openethereum/util/kvdb-memorydb/src/lib.rs

128 lines
3.7 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/>.
extern crate parking_lot;
extern crate kvdb;
extern crate rlp;
use std::collections::{BTreeMap, HashMap};
use parking_lot::RwLock;
use kvdb::{DBValue, DBTransaction, KeyValueDB, DBOp, Result};
use rlp::{RlpType, UntrustedRlp, Compressible};
/// A key-value database fulfilling the `KeyValueDB` trait, living in memory.
/// This is generally intended for tests and is not particularly optimized.
#[derive(Default)]
pub struct InMemory {
columns: RwLock<HashMap<Option<u32>, BTreeMap<Vec<u8>, DBValue>>>,
}
/// Create an in-memory database with the given number of columns.
/// Columns will be indexable by 0..`num_cols`
pub fn create(num_cols: u32) -> InMemory {
let mut cols = HashMap::new();
cols.insert(None, BTreeMap::new());
for idx in 0..num_cols {
cols.insert(Some(idx), BTreeMap::new());
}
InMemory {
columns: RwLock::new(cols)
}
}
impl KeyValueDB for InMemory {
fn get(&self, col: Option<u32>, key: &[u8]) -> Result<Option<DBValue>> {
let columns = self.columns.read();
match columns.get(&col) {
None => Err(format!("No such column family: {:?}", col).into()),
Some(map) => Ok(map.get(key).cloned()),
}
}
fn get_by_prefix(&self, col: Option<u32>, prefix: &[u8]) -> Option<Box<[u8]>> {
let columns = self.columns.read();
match columns.get(&col) {
None => None,
Some(map) =>
map.iter()
.find(|&(ref k ,_)| k.starts_with(prefix))
.map(|(_, v)| v.to_vec().into_boxed_slice())
}
}
fn write_buffered(&self, transaction: DBTransaction) {
let mut columns = self.columns.write();
let ops = transaction.ops;
for op in ops {
match op {
DBOp::Insert { col, key, value } => {
if let Some(col) = columns.get_mut(&col) {
col.insert(key.into_vec(), value);
}
},
DBOp::InsertCompressed { col, key, value } => {
if let Some(col) = columns.get_mut(&col) {
let compressed = UntrustedRlp::new(&value).compress(RlpType::Blocks);
let mut value = DBValue::new();
value.append_slice(&compressed);
col.insert(key.into_vec(), value);
}
},
DBOp::Delete { col, key } => {
if let Some(col) = columns.get_mut(&col) {
col.remove(&*key);
}
},
}
}
}
fn flush(&self) -> Result<()> {
Ok(())
}
fn iter<'a>(&'a self, col: Option<u32>) -> Box<Iterator<Item=(Box<[u8]>, Box<[u8]>)> + 'a> {
match self.columns.read().get(&col) {
Some(map) => Box::new( // TODO: worth optimizing at all?
map.clone()
.into_iter()
.map(|(k, v)| (k.into_boxed_slice(), v.into_vec().into_boxed_slice()))
),
None => Box::new(None.into_iter()),
}
}
fn iter_from_prefix<'a>(&'a self, col: Option<u32>, prefix: &'a [u8])
-> Box<Iterator<Item=(Box<[u8]>, Box<[u8]>)> + 'a>
{
match self.columns.read().get(&col) {
Some(map) => Box::new(
map.clone()
.into_iter()
.skip_while(move |&(ref k, _)| !k.starts_with(prefix))
.map(|(k, v)| (k.into_boxed_slice(), v.into_vec().into_boxed_slice()))
),
None => Box::new(None.into_iter()),
}
}
fn restore(&self, _new_db: &str) -> Result<()> {
Err("Attempted to restore in-memory database".into())
}
}