272 lines
6.9 KiB
Rust
272 lines
6.9 KiB
Rust
// Copyright 2015, 2016 Ethcore (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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//! Reference-counted memory-based `HashDB` implementation.
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use hash::*;
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use bytes::*;
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use rlp::*;
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use sha3::*;
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use hashdb::*;
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use heapsize::*;
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use std::mem;
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use std::collections::HashMap;
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use std::default::Default;
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#[derive(Debug,Clone)]
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/// Reference-counted memory-based `HashDB` implementation.
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///
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/// Use `new()` to create a new database. Insert items with `insert()`, remove items
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/// with `remove()`, check for existence with `containce()` and lookup a hash to derive
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/// the data with `get()`. Clear with `clear()` and purge the portions of the data
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/// that have no references with `purge()`.
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///
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/// # Example
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/// ```rust
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/// extern crate ethcore_util;
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/// use ethcore_util::hashdb::*;
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/// use ethcore_util::memorydb::*;
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/// fn main() {
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/// let mut m = MemoryDB::new();
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/// let d = "Hello world!".as_bytes();
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///
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/// let k = m.insert(d);
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/// assert!(m.contains(&k));
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/// assert_eq!(m.get(&k).unwrap(), d);
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///
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/// m.insert(d);
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/// assert!(m.contains(&k));
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///
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/// m.remove(&k);
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/// assert!(m.contains(&k));
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///
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/// m.remove(&k);
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/// assert!(!m.contains(&k));
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///
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/// m.remove(&k);
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/// assert!(!m.contains(&k));
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///
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/// m.insert(d);
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/// assert!(!m.contains(&k));
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/// m.insert(d);
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/// assert!(m.contains(&k));
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/// assert_eq!(m.get(&k).unwrap(), d);
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///
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/// m.remove(&k);
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/// assert!(!m.contains(&k));
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/// }
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/// ```
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#[derive(PartialEq)]
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pub struct MemoryDB {
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data: HashMap<H256, (Bytes, i32)>,
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static_null_rlp: (Bytes, i32),
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aux: HashMap<Bytes, Bytes>,
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}
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impl Default for MemoryDB {
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fn default() -> Self {
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MemoryDB::new()
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}
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}
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impl MemoryDB {
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/// Create a new instance of the memory DB.
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pub fn new() -> MemoryDB {
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MemoryDB {
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data: HashMap::new(),
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static_null_rlp: (vec![0x80u8; 1], 1),
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aux: HashMap::new(),
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}
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}
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/// Clear all data from the database.
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///
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/// # Examples
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/// ```rust
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/// extern crate ethcore_util;
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/// use ethcore_util::hashdb::*;
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/// use ethcore_util::memorydb::*;
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/// fn main() {
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/// let mut m = MemoryDB::new();
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/// let hello_bytes = "Hello world!".as_bytes();
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/// let hash = m.insert(hello_bytes);
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/// assert!(m.contains(&hash));
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/// m.clear();
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/// assert!(!m.contains(&hash));
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/// }
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/// ```
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pub fn clear(&mut self) {
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self.data.clear();
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}
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/// Purge all zero-referenced data from the database.
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pub fn purge(&mut self) {
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let empties: Vec<_> = self.data.iter()
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.filter(|&(_, &(_, rc))| rc == 0)
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.map(|(k, _)| k.clone())
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.collect();
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for empty in empties { self.data.remove(&empty); }
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}
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/// Grab the raw information associated with a key. Returns None if the key
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/// doesn't exist.
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///
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/// Even when Some is returned, the data is only guaranteed to be useful
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/// when the refs > 0.
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pub fn raw(&self, key: &H256) -> Option<&(Bytes, i32)> {
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if key == &SHA3_NULL_RLP {
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return Some(&self.static_null_rlp);
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}
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self.data.get(key)
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}
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/// Return the internal map of hashes to data, clearing the current state.
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pub fn drain(&mut self) -> HashMap<H256, (Bytes, i32)> {
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mem::replace(&mut self.data, HashMap::new())
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}
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/// Return the internal map of auxiliary data, clearing the current state.
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pub fn drain_aux(&mut self) -> HashMap<Bytes, Bytes> {
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mem::replace(&mut self.aux, HashMap::new())
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}
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/// Denote than an existing value has the given key. Used when a key gets removed without
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/// a prior insert and thus has a negative reference with no value.
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///
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/// May safely be called even if the key's value is known, in which case it will be a no-op.
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pub fn denote(&self, key: &H256, value: Bytes) -> &(Bytes, i32) {
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if self.raw(key) == None {
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unsafe {
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let p = &self.data as *const HashMap<H256, (Bytes, i32)> as *mut HashMap<H256, (Bytes, i32)>;
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(*p).insert(key.clone(), (value, 0));
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}
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}
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self.raw(key).unwrap()
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}
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/// Returns the size of allocated heap memory
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pub fn mem_used(&self) -> usize {
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self.data.heap_size_of_children()
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}
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}
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static NULL_RLP_STATIC: [u8; 1] = [0x80; 1];
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impl HashDB for MemoryDB {
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fn get(&self, key: &H256) -> Option<&[u8]> {
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if key == &SHA3_NULL_RLP {
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return Some(&NULL_RLP_STATIC);
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}
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match self.data.get(key) {
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Some(&(ref d, rc)) if rc > 0 => Some(d),
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_ => None
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}
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}
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fn keys(&self) -> HashMap<H256, i32> {
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self.data.iter().filter_map(|(k, v)| if v.1 != 0 {Some((k.clone(), v.1))} else {None}).collect()
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}
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fn contains(&self, key: &H256) -> bool {
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if key == &SHA3_NULL_RLP {
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return true;
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}
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match self.data.get(key) {
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Some(&(_, x)) if x > 0 => true,
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_ => false
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}
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}
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fn insert(&mut self, value: &[u8]) -> H256 {
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if value == &NULL_RLP {
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return SHA3_NULL_RLP.clone();
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}
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let key = value.sha3();
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if match self.data.get_mut(&key) {
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Some(&mut (ref mut old_value, ref mut rc @ -0x80000000i32 ... 0)) => {
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*old_value = From::from(value);
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*rc += 1;
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false
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},
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Some(&mut (_, ref mut x)) => { *x += 1; false } ,
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None => true,
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}{ // ... None falls through into...
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self.data.insert(key.clone(), (From::from(value), 1));
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}
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key
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}
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fn emplace(&mut self, key: H256, value: Bytes) {
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if value == &NULL_RLP {
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return;
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}
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match self.data.get_mut(&key) {
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Some(&mut (ref mut old_value, ref mut rc @ -0x80000000i32 ... 0)) => {
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*old_value = value;
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*rc += 1;
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return;
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},
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Some(&mut (_, ref mut x)) => { *x += 1; return; } ,
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None => {},
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}
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// ... None falls through into...
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self.data.insert(key, (value, 1));
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}
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fn remove(&mut self, key: &H256) {
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if key == &SHA3_NULL_RLP {
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return;
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}
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if match self.data.get_mut(key) {
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Some(&mut (_, ref mut x)) => { *x -= 1; false }
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None => true
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}{ // ... None falls through into...
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self.data.insert(key.clone(), (Bytes::new(), -1));
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}
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}
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fn insert_aux(&mut self, hash: Vec<u8>, value: Vec<u8>) {
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self.aux.insert(hash, value);
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}
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fn get_aux(&self, hash: &[u8]) -> Option<Vec<u8>> {
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self.aux.get(hash).cloned()
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}
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fn remove_aux(&mut self, hash: &[u8]) {
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self.aux.remove(hash);
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}
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}
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#[test]
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fn memorydb_denote() {
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let mut m = MemoryDB::new();
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let hello_bytes = b"Hello world!";
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let hash = m.insert(hello_bytes);
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assert_eq!(m.get(&hash).unwrap(), b"Hello world!");
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for _ in 0..1000 {
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let r = H256::random();
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let k = r.sha3();
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let &(ref v, ref rc) = m.denote(&k, r.to_bytes());
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assert_eq!(v.as_slice(), r.as_slice());
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assert_eq!(*rc, 0);
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}
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assert_eq!(m.get(&hash).unwrap(), b"Hello world!");
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}
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