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use std::cmp::Ordering;
use std::fmt::{self, Debug, Display};
use std::mem;
use serde::{Deserialize, Serialize};
use crate::ctx::{AddCtx, ReadCtx};
use crate::traits::{Causal, CmRDT, CvRDT};
use crate::vclock::{Actor, VClock};
pub trait Val: Debug + Clone {}
impl<T: Debug + Clone> Val for T {}
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MVReg<V: Val, A: Actor> {
vals: Vec<(VClock<A>, V)>,
}
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum Op<V: Val, A: Actor> {
Put {
clock: VClock<A>,
val: V,
},
}
impl<V: Val + Display, A: Actor + Display> Display for MVReg<V, A> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "|")?;
for (i, (ctx, val)) in self.vals.iter().enumerate() {
if i > 0 {
write!(f, ", ")?;
}
write!(f, "{}@{}", val, ctx)?;
}
write!(f, "|")
}
}
impl<V: Val + PartialEq, A: Actor> PartialEq for MVReg<V, A> {
fn eq(&self, other: &Self) -> bool {
for dot in self.vals.iter() {
let num_found = other.vals.iter().filter(|d| d == &dot).count();
if num_found == 0 {
return false;
}
assert_eq!(num_found, 1);
}
for dot in other.vals.iter() {
let num_found = self.vals.iter().filter(|d| d == &dot).count();
if num_found == 0 {
return false;
}
assert_eq!(num_found, 1);
}
true
}
}
impl<V: Val + Eq, A: Actor> Eq for MVReg<V, A> {}
impl<V: Val, A: Actor> Causal<A> for MVReg<V, A> {
fn forget(&mut self, clock: &VClock<A>) {
self.vals = self
.vals
.clone()
.into_iter()
.filter_map(|(mut val_clock, val)| {
val_clock.forget(&clock);
if val_clock.is_empty() {
None
} else {
Some((val_clock, val))
}
})
.collect()
}
}
impl<V: Val, A: Actor> Default for MVReg<V, A> {
fn default() -> Self {
MVReg::new()
}
}
impl<V: Val, A: Actor> CvRDT for MVReg<V, A> {
fn merge(&mut self, other: Self) {
self.vals = mem::replace(&mut self.vals, Vec::new())
.into_iter()
.filter(|(clock, _)| other.vals.iter().filter(|(c, _)| clock < c).count() == 0)
.collect();
self.vals.extend(
other
.vals
.into_iter()
.filter(|(clock, _)| self.vals.iter().filter(|(c, _)| clock < c).count() == 0)
.filter(|(clock, _)| self.vals.iter().all(|(c, _)| clock != c))
.collect::<Vec<_>>(),
);
}
}
impl<V: Val, A: Actor> CmRDT for MVReg<V, A> {
type Op = Op<V, A>;
fn apply(&mut self, op: Self::Op) {
match op {
Op::Put { clock, val } => {
if clock.is_empty() {
return;
}
self.vals
.retain(|(val_clock, _)| match val_clock.partial_cmp(&clock) {
None | Some(Ordering::Greater) => true,
_ => false,
});
let mut should_add = true;
for (existing_clock, _) in self.vals.iter() {
if existing_clock > &clock {
should_add = false;
}
}
if should_add {
self.vals.push((clock, val));
}
}
}
}
}
impl<V: Val, A: Actor> MVReg<V, A> {
pub fn new() -> Self {
MVReg { vals: Vec::new() }
}
pub fn write(&self, val: V, ctx: AddCtx<A>) -> Op<V, A> {
Op::Put {
clock: ctx.clock,
val,
}
}
pub fn read(&self) -> ReadCtx<Vec<V>, A> {
let clock = self.clock().clone();
let concurrent_vals = self.vals.iter().cloned().map(|(_, v)| v).collect();
ReadCtx {
add_clock: clock.clone(),
rm_clock: clock,
val: concurrent_vals,
}
}
fn clock(&self) -> VClock<A> {
self.vals
.iter()
.fold(VClock::new(), |mut accum_clock, (c, _)| {
accum_clock.merge(c.clone());
accum_clock
})
}
}