From 1da9f9f05a67ae8190236c698b40c7c1538ab578 Mon Sep 17 00:00:00 2001
From: Tyera Eulberg <teulberg@gmail.com>
Date: Wed, 15 Jul 2020 15:45:30 -0600
Subject: [PATCH] Gate nonce-overwrite change (#11081)

---
 runtime/src/accounts.rs    |  5 +++++
 runtime/src/bank.rs        |  1 +
 runtime/src/nonce_utils.rs | 15 ++++++++++++---
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/runtime/src/accounts.rs b/runtime/src/accounts.rs
index 161c873909..84ae15a0b8 100644
--- a/runtime/src/accounts.rs
+++ b/runtime/src/accounts.rs
@@ -650,6 +650,7 @@ impl Accounts {
         loaded: &mut [(Result<TransactionLoadResult>, Option<HashAgeKind>)],
         rent_collector: &RentCollector,
         last_blockhash_with_fee_calculator: &(Hash, FeeCalculator),
+        fix_recent_blockhashes_sysvar_delay: bool,
     ) {
         let accounts_to_store = self.collect_accounts_to_store(
             txs,
@@ -658,6 +659,7 @@ impl Accounts {
             loaded,
             rent_collector,
             last_blockhash_with_fee_calculator,
+            fix_recent_blockhashes_sysvar_delay,
         );
         self.accounts_db.store(slot, &accounts_to_store);
     }
@@ -684,6 +686,7 @@ impl Accounts {
         loaded: &'a mut [(Result<TransactionLoadResult>, Option<HashAgeKind>)],
         rent_collector: &RentCollector,
         last_blockhash_with_fee_calculator: &(Hash, FeeCalculator),
+        fix_recent_blockhashes_sysvar_delay: bool,
     ) -> Vec<(&'a Pubkey, &'a Account)> {
         let mut accounts = Vec::with_capacity(loaded.len());
         for (i, ((raccs, _hash_age_kind), tx)) in loaded
@@ -720,6 +723,7 @@ impl Accounts {
                     res,
                     maybe_nonce,
                     last_blockhash_with_fee_calculator,
+                    fix_recent_blockhashes_sysvar_delay,
                 );
                 if message.is_writable(i) {
                     if account.rent_epoch == 0 {
@@ -1675,6 +1679,7 @@ mod tests {
             &mut loaded,
             &rent_collector,
             &(Hash::default(), FeeCalculator::default()),
+            true,
         );
         assert_eq!(collected_accounts.len(), 2);
         assert!(collected_accounts
diff --git a/runtime/src/bank.rs b/runtime/src/bank.rs
index 5aabdda5ff..3b834d8f2b 100644
--- a/runtime/src/bank.rs
+++ b/runtime/src/bank.rs
@@ -1776,6 +1776,7 @@ impl Bank {
             loaded_accounts,
             &self.rent_collector,
             &self.last_blockhash_with_fee_calculator(),
+            self.fix_recent_blockhashes_sysvar_delay(),
         );
         self.collect_rent(executed, loaded_accounts);
 
diff --git a/runtime/src/nonce_utils.rs b/runtime/src/nonce_utils.rs
index 4fc813e836..d257e9a86a 100644
--- a/runtime/src/nonce_utils.rs
+++ b/runtime/src/nonce_utils.rs
@@ -52,13 +52,21 @@ pub fn prepare_if_nonce_account(
     tx_result: &transaction::Result<()>,
     maybe_nonce: Option<(&Pubkey, &Account)>,
     last_blockhash_with_fee_calculator: &(Hash, FeeCalculator),
+    fix_recent_blockhashes_sysvar_delay: bool,
 ) {
     if let Some((nonce_key, nonce_acc)) = maybe_nonce {
         if account_pubkey == nonce_key {
-            // Nonce TX failed with an InstructionError. Roll back
-            // its account state
-            if tx_result.is_err() {
+            let overwrite = if tx_result.is_err() {
+                // Nonce TX failed with an InstructionError. Roll back
+                // its account state
                 *account = nonce_acc.clone();
+                true
+            } else {
+                // Retain overwrite on successful transactions until
+                // recent_blockhashes_sysvar_delay fix is activated
+                !fix_recent_blockhashes_sysvar_delay
+            };
+            if overwrite {
                 // Since hash_age_kind is DurableNonce, unwrap is safe here
                 let state = StateMut::<Versions>::state(nonce_acc)
                     .unwrap()
@@ -294,6 +302,7 @@ mod tests {
             tx_result,
             maybe_nonce,
             last_blockhash_with_fee_calculator,
+            true,
         );
         expect_account == account
     }