openethereum/ethcore/db/src/db.rs

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// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.
// Parity Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity Ethereum. If not, see <http://www.gnu.org/licenses/>.
//! Database utilities and definitions.
use kvdb::{DBTransaction, KeyValueDB};
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use parking_lot::RwLock;
use std::{collections::HashMap, hash::Hash, ops::Deref};
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use rlp;
// database columns
/// Column for State
pub const COL_STATE: Option<u32> = Some(0);
/// Column for Block headers
pub const COL_HEADERS: Option<u32> = Some(1);
/// Column for Block bodies
pub const COL_BODIES: Option<u32> = Some(2);
/// Column for Extras
pub const COL_EXTRA: Option<u32> = Some(3);
/// Column for Traces
pub const COL_TRACE: Option<u32> = Some(4);
/// Column for the empty accounts bloom filter.
pub const COL_ACCOUNT_BLOOM: Option<u32> = Some(5);
/// Column for general information from the local node which can persist.
pub const COL_NODE_INFO: Option<u32> = Some(6);
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/// Column for the light client chain.
pub const COL_LIGHT_CHAIN: Option<u32> = Some(7);
/// Number of columns in DB
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pub const NUM_COLUMNS: Option<u32> = Some(8);
/// Modes for updating caches.
#[derive(Clone, Copy)]
pub enum CacheUpdatePolicy {
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/// Overwrite entries.
Overwrite,
/// Remove entries.
Remove,
}
/// A cache for arbitrary key-value pairs.
pub trait Cache<K, V> {
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/// Insert an entry into the cache and get the old value.
fn insert(&mut self, k: K, v: V) -> Option<V>;
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/// Remove an entry from the cache, getting the old value if it existed.
fn remove(&mut self, k: &K) -> Option<V>;
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/// Query the cache for a key's associated value.
fn get(&self, k: &K) -> Option<&V>;
}
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impl<K, V> Cache<K, V> for HashMap<K, V>
where
K: Hash + Eq,
{
fn insert(&mut self, k: K, v: V) -> Option<V> {
HashMap::insert(self, k, v)
}
fn remove(&mut self, k: &K) -> Option<V> {
HashMap::remove(self, k)
}
fn get(&self, k: &K) -> Option<&V> {
HashMap::get(self, k)
}
}
/// Should be used to get database key associated with given value.
pub trait Key<T> {
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/// The db key associated with this value.
type Target: Deref<Target = [u8]>;
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/// Returns db key.
fn key(&self) -> Self::Target;
}
/// Should be used to write value into database.
pub trait Writable {
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/// Writes the value into the database.
fn write<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>, value: &T)
where
T: rlp::Encodable,
R: Deref<Target = [u8]>;
/// Deletes key from the databse.
fn delete<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>)
where
T: rlp::Encodable,
R: Deref<Target = [u8]>;
/// Writes the value into the database and updates the cache.
fn write_with_cache<K, T, R>(
&mut self,
col: Option<u32>,
cache: &mut Cache<K, T>,
key: K,
value: T,
policy: CacheUpdatePolicy,
) where
K: Key<T, Target = R> + Hash + Eq,
T: rlp::Encodable,
R: Deref<Target = [u8]>,
{
self.write(col, &key, &value);
match policy {
CacheUpdatePolicy::Overwrite => {
cache.insert(key, value);
}
CacheUpdatePolicy::Remove => {
cache.remove(&key);
}
}
}
/// Writes the values into the database and updates the cache.
fn extend_with_cache<K, T, R>(
&mut self,
col: Option<u32>,
cache: &mut Cache<K, T>,
values: HashMap<K, T>,
policy: CacheUpdatePolicy,
) where
K: Key<T, Target = R> + Hash + Eq,
T: rlp::Encodable,
R: Deref<Target = [u8]>,
{
match policy {
CacheUpdatePolicy::Overwrite => {
for (key, value) in values {
self.write(col, &key, &value);
cache.insert(key, value);
}
}
CacheUpdatePolicy::Remove => {
for (key, value) in &values {
self.write(col, key, value);
cache.remove(key);
}
}
}
}
/// Writes and removes the values into the database and updates the cache.
fn extend_with_option_cache<K, T, R>(
&mut self,
col: Option<u32>,
cache: &mut Cache<K, Option<T>>,
values: HashMap<K, Option<T>>,
policy: CacheUpdatePolicy,
) where
K: Key<T, Target = R> + Hash + Eq,
T: rlp::Encodable,
R: Deref<Target = [u8]>,
{
match policy {
CacheUpdatePolicy::Overwrite => {
for (key, value) in values {
match value {
Some(ref v) => self.write(col, &key, v),
None => self.delete(col, &key),
}
cache.insert(key, value);
}
}
CacheUpdatePolicy::Remove => {
for (key, value) in values {
match value {
Some(v) => self.write(col, &key, &v),
None => self.delete(col, &key),
}
cache.remove(&key);
}
}
}
}
}
/// Should be used to read values from database.
pub trait Readable {
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/// Returns value for given key.
fn read<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> Option<T>
where
T: rlp::Decodable,
R: Deref<Target = [u8]>;
/// Returns value for given key either in cache or in database.
fn read_with_cache<K, T, C>(&self, col: Option<u32>, cache: &RwLock<C>, key: &K) -> Option<T>
where
K: Key<T> + Eq + Hash + Clone,
T: Clone + rlp::Decodable,
C: Cache<K, T>,
{
{
let read = cache.read();
if let Some(v) = read.get(key) {
return Some(v.clone());
}
}
self.read(col, key).map(|value: T| {
let mut write = cache.write();
write.insert(key.clone(), value.clone());
value
})
}
/// Returns value for given key either in two-layered cache or in database.
fn read_with_two_layer_cache<K, T, C>(
&self,
col: Option<u32>,
l1_cache: &RwLock<C>,
l2_cache: &RwLock<C>,
key: &K,
) -> Option<T>
where
K: Key<T> + Eq + Hash + Clone,
T: Clone + rlp::Decodable,
C: Cache<K, T>,
{
{
let read = l1_cache.read();
if let Some(v) = read.get(key) {
return Some(v.clone());
}
}
self.read_with_cache(col, l2_cache, key)
}
/// Returns true if given value exists.
fn exists<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> bool
where
R: Deref<Target = [u8]>;
/// Returns true if given value exists either in cache or in database.
fn exists_with_cache<K, T, R, C>(&self, col: Option<u32>, cache: &RwLock<C>, key: &K) -> bool
where
K: Eq + Hash + Key<T, Target = R>,
R: Deref<Target = [u8]>,
C: Cache<K, T>,
{
{
let read = cache.read();
if read.get(key).is_some() {
return true;
}
}
self.exists::<T, R>(col, key)
}
}
impl Writable for DBTransaction {
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fn write<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>, value: &T)
where
T: rlp::Encodable,
R: Deref<Target = [u8]>,
{
self.put(col, &key.key(), &rlp::encode(value));
}
fn delete<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>)
where
T: rlp::Encodable,
R: Deref<Target = [u8]>,
{
self.delete(col, &key.key());
}
}
impl<KVDB: KeyValueDB + ?Sized> Readable for KVDB {
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fn read<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> Option<T>
where
T: rlp::Decodable,
R: Deref<Target = [u8]>,
{
self.get(col, &key.key())
.expect(&format!("db get failed, key: {:?}", &key.key() as &[u8]))
.map(|v| rlp::decode(&v).expect("decode db value failed"))
}
fn exists<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> bool
where
R: Deref<Target = [u8]>,
{
let result = self.get(col, &key.key());
match result {
Ok(v) => v.is_some(),
Err(err) => {
panic!(
"db get failed, key: {:?}, err: {:?}",
&key.key() as &[u8],
err
);
}
}
}
}