openethereum/ethcore/src/state/backend.rs
Hawstein ade37be25b separate trie from util and make its dependencies into libs:
* bytes
* hashdb
* memorydb
* nibbleslice
* nibblevec
2017-09-15 11:03:53 +08:00

257 lines
7.6 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/>.
//! A minimal "state backend" trait: an abstraction over the sources of data
//! a blockchain state may draw upon.
//!
//! Currently assumes a very specific DB + cache structure, but
//! should become general over time to the point where not even a
//! merkle trie is strictly necessary.
use std::collections::{HashSet, HashMap};
use std::sync::Arc;
use state::Account;
use bigint::hash::H256;
use parking_lot::Mutex;
use util::{Address, MemoryDB};
use hashdb::{AsHashDB, HashDB, DBValue};
/// State backend. See module docs for more details.
pub trait Backend: Send {
/// Treat the backend as a read-only hashdb.
fn as_hashdb(&self) -> &HashDB;
/// Treat the backend as a writeable hashdb.
fn as_hashdb_mut(&mut self) -> &mut HashDB;
/// Add an account entry to the cache.
fn add_to_account_cache(&mut self, addr: Address, data: Option<Account>, modified: bool);
/// Add a global code cache entry. This doesn't need to worry about canonicality because
/// it simply maps hashes to raw code and will always be correct in the absence of
/// hash collisions.
fn cache_code(&self, hash: H256, code: Arc<Vec<u8>>);
/// Get basic copy of the cached account. Not required to include storage.
/// Returns 'None' if cache is disabled or if the account is not cached.
fn get_cached_account(&self, addr: &Address) -> Option<Option<Account>>;
/// Get value from a cached account.
/// `None` is passed to the closure if the account entry cached
/// is known not to exist.
/// `None` is returned if the entry is not cached.
fn get_cached<F, U>(&self, a: &Address, f: F) -> Option<U>
where F: FnOnce(Option<&mut Account>) -> U;
/// Get cached code based on hash.
fn get_cached_code(&self, hash: &H256) -> Option<Arc<Vec<u8>>>;
/// Note that an account with the given address is non-null.
fn note_non_null_account(&self, address: &Address);
/// Check whether an account is known to be empty. Returns true if known to be
/// empty, false otherwise.
fn is_known_null(&self, address: &Address) -> bool;
}
/// A raw backend used to check proofs of execution.
///
/// This doesn't delete anything since execution proofs won't have mangled keys
/// and we want to avoid collisions.
// TODO: when account lookup moved into backends, this won't rely as tenuously on intended
// usage.
#[derive(Clone, PartialEq)]
pub struct ProofCheck(MemoryDB);
impl ProofCheck {
/// Create a new `ProofCheck` backend from the given state items.
pub fn new(proof: &[DBValue]) -> Self {
let mut db = MemoryDB::new();
for item in proof { db.insert(item); }
ProofCheck(db)
}
}
impl HashDB for ProofCheck {
fn keys(&self) -> HashMap<H256, i32> { self.0.keys() }
fn get(&self, key: &H256) -> Option<DBValue> {
self.0.get(key)
}
fn contains(&self, key: &H256) -> bool {
self.0.contains(key)
}
fn insert(&mut self, value: &[u8]) -> H256 {
self.0.insert(value)
}
fn emplace(&mut self, key: H256, value: DBValue) {
self.0.emplace(key, value)
}
fn remove(&mut self, _key: &H256) { }
}
impl Backend for ProofCheck {
fn as_hashdb(&self) -> &HashDB { self }
fn as_hashdb_mut(&mut self) -> &mut HashDB { self }
fn add_to_account_cache(&mut self, _addr: Address, _data: Option<Account>, _modified: bool) {}
fn cache_code(&self, _hash: H256, _code: Arc<Vec<u8>>) {}
fn get_cached_account(&self, _addr: &Address) -> Option<Option<Account>> { None }
fn get_cached<F, U>(&self, _a: &Address, _f: F) -> Option<U>
where F: FnOnce(Option<&mut Account>) -> U
{
None
}
fn get_cached_code(&self, _hash: &H256) -> Option<Arc<Vec<u8>>> { None }
fn note_non_null_account(&self, _address: &Address) {}
fn is_known_null(&self, _address: &Address) -> bool { false }
}
/// Proving state backend.
/// This keeps track of all state values loaded during usage of this backend.
/// The proof-of-execution can be extracted with `extract_proof`.
///
/// This doesn't cache anything or rely on the canonical state caches.
pub struct Proving<H: AsHashDB> {
base: H, // state we're proving values from.
changed: MemoryDB, // changed state via insertions.
proof: Mutex<HashSet<DBValue>>,
}
impl<H: AsHashDB + Send + Sync> HashDB for Proving<H> {
fn keys(&self) -> HashMap<H256, i32> {
let mut keys = self.base.as_hashdb().keys();
keys.extend(self.changed.keys());
keys
}
fn get(&self, key: &H256) -> Option<DBValue> {
match self.base.as_hashdb().get(key) {
Some(val) => {
self.proof.lock().insert(val.clone());
Some(val)
}
None => self.changed.get(key)
}
}
fn contains(&self, key: &H256) -> bool {
self.get(key).is_some()
}
fn insert(&mut self, value: &[u8]) -> H256 {
self.changed.insert(value)
}
fn emplace(&mut self, key: H256, value: DBValue) {
self.changed.emplace(key, value)
}
fn remove(&mut self, key: &H256) {
// only remove from `changed`
if self.changed.contains(key) {
self.changed.remove(key)
}
}
}
impl<H: AsHashDB + Send + Sync> Backend for Proving<H> {
fn as_hashdb(&self) -> &HashDB {
self
}
fn as_hashdb_mut(&mut self) -> &mut HashDB {
self
}
fn add_to_account_cache(&mut self, _: Address, _: Option<Account>, _: bool) { }
fn cache_code(&self, _: H256, _: Arc<Vec<u8>>) { }
fn get_cached_account(&self, _: &Address) -> Option<Option<Account>> { None }
fn get_cached<F, U>(&self, _: &Address, _: F) -> Option<U>
where F: FnOnce(Option<&mut Account>) -> U
{
None
}
fn get_cached_code(&self, _: &H256) -> Option<Arc<Vec<u8>>> { None }
fn note_non_null_account(&self, _: &Address) { }
fn is_known_null(&self, _: &Address) -> bool { false }
}
impl<H: AsHashDB> Proving<H> {
/// Create a new `Proving` over a base database.
/// This will store all values ever fetched from that base.
pub fn new(base: H) -> Self {
Proving {
base: base,
changed: MemoryDB::new(),
proof: Mutex::new(HashSet::new()),
}
}
/// Consume the backend, extracting the gathered proof in lexicographical order
/// by value.
pub fn extract_proof(self) -> Vec<DBValue> {
self.proof.into_inner().into_iter().collect()
}
}
impl<H: AsHashDB + Clone> Clone for Proving<H> {
fn clone(&self) -> Self {
Proving {
base: self.base.clone(),
changed: self.changed.clone(),
proof: Mutex::new(self.proof.lock().clone()),
}
}
}
/// A basic backend. Just wraps the given database, directly inserting into and deleting from
/// it. Doesn't cache anything.
pub struct Basic<H>(pub H);
impl<H: AsHashDB + Send + Sync> Backend for Basic<H> {
fn as_hashdb(&self) -> &HashDB {
self.0.as_hashdb()
}
fn as_hashdb_mut(&mut self) -> &mut HashDB {
self.0.as_hashdb_mut()
}
fn add_to_account_cache(&mut self, _: Address, _: Option<Account>, _: bool) { }
fn cache_code(&self, _: H256, _: Arc<Vec<u8>>) { }
fn get_cached_account(&self, _: &Address) -> Option<Option<Account>> { None }
fn get_cached<F, U>(&self, _: &Address, _: F) -> Option<U>
where F: FnOnce(Option<&mut Account>) -> U
{
None
}
fn get_cached_code(&self, _: &H256) -> Option<Arc<Vec<u8>>> { None }
fn note_non_null_account(&self, _: &Address) { }
fn is_known_null(&self, _: &Address) -> bool { false }
}