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// 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/>. //! Database of byte-slices keyed to their Keccak hash. extern crate elastic_array; extern crate ethcore_bigint as bigint; use bigint::hash::*; use std::collections::HashMap; use elastic_array::ElasticArray128; /// `HashDB` value type. pub type DBValue = ElasticArray128<u8>; /// Trait modelling datastore keyed by a 32-byte Keccak hash. pub trait HashDB: AsHashDB + Send + Sync { /// Get the keys in the database together with number of underlying references. fn keys(&self) -> HashMap<H256, i32>; /// Look up a given hash into the bytes that hash to it, returning None if the /// hash is not known. fn get(&self, key: &H256) -> Option<DBValue>; /// Check for the existance of a hash-key. fn contains(&self, key: &H256) -> bool; /// Insert a datum item into the DB and return the datum's hash for a later lookup. Insertions /// are counted and the equivalent number of `remove()`s must be performed before the data /// is considered dead. fn insert(&mut self, value: &[u8]) -> H256; /// Like `insert()` , except you provide the key and the data is all moved. fn emplace(&mut self, key: H256, value: DBValue); /// Remove a datum previously inserted. Insertions can be "owed" such that the same number of `insert()`s may /// happen without the data being eventually being inserted into the DB. It can be "owed" more than once. fn remove(&mut self, key: &H256); } /// Upcast trait. pub trait AsHashDB { /// Perform upcast to HashDB for anything that derives from HashDB. fn as_hashdb(&self) -> &HashDB; /// Perform mutable upcast to HashDB for anything that derives from HashDB. fn as_hashdb_mut(&mut self) -> &mut HashDB; } impl<T: HashDB> AsHashDB for T { fn as_hashdb(&self) -> &HashDB { self } fn as_hashdb_mut(&mut self) -> &mut HashDB { self } } impl<'a> AsHashDB for &'a mut HashDB { fn as_hashdb(&self) -> &HashDB { &**self } fn as_hashdb_mut(&mut self) -> &mut HashDB { &mut **self } }