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use ::kvdb::{DBTransaction, KeyValueDB};
use crate::{error, Change, ColumnId, Database, Transaction};
struct DbAdapter<D: KeyValueDB + 'static>(D);
fn handle_err<T>(result: std::io::Result<T>) -> T {
match result {
Ok(r) => r,
Err(e) => {
panic!("Critical database error: {:?}", e);
},
}
}
pub fn as_database<D, H>(db: D) -> std::sync::Arc<dyn Database<H>>
where
D: KeyValueDB + 'static,
H: Clone + AsRef<[u8]>,
{
std::sync::Arc::new(DbAdapter(db))
}
impl<D: KeyValueDB> DbAdapter<D> {
fn read_counter(&self, col: ColumnId, key: &[u8]) -> error::Result<(Vec<u8>, Option<u32>)> {
let mut counter_key = key.to_vec();
counter_key.push(0);
Ok(match self.0.get(col, &counter_key).map_err(|e| error::DatabaseError(Box::new(e)))? {
Some(data) => {
let mut counter_data = [0; 4];
if data.len() != 4 {
return Err(error::DatabaseError(Box::new(std::io::Error::new(
std::io::ErrorKind::Other,
format!("Unexpected counter len {}", data.len()),
))))
}
counter_data.copy_from_slice(&data);
let counter = u32::from_le_bytes(counter_data);
(counter_key, Some(counter))
},
None => (counter_key, None),
})
}
}
impl<D: KeyValueDB, H: Clone + AsRef<[u8]>> Database<H> for DbAdapter<D> {
fn commit(&self, transaction: Transaction<H>) -> error::Result<()> {
let mut tx = DBTransaction::new();
for change in transaction.0.into_iter() {
match change {
Change::Set(col, key, value) => tx.put_vec(col, &key, value),
Change::Remove(col, key) => tx.delete(col, &key),
Change::Store(col, key, value) => match self.read_counter(col, key.as_ref())? {
(counter_key, Some(mut counter)) => {
counter += 1;
tx.put(col, &counter_key, &counter.to_le_bytes());
},
(counter_key, None) => {
let d = 1u32.to_le_bytes();
tx.put(col, &counter_key, &d);
tx.put_vec(col, key.as_ref(), value);
},
},
Change::Reference(col, key) => {
if let (counter_key, Some(mut counter)) =
self.read_counter(col, key.as_ref())?
{
counter += 1;
tx.put(col, &counter_key, &counter.to_le_bytes());
}
},
Change::Release(col, key) => {
if let (counter_key, Some(mut counter)) =
self.read_counter(col, key.as_ref())?
{
counter -= 1;
if counter == 0 {
tx.delete(col, &counter_key);
tx.delete(col, key.as_ref());
} else {
tx.put(col, &counter_key, &counter.to_le_bytes());
}
}
},
}
}
self.0.write(tx).map_err(|e| error::DatabaseError(Box::new(e)))
}
fn get(&self, col: ColumnId, key: &[u8]) -> Option<Vec<u8>> {
handle_err(self.0.get(col, key))
}
fn contains(&self, col: ColumnId, key: &[u8]) -> bool {
handle_err(self.0.has_key(col, key))
}
}