Add RPC & client call to replay a transaction. (#1734)

* Add RPC & client call to replay a transaction.

* Address grumbles

ethcore/src/client/client.rs

@@ -35,7 +35,7 @@ use util::kvdb::*;
 
 // other
 use views::BlockView;
-use error::{ImportError, ExecutionError, BlockError, ImportResult};
+use error::{ImportError, ExecutionError, ReplayError, BlockError, ImportResult};
 use header::BlockNumber;
 use state::State;
 use spec::Spec;
@@ -473,7 +473,7 @@ impl Client {
 		results.len()
 	}
 
-	/// Attempt to get a copy of a specific block's state.
+	/// Attempt to get a copy of a specific block's final state.
 	///
 	/// This will not fail if given BlockID::Latest.
 	/// Otherwise, this can fail (but may not) if the DB prunes state.
@@ -504,6 +504,21 @@ impl Client {
 		})
 	}
 
+	/// Attempt to get a copy of a specific block's beginning state.
+	///
+	/// This will not fail if given BlockID::Latest.
+	/// Otherwise, this can fail (but may not) if the DB prunes state.
+	pub fn state_at_beginning(&self, id: BlockID) -> Option<State> {
+		// fast path for latest state.
+		match id {
+			BlockID::Pending => self.state_at(BlockID::Latest),
+			id => match self.block_number(id) {
+				None | Some(0) => None,
+				Some(n) => self.state_at(BlockID::Number(n - 1)),
+			}
+		}
+	}
+
 	/// Get a copy of the best block's state.
 	pub fn state(&self) -> State {
 		State::from_existing(
@@ -660,6 +675,46 @@ impl BlockChainClient for Client {
 		ret
 	}
 
+	fn replay(&self, id: TransactionID, analytics: CallAnalytics) -> Result<Executed, ReplayError> {
+		let address = try!(self.transaction_address(id).ok_or(ReplayError::TransactionNotFound));
+		let block_data = try!(self.block(BlockID::Hash(address.block_hash)).ok_or(ReplayError::StatePruned));
+		let mut state = try!(self.state_at_beginning(BlockID::Hash(address.block_hash)).ok_or(ReplayError::StatePruned));
+		let block = BlockView::new(&block_data);
+		let txs = block.transactions();
+
+		if address.index >= txs.len() {
+			return Err(ReplayError::TransactionNotFound);
+		}
+
+		let options = TransactOptions { tracing: analytics.transaction_tracing, vm_tracing: analytics.vm_tracing, check_nonce: false };
+		let view = block.header_view();
+		let last_hashes = self.build_last_hashes(view.hash());
+		let mut env_info = EnvInfo {
+			number: view.number(),
+			author: view.author(),
+			timestamp: view.timestamp(),
+			difficulty: view.difficulty(),
+			last_hashes: last_hashes,
+			gas_used: U256::zero(),
+			gas_limit: view.gas_limit(),
+		};
+		for t in txs.iter().take(address.index) {
+			match Executive::new(&mut state, &env_info, self.engine.deref().deref(), &self.vm_factory).transact(t, Default::default()) {
+				Ok(x) => { env_info.gas_used = env_info.gas_used + x.gas_used; }
+				Err(ee) => { return Err(ReplayError::Execution(ee)) }
+			}
+		}
+		let t = &txs[address.index];
+		let orig = state.clone();
+		let mut ret = Executive::new(&mut state, &env_info, self.engine.deref().deref(), &self.vm_factory).transact(t, options);
+		if analytics.state_diffing {
+			if let Ok(ref mut x) = ret {
+				x.state_diff = Some(state.diff_from(orig));
+			}
+		}
+		ret.map_err(|ee| ReplayError::Execution(ee))
+	}
+
 	fn keep_alive(&self) {
 		if self.mode != Mode::Active {
 			self.wake_up();

ethcore/src/client/test_client.rs

@@ -37,7 +37,7 @@ use spec::Spec;
 use block_queue::BlockQueueInfo;
 use block::{OpenBlock, SealedBlock};
 use executive::Executed;
-use error::ExecutionError;
+use error::{ExecutionError, ReplayError};
 use trace::LocalizedTrace;
 
 /// Test client.
@@ -292,6 +292,10 @@ impl BlockChainClient for TestBlockChainClient {
 		Ok(self.execution_result.read().clone().unwrap())
 	}
 
+	fn replay(&self, _id: TransactionID, _analytics: CallAnalytics) -> Result<Executed, ReplayError> {
+		Ok(self.execution_result.read().clone().unwrap())
+	}
+
 	fn block_total_difficulty(&self, _id: BlockID) -> Option<U256> {
 		Some(U256::zero())
 	}

ethcore/src/client/traits.rs

@@ -26,7 +26,7 @@ use transaction::{LocalizedTransaction, SignedTransaction};
 use log_entry::LocalizedLogEntry;
 use filter::Filter;
 use views::{BlockView};
-use error::{ImportResult, ExecutionError};
+use error::{ImportResult, ExecutionError, ReplayError};
 use receipt::LocalizedReceipt;
 use trace::LocalizedTrace;
 use evm::Factory as EvmFactory;
@@ -160,6 +160,9 @@ pub trait BlockChainClient : Sync + Send {
 	// TODO: should be able to accept blockchain location for call.
 	fn call(&self, t: &SignedTransaction, analytics: CallAnalytics) -> Result<Executed, ExecutionError>;
 
+	/// Replays a given transaction for inspection.
+	fn replay(&self, t: TransactionID, analytics: CallAnalytics) -> Result<Executed, ReplayError>;
+
 	/// Returns traces matching given filter.
 	fn filter_traces(&self, filter: TraceFilter) -> Option<Vec<LocalizedTrace>>;
 

ethcore/src/error.rs

@@ -22,7 +22,7 @@ use basic_types::LogBloom;
 use client::Error as ClientError;
 use ipc::binary::{BinaryConvertError, BinaryConvertable};
 use types::block_import_error::BlockImportError;
-pub use types::executed::ExecutionError;
+pub use types::executed::{ExecutionError, ReplayError};
 
 #[derive(Debug, PartialEq, Clone)]
 /// Errors concerning transaction processing.

ethcore/src/executive.rs

@@ -40,6 +40,7 @@ pub fn contract_address(address: &Address, nonce: &U256) -> Address {
 }
 
 /// Transaction execution options.
+#[derive(Default)]
 pub struct TransactOptions {
 	/// Enable call tracing.
 	pub tracing: bool,

ethcore/src/trace/executive_tracer.rs

@@ -50,6 +50,7 @@ impl Tracer for ExecutiveTracer {
 				output: output.expect("self.prepare_trace_output().is_some(): so we must be tracing: qed")
 			})
 		};
+		debug!(target: "trace", "Traced call {:?}", trace);
 		self.traces.push(trace);
 	}
 
@@ -64,6 +65,7 @@ impl Tracer for ExecutiveTracer {
 				address: address
 			})
 		};
+		debug!(target: "trace", "Traced create {:?}", trace);
 		self.traces.push(trace);
 	}
 
@@ -74,6 +76,7 @@ impl Tracer for ExecutiveTracer {
 			action: Action::Call(call.expect("self.prepare_trace_call().is_some(): so we must be tracing: qed")),
 			result: Res::FailedCall,
 		};
+		debug!(target: "trace", "Traced failed call {:?}", trace);
 		self.traces.push(trace);
 	}
 
@@ -84,6 +87,7 @@ impl Tracer for ExecutiveTracer {
 			action: Action::Create(create.expect("self.prepare_trace_create().is_some(): so we must be tracing: qed")),
 			result: Res::FailedCreate,
 		};
+		debug!(target: "trace", "Traced failed create {:?}", trace);
 		self.traces.push(trace);
 	}
 
@@ -98,6 +102,7 @@ impl Tracer for ExecutiveTracer {
 			}),
 			result: Res::None,
 		};
+		debug!(target: "trace", "Traced failed suicide {:?}", trace);
 		self.traces.push(trace);
 	}
 

ethcore/src/types/executed.rs

@@ -171,6 +171,31 @@ impl fmt::Display for ExecutionError {
 	}
 }
 
+/// Result of executing the transaction.
+#[derive(PartialEq, Debug, Binary)]
+pub enum ReplayError {
+	/// Couldn't find the transaction in the chain.
+	TransactionNotFound,
+	/// Couldn't find the transaction block's state in the chain.
+	StatePruned,
+	/// Error executing.
+	Execution(ExecutionError),
+}
+
+impl fmt::Display for ReplayError {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		use self::ReplayError::*;
+
+		let msg = match *self {
+			TransactionNotFound => "Transaction couldn't be found in the chain".into(),
+			StatePruned => "Couldn't find the transaction block's state in the chain".into(),
+			Execution(ref e) => format!("{}", e),
+		};
+
+		f.write_fmt(format_args!("Transaction replay error ({}).", msg))
+	}
+}
+
 /// Transaction execution result.
 pub type ExecutionResult = Result<Executed, ExecutionError>;