mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-04-26 14:37:57 +00:00
Bastian Köcher
90 lines
2.5 KiB
Rust
90 lines
2.5 KiB
Rust
// This file is part of Substrate.
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// Copyright (C) 2017-2022 Parity Technologies (UK) Ltd.
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// SPDX-License-Identifier: Apache-2.0
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//! In-memory implementation of `Database`
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use crate::{error, Change, ColumnId, Database, Transaction};
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use parking_lot::RwLock;
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use std::collections::{hash_map::Entry, HashMap};
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#[derive(Default)]
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/// This implements `Database` as an in-memory hash map. `commit` is not atomic.
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pub struct MemDb(RwLock<HashMap<ColumnId, HashMap<Vec<u8>, (u32, Vec<u8>)>>>);
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impl<H> Database<H> for MemDb
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where
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H: Clone + AsRef<[u8]>,
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{
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fn commit(&self, transaction: Transaction<H>) -> error::Result<()> {
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let mut s = self.0.write();
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for change in transaction.0.into_iter() {
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match change {
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Change::Set(col, key, value) => {
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s.entry(col).or_default().insert(key, (1, value));
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},
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Change::Remove(col, key) => {
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s.entry(col).or_default().remove(&key);
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},
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Change::Store(col, hash, value) => {
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s.entry(col)
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.or_default()
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.entry(hash.as_ref().to_vec())
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.and_modify(|(c, _)| *c += 1)
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.or_insert_with(|| (1, value));
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},
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Change::Reference(col, hash) => {
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if let Entry::Occupied(mut entry) =
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s.entry(col).or_default().entry(hash.as_ref().to_vec())
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{
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entry.get_mut().0 += 1;
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}
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},
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Change::Release(col, hash) => {
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if let Entry::Occupied(mut entry) =
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s.entry(col).or_default().entry(hash.as_ref().to_vec())
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{
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entry.get_mut().0 -= 1;
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if entry.get().0 == 0 {
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entry.remove();
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}
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}
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},
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}
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}
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Ok(())
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}
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fn get(&self, col: ColumnId, key: &[u8]) -> Option<Vec<u8>> {
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let s = self.0.read();
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s.get(&col).and_then(|c| c.get(key).map(|(_, v)| v.clone()))
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}
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}
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impl MemDb {
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/// Create a new instance
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pub fn new() -> Self {
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MemDb::default()
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}
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/// Count number of values in a column
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pub fn count(&self, col: ColumnId) -> usize {
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let s = self.0.read();
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s.get(&col).map(|c| c.len()).unwrap_or(0)
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}
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}
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