Break circular dependency between Client and Engine (part 1)

ethcore/src/block.rs

@@ -22,13 +22,13 @@
 //! and can be appended to with transactions and uncles.
 //!
 //! When ready, `OpenBlock` can be closed and turned into a `ClosedBlock`. A `ClosedBlock` can
-//! be reopend again by a miner under certain circumstances. On block close, state commit is
+//! be re-opend again by a miner under certain circumstances. On block close, state commit is
 //! performed.
 //!
 //! `LockedBlock` is a version of a `ClosedBlock` that cannot be reopened. It can be sealed
 //! using an engine.
 //!
-//! `ExecutedBlock` is an underlaying data structure used by all structs above to store block
+//! `ExecutedBlock` is an underlying data structure used by all structs above to store block
 //! related info.
 
 use std::{cmp, ops};
@@ -62,6 +62,7 @@ use types::receipt::{Receipt, TransactionOutcome};
 pub struct OpenBlock<'x> {
 	block: ExecutedBlock,
 	engine: &'x dyn Engine,
+	parent: Header,
 }
 
 /// Just like `OpenBlock`, except that we've applied `Engine::on_close_block`, finished up the non-seal header fields,
@@ -72,6 +73,7 @@ pub struct OpenBlock<'x> {
 pub struct ClosedBlock {
 	block: ExecutedBlock,
 	unclosed_state: State<StateDB>,
+	parent: Header,
 }
 
 /// Just like `ClosedBlock` except that we can't reopen it and it's faster.
@@ -102,7 +104,7 @@ pub struct ExecutedBlock {
 	pub receipts: Vec<Receipt>,
 	/// Hashes of already executed transactions.
 	pub transactions_set: HashSet<H256>,
-	/// Underlaying state.
+	/// Underlying state.
 	pub state: State<StateDB>,
 	/// Transaction traces.
 	pub traces: Tracing,
@@ -119,13 +121,13 @@ impl ExecutedBlock {
 			uncles: Default::default(),
 			receipts: Default::default(),
 			transactions_set: Default::default(),
-			state: state,
+			state,
 			traces: if tracing {
 				Tracing::enabled()
 			} else {
 				Tracing::Disabled
 			},
-			last_hashes: last_hashes,
+			last_hashes,
 		}
 	}
 
@@ -173,14 +175,12 @@ impl<'x> OpenBlock<'x> {
 		gas_range_target: (U256, U256),
 		extra_data: Bytes,
 		is_epoch_begin: bool,
-		ancestry: I,
+		ancestry: I, // TODO: remove this
 	) -> Result<Self, Error> {
 		let number = parent.number() + 1;
 		let state = State::from_existing(db, parent.state_root().clone(), engine.account_start_nonce(number), factories)?;
-		let mut r = OpenBlock {
-			block: ExecutedBlock::new(state, last_hashes, tracing),
-			engine: engine,
-		};
+
+		let mut r = OpenBlock { block: ExecutedBlock::new(state, last_hashes, tracing), engine, parent: parent.clone() };
 
 		r.block.header.set_parent_hash(parent.hash());
 		r.block.header.set_number(number);
@@ -195,7 +195,7 @@ impl<'x> OpenBlock<'x> {
 		engine.populate_from_parent(&mut r.block.header, parent);
 
 		engine.machine().on_new_block(&mut r.block)?;
-		engine.on_new_block(&mut r.block, is_epoch_begin, &mut ancestry.into_iter())?;
+		engine.on_new_block(&mut r.block, is_epoch_begin)?;
 
 		Ok(r)
 	}
@@ -297,19 +297,20 @@ impl<'x> OpenBlock<'x> {
 	/// Turn this into a `ClosedBlock`.
 	pub fn close(self) -> Result<ClosedBlock, Error> {
 		let unclosed_state = self.block.state.clone();
+		let parent = self.parent.clone();
 		let locked = self.close_and_lock()?;
 
 		Ok(ClosedBlock {
 			block: locked.block,
 			unclosed_state,
+			parent,
 		})
 	}
 
 	/// Turn this into a `LockedBlock`.
 	pub fn close_and_lock(self) -> Result<LockedBlock, Error> {
 		let mut s = self;
-
-		s.engine.on_close_block(&mut s.block)?;
+		s.engine.on_close_block(&mut s.block, &s.parent)?;
 		s.block.state.commit()?;
 
 		s.block.header.set_transactions_root(ordered_trie_root(s.block.transactions.iter().map(|e| e.rlp_bytes())));
@@ -378,10 +379,8 @@ impl ClosedBlock {
 		// revert rewards (i.e. set state back at last transaction's state).
 		let mut block = self.block;
 		block.state = self.unclosed_state;
-		OpenBlock {
-			block: block,
-			engine: engine,
-		}
+		let parent = self.parent;
+		OpenBlock { block, engine, parent }
 	}
 }
 
@@ -522,7 +521,7 @@ pub(crate) fn enact(
 	b.close_and_lock()
 }
 
-/// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
+/// Enact the block given by `block_bytes` using `engine` on the database `db` with the given `parent` block header
 pub fn enact_verified(
 	block: PreverifiedBlock,
 	engine: &dyn Engine,

ethcore/src/engines/authority_round/mod.rs

@@ -1211,7 +1211,6 @@ impl Engine for AuthorityRound {
 		&self,
 		block: &mut ExecutedBlock,
 		epoch_begin: bool,
-		_ancestry: &mut dyn Iterator<Item=ExtendedHeader>,
 	) -> Result<(), Error> {
 		// with immediate transitions, we don't use the epoch mechanism anyway.
 		// the genesis is always considered an epoch, but we ignore it intentionally.
@@ -1236,26 +1235,18 @@ impl Engine for AuthorityRound {
 	}
 
 	/// Apply the block reward on finalisation of the block.
-	fn on_close_block(&self, block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		block: &mut ExecutedBlock,
+		parent: &Header,
+	) -> Result<(), Error> {
 		let mut beneficiaries = Vec::new();
 		if block.header.number() >= self.empty_steps_transition {
 			let empty_steps = if block.header.seal().is_empty() {
 				// this is a new block, calculate rewards based on the empty steps messages we have accumulated
-				let client = match self.client.read().as_ref().and_then(|weak| weak.upgrade()) {
-					Some(client) => client,
-					None => {
-						debug!(target: "engine", "Unable to close block: missing client ref.");
-						return Err(EngineError::RequiresClient.into())
-					},
-				};
-
-				let parent = client.block_header(::client::BlockId::Hash(*block.header.parent_hash()))
-					.expect("hash is from parent; parent header must exist; qed")
-					.decode()?;
-
-				let parent_step = header_step(&parent, self.empty_steps_transition)?;
+				let parent_step = header_step(parent, self.empty_steps_transition)?;
 				let current_step = self.step.inner.load();
-				self.empty_steps(parent_step.into(), current_step.into(), parent.hash())
+				self.empty_steps(parent_step, current_step, parent.hash())
 			} else {
 				// we're verifying a block, extract empty steps from the seal
 				header_empty_steps(&block.header)?

ethcore/src/engines/clique/mod.rs

@@ -368,13 +368,16 @@ impl Engine for Clique {
 		&self,
 		_block: &mut ExecutedBlock,
 		_epoch_begin: bool,
-		_ancestry: &mut dyn Iterator<Item=ExtendedHeader>,
 	) -> Result<(), Error> {
 		Ok(())
 	}
 
 	// Clique has no block reward.
-	fn on_close_block(&self, _block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		_block: &mut ExecutedBlock,
+		_parent_header: &Header
+	) -> Result<(), Error> {
 		Ok(())
 	}
 

ethcore/src/engines/mod.rs

@@ -304,13 +304,16 @@ pub trait Engine: Sync + Send {
 		&self,
 		_block: &mut ExecutedBlock,
 		_epoch_begin: bool,
-		_ancestry: &mut dyn Iterator<Item = ExtendedHeader>,
 	) -> Result<(), Error> {
 		Ok(())
 	}
 
 	/// Block transformation functions, after the transactions.
-	fn on_close_block(&self, _block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		_block: &mut ExecutedBlock,
+		_parent_header: &Header,
+	) -> Result<(), Error> {
 		Ok(())
 	}
 

ethcore/src/engines/null_engine.rs

@@ -61,7 +61,11 @@ impl Engine for NullEngine {
 
 	fn machine(&self) -> &Machine { &self.machine }
 
-	fn on_close_block(&self, block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		block: &mut ExecutedBlock,
+		_parent_header: &Header
+	) -> Result<(), Error> {
 		use std::ops::Shr;
 
 		let author = *block.header.author();

ethcore/src/ethereum/ethash.rs

@@ -239,7 +239,7 @@ impl Engine for Arc<Ethash> {
 
 	/// Apply the block reward on finalisation of the block.
 	/// This assumes that all uncles are valid uncles (i.e. of at least one generation before the current).
-	fn on_close_block(&self, block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(&self, block: &mut ExecutedBlock, _parent_header: &Header) -> Result<(), Error> {
 		use std::ops::Shr;
 
 		let author = *block.header.author();

ethcore/src/miner/miner.rs

@@ -548,7 +548,7 @@ impl Miner {
 					}
 				},
 				// Invalid nonce error can happen only if previous transaction is skipped because of gas limit.
-				// If there is errornous state of transaction queue it will be fixed when next block is imported.
+				// If there is erroneous state of transaction queue it will be fixed when next block is imported.
 				Err(Error::Execution(ExecutionError::InvalidNonce { expected, got })) => {
 					debug!(target: "miner", "Skipping adding transaction to block because of invalid nonce: {:?} (expected: {:?}, got: {:?})", hash, expected, got);
 				},

ethcore/src/tests/client.rs

@@ -117,7 +117,7 @@ fn query_none_block() {
 		Arc::new(Miner::new_for_tests(&spec, None)),
 		IoChannel::disconnected(),
 	).unwrap();
-    let non_existant = client.block_header(BlockId::Number(188));
+	let non_existant = client.block_header(BlockId::Number(188));
 	assert!(non_existant.is_none());
 }