写了一个简单的数据库连接池

发布一个k8s部署视频：https://edu.youkuaiyun.com/course/detail/26967

课程内容：各种k8s部署方式。包括minikube部署，kubeadm部署，kubeasz部署，rancher部署，k3s部署。包括开发测试环境部署k8s，和生产环境部署k8s。

腾讯课堂连接地址https://ke.qq.com/course/478827?taid=4373109931462251&tuin=ba64518

第二个视频发布  https://edu.youkuaiyun.com/course/detail/27109

腾讯课堂连接地址https://ke.qq.com/course/484107?tuin=ba64518

介绍主要的k8s资源的使用配置和命令。包括configmap，pod，service，replicaset，namespace，deployment，daemonset，ingress，pv，pvc，sc，role，rolebinding，clusterrole，clusterrolebinding，secret，serviceaccount，statefulset，job，cronjob，podDisruptionbudget，podSecurityPolicy,networkPolicy,resourceQuota，limitrange，endpoint，event，conponentstatus，node，apiservice，controllerRevision等。

第三个视频发布：https://edu.youkuaiyun.com/course/detail/27574

详细介绍helm命令，学习helm chart语法，编写helm chart。深入分析各项目源码，学习编写helm插件

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import java.sql.Connection;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;


public class ConnectionPool {
	private static  ConcurrentHashMap<String,ConnectionEntity> idelConnections=null;
	private static  ConcurrentHashMap<String,ConnectionEntity> activeConnections=null;
	private static int initSize;
	private static int maxSize;
	private static AtomicInteger idelSize=new AtomicInteger(0);
	private static AtomicInteger activeSize=new AtomicInteger(0);
	private static ConnectionPool instance=null;
	private static Lock lock= new ReentrantLock();
	private  Object object=new Object();
	private ConnectionPool(int initSize,int maxSize){
		this.initSize=initSize;
		this.maxSize=maxSize;
		idelConnections=new ConcurrentHashMap<String,ConnectionEntity>();
		activeConnections=new ConcurrentHashMap<String,ConnectionEntity>();
		initConnections();
		new DetectFailConnection().start();
	}
	
	public  ConnectionEntity getConnection() throws InterruptedException, SQLException{
	    lock.lock();
	    try{
			if(idelSize.get()>0){
				if(idelConnections.size()<=0){
					throw new RuntimeException("");
				}
				String key=idelConnections.entrySet().iterator().next().getKey();
				ConnectionEntity entity=idelConnections.entrySet().iterator().next().getValue();
				entity.setStatus(Connection_Status.active);
				idelConnections.remove(key);				
				idelSize.decrementAndGet();
				if(entity.getConnection().isClosed()){
					return getConnection();
				}
				activeConnections.put(key, entity);
				activeSize.incrementAndGet();
				return entity;
			}
	    }finally{
	    	lock.unlock();
	    }
	    
	    if(activeSize.get()>maxSize){
	    	throw new RuntimeException("活跃数量大于最大值");
	    }
	    if(activeSize.get()==maxSize){
	    	synchronized (object) {
	    		object.wait();
			}
	    	
	    }
	    
	    Connection conn=OracleUtils.getConnection();
	    String id=UUID.randomUUID().toString();
	    ConnectionEntity entity=new ConnectionEntity();
	    entity.setId(id);
	    entity.setConnection(conn);
	    entity.setStatus(Connection_Status.active);
	    activeConnections.put(id, entity);
	    activeSize.incrementAndGet();
	    return entity;
	}
	
	
	
	public  void releaseConnection(String id) throws SQLException{
		if(idelSize.get()==maxSize){
			OracleUtils.closeConnection(activeConnections.remove(id).getConnection());
		}else{
			ConnectionEntity entity=activeConnections.remove(id);
			entity.setStatus(Connection_Status.idel);
			idelConnections.put(id, entity);
			idelSize.incrementAndGet();
			activeSize.decrementAndGet();
			synchronized (object) {
				object.notify();
			}
			
		}
	}
	
	private void initConnections(){
		for(int i=0;i<this.initSize;i++){
			ConnectionEntity entity=new ConnectionEntity();
			String id=UUID.randomUUID().toString();
			entity.setId(id);
			entity.setConnection(OracleUtils.getConnection());
			entity.setStatus(Connection_Status.idel);
			idelConnections.put(id, entity);
			idelSize.getAndAdd(1);
		}
	}
	
	public int getIdelSize(){
		return this.idelSize.get();
	}
	
	public int getActiveSize(){
		return this.activeSize.get();
	}
	
	public static ConnectionPool getInstance(int initSize,int maxSize){
		if(initSize<0||maxSize<1){
			throw new RuntimeException("initSize必须不小于0，maxsize必须大于等于1");
		}
		if(initSize>maxSize){
			initSize=maxSize;
		}
		synchronized (ConnectionPool.class) {
			if(instance==null){
				instance=new ConnectionPool(initSize,maxSize);
			}
		}
		return instance;
	}
	
	public  static class ConnectionEntity{
		private String id;
		private Connection connection;
		private Connection_Status status;
		
		public Connection getConnection() {
			return connection;
		}
		public void setConnection(Connection connection) {
			this.connection = connection;
		}
		public Connection_Status getStatus() {
			return status;
		}
		public void setStatus(Connection_Status status) {
			this.status = status;
		}
		public String getId() {
			return id;
		}
		public void setId(String id) {
			this.id = id;
		}
		
		
		
	}
	
	private enum Connection_Status{
		idel,active,close
	}
	
	class DetectFailConnection extends Thread{
		@Override
		public void run() {
			Iterator<String> itIdel=idelConnections.keySet().iterator();
			while(itIdel.hasNext()){
				String key =itIdel.next();
				ConnectionEntity entity=idelConnections.get(key);
				try {
					if(entity.getConnection().isClosed()){
						idelConnections.remove(key);
						idelSize.decrementAndGet();
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
			
			Iterator<String> itActive=activeConnections.keySet().iterator();
			while(itActive.hasNext()){
				String key=itActive.next();
				ConnectionEntity entity=activeConnections.get(key);
				try {
					if(entity.getConnection().isClosed()){
						activeConnections.remove(key);
						activeSize.decrementAndGet();
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
			try {
				Thread.sleep(10000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
}

测试用例

 

public class TestConnectionPool extends TestCase {
	private ConnectionPool pool=null;
	@Override
	protected void setUp() throws Exception {
		pool=ConnectionPool.getInstance(3, 10);
	}
	
	public void testGetConnection() throws InterruptedException, SQLException{
		Assert.assertEquals(0,pool.getActiveSize());
		Assert.assertEquals(3,pool.getIdelSize());
		ConnectionEntity entity=pool.getConnection();
		ConnectionEntity entity1=pool.getConnection();
		ConnectionEntity entity2=pool.getConnection();
		Assert.assertEquals(3,pool.getActiveSize());
		Assert.assertEquals(0,pool.getIdelSize());
		pool.releaseConnection(entity.getId());
		pool.releaseConnection(entity1.getId());
		pool.releaseConnection(entity2.getId());
		Assert.assertEquals(0,pool.getActiveSize());
		Assert.assertEquals(3,pool.getIdelSize());
		final CountDownLatch latch=new CountDownLatch(5);
		for(int i=0;i<5;i++){
			new Thread(){
				public void run() {
					try {
						
						ConnectionEntity entity=pool.getConnection();
						latch.countDown();
					} catch (InterruptedException e) {
						e.printStackTrace();
					}catch (SQLException e) {
						e.printStackTrace();
					}
				};
			}.start();
		}
		
		latch.await();
		Assert.assertEquals(5,pool.getActiveSize());
		Assert.assertEquals(0,pool.getIdelSize());
		
		final CountDownLatch latch2=new CountDownLatch(5);
		for(int i=0;i<5;i++){
			new Thread(){
				public void run() {
					try {
						for(int i=0;i<20;i++){
							ConnectionEntity entity=pool.getConnection();
							pool.releaseConnection(entity.getId());
						}
						latch2.countDown();
					} catch (InterruptedException e) {
						e.printStackTrace();
					}catch (SQLException e) {
						e.printStackTrace();
					}
				};
			}.start();
		}
		
		latch2.await();
		System.out.println(1);
	}
}