openethereum/ethash/src/lib.rs

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// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.
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// Parity Ethereum is free software: you can redistribute it and/or modify
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// 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 Ethereum is distributed in the hope that it will be useful,
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// 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 Ethereum. If not, see <http://www.gnu.org/licenses/>.
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extern crate either;
extern crate ethereum_types;
extern crate memmap;
extern crate parking_lot;
extern crate primal;
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#[macro_use]
extern crate crunchy;
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#[macro_use]
extern crate log;
#[cfg(test)]
extern crate tempdir;
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mod compute;
mod seed_compute;
mod cache;
mod keccak;
mod shared;
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pub use cache::{NodeCacheBuilder, OptimizeFor};
pub use compute::{ProofOfWork, quick_get_difficulty, slow_hash_block_number};
use compute::Light;
use ethereum_types::{U256, U512};
use keccak::H256;
use parking_lot::Mutex;
pub use seed_compute::SeedHashCompute;
pub use shared::ETHASH_EPOCH_LENGTH;
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use std::mem;
use std::path::{Path, PathBuf};
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use std::sync::Arc;
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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 {
nodecache_builder: NodeCacheBuilder,
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cache: Mutex<LightCache>,
cache_dir: PathBuf,
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}
impl EthashManager {
/// Create a new new instance of ethash manager
pub fn new<T: Into<Option<OptimizeFor>>>(cache_dir: &Path, optimize_for: T) -> EthashManager {
EthashManager {
cache_dir: cache_dir.to_path_buf(),
nodecache_builder: NodeCacheBuilder::new(optimize_for.into().unwrap_or_default()),
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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 => {
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let light = match self.nodecache_builder.light_from_file(
&self.cache_dir,
block_number,
) {
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Ok(light) => Arc::new(light),
Err(e) => {
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debug!("Light cache file not found for {}:{}", block_number, e);
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let mut light = self.nodecache_builder.light(
&self.cache_dir,
block_number,
);
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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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/// Convert an Ethash boundary to its original difficulty. Basically just `f(x) = 2^256 / x`.
pub fn boundary_to_difficulty(boundary: &ethereum_types::H256) -> U256 {
difficulty_to_boundary_aux(&**boundary)
}
/// Convert an Ethash difficulty to the target boundary. Basically just `f(x) = 2^256 / x`.
pub fn difficulty_to_boundary(difficulty: &U256) -> ethereum_types::H256 {
difficulty_to_boundary_aux(difficulty).into()
}
fn difficulty_to_boundary_aux<T: Into<U512>>(difficulty: T) -> ethereum_types::U256 {
let difficulty = difficulty.into();
assert!(!difficulty.is_zero());
if difficulty == U512::one() {
U256::max_value()
} else {
// difficulty > 1, so result should never overflow 256 bits
U256::from((U512::one() << 256) / difficulty)
}
}
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#[test]
fn test_lru() {
use tempdir::TempDir;
let tempdir = TempDir::new("").unwrap();
let ethash = EthashManager::new(tempdir.path(), None);
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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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}
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#[test]
fn test_difficulty_to_boundary() {
use ethereum_types::H256;
use std::str::FromStr;
assert_eq!(difficulty_to_boundary(&U256::from(1)), H256::from(U256::max_value()));
assert_eq!(difficulty_to_boundary(&U256::from(2)), H256::from_str("8000000000000000000000000000000000000000000000000000000000000000").unwrap());
assert_eq!(difficulty_to_boundary(&U256::from(4)), H256::from_str("4000000000000000000000000000000000000000000000000000000000000000").unwrap());
assert_eq!(difficulty_to_boundary(&U256::from(32)), H256::from_str("0800000000000000000000000000000000000000000000000000000000000000").unwrap());
}
#[test]
fn test_difficulty_to_boundary_regression() {
use ethereum_types::H256;
// the last bit was originally being truncated when performing the conversion
// https://github.com/paritytech/parity-ethereum/issues/8397
for difficulty in 1..9 {
assert_eq!(U256::from(difficulty), boundary_to_difficulty(&difficulty_to_boundary(&difficulty.into())));
assert_eq!(H256::from(difficulty), difficulty_to_boundary(&boundary_to_difficulty(&difficulty.into())));
assert_eq!(U256::from(difficulty), boundary_to_difficulty(&boundary_to_difficulty(&difficulty.into()).into()));
assert_eq!(H256::from(difficulty), difficulty_to_boundary(&difficulty_to_boundary(&difficulty.into()).into()));
}
}
#[test]
#[should_panic]
fn test_difficulty_to_boundary_panics_on_zero() {
difficulty_to_boundary(&U256::from(0));
}
#[test]
#[should_panic]
fn test_boundary_to_difficulty_panics_on_zero() {
boundary_to_difficulty(&ethereum_types::H256::from(0));
}