use crate::errors::DbResult;
use crate::logger::Logger;
use crate::table::Table;
use crate::TableId;
use serde::de::DeserializeOwned;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::hash::Hash;
#[derive(Debug)]
#[cfg_attr(feature = "clone", derive(Clone))]
pub struct LookupTable<K, V>
where
K: Hash + Eq + Serialize,
V: Serialize,
{
table_id: TableId,
inner: HashMap<K, V>,
pub logger: Logger,
}
#[derive(Serialize, Deserialize)]
pub enum LogEntry<K, V> {
Insert(K, V),
Remove(K),
Clear,
}
impl<K, V> Table for LookupTable<K, V>
where
K: Hash + Eq + Serialize + DeserializeOwned,
V: Serialize + DeserializeOwned,
{
fn init(table_id: TableId, logger: Logger) -> Self {
Self { table_id, inner: HashMap::default(), logger }
}
fn handle_event(&mut self, bytes: &[u8]) -> DbResult<()> {
match bincode::deserialize(bytes)? {
LogEntry::Insert(k, v) => {
self.inner.insert(k, v);
}
LogEntry::Remove(k) => {
self.inner.remove(&k);
}
LogEntry::Clear => {
self.inner.clear();
}
};
Ok(())
}
fn compact_repr(&self) -> DbResult<Vec<u8>> {
let mut repr = vec![];
for (k, v) in &self.inner {
let data = bincode::serialize(&LogEntry::Insert(k, v))?;
let mut data = Logger::log_entry(self.table_id, data);
repr.append(&mut data);
}
Ok(repr)
}
}
impl<K, V> LookupTable<K, V>
where
K: Hash + Eq + Serialize,
V: Serialize,
{
pub fn insert(&mut self, key: K, value: V) -> DbResult<Option<V>> {
let log_entry = LogEntry::Insert(&key, &value);
let data = bincode::serialize(&log_entry)?;
let ret = self.inner.insert(key, value);
self.logger.write(self.table_id, data)?;
Ok(ret)
}
pub fn remove(&mut self, key: &K) -> DbResult<Option<V>> {
let log_entry = LogEntry::Remove::<&K, &V>(key);
let data = bincode::serialize(&log_entry)?;
let ret = self.inner.remove(key);
self.logger.write(self.table_id, data)?;
Ok(ret)
}
pub fn get(&self) -> &HashMap<K, V> {
&self.inner
}
pub fn clear(&mut self) -> DbResult<()> {
self.inner.clear();
let log_entry = LogEntry::<K, V>::Clear;
let data = bincode::serialize(&log_entry)?;
self.logger.write(self.table_id, data)?;
Ok(())
}
}