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use std::collections::HashMap;
use std::sync::{Arc, RwLock};
use arc_swap::ArcSwapOption;
use sled::transaction::{
ConflictableTransactionError, TransactionError, Transactional, TransactionalTree, UnabortableTransactionError
};
use crate::{Error, IDb, ITx, ITxFn, Result, TxError, TxFnResult, TxResult, Value, Db};
impl From<sled::Error> for Error {
fn from(e: sled::Error) -> Error {
Error(format!("{}", e).into())
}
}
pub struct SledDb {
db: sled::Db,
trees: RwLock<(Vec<sled::Tree>, HashMap<String, usize>)>,
}
impl SledDb {
pub fn new(db: sled::Db) -> Db {
let s = Self {
db,
trees: RwLock::new((Vec::new(), HashMap::new())),
};
Db(Arc::new(s))
}
fn get_tree(&self, i: usize) -> Result<sled::Tree> {
self.trees
.read()
.unwrap()
.0
.get(i)
.cloned()
.ok_or(Error("invalid tree id".into()))
}
}
impl IDb for SledDb {
fn tree(&self, name: &str) -> Result<usize> {
let mut trees = self.trees.write().unwrap();
if let Some(i) = trees.1.get(name) {
Ok(*i)
} else {
let tree = self.db.open_tree(name)?;
let i = trees.0.len();
trees.0.push(tree);
trees.1.insert(name.to_string(), i);
Ok(i)
}
}
fn get<'a>(&'a self, tree: usize, key: &[u8]) -> Result<Option<Value<'a>>> {
let tree = self.get_tree(tree)?;
Ok(tree.get(key)?.map(|v| v.to_vec().into()))
}
fn put(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()> {
let tree = self.get_tree(tree)?;
tree.insert(key, value)?;
Ok(())
}
fn transaction(&self, f: &dyn ITxFn) -> TxResult<(), ()> {
let trees = self.trees.read().unwrap();
let res = trees.0.transaction(|txtrees| {
let tx = SledTx {
trees: txtrees,
err: ArcSwapOption::new(None),
};
match f.try_on(&tx) {
TxFnResult::Ok => {
assert!(tx.err.into_inner().is_none());
Ok(())
}
TxFnResult::Abort => Err(ConflictableTransactionError::Abort(())),
TxFnResult::Err => {
let err_arc = tx
.err
.into_inner()
.expect("Transaction did not store error");
let err = Arc::try_unwrap(err_arc).ok().expect("Many refs");
Err(err.into())
}
}
});
match res {
Ok(()) => Ok(()),
Err(TransactionError::Abort(())) => Err(TxError::Abort(())),
Err(TransactionError::Storage(s)) => Err(TxError::Db(s.into())),
}
}
}
// ----
struct SledTx<'a> {
trees: &'a [TransactionalTree],
err: ArcSwapOption<UnabortableTransactionError>,
}
impl<'a> SledTx<'a> {
fn save_error<R>(&self, v: std::result::Result<R, UnabortableTransactionError>) -> Result<R> {
match v {
Ok(x) => Ok(x),
Err(e) => {
let txt = format!("{}", e);
self.err.store(Some(Arc::new(e)));
Err(Error(txt.into()))
}
}
}
}
impl<'a> ITx<'a> for SledTx<'a> {
fn get(&self, tree: usize, key: &[u8]) -> Result<Option<Value<'a>>> {
let tree = self.trees.get(tree)
.ok_or(Error("invalid tree id".into()))?;
let tmp = self.save_error(tree.get(key))?;
Ok(tmp.map(|v| v.to_vec().into()))
}
fn put(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()> {
let tree = self.trees.get(tree)
.ok_or(Error("invalid tree id".into()))?;
self.save_error(tree.insert(key, value))?;
Ok(())
}
}
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