Sequoiadb 测试体验系列之六 – Java 开发3

上一篇笔记中更新了在集合中的删除，更新，查询等操作。这次尝试一下SequoiaDB的集群操作。包括复制组的创建和删除，复制组的启动和停止，在复制组中添加、删除、启动、停止节点，获取复制组中的主从节点等。

import java.util.ArrayList;
import java.util.List;

import org.bson.BSONObject;
import org.bson.BasicBSONObject;

import com.sequoiadb.base.Node.NodeStatus;
import com.sequoiadb.base.DBCursor;
import com.sequoiadb.base.Node;
import com.sequoiadb.base.ReplicaGroup;
import com.sequoiadb.base.Sequoiadb;
import com.sequoiadb.exception.BaseException;

public class BlogRG {

static String rgName = "testRG";
static String hostName = "sdbserver1";

public static void main(String[] args) {

//连接数据库
String host = "192.168.20.46";
String port = "11810";
String usr = "admin";
String password = "admin";

Sequoiadb sdb = null;

try {
sdb = new Sequoiadb(host + ":" + port, usr, password);
} catch (BaseException e) {
e.printStackTrace();
System.exit(1);
}

//打印有关复制组信息（名称、个数）
printGroupInfo(sdb);

//清除环境，删掉重复的复制组
if(isGroupExist(sdb,rgName)){
System.out.println("Removing the old replica group...");
sdb.removeReplicaGroup(rgName);
}

printGroupInfo(sdb);

//添加新复制组
System.out.println("Adding the new replica group...");
ReplicaGroup rg = sdb.createReplicaGroup(rgName);

printGroupInfo(sdb);

//打印复制组内节点信息
System.out.println("Tere are " + rg.getNodeNum(NodeStatus.SDB_NODE_ALL) + " nodes in the group.");

//添加三个新的节点
Node node1 = addNode(rg,50000);
Node node2 = addNode(rg,50010);
Node node3 = addNode(rg,50020);

//打印复制组内节点信息
System.out.println("Tere are " + rg.getNodeNum(NodeStatus.SDB_NODE_ALL) + " nodes in the group.");

//获取复制组的主从节点
Node master = rg.getMaster();
System.out.println("The master node is " +master.getPort());
System.out.println("The slave node is " + rg.getSlave().getPort());

//停止主节点
System.out.println("stoping the master node...");
master.stop();

//等待主节点停止
while(rg.getMaster().getPort() == master.getPort()){
try{
Thread.sleep(2000);
} catch (Exception e){
}
}

//查看新选举的主节点
System.out.println("re-selecting the master node...");
System.out.println("The master node is " + rg.getMaster().getPort());

}

private static void printGroupInfo(Sequoiadb sdb){
ArrayList names = sdb.getReplicaGroupNames();
int count = 0;
System.out.print("The replica groups are ");
for (Object name : names){
count++;
System.out.print((String)name + ", ");
}
System.out.println("\nThere are " + count + " replica groups in total.");
}

private static boolean isGroupExist(Sequoiadb sdb, String rgName){
ArrayList names = sdb.getReplicaGroupNames();
for (Object name : names){
if(rgName.equals((String)name))
return true;
}
return false;
}

private static Node addNode(ReplicaGroup rg, int port){
if(rg.getNode(hostName,port)!= null)
rg.removeNode(hostName, port, null);
Node node = rg.createNode(hostName,port,"/opt/sequoiadb/database/test/" + port,null);
System.out.println("starting the node " + port + "...");
node.start();
return node;
}

}

上面的代码在数据库中添加新的复制组，并在新的复制组内添加三个主节点，数据组自动选举出新的主节点，停止主节点后，复制组内重新选举新的主节点。

运行以上代码后的结果是：

The replica groups are SYSCatalogGroup, datagroup, testRG,
There are 3 replica groups in total.
Removing the old replica group...
The replica groups are SYSCatalogGroup, datagroup,
There are 2 replica groups in total.
Adding the new replica group...
The replica groups are SYSCatalogGroup, datagroup, testRG,
There are 3 replica groups in total.
Tere are 0 nodes in the group.
starting the node 50000...
starting the node 50010...
starting the node 50020...
Tere are 3 nodes in the group.
The master node is 50000
The slave node is 50010
stoping the master node...
re-selecting the master node...
The master node is 50020

可以看出，程序开始运行时，数据库内有三个复制组，其中testRG是上次运行遗留下来的无用复制组，另外两个是数据库默认的两个复制组。通过removeReplicaGroup()方法删除多余的testRG复制组，之后通过createReplicaGroup()添加新的testRG复制组，并且在新建的组内通过createNode()和start()添加并启动50000,50010,50020三个新的节点。通过getMaster()和getSlave()方法获取组内的主从节点，并利用stop()停止主节点50000，主节点完全停止后，组内将重新自动选举出新的主节点50020。

运行完成后，通过shell控制台查看数据库testRG复制组的详细情况：

>rg.getDetail()
{
"Group": [
{
"HostName": "sdbserver1",
"dbpath": "/opt/sequoiadb/database/test/50000",
"Service": [
{
"Type": 0,
"Name": "50000"
},
{
"Type": 1,
"Name": "50001"
},
{
"Type": 2,
"Name": "50002"
}
],
"NodeID": 1053
},
{
"HostName": "sdbserver1",
"dbpath": "/opt/sequoiadb/database/test/50010",
"Service": [
{
"Type": 0,
"Name": "50010"
},
{
"Type": 1,
"Name": "50011"
},
{
"Type": 2,
"Name": "50012"
}
],
"NodeID": 1054
},
{
"HostName": "sdbserver1",
"dbpath": "/opt/sequoiadb/database/test/50020",
"Service": [
{
"Type": 0,
"Name": "50020"
},
{
"Type": 1,
"Name": "50021"
},
{
"Type": 2,
"Name": "50022"
}
],
"NodeID": 1055
}
],
"GroupID": 1023,
"GroupName": "testRG",
"PrimaryNode": 1055,
"Role": 0,
"Status": 0,
"Version": 4,
"_id": {
"$oid": "53d9d38e14a63a88c621edd8"
}
}
Return 1 row(s).
Takes 0.4716s.

可以看出组内有三个节点，主节点（PrimaryNode）为1055，也就是50020。