This commit is contained in:
Quentin 2020-11-23 17:49:21 +01:00
parent ba1f8060fe
commit 8722e27600
2 changed files with 31 additions and 4 deletions

View file

@ -8,6 +8,9 @@ use garage_util::error::Error;
use crate::key_table::PermissionSet; use crate::key_table::PermissionSet;
// We import the same file but in its version 0.1.0.
// We can then access v0.1.0 data structures.
// We use them to perform migrations.
use model010::bucket_table as prev; use model010::bucket_table as prev;
#[derive(PartialEq, Clone, Debug, Serialize, Deserialize)] #[derive(PartialEq, Clone, Debug, Serialize, Deserialize)]

View file

@ -2,7 +2,26 @@ use serde::{Deserialize, Serialize};
use garage_util::data::*; use garage_util::data::*;
/// Conflict-free replicated data type (CRDT)
///
/// CRDT are a type of data structures that do not require coordination.
/// In other words, we can edit them in parallel, we will always
/// find a way to merge it.
///
/// A general example is a counter. Its initial value is 0.
/// Alice and Bob get a copy of the counter.
/// Alice does +1 on her copy, she reads 1.
/// Bob does +3 on his copy, he reads 3.
/// Now, it is easy to merge their counters, order does not count:
/// we always get 4.
///
/// Learn more about CRDT [on Wikipedia](https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type)
pub trait CRDT { pub trait CRDT {
/// Merge the two datastructures according to the CRDT rules
///
/// # Arguments
///
/// * `other` - the other copy of the CRDT
fn merge(&mut self, other: &Self); fn merge(&mut self, other: &Self);
} }
@ -19,6 +38,9 @@ where
// ---- LWW Register ---- // ---- LWW Register ----
/// Last Write Win (LWW)
///
/// LWW is a very simple
#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)] #[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
pub struct LWW<T> { pub struct LWW<T> {
ts: u64, ts: u64,
@ -64,8 +86,9 @@ where
} }
} }
// ---- Boolean (true as absorbing state) ---- /// Boolean
///
/// with True as absorbing state
#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq)] #[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq)]
pub struct Bool(bool); pub struct Bool(bool);
@ -87,8 +110,9 @@ impl CRDT for Bool {
} }
} }
// ---- LWW Map ---- /// Last Write Win Map
///
///
#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)] #[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
pub struct LWWMap<K, V> { pub struct LWWMap<K, V> {
vals: Vec<(K, u64, V)>, vals: Vec<(K, u64, V)>,