add config to simulate on top of working bank

rpc-client-api/src/config.rs

@@ -49,8 +49,14 @@ pub struct RpcSimulateTransactionConfig {
 #[derive(Serialize, Deserialize, Clone, Copy, Debug, Eq, PartialEq)]
 #[serde(rename_all = "camelCase")]
 pub enum SimulationSlotConfig {
+    /// Simulate on top of bank with the provided commitment.
     Commitment(CommitmentConfig),
+
+    /// Simulate on the provided slot's bank.
     Slot(Slot),
+
+    /// Simulates on top of the RPC's highest slot's bank i.e. the working bank.
+    Tip,
 }
 
 impl Default for SimulationSlotConfig {

rpc-client/src/nonblocking/rpc_client.rs

@@ -5446,6 +5446,7 @@ impl RpcClient {
         T: serde::de::DeserializeOwned,
     {
         let response = self.sender.send_batch(requests_and_params).await?;
+        debug!("response: {:?}", response);
 
         serde_json::from_value(response).map_err(|err| ClientError {
             request: None,

rpc/src/rpc.rs

@@ -4036,6 +4036,7 @@ pub mod rpc_full {
                 SimulationSlotConfig::Slot(slot) => meta.bank_from_slot(slot).ok_or_else(|| {
                     Error::invalid_params(format!("bank not found for the provided slot: {}", slot))
                 }),
+                SimulationSlotConfig::Tip => Ok(meta.bank_forks.read().unwrap().working_bank()),
             }?;
 
             // TODO: Come back to this and allow unfrozen bank as long as the parent is frozen.

runtime/src/bank.rs

@@ -3851,24 +3851,9 @@ impl Bank {
         pre_execution_accounts_requested: Vec<Option<Vec<Pubkey>>>,
         post_execution_accounts_requested: Vec<Option<Vec<Pubkey>>>,
     ) -> result::Result<BundleSimulationResult, Box<dyn Error>> {
-        assert!(self.is_frozen(), "simulation bank must be frozen");
         assert_eq!(pre_execution_accounts_requested.len(), bundle.len());
         assert_eq!(post_execution_accounts_requested.len(), bundle.len());
 
-        self.simulate_bundle_unchecked(
-            bundle,
-            pre_execution_accounts_requested,
-            post_execution_accounts_requested,
-        )
-    }
-
-    /// Run transactions against a bank without committing the results; does not check if the bank is frozen.
-    fn simulate_bundle_unchecked(
-        &self,
-        bundle: Vec<SanitizedTransaction>,
-        pre_execution_accounts_requested: Vec<Option<Vec<Pubkey>>>,
-        post_execution_accounts_requested: Vec<Option<Vec<Pubkey>>>,
-    ) -> result::Result<BundleSimulationResult, Box<dyn Error>> {
         // Used to cache account data in between batch execution iterations
         let mut account_overrides = AccountOverrides::default();
 
@@ -9020,14 +9005,6 @@ pub(crate) mod tests {
         assert_eq!(account, bank.get_account(&pubkey).unwrap());
     }
 
-    #[test]
-    #[should_panic]
-    fn test_simulate_bundle_unfrozen_bank() {
-        let (genesis_config, _mint_keypair) = create_genesis_config(1_000_000);
-        let bank = Bank::new_for_tests(&genesis_config);
-        let _ = bank.simulate_bundle(vec![], vec![], vec![]);
-    }
-
     #[test]
     #[should_panic]
     fn test_simulate_bundle_mismatched_lengths() {