openethereum/ethcore/evm/src/interpreter/shared_cache.rs

107 lines
2.9 KiB
Rust

// 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/>.
use std::sync::Arc;
use hash::KECCAK_EMPTY;
use heapsize::HeapSizeOf;
use bigint::hash::H256;
use parking_lot::Mutex;
use memory_cache::MemoryLruCache;
use bit_set::BitSet;
use super::super::instructions;
const DEFAULT_CACHE_SIZE: usize = 4 * 1024 * 1024;
// stub for a HeapSizeOf implementation.
struct Bits(Arc<BitSet>);
impl HeapSizeOf for Bits {
fn heap_size_of_children(&self) -> usize {
// dealing in bits here
self.0.capacity() * 8
}
}
/// Global cache for EVM interpreter
pub struct SharedCache {
jump_destinations: Mutex<MemoryLruCache<H256, Bits>>,
}
impl SharedCache {
/// Create a jump destinations cache with a maximum size in bytes
/// to cache.
pub fn new(max_size: usize) -> Self {
SharedCache {
jump_destinations: Mutex::new(MemoryLruCache::new(max_size)),
}
}
/// Get jump destinations bitmap for a contract.
pub fn jump_destinations(&self, code_hash: &H256, code: &[u8]) -> Arc<BitSet> {
if code_hash == &KECCAK_EMPTY {
return Self::find_jump_destinations(code);
}
if let Some(d) = self.jump_destinations.lock().get_mut(code_hash) {
return d.0.clone();
}
let d = Self::find_jump_destinations(code);
self.jump_destinations.lock().insert(code_hash.clone(), Bits(d.clone()));
d
}
fn find_jump_destinations(code: &[u8]) -> Arc<BitSet> {
let mut jump_dests = BitSet::with_capacity(code.len());
let mut position = 0;
while position < code.len() {
let instruction = code[position];
if instruction == instructions::JUMPDEST {
jump_dests.insert(position);
} else if instructions::is_push(instruction) {
position += instructions::get_push_bytes(instruction);
}
position += 1;
}
jump_dests.shrink_to_fit();
Arc::new(jump_dests)
}
}
impl Default for SharedCache {
fn default() -> Self {
SharedCache::new(DEFAULT_CACHE_SIZE)
}
}
#[test]
fn test_find_jump_destinations() {
use rustc_hex::FromHex;
// given
let code = "7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff5b01600055".from_hex().unwrap();
// when
let valid_jump_destinations = SharedCache::find_jump_destinations(&code);
// then
assert!(valid_jump_destinations.contains(66));
}