starknet_os_runner: simulate tx

Author: AvivYossef-starkware

Cargo.lock

@@ -7,7 +7,10 @@ license-file.workspace = true
 description = "Runs transactions through the Starknet OS and returns Cairo PIE and OS output."
 
 [dependencies]
+blockifier.workspace = true
+blockifier_reexecution = { path = "../blockifier_reexecution" }
+starknet_api.workspace = true
+thiserror.workspace = true
 
 [lints]
 workspace = true
-

crates/starknet_os_runner/Cargo.toml

@@ -0,0 +1,8 @@
+use blockifier_reexecution::errors::ReexecutionError;
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum SimulationError {
+    #[error(transparent)]
+    ReexecutionError(#[from] ReexecutionError),
+}

crates/starknet_os_runner/src/errors.rs

@@ -1 +1,2 @@
-//! Starknet OS Runner - executes transactions through the OS and returns Cairo PIE and output.
+pub mod errors;
+pub mod simulator;

crates/starknet_os_runner/src/lib.rs

@@ -0,0 +1,45 @@
+use blockifier::blockifier::transaction_executor::TransactionExecutionOutput;
+use blockifier::context::BlockContext;
+use blockifier::state::cached_state::StateMaps;
+use blockifier_reexecution::execute_single_transaction;
+use starknet_api::block::BlockNumber;
+use starknet_api::core::ChainId;
+use starknet_api::transaction::Transaction;
+
+use crate::errors::SimulationError;
+
+pub struct SimulationOutput {
+    pub execution_output: TransactionExecutionOutput,
+    pub block_context: BlockContext,
+    pub initial_reads: StateMaps,
+}
+
+pub trait TxSimulator {
+    fn simulate_tx(
+        &self,
+        block_number: BlockNumber,
+        tx: Transaction,
+    ) -> Result<SimulationOutput, SimulationError>;
+}
+
+pub struct RpcBlockifierTxSimulator {
+    pub rpc_url: String,
+    pub chain_id: ChainId,
+}
+
+impl TxSimulator for RpcBlockifierTxSimulator {
+    fn simulate_tx(
+        &self,
+        block_number: BlockNumber,
+        tx: Transaction,
+    ) -> Result<SimulationOutput, SimulationError> {
+        let (execution_output, initial_reads, block_context) = execute_single_transaction(
+            block_number,
+            self.rpc_url.clone(),
+            self.chain_id.clone(),
+            tx,
+        )?;
+
+        Ok(SimulationOutput { execution_output, block_context, initial_reads })
+    }
+}