mirror of
https://github.com/0glabs/0g-storage-node.git
synced 2024-11-15 04:25:19 +00:00
136 lines
3.5 KiB
Rust
136 lines
3.5 KiB
Rust
//! Hash infrastructure for items in Merkle Tree.
|
|
|
|
use core::hash::Hasher;
|
|
|
|
/// A hashable type.
|
|
///
|
|
/// Types implementing `Hashable` are able to be [`hash`]ed with an instance of
|
|
/// [`Hasher`].
|
|
///
|
|
/// ## Implementing `Hashable`
|
|
///
|
|
/// You can derive `Hashable` with `#[derive(Hashable)]` if all fields implement `Hashable`.
|
|
/// The resulting hash will be the combination of the values from calling
|
|
/// [`hash`] on each field.
|
|
///
|
|
/// ```text
|
|
/// #[macro_use]
|
|
/// extern crate merkle_light_derive;
|
|
/// extern crate merkle_light;
|
|
///
|
|
/// use merkle_light::hash::Hashable;
|
|
///
|
|
/// fn main() {
|
|
/// #[derive(Hashable)]
|
|
/// struct Foo {
|
|
/// name: String,
|
|
/// country: String,
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// If you need more control over how a value is hashed, you can of course
|
|
/// implement the `Hashable` trait yourself:
|
|
///
|
|
/// ```
|
|
/// extern crate merkle_light;
|
|
///
|
|
/// use merkle_light::hash::Hashable;
|
|
/// use std::hash::Hasher;
|
|
/// use std::collections::hash_map::DefaultHasher;
|
|
///
|
|
/// fn main() {
|
|
/// struct Person {
|
|
/// id: u32,
|
|
/// name: String,
|
|
/// phone: u64,
|
|
/// }
|
|
///
|
|
/// impl<H: Hasher> Hashable<H> for Person {
|
|
/// fn hash(&self, state: &mut H) {
|
|
/// self.id.hash(state);
|
|
/// self.name.hash(state);
|
|
/// self.phone.hash(state);
|
|
/// }
|
|
/// }
|
|
///
|
|
/// let foo = Person{
|
|
/// id: 1,
|
|
/// name: String::from("blah"),
|
|
/// phone: 2,
|
|
/// };
|
|
///
|
|
/// let mut hr = DefaultHasher::new();
|
|
/// foo.hash(&mut hr);
|
|
/// assert_eq!(hr.finish(), 7101638158313343130)
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// ## `Hashable` and `Eq`
|
|
///
|
|
/// When implementing both `Hashable` and [`Eq`], it is important that the following
|
|
/// property holds:
|
|
///
|
|
/// ```text
|
|
/// k1 == k2 -> hash(k1) == hash(k2)
|
|
/// ```
|
|
///
|
|
/// In other words, if two keys are equal, their hashes must also be equal.
|
|
pub trait Hashable<H: Hasher> {
|
|
/// Feeds this value into the given [`Hasher`].
|
|
///
|
|
/// [`Hasher`]: trait.Hasher.html
|
|
fn hash(&self, state: &mut H);
|
|
|
|
/// Feeds a slice of this type into the given [`Hasher`].
|
|
///
|
|
/// [`Hasher`]: trait.Hasher.html
|
|
fn hash_slice(data: &[Self], state: &mut H)
|
|
where
|
|
Self: Sized,
|
|
{
|
|
for piece in data {
|
|
piece.hash(state);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// A trait for hashing an arbitrary stream of bytes for calculating merkle tree
|
|
/// nodes.
|
|
///
|
|
/// T is a hash item must be of known size at compile time, globally ordered, with
|
|
/// default value as a neutral element of the hash space. Neutral element is
|
|
/// interpreted as 0 or nil and required for evaluation of merkle tree.
|
|
///
|
|
/// [`Algorithm`] breaks the [`Hasher`] contract at `finish()`, but that is intended.
|
|
/// This trait extends [`Hasher`] with `hash -> T` and `reset` state methods,
|
|
/// plus implements default behavior of evaluation of MT interior nodes.
|
|
pub trait Algorithm<T>: Hasher + Default
|
|
where
|
|
T: Clone + AsRef<[u8]>,
|
|
{
|
|
/// Returns the hash value for the data stream written so far.
|
|
fn hash(&mut self) -> T;
|
|
|
|
/// Reset Hasher state.
|
|
#[inline]
|
|
fn reset(&mut self) {
|
|
*self = Self::default();
|
|
}
|
|
|
|
/// Returns hash value for MT leaf (prefix 0x00).
|
|
#[inline]
|
|
fn leaf(&mut self, leaf: T) -> T {
|
|
self.write(leaf.as_ref());
|
|
self.hash()
|
|
}
|
|
|
|
/// Returns hash value for MT interior node (prefix 0x01).
|
|
#[inline]
|
|
fn node(&mut self, left: T, right: T) -> T {
|
|
self.write(left.as_ref());
|
|
self.write(right.as_ref());
|
|
self.hash()
|
|
}
|
|
}
|