LWW-Element-Dictionary
👓 Introduction
In distributed computing, a conflict-free replicated data type (CRDT) is a data structure that is replicated across multiple computers in a network, with the following features:
- The application can update any replica independently, concurrently and without coordinating with other replicas.
- An algorithm (itself part of the data type) automatically resolves any inconsistencies that might occur.
- Although replicas may have different state at any particular point in time, they are guaranteed to eventually converge.
A state-based CRDT (CvRDT) must...
- Have a partial order to the values.
- "Monotonically increase" in state, meaning a new state only ever succeeds the current state in the value's ordering.
- Define a merge function ("least upper bound") which is idempotent and order-independent.
Different from LWW-Element-Set, LWW-Element-Dictionary store Object/Dictionary which is Element but not only storing string. It gives various data type option on using CRDT.
✨ Features
- Dictionary List that works under CRDTs Principle
- Add (Only latest element will be added if key already exists)
- Update (Only latest element will be updated if key already exists)
- Lookup (Only element in Addset with latest timestamp can be lookup if RemoveSet has same key)
- Remove (Add element into RemoveSet if not exist in Add Set or the element is later then AddSet element with same key)
- Merge two LWW-Element-Dictionary withou any conflict (Merge two dicts under go LWW CRDTs princial)
📦 Install
$ git clone https://github.com/dominwong4/LWW-Element-Dictionary
$ cd LWW-Element-Dictionary
$ npm install
# or
$ yarn install
# or
$ pnpm install🧪 Test
$ npm test
$ npm coverage
# or
$ yarn test
$ yarn coverage
# or
$ pnpm test
$ pnpm coverage🔨 Usage
import { LWWElementDictionary } from '../LWWElementDictionary';
import { Element } from '../utils/types';
const dict = new LWWElementDictionary();
const dict2 = new LWWElementDictionary();
const element1: Element = {
string_data: 'test', //optional
timestamp: 1, //required
};
const element2: Element = {
string_data: 'test2',
number_data: 123,
timestamp: 2,
};
dict.add('key1', element1);
dict2.add('key2', eleemnt2);
dict.lookup('key1'); //return True
dict2.lookup('key2'); //return True
dict.remove('key1', 2);
dict.lookup('key1'); //return False
dict2.remove('key2', 1);
dict2.lookup('key2'); //return True
dict.merge(dict2);