separated tracing logic to its own trait

ethcore/src/executive.rs

@@ -113,12 +113,20 @@ impl<'a> Executive<'a> {
 	}
 
 	/// Creates `Externalities` from `Executive`.
-	pub fn as_externalities<'_>(&'_ mut self, origin_info: OriginInfo, substate: &'_ mut Substate, output: OutputPolicy<'_, '_>) -> Externalities {
+	pub fn as_externalities<'_, T>(&'_ mut self, origin_info: OriginInfo, substate: &'_ mut Substate, output: OutputPolicy<'_, '_>, tracer: &'_ mut T) -> Externalities<'_, T> where T: Tracer {
-		Externalities::new(self.state, self.info, self.engine, self.depth, origin_info, substate, output)
+		Externalities::new(self.state, self.info, self.engine, self.depth, origin_info, substate, output, tracer)
 	}
 
 	/// This funtion should be used to execute transaction.
 	pub fn transact(&'a mut self, t: &SignedTransaction, options: TransactOptions) -> Result<Executed, Error> {
+		let check = options.check_nonce;
+		match options.tracing {
+			true => self.transact_with_tracer(t, check, ExecutiveTracer::default()),
+			false => self.transact_with_tracer(t, check, NoopTracer),
+		}
+	}
+
+	pub fn transact_with_tracer<T>(&'a mut self, t: &SignedTransaction, check_nonce: bool, mut tracer: T) -> Result<Executed, Error> where T: Tracer {
 		let sender = try!(t.sender());
 		let nonce = self.state.nonce(&sender);
 
@@ -132,7 +140,7 @@ impl<'a> Executive<'a> {
 		let init_gas = t.gas - base_gas_required;
 
 		// validate transaction nonce
-		if options.check_nonce {
+		if check_nonce {
 			if t.nonce != nonce {
 				return Err(From::from(ExecutionError::InvalidNonce { expected: nonce, got: t.nonce }));
 			}
@@ -161,7 +169,7 @@ impl<'a> Executive<'a> {
 		self.state.inc_nonce(&sender);
 		self.state.sub_balance(&sender, &U256::from(gas_cost));
 
-		let mut substate = Substate::new(options.tracing);
+		let mut substate = Substate::new();
 
 		let (gas_left, output) = match t.action {
 			Action::Create => {
@@ -177,7 +185,7 @@ impl<'a> Executive<'a> {
 					code: Some(t.data.clone()),
 					data: None,
 				};
-				(self.create(params, &mut substate), vec![])
+				(self.create(params, &mut substate, &mut tracer), vec![])
 			},
 			Action::Call(ref address) => {
 				let params = ActionParams {
@@ -193,18 +201,19 @@ impl<'a> Executive<'a> {
 				};
 				// TODO: move output upstream
 				let mut out = vec![];
-				(self.call(params, &mut substate, BytesRef::Flexible(&mut out)), out)
+				(self.call(params, &mut substate, BytesRef::Flexible(&mut out), &mut tracer), out)
 			}
 		};
 
 		// finalize here!
-		Ok(try!(self.finalize(t, substate, gas_left, output)))
+		Ok(try!(self.finalize(t, substate, gas_left, output, tracer.traces().pop())))
 	}
 
-	fn exec_vm(&mut self, params: ActionParams, unconfirmed_substate: &mut Substate, output_policy: OutputPolicy) -> evm::Result {
+	fn exec_vm<T>(&mut self, params: ActionParams, unconfirmed_substate: &mut Substate, output_policy: OutputPolicy, tracer: &mut T)
+		-> evm::Result where T: Tracer {
 		// Ordinary execution - keep VM in same thread
 		if (self.depth + 1) % MAX_VM_DEPTH_FOR_THREAD != 0 {
-			let mut ext = self.as_externalities(OriginInfo::from(&params), unconfirmed_substate, output_policy);
+			let mut ext = self.as_externalities(OriginInfo::from(&params), unconfirmed_substate, output_policy, tracer);
 			let vm_factory = self.engine.vm_factory();
 			trace!(target: "executive", "ext.schedule.have_delegate_call: {}", ext.schedule().have_delegate_call);
 			return vm_factory.create().exec(params, &mut ext);
@@ -214,7 +223,7 @@ impl<'a> Executive<'a> {
 		// TODO [todr] No thread builder yet, so we need to reset once for a while
 		// https://github.com/aturon/crossbeam/issues/16
 		crossbeam::scope(|scope| {
-			let mut ext = self.as_externalities(OriginInfo::from(&params), unconfirmed_substate, output_policy);
+			let mut ext = self.as_externalities(OriginInfo::from(&params), unconfirmed_substate, output_policy, tracer);
 			let vm_factory = self.engine.vm_factory();
 
 			scope.spawn(move || {
@@ -227,7 +236,8 @@ impl<'a> Executive<'a> {
 	/// NOTE. It does not finalize the transaction (doesn't do refunds, nor suicides).
 	/// Modifies the substate and the output.
 	/// Returns either gas_left or `evm::Error`.
-	pub fn call(&mut self, params: ActionParams, substate: &mut Substate, mut output: BytesRef) -> evm::Result {
+	pub fn call<T>(&mut self, params: ActionParams, substate: &mut Substate, mut output: BytesRef, tracer: &mut T)
+		-> evm::Result where T: Tracer {
 		// backup used in case of running out of gas
 		self.state.snapshot();
 
@@ -257,49 +267,45 @@ impl<'a> Executive<'a> {
 				}
 			}
 		} else {
-			// if destination is a contract, do normal message call
+			let trace_info = tracer.prepare_trace_call(&params);
-
+			let mut trace_output = tracer.prepare_trace_output();
-			// don't trace if it's DELEGATECALL or CALLCODE.
+			let mut subtracer = tracer.subtracer();
-			let should_trace = if let ActionValue::Transfer(_) = params.value {
+			let delegate_call = params.code_address != params.address;
-				params.code_address == params.address && substate.subtraces.is_some()
+			let gas = params.gas;
-			} else { false };
-
-			// transaction tracing stuff. None if there's no tracing.
-			let (mut trace_info, mut trace_output) = if should_trace {
-				(Some((TraceAction::from_call(&params), self.depth)), Some(vec![]))
-			} else { (None, None) };
 
 			if params.code.is_some() {
 				// part of substate that may be reverted
-				let mut unconfirmed_substate = Substate::new(should_trace);
+				let mut unconfirmed_substate = Substate::new();
 
 				let res = {
-					self.exec_vm(params, &mut unconfirmed_substate, OutputPolicy::Return(output, trace_output.as_mut()))
+					self.exec_vm(params, &mut unconfirmed_substate, OutputPolicy::Return(output, trace_output.as_mut()), &mut subtracer)
 				};
 
 				trace!(target: "executive", "res={:?}", res);
 
-				// if there's tracing, make up trace_info's result with trace_output and some arithmetic.
+				let traces = subtracer.traces();
-				if let Some((TraceAction::Call(ref mut c), _)) = trace_info {
+				match res {
-					c.result = res.as_ref().ok().map(|gas_left| TraceCallResult {
+					Ok(gas_left) => tracer.trace_call(
-						gas_used: c.gas - *gas_left,
+						trace_info,
-						output: trace_output.expect("trace_info is Some: qed")
+						gas - gas_left,
-					});
+						trace_output,
-				}
+						self.depth,
+						traces,
+						delegate_call
+					),
+					_ => tracer.trace_failed_call(trace_info, self.depth, traces, delegate_call),
+				};
 
 				trace!(target: "executive", "substate={:?}; unconfirmed_substate={:?}\n", substate, unconfirmed_substate);
 
-				self.enact_result(&res, substate, unconfirmed_substate, trace_info);
+				self.enact_result(&res, substate, unconfirmed_substate);
 				trace!(target: "executive", "enacted: substate={:?}\n", substate);
 				res
 			} else {
 				// otherwise it's just a basic transaction, only do tracing, if necessary.
-				trace!(target: "executive", "Basic message (send funds) should_trace={}", should_trace);
 				self.state.clear_snapshot();
-				if let Some((TraceAction::Call(ref mut c), _)) = trace_info {
+
-					c.result = Some(TraceCallResult::default());// Some((x!(0), vec![]));
+				tracer.trace_call(trace_info, U256::zero(), Some(vec![]), self.depth, vec![], delegate_call);
-				}
-				substate.accrue_trace(if should_trace {Some(vec![])} else {None}, trace_info);
 				Ok(params.gas)
 			}
 		}
@@ -308,12 +314,13 @@ impl<'a> Executive<'a> {
 	/// Creates contract with given contract params.
 	/// NOTE. It does not finalize the transaction (doesn't do refunds, nor suicides).
 	/// Modifies the substate.
-	pub fn create(&mut self, params: ActionParams, substate: &mut Substate) -> evm::Result {
+	pub fn create<T>(&mut self, params: ActionParams, substate: &mut Substate, tracer: &mut T) -> evm::Result where T:
+		Tracer {
 		// backup used in case of running out of gas
 		self.state.snapshot();
 
 		// part of substate that may be reverted
-		let mut unconfirmed_substate = Substate::new(substate.subtraces.is_some());
+		let mut unconfirmed_substate = Substate::new();
 
 		// create contract and transfer value to it if necessary
 		let prev_bal = self.state.balance(&params.address);
@@ -324,30 +331,34 @@ impl<'a> Executive<'a> {
 			self.state.new_contract(&params.address, prev_bal);
 		}
 
-		let mut trace_info = substate.subtraces.as_ref().map(|_| (TraceAction::from_create(&params), self.depth));
+		let trace_info = tracer.prepare_trace_create(&params);
-		let mut trace_output = trace_info.as_ref().map(|_| vec![]);
+		let mut trace_output = tracer.prepare_trace_output();
+		let mut subtracer = tracer.subtracer();
+		let gas = params.gas;
 		let created = params.address.clone();
 
 		let res = {
-			self.exec_vm(params, &mut unconfirmed_substate, OutputPolicy::InitContract(trace_output.as_mut()))
+			self.exec_vm(params, &mut unconfirmed_substate, OutputPolicy::InitContract(trace_output.as_mut()), &mut subtracer)
 		};
 
-		if let Some((TraceAction::Create(ref mut c), _)) = trace_info {
+		match res {
-			c.result = res.as_ref().ok().map(|gas_left| TraceCreateResult {
+			Ok(gas_left) => tracer.trace_create(
-				gas_used: c.gas - *gas_left,
+				trace_info,
-				address: created,
+				gas - gas_left,
-				code: trace_output.expect("trace_info is Some: qed")
+				trace_output,
-			});
+				created,
-		}
+				self.depth,
+				subtracer.traces()
+			),
+			_ => tracer.trace_failed_create(trace_info, self.depth, subtracer.traces())
+		};
 
-		trace!(target: "executive", "trace_info={:?}", trace_info);
+		self.enact_result(&res, substate, unconfirmed_substate);
-
-		self.enact_result(&res, substate, unconfirmed_substate, trace_info);
 		res
 	}
 
 	/// Finalizes the transaction (does refunds and suicides).
-	fn finalize(&mut self, t: &SignedTransaction, substate: Substate, result: evm::Result, output: Bytes) -> ExecutionResult {
+	fn finalize(&mut self, t: &SignedTransaction, substate: Substate, result: evm::Result, output: Bytes, trace: Option<Trace>) -> ExecutionResult {
 		let schedule = self.engine.schedule(self.info);
 
 		// refunds from SSTORE nonzero -> zero
@@ -378,8 +389,6 @@ impl<'a> Executive<'a> {
 			self.state.kill_account(address);
 		}
 
-		let trace = substate.subtraces.and_then(|mut v| v.pop());
-
 		match result {
 			Err(evm::Error::Internal) => Err(ExecutionError::Internal),
 			Err(_) => {
@@ -409,7 +418,7 @@ impl<'a> Executive<'a> {
 		}
 	}
 
-	fn enact_result(&mut self, result: &evm::Result, substate: &mut Substate, un_substate: Substate, maybe_info: Option<(TraceAction, usize)>) {
+	fn enact_result(&mut self, result: &evm::Result, substate: &mut Substate, un_substate: Substate) {
 		match *result {
 			Err(evm::Error::OutOfGas)
 				| Err(evm::Error::BadJumpDestination {..})
@@ -417,11 +426,10 @@ impl<'a> Executive<'a> {
 				| Err(evm::Error::StackUnderflow {..})
 				| Err(evm::Error::OutOfStack {..}) => {
 					self.state.revert_snapshot();
-				substate.accrue_trace(un_substate.subtraces, maybe_info)
 			},
 			Ok(_) | Err(evm::Error::Internal) => {
 				self.state.clear_snapshot();
-				substate.accrue(un_substate, maybe_info)
+				substate.accrue(un_substate);
 			}
 		}
 	}
@@ -459,11 +467,11 @@ mod tests {
 		state.add_balance(&sender, &U256::from(0x100u64));
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(0, factory);
-		let mut substate = Substate::new(false);
+		let mut substate = Substate::new();
 
 		let gas_left = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.create(params, &mut substate).unwrap()
+			ex.create(params, &mut substate, &mut NoopTracer).unwrap()
 		};
 
 		assert_eq!(gas_left, U256::from(79_975));
@@ -518,11 +526,11 @@ mod tests {
 		state.add_balance(&sender, &U256::from(100));
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(0, factory);
-		let mut substate = Substate::new(false);
+		let mut substate = Substate::new();
 
 		let gas_left = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.create(params, &mut substate).unwrap()
+			ex.create(params, &mut substate, &mut NoopTracer).unwrap()
 		};
 
 		assert_eq!(gas_left, U256::from(62_976));
@@ -573,16 +581,16 @@ mod tests {
 		state.add_balance(&sender, &U256::from(100));
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(5, factory);
-		let mut substate = Substate::new(true);
+		let mut substate = Substate::new();
+		let mut tracer = ExecutiveTracer::default();
 
 		let gas_left = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
 			let output = BytesRef::Fixed(&mut[0u8;0]);
-			ex.call(params, &mut substate, output).unwrap()
+			ex.call(params, &mut substate, output, &mut tracer).unwrap()
 		};
 
-		println!("trace: {:?}", substate.subtraces);
+		let expected_trace = vec![ Trace {
-		let expected_trace = Some(vec![ Trace {
 			depth: 0,
 			action: TraceAction::Call(TraceCall {
 				from: x!("cd1722f3947def4cf144679da39c4c32bdc35681"),
@@ -590,10 +598,10 @@ mod tests {
 				value: x!(100),
 				gas: x!(100000),
 				input: vec![],
-				result: Some(TraceCallResult {
+			}),
+			result: TraceResult::Call(TraceCallResult {
 				gas_used: U256::from(55_248),
 				output: vec![],
-				})
 			}),
 			subs: vec![Trace {
 				depth: 1,
@@ -601,17 +609,17 @@ mod tests {
 					from: x!("b010143a42d5980c7e5ef0e4a4416dc098a4fed3"),
 					value: x!(23),
 					gas: x!(67979),
-					init: vec![96, 16, 128, 96, 12, 96, 0, 57, 96, 0, 243, 0, 96, 0, 53, 84, 21, 96, 9, 87, 0, 91, 96, 32, 53, 96, 0, 53, 85],
+					init: vec![96, 16, 128, 96, 12, 96, 0, 57, 96, 0, 243, 0, 96, 0, 53, 84, 21, 96, 9, 87, 0, 91, 96, 32, 53, 96, 0, 53, 85]
-					result: Some(TraceCreateResult {
+				}),
+				result: TraceResult::Create(TraceCreateResult {
 					gas_used: U256::from(3224),
 					address: Address::from_str("c6d80f262ae5e0f164e5fde365044d7ada2bfa34").unwrap(),
 					code: vec![96, 0, 53, 84, 21, 96, 9, 87, 0, 91, 96, 32, 53, 96, 0, 53]
-					})
 				}),
 				subs: vec![]
 			}]
-		} ]);
+		}];
-		assert_eq!(substate.subtraces, expected_trace);
+		assert_eq!(tracer.traces(), expected_trace);
 		assert_eq!(gas_left, U256::from(44_752));
 	}
 
@@ -645,30 +653,31 @@ mod tests {
 		state.add_balance(&sender, &U256::from(100));
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(5, factory);
-		let mut substate = Substate::new(true);
+		let mut substate = Substate::new();
+		let mut tracer = ExecutiveTracer::default();
 
 		let gas_left = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.create(params.clone(), &mut substate).unwrap()
+			ex.create(params.clone(), &mut substate, &mut tracer).unwrap()
 		};
 
-		println!("trace: {:?}", substate.subtraces);
+		let expected_trace = vec![Trace {
-		let expected_trace = Some(vec![Trace {
 			depth: 0,
 			action: TraceAction::Create(TraceCreate {
 				from: params.sender,
 				value: x!(100),
 				gas: params.gas,
 				init: vec![96, 16, 128, 96, 12, 96, 0, 57, 96, 0, 243, 0, 96, 0, 53, 84, 21, 96, 9, 87, 0, 91, 96, 32, 53, 96, 0, 53, 85],
-				result: Some(TraceCreateResult {
+			}),
+			result: TraceResult::Create(TraceCreateResult {
 				gas_used: U256::from(3224),
 				address: params.address,
 				code: vec![96, 0, 53, 84, 21, 96, 9, 87, 0, 91, 96, 32, 53, 96, 0, 53]
-				})
 			}),
 			subs: vec![]
-		} ]);
+		}];
-		assert_eq!(substate.subtraces, expected_trace);
+
+		assert_eq!(tracer.traces(), expected_trace);
 		assert_eq!(gas_left, U256::from(96_776));
 	}
 
@@ -714,11 +723,11 @@ mod tests {
 		state.add_balance(&sender, &U256::from(100));
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(0, factory);
-		let mut substate = Substate::new(false);
+		let mut substate = Substate::new();
 
 		let gas_left = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.create(params, &mut substate).unwrap()
+			ex.create(params, &mut substate, &mut NoopTracer).unwrap()
 		};
 
 		assert_eq!(gas_left, U256::from(62_976));
@@ -766,11 +775,11 @@ mod tests {
 		state.add_balance(&sender, &U256::from(100));
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(1024, factory);
-		let mut substate = Substate::new(false);
+		let mut substate = Substate::new();
 
 		{
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.create(params, &mut substate).unwrap();
+			ex.create(params, &mut substate, &mut NoopTracer).unwrap();
 		}
 
 		assert_eq!(substate.contracts_created.len(), 1);
@@ -827,11 +836,11 @@ mod tests {
 
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(0, factory);
-		let mut substate = Substate::new(false);
+		let mut substate = Substate::new();
 
 		let gas_left = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.call(params, &mut substate, BytesRef::Fixed(&mut [])).unwrap()
+			ex.call(params, &mut substate, BytesRef::Fixed(&mut []), &mut NoopTracer).unwrap()
 		};
 
 		assert_eq!(gas_left, U256::from(73_237));
@@ -872,11 +881,11 @@ mod tests {
 		state.init_code(&address, code.clone());
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(0, factory);
-		let mut substate = Substate::new(false);
+		let mut substate = Substate::new();
 
 		let gas_left = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.call(params, &mut substate, BytesRef::Fixed(&mut [])).unwrap()
+			ex.call(params, &mut substate, BytesRef::Fixed(&mut []), &mut NoopTracer).unwrap()
 		};
 
 		assert_eq!(gas_left, U256::from(59_870));
@@ -1074,11 +1083,11 @@ mod tests {
 		state.add_balance(&sender, &U256::from_str("152d02c7e14af6800000").unwrap());
 		let info = EnvInfo::default();
 		let engine = TestEngine::new(0, factory);
-		let mut substate = Substate::new(false);
+		let mut substate = Substate::new();
 
 		let result = {
 			let mut ex = Executive::new(&mut state, &info, &engine);
-			ex.create(params, &mut substate)
+			ex.create(params, &mut substate, &mut NoopTracer)
 		};
 
 		match result {

ethcore/src/externalities.rs

@@ -54,7 +54,7 @@ impl OriginInfo {
 }
 
 /// Implementation of evm Externalities.
-pub struct Externalities<'a> {
+pub struct Externalities<'a, T> where T: 'a + Tracer {
 	state: &'a mut State,
 	env_info: &'a EnvInfo,
 	engine: &'a Engine,
@@ -62,10 +62,11 @@ pub struct Externalities<'a> {
 	origin_info: OriginInfo,
 	substate: &'a mut Substate,
 	schedule: Schedule,
-	output: OutputPolicy<'a, 'a>
+	output: OutputPolicy<'a, 'a>,
+	tracer: &'a mut T,
 }
 
-impl<'a> Externalities<'a> {
+impl<'a, T> Externalities<'a, T> where T: 'a + Tracer {
 	/// Basic `Externalities` constructor.
 	pub fn new(state: &'a mut State,
 		env_info: &'a EnvInfo,
@@ -73,7 +74,8 @@ impl<'a> Externalities<'a> {
 		depth: usize,
 		origin_info: OriginInfo,
 		substate: &'a mut Substate,
-		output: OutputPolicy<'a, 'a>
+		output: OutputPolicy<'a, 'a>,
+		tracer: &'a mut T,
 	) -> Self {
 		Externalities {
 			state: state,
@@ -83,12 +85,13 @@ impl<'a> Externalities<'a> {
 			origin_info: origin_info,
 			substate: substate,
 			schedule: engine.schedule(env_info),
-			output: output
+			output: output,
+			tracer: tracer,
 		}
 	}
 }
 
-impl<'a> Ext for Externalities<'a> {
+impl<'a, T> Ext for Externalities<'a, T> where T: 'a + Tracer {
 	fn storage_at(&self, key: &H256) -> H256 {
 		self.state.storage_at(&self.origin_info.address, key)
 	}
@@ -143,7 +146,7 @@ impl<'a> Ext for Externalities<'a> {
 		let mut ex = Executive::from_parent(self.state, self.env_info, self.engine, self.depth);
 
 		// TODO: handle internal error separately
-		match ex.create(params, self.substate) {
+		match ex.create(params, self.substate, self.tracer) {
 			Ok(gas_left) => {
 				self.substate.contracts_created.push(address.clone());
 				ContractCreateResult::Created(address, gas_left)
@@ -181,7 +184,7 @@ impl<'a> Ext for Externalities<'a> {
 
 		let mut ex = Executive::from_parent(self.state, self.env_info, self.engine, self.depth);
 
-		match ex.call(params, self.substate, BytesRef::Fixed(output)) {
+		match ex.call(params, self.substate, BytesRef::Fixed(output), self.tracer) {
 			Ok(gas_left) => MessageCallResult::Success(gas_left),
 			_ => MessageCallResult::Failed
 		}
@@ -328,7 +331,7 @@ mod tests {
 			TestSetup {
 				state: get_temp_state(),
 				engine: get_test_spec().to_engine().unwrap(),
-				sub_state: Substate::new(false),
+				sub_state: Substate::new(),
 				env_info: get_test_env_info()
 			}
 		}
@@ -338,8 +341,9 @@ mod tests {
 	fn can_be_created() {
 		let mut setup = TestSetup::new();
 		let state = setup.state.reference_mut();
+		let mut tracer = NoopTracer;
 
-		let ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None));
+		let ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None), &mut tracer);
 
 		assert_eq!(ext.env_info().number, 100);
 	}
@@ -348,7 +352,9 @@ mod tests {
 	fn can_return_block_hash_no_env() {
 		let mut setup = TestSetup::new();
 		let state = setup.state.reference_mut();
-		let ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None));
+		let mut tracer = NoopTracer;
+
+		let ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None), &mut tracer);
 
 		let hash = ext.blockhash(&U256::from_str("0000000000000000000000000000000000000000000000000000000000120000").unwrap());
 
@@ -367,7 +373,9 @@ mod tests {
 			env_info.last_hashes.push(test_hash.clone());
 		}
 		let state = setup.state.reference_mut();
-		let ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None));
+		let mut tracer = NoopTracer;
+
+		let ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None), &mut tracer);
 
 		let hash = ext.blockhash(&U256::from_str("0000000000000000000000000000000000000000000000000000000000120000").unwrap());
 
@@ -379,7 +387,9 @@ mod tests {
 	fn can_call_fail_empty() {
 		let mut setup = TestSetup::new();
 		let state = setup.state.reference_mut();
-		let mut ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None));
+		let mut tracer = NoopTracer;
+
+		let mut ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None), &mut tracer);
 
 		let mut output = vec![];
 
@@ -401,9 +411,10 @@ mod tests {
 
 		let mut setup = TestSetup::new();
 		let state = setup.state.reference_mut();
+		let mut tracer = NoopTracer;
 
 		{
-			let mut ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None));
+			let mut ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None), &mut tracer);
 			ext.log(log_topics, &log_data);
 		}
 
@@ -416,9 +427,10 @@ mod tests {
 
 		let mut setup = TestSetup::new();
 		let state = setup.state.reference_mut();
+		let mut tracer = NoopTracer;
 
 		{
-			let mut ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None));
+			let mut ext = Externalities::new(state, &setup.env_info, &*setup.engine, 0, get_test_origin(), &mut setup.sub_state, OutputPolicy::InitContract(None), &mut tracer);
 			ext.suicide(&refund_account);
 		}
 

ethcore/src/state.rs

@@ -398,11 +398,11 @@ fn should_apply_create_transaction() {
 			value: x!(100),
 			gas: x!(77412),
 			init: vec![96, 16, 128, 96, 12, 96, 0, 57, 96, 0, 243, 0, 96, 0, 53, 84, 21, 96, 9, 87, 0, 91, 96, 32, 53, 96, 0, 53, 85],
-			result: Some(TraceCreateResult {
+		}),
+		result: TraceResult::Create(TraceCreateResult {
 			gas_used: U256::from(3224),
 			address: Address::from_str("8988167e088c87cd314df6d3c2b83da5acb93ace").unwrap(),
 			code: vec![96, 0, 53, 84, 21, 96, 9, 87, 0, 91, 96, 32, 53, 96, 0, 53]
-			})
 		}),
 		subs: vec![]
 	});
@@ -458,8 +458,8 @@ fn should_trace_failed_create_transaction() {
 			value: x!(100),
 			gas: x!(78792),
 			init: vec![91, 96, 0, 86],
-			result: None
 		}),
+		result: TraceResult::FailedCreate,
 		subs: vec![]
 	});
 
@@ -497,10 +497,10 @@ fn should_trace_call_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(3),
 			output: vec![]
-			})
 		}),
 		subs: vec![]
 	});
@@ -538,10 +538,10 @@ fn should_trace_basic_call_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(0),
 			output: vec![]
-			})
 		}),
 		subs: vec![]
 	});
@@ -605,10 +605,10 @@ fn should_not_trace_subcall_transaction_to_builtin() {
 			value: x!(0),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(28_061),
 			output: vec![]
-			})
 		}),
 		subs: vec![]
 	});
@@ -647,10 +647,10 @@ fn should_not_trace_callcode() {
 			value: x!(0),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(64),
 			output: vec![]
-			})
 		}),
 		subs: vec![]
 	});
@@ -692,10 +692,10 @@ fn should_not_trace_delegatecall() {
 			value: x!(0),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(61),
 			output: vec![]
-			})
 		}),
 		subs: vec![]
 	});
@@ -733,8 +733,8 @@ fn should_trace_failed_call_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: None
 		}),
+		result: TraceResult::FailedCall,
 		subs: vec![]
 	});
 
@@ -775,10 +775,10 @@ fn should_trace_call_with_subcall_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(69),
 			output: vec![]
-			})
 		}),
 		subs: vec![Trace {
 			depth: 1,
@@ -788,10 +788,10 @@ fn should_trace_call_with_subcall_transaction() {
 				value: x!(0),
 				gas: x!(78934),
 				input: vec![],
-				result: Some(TraceCallResult {
+			}),
+			result: TraceResult::Call(TraceCallResult {
 				gas_used: U256::from(3),
 				output: vec![]
-				})
 			}),
 			subs: vec![]
 		}]
@@ -831,10 +831,10 @@ fn should_trace_call_with_basic_subcall_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(31761),
 			output: vec![]
-			})
 		}),
 		subs: vec![Trace {
 			depth: 1,
@@ -844,8 +844,8 @@ fn should_trace_call_with_basic_subcall_transaction() {
 				value: x!(69),
 				gas: x!(2300),
 				input: vec![],
-				result: Some(TraceCallResult::default())
 			}),
+			result: TraceResult::Call(TraceCallResult::default()),
 			subs: vec![]
 		}]
 	});
@@ -884,10 +884,10 @@ fn should_not_trace_call_with_invalid_basic_subcall_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(31761),
 			output: vec![]
-			})
 		}),
 		subs: vec![]
 	});
@@ -927,12 +927,10 @@ fn should_trace_failed_subcall_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(79_000),
 			output: vec![]
-			})
-
-			//	Some((x!(79000), vec![]))
 		}),
 		subs: vec![Trace {
 			depth: 1,
@@ -942,8 +940,8 @@ fn should_trace_failed_subcall_transaction() {
 				value: x!(0),
 				gas: x!(78934),
 				input: vec![],
-				result: None
 			}),
+			result: TraceResult::FailedCall,
 			subs: vec![]
 		}]
 	});
@@ -984,10 +982,10 @@ fn should_trace_call_with_subcall_with_subcall_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(135),
 			output: vec![]
-			})
 		}),
 		subs: vec![Trace {
 			depth: 1,
@@ -997,10 +995,10 @@ fn should_trace_call_with_subcall_with_subcall_transaction() {
 				value: x!(0),
 				gas: x!(78934),
 				input: vec![],
-				result: Some(TraceCallResult {
+			}),
+			result: TraceResult::Call(TraceCallResult {
 				gas_used: U256::from(69),
 				output: vec![]
-				})
 			}),
 			subs: vec![Trace {
 				depth: 2,
@@ -1010,10 +1008,10 @@ fn should_trace_call_with_subcall_with_subcall_transaction() {
 					value: x!(0),
 					gas: x!(78868),
 					input: vec![],
-					result: Some(TraceCallResult {
+				}),
+				result: TraceResult::Call(TraceCallResult {
 					gas_used: U256::from(3),
 					output: vec![]
-					})
 				}),
 				subs: vec![]
 			}]
@@ -1056,10 +1054,10 @@ fn should_trace_failed_subcall_with_subcall_transaction() {
 			value: x!(100),
 			gas: x!(79000),
 			input: vec![],
-			result: Some(TraceCallResult {
+		}),
+		result: TraceResult::Call(TraceCallResult {
 			gas_used: U256::from(79_000),
 			output: vec![]
-			})
 		}),
 		subs: vec![Trace {
 			depth: 1,
@@ -1069,8 +1067,8 @@ fn should_trace_failed_subcall_with_subcall_transaction() {
 				value: x!(0),
 				gas: x!(78934),
 				input: vec![],
-				result: None
 			}),
+			result: TraceResult::FailedCall,
 			subs: vec![Trace {
 				depth: 2,
 				action: TraceAction::Call(TraceCall {
@@ -1079,10 +1077,10 @@ fn should_trace_failed_subcall_with_subcall_transaction() {
 					value: x!(0),
 					gas: x!(78868),
 					input: vec![],
-					result: Some(TraceCallResult {
+				}),
+				result: TraceResult::Call(TraceCallResult {
 					gas_used: U256::from(3),
 					output: vec![]
-					})
 				}),
 				subs: vec![]
 			}]

ethcore/src/substate.rs

@@ -32,44 +32,25 @@ pub struct Substate {
 
 	/// Created contracts.
 	pub contracts_created: Vec<Address>,
-
-	/// The trace during this execution or `None` if we're not tracing.
-	pub subtraces: Option<Vec<Trace>>,
 }
 
 impl Substate {
 	/// Creates new substate.
-	pub fn new(tracing: bool) -> Self {
+	pub fn new() -> Self {
 		Substate {
 			suicides: Default::default(),
 			logs: Default::default(),
 			sstore_clears_count: Default::default(),
 			contracts_created: Default::default(),
-			subtraces: if tracing {Some(vec![])} else {None},
 		}
 	}
 
-	/// Merge tracing information from substate `s` if enabled.
+	/// Merge secondary substate `s` into self, accruing each element correspondingly.
-	pub fn accrue_trace(&mut self, subs: Option<Vec<Trace>>, maybe_info: Option<(TraceAction, usize)>) {
+	pub fn accrue(&mut self, s: Substate) {
-		// it failed, so we don't bother accrueing any protocol-level stuff, only the
-		// trace info.
-		if let Some(info) = maybe_info {
-			self.subtraces.as_mut().expect("maybe_action is Some: so we must be tracing: qed").push(Trace {
-				action: info.0,
-				depth: info.1,
-				subs: subs.expect("maybe_action is Some: so we must be tracing: qed"),
-			});
-		}
-	}
-
-	/// Merge secondary substate `s` into self, accruing each element correspondingly; will merge
-	/// tracing information too, if enabled.
-	pub fn accrue(&mut self, s: Substate, maybe_info: Option<(TraceAction, usize)>) {
 		self.suicides.extend(s.suicides.into_iter());
 		self.logs.extend(s.logs.into_iter());
 		self.sstore_clears_count = self.sstore_clears_count + s.sstore_clears_count;
 		self.contracts_created.extend(s.contracts_created.into_iter());
-		self.accrue_trace(s.subtraces, maybe_info);
 	}
 }
 
@@ -80,13 +61,13 @@ mod tests {
 
 	#[test]
 	fn created() {
-		let sub_state = Substate::new(false);
+		let sub_state = Substate::new();
 		assert_eq!(sub_state.suicides.len(), 0);
 	}
 
 	#[test]
 	fn accrue() {
-		let mut sub_state = Substate::new(false);
+		let mut sub_state = Substate::new();
 		sub_state.contracts_created.push(address_from_u64(1u64));
 		sub_state.logs.push(LogEntry {
 			address: address_from_u64(1u64),
@@ -96,7 +77,7 @@ mod tests {
 		sub_state.sstore_clears_count = x!(5);
 		sub_state.suicides.insert(address_from_u64(10u64));
 
-		let mut sub_state_2 = Substate::new(false);
+		let mut sub_state_2 = Substate::new();
 		sub_state_2.contracts_created.push(address_from_u64(2u64));
 		sub_state_2.logs.push(LogEntry {
 			address: address_from_u64(1u64),
@@ -105,7 +86,7 @@ mod tests {
 		});
 		sub_state_2.sstore_clears_count = x!(7);
 
-		sub_state.accrue(sub_state_2, None);
+		sub_state.accrue(sub_state_2);
 		assert_eq!(sub_state.contracts_created.len(), 2);
 		assert_eq!(sub_state.sstore_clears_count, x!(12));
 		assert_eq!(sub_state.suicides.len(), 1);

ethcore/src/trace/mod.rs

@@ -19,3 +19,181 @@
 mod trace;
 
 pub use self::trace::*;
+use util::bytes::Bytes;
+use util::hash::Address;
+use util::numbers::U256;
+use action_params::ActionParams;
+
+/// This trait is used by executive to build traces.
+pub trait Tracer: Send {
+	/// Prepares call trace for given params. Noop tracer should return None.
+	fn prepare_trace_call(&self, params: &ActionParams) -> Option<TraceCall>;
+
+	/// Prepares create trace for given params. Noop tracer should return None.
+	fn prepare_trace_create(&self, params: &ActionParams) -> Option<TraceCreate>;
+
+	/// Prepare trace output. Noop tracer should return None.
+	fn prepare_trace_output(&self) -> Option<Bytes>;
+
+	/// Stores trace call info.
+	fn trace_call(
+		&mut self,
+		call: Option<TraceCall>,
+		gas_used: U256,
+		output: Option<Bytes>,
+		depth: usize,
+		subs: Vec<Trace>,
+		delegate_call: bool
+	);
+
+	/// Stores trace create info.
+	fn trace_create(
+		&mut self,
+		create: Option<TraceCreate>,
+		gas_used: U256,
+		code: Option<Bytes>,
+		address: Address,
+		depth: usize,
+		subs: Vec<Trace>
+	);
+
+	/// Stores failed call trace.
+	fn trace_failed_call(&mut self, call: Option<TraceCall>, depth: usize, subs: Vec<Trace>, delegate_call: bool);
+
+	/// Stores failed create trace.
+	fn trace_failed_create(&mut self, create: Option<TraceCreate>, depth: usize, subs: Vec<Trace>);
+
+	/// Spawn subracer which will be used to trace deeper levels of execution.
+	fn subtracer(&self) -> Self where Self: Sized;
+
+	/// Consumes self and returns all traces.
+	fn traces(self) -> Vec<Trace>;
+}
+
+/// Nonoperative tracer. Does not trace anything.
+pub struct NoopTracer;
+
+impl Tracer for NoopTracer {
+	fn prepare_trace_call(&self, _: &ActionParams) -> Option<TraceCall> {
+		None
+	}
+
+	fn prepare_trace_create(&self, _: &ActionParams) -> Option<TraceCreate> {
+		None
+	}
+
+	fn prepare_trace_output(&self) -> Option<Bytes> {
+		None
+	}
+
+	fn trace_call(&mut self, call: Option<TraceCall>, _: U256, output: Option<Bytes>, _: usize, _: Vec<Trace>,
+				  _: bool) {
+		assert!(call.is_none());
+		assert!(output.is_none());
+	}
+
+	fn trace_create(&mut self, create: Option<TraceCreate>, _: U256, code: Option<Bytes>, _: Address, _: usize, _: Vec<Trace>) {
+		assert!(create.is_none());
+		assert!(code.is_none());
+	}
+
+	fn trace_failed_call(&mut self, call: Option<TraceCall>, _: usize, _: Vec<Trace>, _: bool) {
+		assert!(call.is_none());
+	}
+
+	fn trace_failed_create(&mut self, create: Option<TraceCreate>, _: usize, _: Vec<Trace>) {
+		assert!(create.is_none());
+	}
+
+	fn subtracer(&self) -> Self {
+		NoopTracer
+	}
+
+	fn traces(self) -> Vec<Trace> {
+		vec![]
+	}
+}
+
+/// Simple executive tracer. Traces all calls and creates. Ignores delegatecalls.
+#[derive(Default)]
+pub struct ExecutiveTracer {
+	traces: Vec<Trace>
+}
+
+impl Tracer for ExecutiveTracer {
+	fn prepare_trace_call(&self, params: &ActionParams) -> Option<TraceCall> {
+		Some(TraceCall::from(params.clone()))
+	}
+
+	fn prepare_trace_create(&self, params: &ActionParams) -> Option<TraceCreate> {
+		Some(TraceCreate::from(params.clone()))
+	}
+
+	fn prepare_trace_output(&self) -> Option<Bytes> {
+		Some(vec![])
+	}
+
+	fn trace_call(&mut self, call: Option<TraceCall>, gas_used: U256, output: Option<Bytes>, depth: usize, subs:
+				  Vec<Trace>, delegate_call: bool) {
+		if delegate_call {
+			return;
+		}
+
+		let trace = Trace {
+			depth: depth,
+			subs: subs,
+			action: TraceAction::Call(call.expect("Trace call expected to be Some.")),
+			result: TraceResult::Call(TraceCallResult {
+				gas_used: gas_used,
+				output: output.expect("Trace call output expected to be Some.")
+			})
+		};
+		self.traces.push(trace);
+	}
+
+	fn trace_create(&mut self, create: Option<TraceCreate>, gas_used: U256, code: Option<Bytes>, address: Address, depth: usize, subs: Vec<Trace>) {
+		let trace = Trace {
+			depth: depth,
+			subs: subs,
+			action: TraceAction::Create(create.expect("Trace create expected to be Some.")),
+			result: TraceResult::Create(TraceCreateResult {
+				gas_used: gas_used,
+				code: code.expect("Trace create code expected to be Some."),
+				address: address
+			})
+		};
+		self.traces.push(trace);
+	}
+
+	fn trace_failed_call(&mut self, call: Option<TraceCall>, depth: usize, subs: Vec<Trace>, delegate_call: bool) {
+		if delegate_call {
+			return;
+		}
+
+		let trace = Trace {
+			depth: depth,
+			subs: subs,
+			action: TraceAction::Call(call.expect("Trace call expected to be Some.")),
+			result: TraceResult::FailedCall,
+		};
+		self.traces.push(trace);
+	}
+
+	fn trace_failed_create(&mut self, create: Option<TraceCreate>, depth: usize, subs: Vec<Trace>) {
+		let trace = Trace {
+			depth: depth,
+			subs: subs,
+			action: TraceAction::Create(create.expect("Trace create expected to be Some.")),
+			result: TraceResult::FailedCreate,
+		};
+		self.traces.push(trace);
+	}
+
+	fn subtracer(&self) -> Self {
+		ExecutiveTracer::default()
+	}
+
+	fn traces(self) -> Vec<Trace> {
+		self.traces
+	}
+}

ethcore/src/trace/trace.rs

@@ -50,8 +50,18 @@ pub struct TraceCall {
 	pub gas: U256,
 	/// The input data provided to the call.
 	pub input: Bytes,
-	/// The result of the operation; the gas used and the output data of the call.
+}
-	pub result: Option<TraceCallResult>,
+
+impl From<ActionParams> for TraceCall {
+	fn from(p: ActionParams) -> Self {
+		TraceCall {
+			from: p.sender,
+			to: p.address,
+			value: p.value.value(),
+			gas: p.gas,
+			input: p.data.unwrap_or_else(Vec::new),
+		}
+	}
 }
 
 /// Description of a _create_ action, either a `CREATE` operation or a create transction.
@@ -65,9 +75,17 @@ pub struct TraceCreate {
 	pub gas: U256,
 	/// The init code.
 	pub init: Bytes,
-	/// The result of the operation; tuple of the gas used, the address of the newly created account and its code.
+}
-	/// NOTE: Presently failed operations are not reported so this will always be `Some`.
+
-	pub result: Option<TraceCreateResult>,
+impl From<ActionParams> for TraceCreate {
+	fn from(p: ActionParams) -> Self {
+		TraceCreate {
+			from: p.sender,
+			value: p.value.value(),
+			gas: p.gas,
+			init: p.code.unwrap_or_else(Vec::new),
+		}
+	}
 }
 
 /// Description of an action that we trace; will be either a call or a create.
@@ -79,6 +97,19 @@ pub enum TraceAction {
 	Create(TraceCreate),
 }
 
+/// The result of the performed action.
+#[derive(Debug, Clone, PartialEq)]
+pub enum TraceResult {
+	/// Successful call action result.
+	Call(TraceCallResult),
+	/// Successful create action result.
+	Create(TraceCreateResult),
+	/// Failed call.
+	FailedCall,
+	/// Failed create.
+	FailedCreate,
+}
+
 #[derive(Debug, Clone, PartialEq)]
 /// A trace; includes a description of the action being traced and sub traces of each interior action.
 pub struct Trace {
@@ -89,30 +120,6 @@ pub struct Trace {
 	pub action: TraceAction,
 	/// The sub traces for each interior action performed as part of this call.
 	pub subs: Vec<Trace>,
+	/// The result of the performed action.
+	pub result: TraceResult,
 }
-
-impl TraceAction {
-	/// Compose a `TraceAction` from an `ActionParams`, knowing that the action is a call.
-	pub fn from_call(p: &ActionParams) -> TraceAction {
-		TraceAction::Call(TraceCall {
-			from: p.sender.clone(),
-			to: p.address.clone(),
-			value: p.value.value(),
-			gas: p.gas,
-			input: p.data.clone().unwrap_or_else(Vec::new),
-			result: None,
-		})
-	}
-
-	/// Compose a `TraceAction` from an `ActionParams`, knowing that the action is a create.
-	pub fn from_create(p: &ActionParams) -> TraceAction {
-		TraceAction::Create(TraceCreate {
-			from: p.sender.clone(),
-			value: p.value.value(),
-			gas: p.gas,
-			init: p.code.clone().unwrap_or_else(Vec::new),
-			result: None,
-		})
-	}
-}
-