114 lines
3.8 KiB
Rust
114 lines
3.8 KiB
Rust
// Copyright 2015, 2016 Ethcore (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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//! Database of byte-slices keyed to their Keccak hash.
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use hash::*;
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use bytes::*;
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use std::collections::HashMap;
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/// Trait modelling datastore keyed by a 32-byte Keccak hash.
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pub trait HashDB {
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/// Get the keys in the database together with number of underlying references.
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fn keys(&self) -> HashMap<H256, i32>;
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/// Deprecated. use `get`.
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fn lookup(&self, key: &H256) -> Option<&[u8]>; // TODO: rename to get.
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/// Look up a given hash into the bytes that hash to it, returning None if the
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/// hash is not known.
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///
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/// # Examples
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/// ```rust
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/// extern crate ethcore_util;
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/// use ethcore_util::hashdb::*;
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/// use ethcore_util::memorydb::*;
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/// fn main() {
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/// let mut m = MemoryDB::new();
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/// let hello_bytes = "Hello world!".as_bytes();
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/// let hash = m.insert(hello_bytes);
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/// assert_eq!(m.lookup(&hash).unwrap(), hello_bytes);
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/// }
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/// ```
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fn get(&self, key: &H256) -> Option<&[u8]> { self.lookup(key) }
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/// Deprecated. Use `contains`.
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fn exists(&self, key: &H256) -> bool; // TODO: rename to contains.
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/// Check for the existance of a hash-key.
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///
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/// # Examples
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/// ```rust
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/// extern crate ethcore_util;
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/// use ethcore_util::hashdb::*;
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/// use ethcore_util::memorydb::*;
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/// use ethcore_util::sha3::*;
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/// fn main() {
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/// let mut m = MemoryDB::new();
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/// let hello_bytes = "Hello world!".as_bytes();
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/// assert!(!m.exists(&hello_bytes.sha3()));
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/// let key = m.insert(hello_bytes);
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/// assert!(m.exists(&key));
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/// m.kill(&key);
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/// assert!(!m.exists(&key));
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/// }
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/// ```
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fn contains(&self, key: &H256) -> bool { self.exists(key) }
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/// Insert a datum item into the DB and return the datum's hash for a later lookup. Insertions
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/// are counted and the equivalent number of `kill()`s must be performed before the data
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/// is considered dead.
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///
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/// # Examples
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/// ```rust
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/// extern crate ethcore_util;
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/// use ethcore_util::hashdb::*;
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/// use ethcore_util::memorydb::*;
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/// use ethcore_util::hash::*;
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/// fn main() {
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/// let mut m = MemoryDB::new();
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/// let key = m.insert("Hello world!".as_bytes());
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/// assert!(m.exists(&key));
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/// }
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/// ```
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fn insert(&mut self, value: &[u8]) -> H256;
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/// Like `insert()` , except you provide the key and the data is all moved.
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fn emplace(&mut self, key: H256, value: Bytes);
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/// Deprecated - use `remove`.
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fn kill(&mut self, key: &H256); // TODO: rename to remove.
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/// Remove a datum previously inserted. Insertions can be "owed" such that the same number of `insert()`s may
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/// happen without the data being eventually being inserted into the DB.
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///
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/// # Examples
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/// ```rust
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/// extern crate ethcore_util;
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/// use ethcore_util::hashdb::*;
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/// use ethcore_util::memorydb::*;
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/// use ethcore_util::sha3::*;
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/// fn main() {
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/// let mut m = MemoryDB::new();
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/// let d = "Hello world!".as_bytes();
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/// let key = &d.sha3();
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/// m.kill(key); // OK - we now owe an insertion.
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/// assert!(!m.exists(key));
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/// m.insert(d); // OK - now it's "empty" again.
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/// assert!(!m.exists(key));
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/// m.insert(d); // OK - now we've
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/// assert_eq!(m.lookup(key).unwrap(), d);
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/// }
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/// ```
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fn remove(&mut self, key: &H256) { self.kill(key) }
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}
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