Maximum uncle count transition (#7196)

* Enable delayed maximum_uncle_count activation.

* Fix tests.

* Defer kovan HF.

ethcore/res/ethereum/kovan.json

@@ -24,6 +24,7 @@
 				},
 				"validateScoreTransition": 1000000,
 				"validateStepTransition": 1500000,
+				"maximumUncleCountTransition": 10000000,
 				"maximumUncleCount": 2
 			}
 		}

ethcore/src/block.rs

@@ -380,8 +380,13 @@ impl<'x> OpenBlock<'x> {
 	/// NOTE Will check chain constraints and the uncle number but will NOT check
 	/// that the header itself is actually valid.
 	pub fn push_uncle(&mut self, valid_uncle_header: Header) -> Result<(), BlockError> {
-		if self.block.uncles.len() + 1 > self.engine.maximum_uncle_count() {
-			return Err(BlockError::TooManyUncles(OutOfBounds{min: None, max: Some(self.engine.maximum_uncle_count()), found: self.block.uncles.len() + 1}));
+		let max_uncles = self.engine.maximum_uncle_count(self.block.header().number());
+		if self.block.uncles.len() + 1 > max_uncles {
+			return Err(BlockError::TooManyUncles(OutOfBounds{
+				min: None,
+				max: Some(max_uncles),
+				found: self.block.uncles.len() + 1,
+			}));
 		}
 		// TODO: check number
 		// TODO: check not a direct ancestor (use last_hashes for that)

ethcore/src/client/client.rs

@@ -1870,7 +1870,7 @@ impl MiningBlockChainClient for Client {
 			.find_uncle_headers(&h, engine.maximum_uncle_age())
 			.unwrap_or_else(Vec::new)
 			.into_iter()
-			.take(engine.maximum_uncle_count())
+			.take(engine.maximum_uncle_count(open_block.header().number()))
 			.foreach(|h| {
 				open_block.push_uncle(h).expect("pushing maximum_uncle_count;
 												open_block was just created;
@@ -1885,7 +1885,7 @@ impl MiningBlockChainClient for Client {
 	fn reopen_block(&self, block: ClosedBlock) -> OpenBlock {
 		let engine = &*self.engine;
 		let mut block = block.reopen(engine);
-		let max_uncles = engine.maximum_uncle_count();
+		let max_uncles = engine.maximum_uncle_count(block.header().number());
 		if block.uncles().len() < max_uncles {
 			let chain = self.chain.read();
 			let h = chain.best_block_hash();

ethcore/src/engines/authority_round/mod.rs

@@ -65,6 +65,8 @@ pub struct AuthorityRoundParams {
 	pub immediate_transitions: bool,
 	/// Block reward in base units.
 	pub block_reward: U256,
+	/// Number of accepted uncles transition block.
+	pub maximum_uncle_count_transition: u64,
 	/// Number of accepted uncles.
 	pub maximum_uncle_count: usize,
 }
@@ -79,6 +81,7 @@ impl From<ethjson::spec::AuthorityRoundParams> for AuthorityRoundParams {
 			validate_step_transition: p.validate_step_transition.map_or(0, Into::into),
 			immediate_transitions: p.immediate_transitions.unwrap_or(false),
 			block_reward: p.block_reward.map_or_else(Default::default, Into::into),
+			maximum_uncle_count_transition: p.maximum_uncle_count_transition.map_or(0, Into::into),
 			maximum_uncle_count: p.maximum_uncle_count.map_or(0, Into::into),
 		}
 	}
@@ -221,6 +224,7 @@ pub struct AuthorityRound {
 	epoch_manager: Mutex<EpochManager>,
 	immediate_transitions: bool,
 	block_reward: U256,
+	maximum_uncle_count_transition: u64,
 	maximum_uncle_count: usize,
 	machine: EthereumMachine,
 }
@@ -369,6 +373,7 @@ impl AuthorityRound {
 				epoch_manager: Mutex::new(EpochManager::blank()),
 				immediate_transitions: our_params.immediate_transitions,
 				block_reward: our_params.block_reward,
+				maximum_uncle_count_transition: our_params.maximum_uncle_count_transition,
 				maximum_uncle_count: our_params.maximum_uncle_count,
 				machine: machine,
 			});
@@ -441,7 +446,14 @@ impl Engine<EthereumMachine> for AuthorityRound {
 		]
 	}
 
-	fn maximum_uncle_count(&self) -> usize { self.maximum_uncle_count }
+	fn maximum_uncle_count(&self, block: BlockNumber) -> usize {
+		if block >= self.maximum_uncle_count_transition {
+			self.maximum_uncle_count
+		} else {
+			// fallback to default value
+			2
+		}
+	}
 
 	fn populate_from_parent(&self, header: &mut Header, parent: &Header) {
 		// Chain scoring: total weight is sqrt(U256::max_value())*height - step
@@ -956,6 +968,7 @@ mod tests {
 			validate_score_transition: 0,
 			validate_step_transition: 0,
 			immediate_transitions: true,
+			maximum_uncle_count_transition: 0,
 			maximum_uncle_count: 0,
 			block_reward: Default::default(),
 		};
@@ -984,4 +997,31 @@ mod tests {
 		assert!(aura.verify_block_family(&header, &parent_header).is_ok());
 		assert_eq!(last_benign.load(AtomicOrdering::SeqCst), 1);
 	}
+
+	#[test]
+	fn test_uncles_transition() {
+		let last_benign = Arc::new(AtomicUsize::new(0));
+		let params = AuthorityRoundParams {
+			step_duration: Default::default(),
+			start_step: Some(1),
+			validators: Box::new(TestSet::new(Default::default(), last_benign.clone())),
+			validate_score_transition: 0,
+			validate_step_transition: 0,
+			immediate_transitions: true,
+			maximum_uncle_count_transition: 1,
+			maximum_uncle_count: 0,
+			block_reward: Default::default(),
+		};
+
+		let aura = {
+			let mut c_params = ::spec::CommonParams::default();
+			c_params.gas_limit_bound_divisor = 5.into();
+			let machine = ::machine::EthereumMachine::regular(c_params, Default::default());
+			AuthorityRound::new(params, machine).unwrap()
+		};
+
+		assert_eq!(aura.maximum_uncle_count(0), 2);
+		assert_eq!(aura.maximum_uncle_count(1), 0);
+		assert_eq!(aura.maximum_uncle_count(100), 0);
+	}
 }

ethcore/src/engines/mod.rs

@@ -192,7 +192,8 @@ pub trait Engine<M: Machine>: Sync + Send {
 	fn extra_info(&self, _header: &M::Header) -> BTreeMap<String, String> { BTreeMap::new() }
 
 	/// Maximum number of uncles a block is allowed to declare.
-	fn maximum_uncle_count(&self) -> usize { 0 }
+	fn maximum_uncle_count(&self, _block: BlockNumber) -> usize { 0 }
+
 	/// The number of generations back that uncles can be.
 	fn maximum_uncle_age(&self) -> usize { 6 }
 
@@ -363,7 +364,7 @@ pub trait EthEngine: Engine<::machine::EthereumMachine> {
 	}
 
 	/// The nonce with which accounts begin at given block.
-	fn account_start_nonce(&self, block: u64) -> U256 {
+	fn account_start_nonce(&self, block: BlockNumber) -> U256 {
 		self.machine().account_start_nonce(block)
 	}
 

ethcore/src/engines/null_engine.rs

@@ -16,6 +16,7 @@
 
 use bigint::prelude::U256;
 use engines::Engine;
+use header::BlockNumber;
 use parity_machine::{Header, LiveBlock, WithBalances};
 
 /// Params for a null engine.
@@ -95,7 +96,7 @@ impl<M: WithBalances> Engine<M> for NullEngine<M> {
 		self.machine.note_rewards(block, &[(author, result_block_reward)], &uncle_rewards)
 	}
 
-	fn maximum_uncle_count(&self) -> usize { 2 }
+	fn maximum_uncle_count(&self, _block: BlockNumber) -> usize { 2 }
 
 	fn verify_local_seal(&self, _header: &M::Header) -> Result<(), M::Error> {
 		Ok(())

ethcore/src/engines/tendermint/mod.rs

@@ -450,7 +450,7 @@ impl Engine<EthereumMachine> for Tendermint {
 
 	fn machine(&self) -> &EthereumMachine { &self.machine }
 
-	fn maximum_uncle_count(&self) -> usize { 0 }
+	fn maximum_uncle_count(&self, _block: BlockNumber) -> usize { 0 }
 
 	fn maximum_uncle_age(&self) -> usize { 0 }
 

ethcore/src/ethereum/ethash.rs

@@ -26,7 +26,7 @@ use util::Address;
 use unexpected::{OutOfBounds, Mismatch};
 use block::*;
 use error::{BlockError, Error};
-use header::Header;
+use header::{Header, BlockNumber};
 use engines::{self, Engine};
 use ethjson;
 use rlp::{self, UntrustedRlp};
@@ -181,7 +181,7 @@ impl Engine<EthereumMachine> for Arc<Ethash> {
 		}
 	}
 
-	fn maximum_uncle_count(&self) -> usize { 2 }
+	fn maximum_uncle_count(&self, _block: BlockNumber) -> usize { 2 }
 
 	fn populate_from_parent(&self, header: &mut Header, parent: &Header) {
 		let difficulty = self.calculate_difficulty(header, parent);
@@ -520,7 +520,7 @@ mod tests {
 		let (eras, reward) = ecip1017_eras_block_reward(eras_rounds, start_reward, block_number);
 		assert_eq!(15, eras);
 		assert_eq!(U256::from_str("271000000000000").unwrap(), reward);
-		
+
 		let block_number = 250000000;
 		let (eras, reward) = ecip1017_eras_block_reward(eras_rounds, start_reward, block_number);
 		assert_eq!(49, eras);

ethcore/src/verification/verification.rs

@@ -137,9 +137,14 @@ pub fn verify_block_family(header: &Header, parent: &Header, engine: &EthEngine,
 
 fn verify_uncles(header: &Header, bytes: &[u8], bc: &BlockProvider, engine: &EthEngine) -> Result<(), Error> {
 	let num_uncles = UntrustedRlp::new(bytes).at(2)?.item_count()?;
+	let max_uncles = engine.maximum_uncle_count(header.number());
 	if num_uncles != 0 {
-		if num_uncles > engine.maximum_uncle_count() {
-			return Err(From::from(BlockError::TooManyUncles(OutOfBounds { min: None, max: Some(engine.maximum_uncle_count()), found: num_uncles })));
+		if num_uncles > max_uncles {
+			return Err(From::from(BlockError::TooManyUncles(OutOfBounds {
+				min: None,
+				max: Some(max_uncles),
+				found: num_uncles,
+			})));
 		}
 
 		let mut excluded = HashSet::new();
@@ -653,7 +658,7 @@ mod tests {
 		let mut bad_uncles = good_uncles.clone();
 		bad_uncles.push(good_uncle1.clone());
 		check_fail(family_test(&create_test_block_with_data(&header, &good_transactions, &bad_uncles), engine, &bc),
-			TooManyUncles(OutOfBounds { max: Some(engine.maximum_uncle_count()), min: None, found: bad_uncles.len() }));
+			TooManyUncles(OutOfBounds { max: Some(engine.maximum_uncle_count(header.number())), min: None, found: bad_uncles.len() }));
 
 		header = good.clone();
 		bad_uncles = vec![ good_uncle1.clone(), good_uncle1.clone() ];

json/src/spec/authority_round.rs

@@ -43,6 +43,10 @@ pub struct AuthorityRoundParams {
 	/// Reward per block in wei.
 	#[serde(rename="blockReward")]
 	pub block_reward: Option<Uint>,
+	/// Block at which maximum uncle count should be considered.
+	#[serde(rename="maximumUncleCountTransition")]
+	pub maximum_uncle_count_transition: Option<Uint>,
+	/// Maximum number of accepted uncles.
 	#[serde(rename="maximumUncleCount")]
 	pub maximum_uncle_count: Option<Uint>,
 }
@@ -73,7 +77,9 @@ mod tests {
 				},
 				"startStep" : 24,
 				"validateStepTransition": 150,
-				"blockReward": 5000000
+				"blockReward": 5000000,
+				"maximumUncleCountTransition": 10000000,
+				"maximumUncleCount": 5
 			}
 		}"#;
 
@@ -82,6 +88,8 @@ mod tests {
 		assert_eq!(deserialized.params.validators, ValidatorSet::List(vec![Address(H160::from("0xc6d9d2cd449a754c494264e1809c50e34d64562b"))]));
 		assert_eq!(deserialized.params.start_step, Some(Uint(U256::from(24))));
 		assert_eq!(deserialized.params.immediate_transitions, None);
+		assert_eq!(deserialized.params.maximum_uncle_count_transition, Some(Uint(10_000_000.into())));
+		assert_eq!(deserialized.params.maximum_uncle_count, Some(Uint(5.into())));
 
 	}
 }