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extern crate parking_lot;
extern crate kvdb;
use std::collections::{BTreeMap, HashMap};
use std::io;
use parking_lot::RwLock;
use kvdb::{DBValue, DBTransaction, KeyValueDB, DBOp};
#[derive(Default)]
pub struct InMemory {
columns: RwLock<HashMap<Option<u32>, BTreeMap<Vec<u8>, DBValue>>>,
}
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]) -> io::Result<Option<DBValue>> {
let columns = self.columns.read();
match columns.get(&col) {
None => Err(io::Error::new(io::ErrorKind::Other, format!("No such column family: {:?}", col))),
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::Delete { col, key } => {
if let Some(col) = columns.get_mut(&col) {
col.remove(&*key);
}
},
}
}
}
fn flush(&self) -> io::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(
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) -> io::Result<()> {
Err(io::Error::new(io::ErrorKind::Other, "Attempted to restore in-memory database"))
}
}