本文主要通过样例代码介绍如何使用只读实例。

注意事项

  • 数据导入只能将数据导入主实例。
  • 通过Gremlin DSL写数据只能将数据写入主实例。
  • 查询请求可以发送给主实例或只读实例。

样例代码

样例模拟社交场景，进行新增查询、建立关系、查询关系等操作。
  • 依赖包
    <dependency>
    <groupId>org.apache.tinkerpop</groupId>
    <artifactId>gremlin-driver</artifactId>
    <version>3.4.3</version>
</dependency>
  • 实例信息
    主实例:
host: $master_host

只读实例1:
host: $read_host1

只读实例2:
host: $read_host2

账号信息：
username: $username
password: $password
  • 实例链接YAML文件
    • 主实例YAML文件 remote-master.yaml，用来初始化写客户端
      # remote-master.yaml
hosts: [$master_host]
port: $port
username: $username
password: $password
connectionPool: {
  maxSize: 16,
  maxInProcessPerConnection: 2,
  maxContentLength: 81928192
}
serializer: { 
  className: org.apache.tinkerpop.gremlin.driver.ser.GraphBinaryMessageSerializerV1 
}
    • 查询实例YAML文件 remote-read.yaml，可配置一批GDB实例来进行查询任务，客户端有负载均衡功能。
      # remote-read.yaml
hosts: [$master_host,$read_host1,$read_host2]
port: $port
username: $username
password: $password
connectionPool: {
  maxSize: 48,
  maxInProcessPerConnection: 2,
  maxContentLength: 81928192
}
serializer: { 
  className: org.apache.tinkerpop.gremlin.driver.ser.GraphBinaryMessageSerializerV1 
}
  • 参考代码
    package com.alibaba.gdb.test;

import org.apache.tinkerpop.gremlin.driver.*;

import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author xxx
 * @date 2021/01/19
 */
public class ReadInstance {
    private static Cluster masterCluster = null;
    private static Client  masterClient = null;

    private static Cluster readCluster = null;
    private static Client  readClient = null;

    private static final String masterYamlFile = "remote-master.yaml";
    private static final String readYamlFile = "remote-read.yaml";

    // 返回写client
    public Client getMasterClient() throws Exception {
        if (masterClient == null) {
            File file = new File(masterYamlFile);
            masterCluster = Cluster.build(file).create();
            masterClient = masterCluster.connect().init();
        }
        return masterClient;
    }

    // 返回查询client
    public Client getReadClient() throws Exception {
        if (readClient == null) {
            File file = new File(readYamlFile);
            readCluster = Cluster.build(file).create();
            readClient = readCluster.connect().init();
        }
        return readClient;
    }

    // 新写入一个用户
    public boolean addUser(String userId, String name, int age, double height, String city) throws Exception {
        String dsl = "g.addV('user').property(id, userId).property('name', name).property('age', age).property('height', height).property('city', city)";
        Map<String , Object> map = new HashMap<>();
        map.put("userId", userId);
        map.put("name", name);
        map.put("age", age);
        map.put("height", height);
        map.put("city", city);
        List<Result> resultList = getMasterClient().submit(dsl, map).all().join();
        return true;
    }

    // 新建立两个用户的关系
    public boolean addReleationship(String userId1, String userId2, long timeStamp) throws Exception {
        String dsl = "g.addE('friend').from(V(userId1)).to(V(userId2)).property('timeStamp', timeStamp)";
        Map<String , Object> map = new HashMap<>();
        map.put("userId1", userId1);
        map.put("userId2", userId2);
        map.put("timeStamp", timeStamp);
        List<Result> resultList = getMasterClient().submit(dsl, map).all().join();
        return true;
    }

    // 查询某个用户所有的好友中和自己年龄一行的好友,返回好友的信息
    public List<Result> querySameAgeFriend(String userId) throws Exception {
        String dsl = "g.V().hasId(userId).as('a').both('friend').where(eq('a')).by('age').valueMap()";
        Map<String , Object> map = new HashMap<>();
        map.put("userId", userId);
        List<Result> resultList = getReadClient().submit(dsl, map).all().join();
        return resultList;
    }

    // 查询用户好友的好友, 哪些还不是自己的好友,返回他们的信息
    public List<Result> query2HopFriend(String userId) throws Exception {
        String dsl = "g.V().hasId(userId).both('friend').aggregate('my_friend').both('friend').where(without('my_friend')).valueMap()";
        Map<String , Object> map = new HashMap<>();
        map.put("userId", userId);
        List<Result> resultList = getReadClient().submit(dsl, map).all().join();
        return resultList;
    }
}