openethereum/ethash/src/lib.rs

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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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//! Ethash implementation
//! See https://github.com/ethereum/wiki/wiki/Ethash
extern crate primal;
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extern crate sha3;
extern crate parking_lot;
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#[macro_use]
extern crate log;
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mod compute;
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use std::mem;
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use compute::Light;
pub use compute::{ETHASH_EPOCH_LENGTH, H256, ProofOfWork, SeedHashCompute, quick_get_difficulty, slow_get_seedhash};
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use std::sync::Arc;
use parking_lot::Mutex;
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struct LightCache {
recent_epoch: Option<u64>,
recent: Option<Arc<Light>>,
prev_epoch: Option<u64>,
prev: Option<Arc<Light>>,
}
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/// Light/Full cache manager.
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pub struct EthashManager {
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cache: Mutex<LightCache>,
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}
impl EthashManager {
/// Create a new new instance of ethash manager
pub fn new() -> EthashManager {
EthashManager {
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cache: Mutex::new(LightCache {
recent_epoch: None,
recent: None,
prev_epoch: None,
prev: None,
}),
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}
}
/// Calculate the light client data
/// `block_number` - Block number to check
/// `light` - The light client handler
/// `header_hash` - The header hash to pack into the mix
/// `nonce` - The nonce to pack into the mix
pub fn compute_light(&self, block_number: u64, header_hash: &H256, nonce: u64) -> ProofOfWork {
let epoch = block_number / ETHASH_EPOCH_LENGTH;
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let light = {
let mut lights = self.cache.lock();
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let light = match lights.recent_epoch.clone() {
Some(ref e) if *e == epoch => lights.recent.clone(),
_ => match lights.prev_epoch.clone() {
Some(e) if e == epoch => {
// don't swap if recent is newer.
if lights.recent_epoch > lights.prev_epoch {
None
} else {
// swap
let t = lights.prev_epoch;
lights.prev_epoch = lights.recent_epoch;
lights.recent_epoch = t;
let t = lights.prev.clone();
lights.prev = lights.recent.clone();
lights.recent = t;
lights.recent.clone()
}
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}
_ => None,
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},
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};
match light {
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None => {
let light = match Light::from_file(block_number) {
Ok(light) => Arc::new(light),
Err(e) => {
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debug!("Light cache file not found for {}:{}", block_number, e);
let light = Light::new(block_number);
if let Err(e) = light.to_file() {
warn!("Light cache file write error: {}", e);
}
Arc::new(light)
}
};
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lights.prev_epoch = mem::replace(&mut lights.recent_epoch, Some(epoch));
lights.prev = mem::replace(&mut lights.recent, Some(light.clone()));
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light
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}
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Some(light) => light,
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}
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};
light.compute(header_hash, nonce)
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}
}
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#[test]
fn test_lru() {
let ethash = EthashManager::new();
let hash = [0u8; 32];
ethash.compute_light(1, &hash, 1);
ethash.compute_light(50000, &hash, 1);
assert_eq!(ethash.cache.lock().recent_epoch.unwrap(), 1);
assert_eq!(ethash.cache.lock().prev_epoch.unwrap(), 0);
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ethash.compute_light(1, &hash, 1);
assert_eq!(ethash.cache.lock().recent_epoch.unwrap(), 0);
assert_eq!(ethash.cache.lock().prev_epoch.unwrap(), 1);
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ethash.compute_light(70000, &hash, 1);
assert_eq!(ethash.cache.lock().recent_epoch.unwrap(), 2);
assert_eq!(ethash.cache.lock().prev_epoch.unwrap(), 0);
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}