Feat(standalone): Add debug tracing of remaining gas values (#391)

engine-standalone-tracing/src/sputnik.rs

@@ -48,14 +48,18 @@ impl evm_gasometer::tracing::EventListener for TransactionTraceBuilder {
  fn event(&mut self, event: evm_gasometer::tracing::Event) {
  use evm_gasometer::tracing::Event;
  match event {
- Event::RecordCost { cost, snapshot: _ } => {
+ Event::RecordCost { cost, snapshot } => {
  self.current.gas_cost = EthGas::new(cost);
+ if let Some(snapshot) = snapshot {
+ self.current.gas =
+ EthGas::new(snapshot.gas_limit - snapshot.used_gas - snapshot.memory_gas);
+ }
  }
  Event::RecordDynamicCost {
  gas_cost,
  memory_gas,
  gas_refund: _,
- snapshot: _,
+ snapshot,
  } => {
  // In SputnikVM memory gas is cumulative (ie this event always shows the total) gas
  // spent on memory up to this point. But geth traces simply show how much gas each step
@@ -68,6 +72,10 @@ impl evm_gasometer::tracing::EventListener for TransactionTraceBuilder {
  };
  self.current_memory_gas = memory_gas;
  self.current.gas_cost = EthGas::new(gas_cost + memory_cost_diff);
+ if let Some(snapshot) = snapshot {
+ self.current.gas =
+ EthGas::new(snapshot.gas_limit - snapshot.used_gas - snapshot.memory_gas);
+ }
  }
  Event::RecordRefund {
  refund: _,

engine-standalone-tracing/src/types.rs

@@ -151,9 +151,9 @@ pub struct TraceLog {
  pub depth: Depth,
  /// Any errors that may have occurred during execution.
  pub error: Option<String>,
- /// Gas used to execute the transaction.
+ /// Remaining (unused) gas.
  pub gas: EthGas,
- /// Gas cost for the transaction.
+ /// Gas cost for the opcode at this step.
  pub gas_cost: EthGas,
  /// The bounded memory.
  pub memory: LogMemory,

engine-tests/src/tests/standalone/tracing.rs

@@ -209,6 +209,11 @@ fn check_transaction_trace<P: AsRef<Path>>(trace: TransactionTrace, expected_tra
  );
  assert_eq!(log.depth.into_u32(), step.depth, "Depths should match");
  assert_eq!(log.opcode.as_u8(), step.op, "opcodes should match");
+ assert_eq!(
+ log.gas.into_u64(),
+ step.gas,
+ "remaining gas values should match"
+ );
  assert_eq!(
  log.gas_cost.into_u64(),
  step.gas_cost,