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https://github.com/wenweihu86/raft-java
Raft Java implementation which is simple and easy to understand.
https://github.com/wenweihu86/raft-java
distributed-file-system distributed-storage raft raft-algorithm raft-consensus raft-consensus-algorithm raft-java raft-protocol
Last synced: about 2 months ago
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Raft Java implementation which is simple and easy to understand.
- Host: GitHub
- URL: https://github.com/wenweihu86/raft-java
- Owner: wenweihu86
- License: apache-2.0
- Created: 2017-05-02T11:29:58.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2024-01-10T04:43:19.000Z (8 months ago)
- Last Synced: 2024-06-12T08:13:43.025Z (3 months ago)
- Topics: distributed-file-system, distributed-storage, raft, raft-algorithm, raft-consensus, raft-consensus-algorithm, raft-java, raft-protocol
- Language: Java
- Homepage:
- Size: 370 KB
- Stars: 1,162
- Watchers: 44
- Forks: 402
- Open Issues: 26
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# raft-java
Raft implementation library for Java.
参考自[Raft论文](https://github.com/maemual/raft-zh_cn)和Raft作者的开源实现[LogCabin](https://github.com/logcabin/logcabin)。
# 支持的功能
* leader选举
* 日志复制
* snapshot
* 集群成员动态更变
## Quick Start
在本地单机上部署一套3实例的raft集群，执行如下脚本：
cd raft-java-example && sh deploy.sh
该脚本会在raft-java-example/env目录部署三个实例example1、example2、example3；
同时会创建一个client目录，用于测试raft集群读写功能。
部署成功后，测试写操作，通过如下脚本：
cd env/client
./bin/run_client.sh "list://127.0.0.1:8051,127.0.0.1:8052,127.0.0.1:8053" hello world
测试读操作命令：
./bin/run_client.sh "list://127.0.0.1:8051,127.0.0.1:8052,127.0.0.1:8053" hello
# 使用方法
下面介绍如何在代码中使用raft-java依赖库来实现一套分布式存储系统。
## 配置依赖（暂未发布到maven中央仓库，需要手动install到本地）
```
com.github.wenweihu86.raft
raft-java-core
1.9.0
```
## 定义数据写入和读取接口
```protobuf
message SetRequest {
string key = 1;
string value = 2;
}
message SetResponse {
bool success = 1;
}
message GetRequest {
string key = 1;
}
message GetResponse {
string value = 1;
}
```
```java
public interface ExampleService {
Example.SetResponse set(Example.SetRequest request);
Example.GetResponse get(Example.GetRequest request);
}
```
## 服务端使用方法
1. 实现状态机StateMachine接口实现类
```java
// 该接口三个方法主要是给Raft内部调用
public interface StateMachine {
/**
* 对状态机中数据进行snapshot，每个节点本地定时调用
* @param snapshotDir snapshot数据输出目录
*/
void writeSnapshot(String snapshotDir);
/**
* 读取snapshot到状态机，节点启动时调用
* @param snapshotDir snapshot数据目录
*/
void readSnapshot(String snapshotDir);
/**
* 将数据应用到状态机
* @param dataBytes 数据二进制
*/
void apply(byte[] dataBytes);
}
```
2. 实现数据写入和读取接口
```
// ExampleService实现类中需要包含以下成员
private RaftNode raftNode;
private ExampleStateMachine stateMachine;
```
```
// 数据写入主要逻辑
byte[] data = request.toByteArray();
// 数据同步写入raft集群
boolean success = raftNode.replicate(data, Raft.EntryType.ENTRY_TYPE_DATA);
Example.SetResponse response = Example.SetResponse.newBuilder().setSuccess(success).build();
```
```
// 数据读取主要逻辑，由具体应用状态机实现
Example.GetResponse response = stateMachine.get(request);
```
3. 服务端启动逻辑
```
// 初始化RPCServer
RPCServer server = new RPCServer(localServer.getEndPoint().getPort());
// 应用状态机
ExampleStateMachine stateMachine = new ExampleStateMachine();
// 设置Raft选项，比如：
RaftOptions.snapshotMinLogSize = 10 * 1024;
RaftOptions.snapshotPeriodSeconds = 30;
RaftOptions.maxSegmentFileSize = 1024 * 1024;
// 初始化RaftNode
RaftNode raftNode = new RaftNode(serverList, localServer, stateMachine);
// 注册Raft节点之间相互调用的服务
RaftConsensusService raftConsensusService = new RaftConsensusServiceImpl(raftNode);
server.registerService(raftConsensusService);
// 注册给Client调用的Raft服务
RaftClientService raftClientService = new RaftClientServiceImpl(raftNode);
server.registerService(raftClientService);
// 注册应用自己提供的服务
ExampleService exampleService = new ExampleServiceImpl(raftNode, stateMachine);
server.registerService(exampleService);
// 启动RPCServer，初始化Raft节点
server.start();
raftNode.init();
```