aura: add transition for block reward contract

ethcore/src/engines/authority_round/mod.rs

@@ -70,6 +70,8 @@ pub struct AuthorityRoundParams {
 	pub immediate_transitions: bool,
 	/// Block reward in base units.
 	pub block_reward: U256,
+	/// Block reward contract transition block.
+	pub block_reward_contract_transition: u64,
 	/// Block reward contract.
 	pub block_reward_contract: Option<BlockRewardContract>,
 	/// Number of accepted uncles transition block.
@@ -99,6 +101,7 @@ 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),
+			block_reward_contract_transition: p.block_reward_contract_transition.map_or(0, Into::into),
 			block_reward_contract: p.block_reward_contract_address.map(BlockRewardContract::new),
 			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),
@@ -1011,7 +1014,7 @@ impl Engine<EthereumMachine> for AuthorityRound {
 		benefactors.push((author, RewardKind::Author));
 
 		let rewards = match self.block_reward_contract {
-			Some(ref c) => {
+			Some(ref c) if block.header().number() >= self.block_reward_contract_transition => {
 				let mut call = |to, data| {
 					let result = self.machine.execute_as_system(
 						block,
@@ -1542,6 +1545,7 @@ mod tests {
 			empty_steps_transition: u64::max_value(),
 			maximum_empty_steps: 0,
 			block_reward: Default::default(),
+			block_reward_contract_transition: 0,
 			block_reward_contract: Default::default(),
 		};
 
@@ -1585,6 +1589,7 @@ mod tests {
 			empty_steps_transition: u64::max_value(),
 			maximum_empty_steps: 0,
 			block_reward: Default::default(),
+			block_reward_contract_transition: 0,
 			block_reward_contract: Default::default(),
 		};
 
@@ -1640,6 +1645,7 @@ mod tests {
 			empty_steps_transition: u64::max_value(),
 			maximum_empty_steps: 0,
 			block_reward: Default::default(),
+			block_reward_contract_transition: 0,
 			block_reward_contract: Default::default(),
 		};
 

json/src/spec/authority_round.rs

@@ -44,6 +44,9 @@ pub struct AuthorityRoundParams {
 	/// Reward per block in wei.
 	#[serde(rename="blockReward")]
 	pub block_reward: Option<Uint>,
+	/// Block at which the block reward contract should start being used.
+	#[serde(rename="blockRewardContractTransition")]
+	pub block_reward_contract_transition: Option<Uint>,
 	/// Block reward contract address (setting the block reward contract
 	/// overrides the static block reward definition).
 	#[serde(rename="blockRewardContractAddress")]