Crate hashgraph_like_consensus 

A lightweight consensus library for making binary decisions in P2P networks.

This library implements the Hashgraph-like Consensus Protocol, which lets groups of peers vote on proposals and reach agreement even when some peers are unreliable or malicious. It’s designed to be fast (O(log n) rounds), secure (Byzantine fault tolerant), and easy to embed in your application.

How it works

1. Someone creates a types::CreateProposalRequest within a scope.
2. Peers cast votes (yes/no), each cryptographically signed and linked into a hashgraph.
3. Once enough votes are collected the session transitions to session::ConsensusState::ConsensusReached and a types::ConsensusEvent is emitted.

Getting started

The main entry point is service::DefaultConsensusService (a type alias for service::ConsensusService with in-memory storage and broadcast events).

use hashgraph_like_consensus::{
    api::ConsensusServiceAPI,
    scope::ScopeID,
    service::DefaultConsensusService,
    types::CreateProposalRequest,
};
use alloy::signers::local::PrivateKeySigner;

let service = DefaultConsensusService::default();
let scope = ScopeID::from("my-scope");
let signer = PrivateKeySigner::random();

let proposal = service
    .create_proposal(
        &scope,
        CreateProposalRequest::new(
            "Upgrade contract".into(),
            b"Switch to v2".to_vec(),
            signer.address().as_slice().to_vec(),
            3,    // expected voters
            60,   // expiration (seconds from now)
            true, // tie-breaker: YES wins on equality
        )?,
    )
    .await?;

let vote = service
    .cast_vote(&scope, proposal.proposal_id, true, signer)
    .await?;

Modules

Module	Purpose
service	Main ConsensusService and DefaultConsensusService
api	ConsensusServiceAPI trait defining the public contract
session	ConsensusSession, ConsensusConfig, and ConsensusState
scope	ConsensusScope trait and ScopeID alias
scope_config	Per-scope defaults (ScopeConfig, NetworkType)
types	Request/event types (CreateProposalRequest, ConsensusEvent)
storage	ConsensusStorage trait and InMemoryConsensusStorage
events	ConsensusEventBus trait and BroadcastEventBus
error	ConsensusError enum
utils	Low-level validation and hashing helpers

Modules

api

Public API trait for the consensus service.

error

Error types for the consensus library.

events

protos

scope

scope_config

Scope-level configuration for consensus defaults.

service

service_consensus

Implementation of ConsensusServiceAPI for ConsensusService.

service_stats

Scope-level statistics for monitoring consensus activity.

session

Consensus session and configuration types.

storage

Storage trait and default in-memory implementation.

types

Core request and event types.

utils

Low-level helpers for hashing, signing, validation, and consensus calculation.