ade37be25b
* bytes * hashdb * memorydb * nibbleslice * nibblevec
257 lines
7.6 KiB
Rust
257 lines
7.6 KiB
Rust
// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity 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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// Parity 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 Parity. If not, see <http://www.gnu.org/licenses/>.
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//! A minimal "state backend" trait: an abstraction over the sources of data
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//! a blockchain state may draw upon.
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//!
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//! Currently assumes a very specific DB + cache structure, but
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//! should become general over time to the point where not even a
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//! merkle trie is strictly necessary.
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use std::collections::{HashSet, HashMap};
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use std::sync::Arc;
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use state::Account;
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use bigint::hash::H256;
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use parking_lot::Mutex;
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use util::{Address, MemoryDB};
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use hashdb::{AsHashDB, HashDB, DBValue};
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/// State backend. See module docs for more details.
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pub trait Backend: Send {
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/// Treat the backend as a read-only hashdb.
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fn as_hashdb(&self) -> &HashDB;
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/// Treat the backend as a writeable hashdb.
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fn as_hashdb_mut(&mut self) -> &mut HashDB;
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/// Add an account entry to the cache.
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fn add_to_account_cache(&mut self, addr: Address, data: Option<Account>, modified: bool);
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/// Add a global code cache entry. This doesn't need to worry about canonicality because
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/// it simply maps hashes to raw code and will always be correct in the absence of
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/// hash collisions.
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fn cache_code(&self, hash: H256, code: Arc<Vec<u8>>);
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/// Get basic copy of the cached account. Not required to include storage.
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/// Returns 'None' if cache is disabled or if the account is not cached.
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fn get_cached_account(&self, addr: &Address) -> Option<Option<Account>>;
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/// Get value from a cached account.
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/// `None` is passed to the closure if the account entry cached
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/// is known not to exist.
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/// `None` is returned if the entry is not cached.
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fn get_cached<F, U>(&self, a: &Address, f: F) -> Option<U>
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where F: FnOnce(Option<&mut Account>) -> U;
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/// Get cached code based on hash.
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fn get_cached_code(&self, hash: &H256) -> Option<Arc<Vec<u8>>>;
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/// Note that an account with the given address is non-null.
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fn note_non_null_account(&self, address: &Address);
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/// Check whether an account is known to be empty. Returns true if known to be
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/// empty, false otherwise.
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fn is_known_null(&self, address: &Address) -> bool;
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}
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/// A raw backend used to check proofs of execution.
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///
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/// This doesn't delete anything since execution proofs won't have mangled keys
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/// and we want to avoid collisions.
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// TODO: when account lookup moved into backends, this won't rely as tenuously on intended
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// usage.
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#[derive(Clone, PartialEq)]
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pub struct ProofCheck(MemoryDB);
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impl ProofCheck {
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/// Create a new `ProofCheck` backend from the given state items.
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pub fn new(proof: &[DBValue]) -> Self {
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let mut db = MemoryDB::new();
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for item in proof { db.insert(item); }
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ProofCheck(db)
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}
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}
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impl HashDB for ProofCheck {
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fn keys(&self) -> HashMap<H256, i32> { self.0.keys() }
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fn get(&self, key: &H256) -> Option<DBValue> {
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self.0.get(key)
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}
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fn contains(&self, key: &H256) -> bool {
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self.0.contains(key)
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}
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fn insert(&mut self, value: &[u8]) -> H256 {
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self.0.insert(value)
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}
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fn emplace(&mut self, key: H256, value: DBValue) {
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self.0.emplace(key, value)
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}
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fn remove(&mut self, _key: &H256) { }
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}
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impl Backend for ProofCheck {
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fn as_hashdb(&self) -> &HashDB { self }
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fn as_hashdb_mut(&mut self) -> &mut HashDB { self }
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fn add_to_account_cache(&mut self, _addr: Address, _data: Option<Account>, _modified: bool) {}
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fn cache_code(&self, _hash: H256, _code: Arc<Vec<u8>>) {}
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fn get_cached_account(&self, _addr: &Address) -> Option<Option<Account>> { None }
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fn get_cached<F, U>(&self, _a: &Address, _f: F) -> Option<U>
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where F: FnOnce(Option<&mut Account>) -> U
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{
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None
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}
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fn get_cached_code(&self, _hash: &H256) -> Option<Arc<Vec<u8>>> { None }
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fn note_non_null_account(&self, _address: &Address) {}
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fn is_known_null(&self, _address: &Address) -> bool { false }
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}
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/// Proving state backend.
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/// This keeps track of all state values loaded during usage of this backend.
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/// The proof-of-execution can be extracted with `extract_proof`.
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///
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/// This doesn't cache anything or rely on the canonical state caches.
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pub struct Proving<H: AsHashDB> {
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base: H, // state we're proving values from.
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changed: MemoryDB, // changed state via insertions.
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proof: Mutex<HashSet<DBValue>>,
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}
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impl<H: AsHashDB + Send + Sync> HashDB for Proving<H> {
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fn keys(&self) -> HashMap<H256, i32> {
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let mut keys = self.base.as_hashdb().keys();
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keys.extend(self.changed.keys());
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keys
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}
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fn get(&self, key: &H256) -> Option<DBValue> {
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match self.base.as_hashdb().get(key) {
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Some(val) => {
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self.proof.lock().insert(val.clone());
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Some(val)
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}
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None => self.changed.get(key)
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}
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}
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fn contains(&self, key: &H256) -> bool {
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self.get(key).is_some()
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}
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fn insert(&mut self, value: &[u8]) -> H256 {
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self.changed.insert(value)
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}
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fn emplace(&mut self, key: H256, value: DBValue) {
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self.changed.emplace(key, value)
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}
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fn remove(&mut self, key: &H256) {
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// only remove from `changed`
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if self.changed.contains(key) {
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self.changed.remove(key)
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}
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}
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}
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impl<H: AsHashDB + Send + Sync> Backend for Proving<H> {
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fn as_hashdb(&self) -> &HashDB {
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self
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}
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fn as_hashdb_mut(&mut self) -> &mut HashDB {
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self
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}
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fn add_to_account_cache(&mut self, _: Address, _: Option<Account>, _: bool) { }
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fn cache_code(&self, _: H256, _: Arc<Vec<u8>>) { }
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fn get_cached_account(&self, _: &Address) -> Option<Option<Account>> { None }
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fn get_cached<F, U>(&self, _: &Address, _: F) -> Option<U>
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where F: FnOnce(Option<&mut Account>) -> U
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{
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None
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}
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fn get_cached_code(&self, _: &H256) -> Option<Arc<Vec<u8>>> { None }
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fn note_non_null_account(&self, _: &Address) { }
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fn is_known_null(&self, _: &Address) -> bool { false }
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}
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impl<H: AsHashDB> Proving<H> {
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/// Create a new `Proving` over a base database.
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/// This will store all values ever fetched from that base.
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pub fn new(base: H) -> Self {
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Proving {
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base: base,
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changed: MemoryDB::new(),
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proof: Mutex::new(HashSet::new()),
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}
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}
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/// Consume the backend, extracting the gathered proof in lexicographical order
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/// by value.
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pub fn extract_proof(self) -> Vec<DBValue> {
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self.proof.into_inner().into_iter().collect()
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}
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}
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impl<H: AsHashDB + Clone> Clone for Proving<H> {
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fn clone(&self) -> Self {
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Proving {
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base: self.base.clone(),
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changed: self.changed.clone(),
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proof: Mutex::new(self.proof.lock().clone()),
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}
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}
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}
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/// A basic backend. Just wraps the given database, directly inserting into and deleting from
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/// it. Doesn't cache anything.
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pub struct Basic<H>(pub H);
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impl<H: AsHashDB + Send + Sync> Backend for Basic<H> {
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fn as_hashdb(&self) -> &HashDB {
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self.0.as_hashdb()
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}
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fn as_hashdb_mut(&mut self) -> &mut HashDB {
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self.0.as_hashdb_mut()
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}
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fn add_to_account_cache(&mut self, _: Address, _: Option<Account>, _: bool) { }
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fn cache_code(&self, _: H256, _: Arc<Vec<u8>>) { }
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fn get_cached_account(&self, _: &Address) -> Option<Option<Account>> { None }
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fn get_cached<F, U>(&self, _: &Address, _: F) -> Option<U>
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where F: FnOnce(Option<&mut Account>) -> U
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{
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None
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}
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fn get_cached_code(&self, _: &H256) -> Option<Arc<Vec<u8>>> { None }
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fn note_non_null_account(&self, _: &Address) { }
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fn is_known_null(&self, _: &Address) -> bool { false }
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}
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