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use std::{collections::HashMap, sync::Arc};
use crate::{columns, Database, DbHash, Transaction};
use parking_lot::Mutex;
use log::error;
#[derive(Clone)]
pub struct LocalStorage {
db: Arc<dyn Database<DbHash>>,
locks: Arc<Mutex<HashMap<Vec<u8>, Arc<Mutex<()>>>>>,
}
impl std::fmt::Debug for LocalStorage {
fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
fmt.debug_struct("LocalStorage")
.finish()
}
}
impl LocalStorage {
#[cfg(any(feature = "test-helpers", test))]
pub fn new_test() -> Self {
let db = kvdb_memorydb::create(crate::utils::NUM_COLUMNS);
let db = sp_database::as_database(db);
Self::new(db as _)
}
pub fn new(db: Arc<dyn Database<DbHash>>) -> Self {
Self {
db,
locks: Default::default(),
}
}
}
impl sp_core::offchain::OffchainStorage for LocalStorage {
fn set(&mut self, prefix: &[u8], key: &[u8], value: &[u8]) {
let mut tx = Transaction::new();
tx.set(columns::OFFCHAIN, &concatenate_prefix_and_key(prefix, key), value);
if let Err(err) = self.db.commit(tx) {
error!("Error setting on local storage: {}", err)
}
}
fn remove(&mut self, prefix: &[u8], key: &[u8]) {
let mut tx = Transaction::new();
tx.remove(columns::OFFCHAIN, &concatenate_prefix_and_key(prefix, key));
if let Err(err) = self.db.commit(tx) {
error!("Error removing on local storage: {}", err)
}
}
fn get(&self, prefix: &[u8], key: &[u8]) -> Option<Vec<u8>> {
self.db.get(columns::OFFCHAIN, &concatenate_prefix_and_key(prefix, key))
}
fn compare_and_set(
&mut self,
prefix: &[u8],
item_key: &[u8],
old_value: Option<&[u8]>,
new_value: &[u8],
) -> bool {
let key = concatenate_prefix_and_key(prefix, item_key);
let key_lock = {
let mut locks = self.locks.lock();
locks.entry(key.clone()).or_default().clone()
};
let is_set;
{
let _key_guard = key_lock.lock();
let val = self.db.get(columns::OFFCHAIN, &key);
is_set = val.as_ref().map(|x| &**x) == old_value;
if is_set {
self.set(prefix, item_key, new_value)
}
}
let mut locks = self.locks.lock();
{
drop(key_lock);
let key_lock = locks.get_mut(&key);
if let Some(_) = key_lock.and_then(Arc::get_mut) {
locks.remove(&key);
}
}
is_set
}
}
pub(crate) fn concatenate_prefix_and_key(prefix: &[u8], key: &[u8]) -> Vec<u8> {
prefix
.iter()
.chain(key.into_iter())
.cloned()
.collect()
}
#[cfg(test)]
mod tests {
use super::*;
use sp_core::offchain::OffchainStorage;
#[test]
fn should_compare_and_set_and_clear_the_locks_map() {
let mut storage = LocalStorage::new_test();
let prefix = b"prefix";
let key = b"key";
let value = b"value";
storage.set(prefix, key, value);
assert_eq!(storage.get(prefix, key), Some(value.to_vec()));
assert_eq!(storage.compare_and_set(prefix, key, Some(value), b"asd"), true);
assert_eq!(storage.get(prefix, key), Some(b"asd".to_vec()));
assert!(storage.locks.lock().is_empty(), "Locks map should be empty!");
}
#[test]
fn should_compare_and_set_on_empty_field() {
let mut storage = LocalStorage::new_test();
let prefix = b"prefix";
let key = b"key";
assert_eq!(storage.compare_and_set(prefix, key, None, b"asd"), true);
assert_eq!(storage.get(prefix, key), Some(b"asd".to_vec()));
assert!(storage.locks.lock().is_empty(), "Locks map should be empty!");
}
}
