openethereum/src/ethereum/ethash.rs

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use common::*;
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use block::*;
use spec::*;
use engine::*;
use evm::Schedule;
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/// Engine using Ethash proof-of-work consensus algorithm, suitable for Ethereum
/// mainnet chains in the Olympic, Frontier and Homestead eras.
pub struct Ethash {
spec: Spec,
}
impl Ethash {
pub fn new_boxed(spec: Spec) -> Box<Engine> {
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Box::new(Ethash{spec: spec})
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}
}
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impl Engine for Ethash {
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fn name(&self) -> &str { "Ethash" }
fn version(&self) -> SemanticVersion { SemanticVersion::new(1, 0, 0) }
// Two fields - mix
fn seal_fields(&self) -> usize { 2 }
// Two empty data items in RLP.
fn seal_rlp(&self) -> Bytes { encode(&H64::new()) }
/// Additional engine-specific information for the user/developer concerning `header`.
fn extra_info(&self, _header: &Header) -> HashMap<String, String> { HashMap::new() }
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fn spec(&self) -> &Spec { &self.spec }
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fn schedule(&self, _env_info: &EnvInfo) -> Schedule { Schedule::new_frontier() }
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/// 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).
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fn on_close_block(&self, block: &mut Block) {
let reward = self.spec().engine_params.get("blockReward").map(|a| decode(&a)).unwrap_or(U256::from(0u64));
let fields = block.fields();
// Bestow block reward
fields.state.add_balance(&fields.header.author, &(reward + reward / U256::from(32) * U256::from(fields.uncles.len())));
// Bestow uncle rewards
let current_number = fields.header.number();
for u in fields.uncles.iter() {
fields.state.add_balance(u.author(), &(reward * U256::from((8 + u.number() - current_number) / 8)));
}
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}
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fn verify_block_basic(&self, header: &Header, _block: Option<&[u8]>) -> result::Result<(), Error> {
let min_difficulty = decode(self.spec().engine_params.get("minimumDifficulty").unwrap());
if header.difficulty < min_difficulty {
return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: min_difficulty, found: header.difficulty })))
}
// TODO: Verify seal (quick)
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Ok(())
}
fn verify_block_unordered(&self, _header: &Header, _block: Option<&[u8]>) -> result::Result<(), Error> {
// TODO: Verify seal (full)
Ok(())
}
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fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> result::Result<(), Error> {
// Check difficulty is correct given the two timestamps.
let expected_difficulty = self.calculate_difficuty(header, parent);
if header.difficulty != expected_difficulty {
return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: expected_difficulty, found: header.difficulty })))
}
let gas_limit_divisor = decode(self.spec().engine_params.get("gasLimitBoundDivisor").unwrap());
let min_gas = parent.gas_limit - parent.gas_limit / gas_limit_divisor;
let max_gas = parent.gas_limit + parent.gas_limit / gas_limit_divisor;
if header.gas_limit <= min_gas || header.gas_limit >= max_gas {
return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: Some(min_gas), max: Some(max_gas), found: header.gas_limit })));
}
Ok(())
}
fn verify_transaction(&self, _t: &Transaction, _header: &Header) -> result::Result<(), Error> { Ok(()) }
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}
impl Ethash {
fn calculate_difficuty(&self, header: &Header, parent: &Header) -> U256 {
const EXP_DIFF_PERIOD: u64 = 100000;
if header.number == 0 {
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panic!("Can't calculate genesis block difficulty");
}
let min_difficulty = decode(self.spec().engine_params.get("minimumDifficulty").unwrap());
let difficulty_bound_divisor = decode(self.spec().engine_params.get("difficultyBoundDivisor").unwrap());
let duration_limit: u64 = decode(self.spec().engine_params.get("durationLimit").unwrap());
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let frontier_limit = decode(self.spec().engine_params.get("frontierCompatibilityModeLimit").unwrap());
let mut target = if header.number < frontier_limit {
if header.timestamp >= parent.timestamp + duration_limit {
parent.difficulty - (parent.difficulty / difficulty_bound_divisor)
}
else {
parent.difficulty + (parent.difficulty / difficulty_bound_divisor)
}
}
else {
let diff_inc = (header.timestamp - parent.timestamp) / 10;
if diff_inc <= 1 {
parent.difficulty + parent.difficulty / From::from(2048) * From::from(1 - diff_inc)
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}
else {
parent.difficulty - parent.difficulty / From::from(2048) * From::from(max(diff_inc - 1, 99))
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}
};
target = max(min_difficulty, target);
let period = ((parent.number + 1) / EXP_DIFF_PERIOD) as usize;
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if period > 1 {
target = max(min_difficulty, target + (U256::from(1) << (period - 2)));
}
target
}
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}
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#[test]
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fn on_close_block() {
use super::*;
let engine = new_morden().to_engine().unwrap();
let genesis_header = engine.spec().genesis_header();
let mut db = OverlayDB::new_temp();
engine.spec().ensure_db_good(&mut db);
let last_hashes = vec![genesis_header.hash()];
let b = OpenBlock::new(engine.deref(), db, &genesis_header, &last_hashes, Address::zero(), vec![]);
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let b = b.close();
assert_eq!(b.state().balance(&Address::zero()), U256::from_str("4563918244f40000").unwrap());
}
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// TODO: difficulty test