[][src]Struct memory_db::MemoryDB

pub struct MemoryDB<H, KF, T, M = DefaultMemTracker<T>> where
    H: KeyHasher,
    KF: KeyFunction<H>,
    M: MemTracker<T>, 
{ /* fields omitted */ }

Reference-counted memory-based HashDB implementation.

Use new() to create a new database. Insert items with insert(), remove items with remove(), check for existence with contains() and lookup a hash to derive the data with get(). Clear with clear() and purge the portions of the data that have no references with purge().

If you're not using the MallocSizeOf implementation to track memory usage, set the M type parameter to NoopTracker.

Example

  use hash_db::{Hasher, HashDB, EMPTY_PREFIX};
  use keccak_hasher::KeccakHasher;
  use memory_db::{MemoryDB, HashKey};

  let mut m = MemoryDB::<KeccakHasher, HashKey<_>, Vec<u8>>::default();
  let d = "Hello world!".as_bytes();

  let k = m.insert(EMPTY_PREFIX, d);
  assert!(m.contains(&k, EMPTY_PREFIX));
  assert_eq!(m.get(&k, EMPTY_PREFIX).unwrap(), d);

  m.insert(EMPTY_PREFIX, d);
  assert!(m.contains(&k, EMPTY_PREFIX));

  m.remove(&k, EMPTY_PREFIX);
  assert!(m.contains(&k, EMPTY_PREFIX));

  m.remove(&k, EMPTY_PREFIX);
  assert!(!m.contains(&k, EMPTY_PREFIX));

  m.remove(&k, EMPTY_PREFIX);
  assert!(!m.contains(&k, EMPTY_PREFIX));

  m.insert(EMPTY_PREFIX, d);
  assert!(!m.contains(&k, EMPTY_PREFIX));
  m.insert(EMPTY_PREFIX, d);
  assert!(m.contains(&k, EMPTY_PREFIX));
  assert_eq!(m.get(&k, EMPTY_PREFIX).unwrap(), d);

  m.remove(&k, EMPTY_PREFIX);
  assert!(!m.contains(&k, EMPTY_PREFIX));

Implementations

impl<H, KF, T, M> MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: Default,
    KF: KeyFunction<H>,
    M: MemTracker<T>, 
[src]

Create a new MemoryDB from a given null key/data

pub fn remove_and_purge(
    &mut self,
    key: &<H as KeyHasher>::Out,
    prefix: Prefix
) -> Option<T>
[src]

Remove an element and delete it from storage if reference count reaches zero. If the value was purged, return the old value.

pub fn shrink_to_fit(&mut self)[src]

Shrinks the capacity of the map as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

impl<'a, H, KF, T, M> MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: From<&'a [u8]>,
    KF: KeyFunction<H>,
    M: MemTracker<T> + Default
[src]

pub fn from_null_node(null_key: &'a [u8], null_node_data: T) -> Self[src]

Create a new MemoryDB from a given null key/data

pub fn new(data: &'a [u8]) -> Self[src]

Create a new instance of Self.

pub fn default_with_root() -> (Self, H::Out)[src]

Create a new default instance of Self and returns Self and the root hash.

pub fn clear(&mut self)[src]

Clear all data from the database.

Examples

extern crate hash_db;
extern crate keccak_hasher;
extern crate memory_db;

use hash_db::{Hasher, HashDB, EMPTY_PREFIX};
use keccak_hasher::KeccakHasher;
use memory_db::{MemoryDB, HashKey};

fn main() {
  let mut m = MemoryDB::<KeccakHasher, HashKey<_>, Vec<u8>>::default();
  let hello_bytes = "Hello world!".as_bytes();
  let hash = m.insert(EMPTY_PREFIX, hello_bytes);
  assert!(m.contains(&hash, EMPTY_PREFIX));
  m.clear();
  assert!(!m.contains(&hash, EMPTY_PREFIX));
}

pub fn purge(&mut self)[src]

Purge all zero-referenced data from the database.

pub fn drain(&mut self) -> HashMap<KF::Key, (T, i32)>[src]

Return the internal key-value HashMap, clearing the current state.

pub fn raw(
    &self,
    key: &<H as KeyHasher>::Out,
    prefix: Prefix
) -> Option<(&T, i32)>
[src]

Grab the raw information associated with a key. Returns None if the key doesn't exist.

Even when Some is returned, the data is only guaranteed to be useful when the refs > 0.

pub fn consolidate(&mut self, other: Self)[src]

Consolidate all the entries of other into self.

pub fn keys(&self) -> HashMap<KF::Key, i32>[src]

Get the keys in the database together with number of underlying references.

Trait Implementations

impl<H, KF, T, M> AsHashDB<H, T> for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: Default + PartialEq<T> + for<'a> From<&'a [u8]> + Clone + Send + Sync,
    KF: KeyFunction<H> + Send + Sync,
    M: MemTracker<T> + Send + Sync
[src]

impl<H, KF, T, M> AsPlainDB<<H as Hasher>::Out, T> for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: Default + PartialEq<T> + for<'a> From<&'a [u8]> + Clone + Send + Sync,
    KF: KeyFunction<H> + Send + Sync,
    KF::Key: Borrow<[u8]> + for<'a> From<&'a [u8]>,
    M: MemTracker<T> + Send + Sync
[src]

impl<H, KF, T, M> Clone for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    KF: KeyFunction<H>,
    T: Clone,
    M: MemTracker<T> + Copy
[src]

impl<'a, H, KF, T, M> Default for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: From<&'a [u8]>,
    KF: KeyFunction<H>,
    M: MemTracker<T> + Default
[src]

impl<H, KF, T, M> Eq for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    KF: KeyFunction<H>,
    <KF as KeyFunction<H>>::Key: Eq + MaybeDebug,
    T: Eq + MaybeDebug,
    M: MemTracker<T> + Eq
[src]

impl<H, KF, T, M> HashDB<H, T> for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: Default + PartialEq<T> + for<'a> From<&'a [u8]> + Clone + Send + Sync,
    KF: Send + Sync + KeyFunction<H>,
    M: MemTracker<T> + Send + Sync
[src]

impl<H, KF, T, M> HashDBRef<H, T> for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: Default + PartialEq<T> + for<'a> From<&'a [u8]> + Clone + Send + Sync,
    KF: KeyFunction<H> + Send + Sync,
    M: MemTracker<T> + Send + Sync
[src]

impl<H, KF, T, M> MallocSizeOf for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    H::Out: MallocSizeOf,
    T: MallocSizeOf,
    KF: KeyFunction<H>,
    KF::Key: MallocSizeOf,
    M: MemTracker<T>, 
[src]

impl<H, KF, T, M> PartialEq<MemoryDB<H, KF, T, M>> for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    KF: KeyFunction<H>,
    <KF as KeyFunction<H>>::Key: Eq + MaybeDebug,
    T: Eq + MaybeDebug,
    M: MemTracker<T> + PartialEq
[src]

impl<H, KF, T, M> PlainDB<<H as Hasher>::Out, T> for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: Default + PartialEq<T> + for<'a> From<&'a [u8]> + Clone + Send + Sync,
    KF: Send + Sync + KeyFunction<H>,
    KF::Key: Borrow<[u8]> + for<'a> From<&'a [u8]>,
    M: MemTracker<T> + Send + Sync
[src]

impl<H, KF, T, M> PlainDBRef<<H as Hasher>::Out, T> for MemoryDB<H, KF, T, M> where
    H: KeyHasher,
    T: Default + PartialEq<T> + for<'a> From<&'a [u8]> + Clone + Send + Sync,
    KF: Send + Sync + KeyFunction<H>,
    KF::Key: Borrow<[u8]> + for<'a> From<&'a [u8]>,
    M: MemTracker<T> + Send + Sync
[src]

Auto Trait Implementations

impl<H, KF, T, M> RefUnwindSafe for MemoryDB<H, KF, T, M> where
    KF: RefUnwindSafe,
    M: RefUnwindSafe,
    T: RefUnwindSafe,
    <KF as KeyFunction<H>>::Key: RefUnwindSafe,
    <H as Hasher>::Out: RefUnwindSafe

impl<H, KF, T, M> Send for MemoryDB<H, KF, T, M> where
    KF: Send,
    M: Send,
    T: Send,
    <KF as KeyFunction<H>>::Key: Send,
    <H as Hasher>::Out: Send

impl<H, KF, T, M> Sync for MemoryDB<H, KF, T, M> where
    KF: Sync,
    M: Sync,
    T: Sync,
    <KF as KeyFunction<H>>::Key: Sync,
    <H as Hasher>::Out: Sync

impl<H, KF, T, M> Unpin for MemoryDB<H, KF, T, M> where
    KF: Unpin,
    M: Unpin,
    T: Unpin,
    <KF as KeyFunction<H>>::Key: Unpin,
    <H as Hasher>::Out: Unpin

impl<H, KF, T, M> UnwindSafe for MemoryDB<H, KF, T, M> where
    KF: UnwindSafe,
    M: UnwindSafe,
    T: UnwindSafe,
    <KF as KeyFunction<H>>::Key: UnwindSafe,
    <H as Hasher>::Out: UnwindSafe

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T> MallocSizeOfExt for T where
    T: MallocSizeOf
[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T

The resulting type after obtaining ownership.

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.