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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. use 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. /// /// # Examples /// ```rust /// extern crate ethcore_util; /// use ethcore_util::hashdb::*; /// use ethcore_util::memorydb::*; /// fn main() { /// let mut m = MemoryDB::new(); /// let hello_bytes = "Hello world!".as_bytes(); /// let hash = m.insert(hello_bytes); /// assert_eq!(m.get(&hash).unwrap(), hello_bytes); /// } /// ``` fn get(&self, key: &H256) -> Option<DBValue>; /// Check for the existance of a hash-key. /// /// # Examples /// ```rust /// extern crate ethcore_util; /// use ethcore_util::hashdb::*; /// use ethcore_util::memorydb::*; /// use ethcore_util::sha3::*; /// fn main() { /// let mut m = MemoryDB::new(); /// let hello_bytes = "Hello world!".as_bytes(); /// assert!(!m.contains(&hello_bytes.sha3())); /// let key = m.insert(hello_bytes); /// assert!(m.contains(&key)); /// m.remove(&key); /// assert!(!m.contains(&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. /// /// # Examples /// ```rust /// extern crate ethcore_util; /// use ethcore_util::hashdb::*; /// use ethcore_util::memorydb::*; /// use ethcore_util::hash::*; /// fn main() { /// let mut m = MemoryDB::new(); /// let key = m.insert("Hello world!".as_bytes()); /// assert!(m.contains(&key)); /// } /// ``` 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. /// /// # Examples /// ```rust /// extern crate ethcore_util; /// use ethcore_util::hashdb::*; /// use ethcore_util::memorydb::*; /// use ethcore_util::sha3::*; /// fn main() { /// let mut m = MemoryDB::new(); /// let d = "Hello world!".as_bytes(); /// let key = &d.sha3(); /// m.remove(key); // OK - we now owe an insertion. /// assert!(!m.contains(key)); /// m.insert(d); // OK - now it's "empty" again. /// assert!(!m.contains(key)); /// m.insert(d); // OK - now we've /// assert_eq!(m.get(key).unwrap(), d); /// } /// ``` 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 } }