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Unittest IntegrationTest

LFT2 is a new consensus algorithm inspired by PBFT. It improves TPS with reducing a pair of votes compared to PBFT when nodes make a consensus. A concept, 'Candidate' has been introduced for keeping safety.

This is implemented as a library. So not only blockchain but also any application which requires a byzantine fault tolerance consensus algorithm can integrate it.

This contains an example application for easy understanding. You can run it without integration. Also it composes multiple nodes in this single app. You can simulate byzantine node actions and observe how it tolerates the actions.

White paper [English] [Korean].

Example Application

You can run example app using this command.

$ lft

This command runs 4 nodes. They make data as results of consensus. If you want to run it with 10 nodes then run this command below.

$ lft -n 10

You can see a lot of event logs.

16:18:34,085 0xd32b RoundEndEvent(is_success=True,epoch_num=1,round_num=1,candidate_id=0xd4ad,commit_id=0x6765)

Event log consists of time, node id and event. This log means round 1 ends successfully with deciding a new candidate. Each round makes a consensus to determine one candidate. A candidate is committed after when next new candidate connected to the candidate is decided. In this case 0xd4ad is connected to 0x6765. 0x6765 has already been decided in previous round.


$ lft record

It records event logs for replaying. The log path is ./data. It contains all nodes' events.

$ lft replay -t 1abde1d6c2eb942df4686116d64f889d

The argument 1abde1d6c2eb942df4686116d64f889d is one of nodes' id located in log path after running with recording command.


Some components are provided for integration. Applications which want to use LFT have to customize abstract classes.

Data(Block), DataFactory(BlockFactory), Vote, VoteFactory, Epoch

The applications have to post the event.


The applications must listen the events.

RoundEnd, BroadcastData, BroadcastVote, ReceiveData, ReceiveVote

Note that LFT2 is not responsible for node communication, storing blocks and executing transactions. So the applications must implement them.