@@ -406,6 +370,7 @@ impl Accounts {
                         )
                     })
                     .collect::<Result<Vec<Vec<usize>>>>()?;
+
                 Ok(LoadedTransaction {
                     accounts,
                     program_indices,
@@ -419,6 +384,60 @@ impl Accounts {
         }
     }
 
+    fn check_fee_payer_balance(
+        accounts: &mut [(Pubkey, AccountSharedData)],
+        payer_index: usize,
+        error_counters: &mut TransactionErrorMetrics,
+        rent_collector: &RentCollector,
+        feature_set: &FeatureSet,
+        fee: u64,
+    ) -> Result<()> {
+        let (ref payer_address, ref mut payer_account) = accounts[payer_index];
+        if payer_account.lamports() == 0 {
+            error_counters.account_not_found += 1;
+            return Err(TransactionError::AccountNotFound);
+        }
+        let min_balance = match get_system_account_kind(payer_account).ok_or_else(|| {
+            error_counters.invalid_account_for_fee += 1;
+            TransactionError::InvalidAccountForFee
+        })? {
+            SystemAccountKind::System => 0,
+            SystemAccountKind::Nonce => {
+                // Should we ever allow a fees charge to zero a nonce account's
+                // balance. The state MUST be set to uninitialized in that case
+                rent_collector.rent.minimum_balance(NonceState::size())
+            }
+        };
+
+        if payer_account.lamports() < fee + min_balance {
+            error_counters.insufficient_funds += 1;
+            return Err(TransactionError::InsufficientFundsForFee);
+        }
+        let payer_pre_rent_state = RentState::from_account(payer_account, &rent_collector.rent);
+        payer_account
+            .checked_sub_lamports(fee)
+            .map_err(|_| TransactionError::InsufficientFundsForFee)?;
+
+        let payer_post_rent_state = RentState::from_account(payer_account, &rent_collector.rent);
+        let rent_state_result = check_rent_state_with_account(
+            &payer_pre_rent_state,
+            &payer_post_rent_state,
+            payer_address,
+            payer_account,
+            feature_set.is_active(&feature_set::do_support_realloc::id()),
+            feature_set
+                .is_active(&feature_set::include_account_index_in_rent_error::ID)
+                .then(|| payer_index),
+        );
+        // Feature gate only wraps the actual error return so that the metrics and debug
+        // logging generated by `check_rent_state_with_account()` can be examined before
+        // feature activation
+        if feature_set.is_active(&feature_set::require_rent_exempt_accounts::id()) {
+            rent_state_result?;
+        }
+        Ok(())
+    }
+
     fn load_executable_accounts(
         &self,
         ancestors: &Ancestors,