Struct GCounter 

pub struct GCounter<V>
where
    V: Display + AddAssign + Clone + Copy + for<'v> Sum<&'v V> + Ord + Add<Output = V> + Default,
{
    pub id: NodeId,
    pub counter: HashMap<NodeId, V>,
    pub default_value: V,
}

Fields

id: NodeId

The identification number of the delta.

counter: HashMap<NodeId, V>

default_value: V

The default value of V. For example, the default value of i32 is 0.

Implementations

impl<V> GCounter<V>

where V: Display + AddAssign + Clone + Copy + for<'v> Sum<&'v V> + Ord + Add<Output = V> + Default,

pub fn new(id: NodeId) -> Self

pub fn local(&self) -> &V

Returns the current value of the local counter.

pub fn read(&self) -> V

Returns the sum of all replica values in the counter.

pub fn inc(&mut self, to_sum: Option<V>)

A mutator that performs an increment of to_sum in the counter.

Example

use crdt_sample::{GCounter,NodeId};
 
let id = NodeId::new(1, "a".to_string());
let mut gcounter: GCounter<i32> = GCounter::new(id);
 
gcounter.inc(Some(1));
let result_local = gcounter.local();    // Reads the local replica
let result_read = gcounter.read();      // Sum of all counters.
assert_eq!(*result_local, 1);
assert_eq!(result_read, 1);

pub fn join(&mut self, gcounter: &GCounter<V>)

Joins the delta_gcounter with a delta or another delta_gcounter.

Examples

use crdt_sample::{GCounter, NodeId};
let id1 = NodeId::new(1, "a".to_string());
let id2 = NodeId::new(2, "a".to_string());
let id3 = NodeId::new(3, "a".to_string());
let mut gcounter_1: GCounter<i32> = GCounter::new(id1);
let mut gcounter_2: GCounter<i32> = GCounter::new(id2);
let mut gcounter_3: GCounter<i32> = GCounter::new(id3);

gcounter_1.inc(Some(3));
gcounter_2.inc(Some(5));
gcounter_3.inc(Some(1));

// Join gcounter_1
gcounter_3.join(&gcounter_1);
let result_read = gcounter_3.read();
let result_local = gcounter_3.local();
assert_eq!(result_read, 4);
assert_eq!(*result_local, 1);

// join gcounter_2
gcounter_3.join(&gcounter_2);
let result_read = gcounter_3.read();
let result_local = gcounter_3.local();
assert_eq!(result_read, 9);
assert_eq!(*result_local, 1);