111 lines
3.6 KiB
Rust
111 lines
3.6 KiB
Rust
// Copyright 2015-2020 Parity Technologies (UK) Ltd.
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// This file is part of OpenEthereum.
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// OpenEthereum 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
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// OpenEthereum is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with OpenEthereum. If not, see <http://www.gnu.org/licenses/>.
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use keccak::{keccak_256, H256};
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use shared;
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use std::cell::Cell;
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#[derive(Default)]
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pub struct SeedHashCompute {
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prev_epoch: Cell<u64>,
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prev_seedhash: Cell<H256>,
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}
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impl SeedHashCompute {
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#[inline]
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fn reset_cache(&self) {
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self.prev_epoch.set(0);
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self.prev_seedhash.set([0u8; 32]);
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}
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#[inline]
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pub fn hash_block_number(&self, block_number: u64) -> H256 {
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self.hash_epoch(shared::epoch(block_number))
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}
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#[inline]
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pub fn hash_epoch(&self, epoch: u64) -> H256 {
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if epoch < self.prev_epoch.get() {
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// can't build on previous hash if requesting an older block
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self.reset_cache();
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}
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if epoch > self.prev_epoch.get() {
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let seed_hash = SeedHashCompute::resume_compute_seedhash(
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self.prev_seedhash.get(),
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self.prev_epoch.get(),
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epoch,
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);
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self.prev_seedhash.set(seed_hash);
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self.prev_epoch.set(epoch);
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}
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self.prev_seedhash.get()
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}
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#[inline]
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pub fn resume_compute_seedhash(mut hash: H256, start_epoch: u64, end_epoch: u64) -> H256 {
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for _ in start_epoch..end_epoch {
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keccak_256::inplace(&mut hash);
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}
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hash
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}
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}
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#[cfg(test)]
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mod tests {
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use super::SeedHashCompute;
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#[test]
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fn test_seed_compute_once() {
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let seed_compute = SeedHashCompute::default();
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let hash = [
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241, 175, 44, 134, 39, 121, 245, 239, 228, 236, 43, 160, 195, 152, 46, 7, 199, 5, 253,
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147, 241, 206, 98, 43, 3, 104, 17, 40, 192, 79, 106, 162,
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];
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assert_eq!(seed_compute.hash_block_number(486382), hash);
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}
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#[test]
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fn test_seed_compute_zero() {
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let seed_compute = SeedHashCompute::default();
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assert_eq!(seed_compute.hash_block_number(0), [0u8; 32]);
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}
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#[test]
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fn test_seed_compute_after_older() {
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let seed_compute = SeedHashCompute::default();
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// calculating an older value first shouldn't affect the result
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let _ = seed_compute.hash_block_number(50000);
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let hash = [
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241, 175, 44, 134, 39, 121, 245, 239, 228, 236, 43, 160, 195, 152, 46, 7, 199, 5, 253,
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147, 241, 206, 98, 43, 3, 104, 17, 40, 192, 79, 106, 162,
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];
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assert_eq!(seed_compute.hash_block_number(486382), hash);
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}
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#[test]
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fn test_seed_compute_after_newer() {
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let seed_compute = SeedHashCompute::default();
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// calculating an newer value first shouldn't affect the result
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let _ = seed_compute.hash_block_number(972764);
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let hash = [
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241, 175, 44, 134, 39, 121, 245, 239, 228, 236, 43, 160, 195, 152, 46, 7, 199, 5, 253,
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147, 241, 206, 98, 43, 3, 104, 17, 40, 192, 79, 106, 162,
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];
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assert_eq!(seed_compute.hash_block_number(486382), hash);
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}
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}
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