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Merge branch 'master' of https://github.com/gavofyork/ethcore-util

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This commit is contained in:
debris 2015-11-28 01:39:07 +01:00
commit e807012894
2 changed files with 137 additions and 104 deletions
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73
src/hashdb.rs
View File

@ -2,8 +2,81 @@ use hash::*;
use bytes::Bytes;
pub trait HashDB {
/// Look up a given hash into the bytes that hash to it, returning None if the
/// hash is not known.
///
/// # Examples
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let hello_bytes = "Hello world!".as_bytes();
/// let hash = m.insert(hello_bytes);
/// assert_eq!(m.lookup(&hash).unwrap(), &hello_bytes);
/// }
/// ```
fn lookup(&self, key: &H256) -> Option<&Bytes>;
/// Check for the existance of a hash-key.
///
/// # Examples
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// use ethcore_util::sha3::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let hello_bytes = "Hello world!".as_bytes();
/// assert!(!m.exists(&hello_bytes.sha3()));
/// let key = m.insert(hello_bytes);
/// assert!(m.exists(&key));
/// m.kill(&key);
/// assert!(!m.exists(&key));
/// }
/// ```
fn exists(&self, key: &H256) -> bool;
/// Insert a datum item into the DB and return the datum's hash for a later lookup. Insertions
/// are counted and the equivalent number of `kill()`s must be performed before the data
/// is considered dead.
///
/// # Examples
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// use ethcore_util::hash::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let key = m.insert("Hello world!".as_bytes());
/// assert!(m.exists(&key));
/// }
/// ```
fn insert(&mut self, value: &[u8]) -> H256;
/// Remove a datum previously inserted. Insertions can be "owed" such that the same number of `insert()`s may
/// happen without the data being eventually being inserted into the DB.
///
/// # Examples
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// use ethcore_util::sha3::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let d = "Hello world!".as_bytes();
/// let key = &d.sha3();
/// m.kill(key); // OK - we now owe an insertion.
/// assert!(!m.exists(key));
/// m.insert(d); // OK - now it's "empty" again.
/// assert!(!m.exists(key));
/// m.insert(d); // OK - now we've
/// assert_eq!(m.lookup(key).unwrap(), &d);
/// }
/// ```
fn kill(&mut self, key: &H256);
}

168
src/memorydb.rs
View File

@ -1,36 +1,5 @@
//! Reference-counted memory-based HashDB implementation.
//!
//! # Example
//! ```rust
//! extern crate ethcore_util;
//! use ethcore_util::hashdb::*;
//! use ethcore_util::memorydb::*;
//! fn main() {
//! let mut m = MemoryDB::new();
//! let d = "Hello world!".as_bytes();
//!
//! let k = m.insert(d);
//! assert!(m.exists(&k));
//! assert_eq!(m.lookup(&k).unwrap(), &d);
//!
//! m.insert(d);
//! assert!(m.exists(&k));
//!
//! m.kill(&k);
//! assert!(m.exists(&k));
//!
//! m.kill(&k);
//! assert!(!m.exists(&k));
//!
//! m.insert(d);
//! assert!(m.exists(&k));
//! assert_eq!(m.lookup(&k).unwrap(), &d);
//!
//! m.kill(&k);
//! assert!(!m.exists(&k));
//! }
//! ```
use hash::*;
use bytes::*;
use sha3::*;
@ -38,31 +7,56 @@ use hashdb::*;
use std::collections::HashMap;
#[derive(Debug,Clone)]
/// Reference-counted memory-based HashDB implementation.
///
/// Use `new()` to create a new database. Insert items with `insert()`, remove items
/// with `kill()`, check for existance with `exists()` and lookup a hash to derive
/// the data with `lookup()`. Clear with `clear()` and purge the portions of the data
/// that have no references with `purge()`.
///
/// # Example
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let d = "Hello world!".as_bytes();
///
/// let k = m.insert(d);
/// assert!(m.exists(&k));
/// assert_eq!(m.lookup(&k).unwrap(), &d);
///
/// m.insert(d);
/// assert!(m.exists(&k));
///
/// m.kill(&k);
/// assert!(m.exists(&k));
///
/// m.kill(&k);
/// assert!(!m.exists(&k));
///
/// m.insert(d);
/// assert!(m.exists(&k));
/// assert_eq!(m.lookup(&k).unwrap(), &d);
///
/// m.kill(&k);
/// assert!(!m.exists(&k));
/// }
/// ```
pub struct MemoryDB {
data: HashMap<H256, (Bytes, i32)>,
}
impl MemoryDB {
/// Create a new instance of the memory DB.
pub fn new() -> MemoryDB {
MemoryDB {
data: HashMap::new()
}
}
pub fn clear(&mut self) {
self.data.clear();
}
pub fn purge(&mut self) {
let empties: Vec<_> = self.data.iter().filter(|&(_, &(_, rc))| rc <= 0).map(|(k, _)| k.clone()).collect();
for empty in empties { self.data.remove(&empty); }
}
}
impl HashDB for MemoryDB {
/// Do a hash dereference and look up a given hash into the bytes that make it up,
/// returning None if nothing is found (or if the only entries have 0 or fewer
/// references).
/// Clear all data from the database.
///
/// # Examples
/// ```rust
@ -73,9 +67,26 @@ impl HashDB for MemoryDB {
/// let mut m = MemoryDB::new();
/// let hello_bytes = "Hello world!".as_bytes();
/// let hash = m.insert(hello_bytes);
/// assert_eq!(m.lookup(&hash).unwrap(), &hello_bytes);
/// assert!(m.exists(&hash));
/// m.clear();
/// assert!(!m.exists(&hash));
/// }
/// ```
pub fn clear(&mut self) {
self.data.clear();
}
/// Purge all zero-referenced data from the database.
pub fn purge(&mut self) {
let empties: Vec<_> = self.data.iter()
.filter(|&(_, &(_, rc))| rc == 0)
.map(|(k, _)| k.clone())
.collect();
for empty in empties { self.data.remove(&empty); }
}
}
impl HashDB for MemoryDB {
fn lookup(&self, key: &H256) -> Option<&Bytes> {
match self.data.get(key) {
Some(&(ref d, rc)) if rc > 0 => Some(d),
@ -83,24 +94,6 @@ impl HashDB for MemoryDB {
}
}
/// Check for the existance of a hash-key.
///
/// # Examples
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// use ethcore_util::sha3::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let hello_bytes = "Hello world!".as_bytes();
/// assert!(!m.exists(&hello_bytes.sha3()));
/// let key = m.insert(hello_bytes);
/// assert!(m.exists(&key));
/// m.kill(&key);
/// assert!(!m.exists(&key));
/// }
/// ```
fn exists(&self, key: &H256) -> bool {
match self.data.get(key) {
Some(&(_, x)) if x > 0 => true,
@ -108,60 +101,27 @@ impl HashDB for MemoryDB {
}
}
/// Insert a datum item into the DB and return the datum's hash for a later lookup. Insertions
/// are counted and the equivalent number of `kill()`s must be performed before the data
/// is considered dead.
///
/// # Examples
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// use ethcore_util::hash::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let key = m.insert("Hello world!".as_bytes());
/// assert!(m.exists(&key));
/// }
/// ```
fn insert(&mut self, value: &[u8]) -> H256 {
let key = value.sha3();
if match self.data.get_mut(&key) {
Some(&mut (ref mut old_value, ref mut rc @ 0)) => { *old_value = From::from(value.bytes()); *rc = 1; false },
Some(&mut (ref mut old_value, ref mut rc @ 0)) => {
*old_value = From::from(value.bytes());
*rc = 1;
false
},
Some(&mut (_, ref mut x)) => { *x += 1; false } ,
None => true,
}{ // ... None falls through into...
self.data.insert(key, (From::from(value.bytes()), 1));
self.data.insert(key.clone(), (From::from(value.bytes()), 1));
}
key
}
/// Remove a datum previously inserted. Insertions can be "owed" such that the same number of inserts may
/// happen without the data being eventually being inserted into the DB.
///
/// # Examples
/// ```rust
/// extern crate ethcore_util;
/// use ethcore_util::hashdb::*;
/// use ethcore_util::memorydb::*;
/// use ethcore_util::sha3::*;
/// fn main() {
/// let mut m = MemoryDB::new();
/// let d = "Hello world!".as_bytes();
/// let key = &d.sha3();
/// m.kill(key); // OK - we now owe an insertion.
/// assert!(!m.exists(key));
/// m.insert(d); // OK - now it's "empty" again.
/// assert!(!m.exists(key));
/// m.insert(d); // OK - now we've
/// assert_eq!(m.lookup(key).unwrap(), &d);
/// }
/// ```
fn kill(&mut self, key: &H256) {
if match self.data.get_mut(key) {
Some(&mut (_, ref mut x)) => { *x -= 1; false }
None => true
}{ // ... None falls through into...
self.data.insert(*key, (Bytes::new(), -1));
self.data.insert(key.clone(), (Bytes::new(), -1));
}
}
}