/* This file is part of VoltDB.
* Copyright (C) 2008-2014 VoltDB Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* Manage a mapping of one VoltDB client to every 50 YCSB client threads.
*/
package com.yahoo.ycsb.db;
import java.io.IOException;
import java.util.HashMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;
import org.voltdb.client.Client;
import org.voltdb.client.ClientConfig;
import org.voltdb.client.ClientFactory;
import org.voltdb.client.NoConnectionsException;
public class ConnectionHelper {
private static final int THREADS_PER_CLIENT = 50;
private static HashMap<Long, ClientConnection> clientMapping = new HashMap<Long, ClientConnection>();
private static ClientConnection activeConnection = null;
/**
* Creates a factory used to connect to a VoltDB instance.
* (Note that if a corresponding connection exists, all parameters other than 'servers' are ignored)
* @param clientId A unique identifier for the connecting client
* @param servers The comma separated list of VoltDB servers in hostname[:port] format that the instance will use.
* @param user The username for the connection
* @param password The password for the specified user
* @param ratelimit A limit on the number of transactions per second for the VoltDB instance
* @return The existing factory if a corresponding connection has already been created; the newly created
* one otherwise.
* @throws IOException Throws if a connection is already open with a different server string.
* @throws InterruptedException
*/
public synchronized static Client createConnection(Long clientId, String servers, String user, String password, int ratelimit) throws IOException, InterruptedException
{
ClientConnection conn = clientMapping.get(clientId);
if (conn != null)
{
return conn.m_client;
}
if (activeConnection != null && activeConnection.m_connectionCount.get() <= THREADS_PER_CLIENT)
{
activeConnection.connect();
clientMapping.put(clientId, activeConnection);
return activeConnection.m_client;
}
ClientConfig config = new ClientConfig(user, password);
config.setMaxTransactionsPerSecond(ratelimit);
Client client = ClientFactory.createClient(config);
connect(client, servers);
activeConnection = new ClientConnection(client);
clientMapping.put(clientId, activeConnection);
return client;
}
public static void disconnect(Long clientId)
{
ClientConnection connection = clientMapping.get(clientId);
if (connection != null)
{
connection.disconnect();
}
}
/**
* Connect to a single server with retry. Limited exponential backoff.
* No timeout. This will run until the process is killed if it's not
* able to connect.
*
* @param server hostname:port or just hostname (hostname can be ip).
*/
private static void connectToOneServerWithRetry(final Client client, String server)
{
int sleep = 1000;
while (true)
{
try
{
client.createConnection(server);
break;
}
catch (Exception e)
{
System.err.printf("Connection failed - retrying in %d second(s).\n", sleep / 1000);
try
{
Thread.sleep(sleep);
}
catch (Exception interruted) {}
if (sleep < 8000)
{
sleep += sleep;
}
}
}
System.out.printf("Connected to VoltDB node at: %s.\n", server);
}
/**
* Connect to a set of servers in parallel. Each will retry until
* connection. This call will block until all have connected.
*
* @param servers A comma separated list of servers using the hostname:port
* syntax (where :port is optional).
* @throws InterruptedException if anything bad happens with the threads.
*/
private static void connect(final Client client, String servers) throws InterruptedException
{
System.out.println("Connecting to VoltDB...");
String[] serverArray = servers.split(",");
final CountDownLatch connections = new CountDownLatch(serverArray.length);
// use a new thread to connect to each server
for (final String server : serverArray)
{
new Thread(new Runnable() {
@Override
public void run()
{
connectToOneServerWithRetry(client, server);
connections.countDown();
}
}).start();
}
// block until all have connected
connections.await();
}
private static class ClientConnection
{
private Client m_client;
private AtomicInteger m_connectionCount;
ClientConnection(Client client)
{
m_client = client;
m_connectionCount = new AtomicInteger(1);
}
void connect()
{
m_connectionCount.incrementAndGet();
}
void disconnect()
{
int count = m_connectionCount.decrementAndGet();
if (count <= 0 && m_client != null)
{
synchronized (this)
{
try
{
m_client.drain();
m_client.close();
}
catch (NoConnectionsException e)
{
e.printStackTrace();
}
catch (InterruptedException e)
{
e.printStackTrace();
}
m_client = null;
}
}
}
}
}