Key-Value Database Raft Distributed System

Prerequisites

• Timer: Callback-Timer
• RPC: Third-Party library buttonrpc
• State Machine: Key-Value DataBase

Features

• Leader election
• Replication and recovery
• Snapshot and log compaction.

Optimization

• Follower tell its expect next log rather than try.
• design multi-thread architecture to accelerate RquestVote and AppendEntries
• set log_increment variable and binary search to optimize matchIndex updating.
• use copy-on-write technique (fork in Linux) for snapshot.

Run

prerequisite

• cmake
• make

build

./make.sh

if you want to remove log and other temp file and build

./clearmake.sh

or just want to remove log and other temp file

./rmtemp.sh

Run

bin/kvRaft/kvRaft [id] #e.g. bin/kvRaft/kvRaft 1

then you will see configure steps and run.

---- Configuring... 
- server connection done.
- term&vote_for done.
- snapshot warning: no snapshot found. 
- logs done.
---- Configuring done!
candidate[2] is calling request_vote, term[1], last_log-term[0]-index[0]

Make Your Distributed System

In Raft class, there are three virtual method, just inherit Raft class and override these to make your Distributed System.

class Raft {
    virtual void apply(const string& command); //apply command to state machine.
    virtual void install_snapshot(const string& filename); //install snapshot to file.
    virtual void load_snapshot(const string& filename); //load snapshot from file.
}

Implementation Details

architecture and more implementation description see in Wiki

TODO

• feature: member change.
• snapshot:
  • leader must occasionally send snapshots to followers that lag behind
  • let follower rather leader create snapshot send to other .