      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127

    // Copyright 2015-2017 Parity Technologies (UK) Ltd.
    // 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/>.

    //! Ethash implementation
    //! See https://github.com/ethereum/wiki/wiki/Ethash
    extern crate primal;
    extern crate sha3;
    extern crate parking_lot;

    #[macro_use]
    extern crate log;
    mod compute;

    use std::mem;
    use compute::Light;
    pub use compute::{ETHASH_EPOCH_LENGTH, H256, ProofOfWork, SeedHashCompute, quick_get_difficulty, slow_get_seedhash};

    use std::sync::Arc;
    use parking_lot::Mutex;

    struct LightCache {
    	recent_epoch: Option<u64>,
    	recent: Option<Arc<Light>>,
    	prev_epoch: Option<u64>,
    	prev: Option<Arc<Light>>,
    }

    /// Light/Full cache manager.
    pub struct EthashManager {
    	cache: Mutex<LightCache>,
    }

    impl EthashManager {
    	/// Create a new new instance of ethash manager
    	pub fn new() -> EthashManager {
    		EthashManager {
    			cache: Mutex::new(LightCache {
    				recent_epoch: None,
    				recent: None,
    				prev_epoch: None,
    				prev: None,
    			}),
    		}
    	}

    	/// 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;
    		let light = {
    			let mut lights = self.cache.lock();
    			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()
    						}
    					}
    					_ => None,
    				},
    			};
    			match light {
    				None => {
    					let light = match Light::from_file(block_number) {
    						Ok(light) => Arc::new(light),
    						Err(e) => {
    							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)
    						}
    					};
    					lights.prev_epoch = mem::replace(&mut lights.recent_epoch, Some(epoch));
    					lights.prev = mem::replace(&mut lights.recent, Some(light.clone()));
    					light
    				}
    				Some(light) => light,
    			}
    		};
    		light.compute(header_hash, nonce)
    	}
    }

    #[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);
    	ethash.compute_light(1, &hash, 1);
    	assert_eq!(ethash.cache.lock().recent_epoch.unwrap(), 0);
    	assert_eq!(ethash.cache.lock().prev_epoch.unwrap(), 1);
    	ethash.compute_light(70000, &hash, 1);
    	assert_eq!(ethash.cache.lock().recent_epoch.unwrap(), 2);
    	assert_eq!(ethash.cache.lock().prev_epoch.unwrap(), 0);
    }

# Help

## Keyboard Shortcuts

?
  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
⇥
  Move down in search results
⏎
  Go to active search result
+
  Collapse/expand all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)