//
// ========================================================================
// Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package com.facebook.presto.jdbc.internal.jetty.client;
import java.io.Closeable;
import java.io.IOException;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.atomic.AtomicInteger;
import com.facebook.presto.jdbc.internal.jetty.client.api.Connection;
import com.facebook.presto.jdbc.internal.jetty.client.api.Destination;
import com.facebook.presto.jdbc.internal.jetty.util.BlockingArrayQueue;
import com.facebook.presto.jdbc.internal.jetty.util.Promise;
import com.facebook.presto.jdbc.internal.jetty.util.component.ContainerLifeCycle;
import com.facebook.presto.jdbc.internal.jetty.util.component.Dumpable;
import com.facebook.presto.jdbc.internal.jetty.util.log.Log;
import com.facebook.presto.jdbc.internal.jetty.util.log.Logger;
public class ConnectionPool implements Closeable, Dumpable
{
protected static final Logger LOG = Log.getLogger(ConnectionPool.class);
private final AtomicInteger connectionCount = new AtomicInteger();
private final Destination destination;
private final int maxConnections;
private final Promise<Connection> connectionPromise;
private final BlockingDeque<Connection> idleConnections;
private final BlockingQueue<Connection> activeConnections;
public ConnectionPool(Destination destination, int maxConnections, Promise<Connection> connectionPromise)
{
this.destination = destination;
this.maxConnections = maxConnections;
this.connectionPromise = connectionPromise;
this.idleConnections = new LinkedBlockingDeque<>(maxConnections);
this.activeConnections = new BlockingArrayQueue<>(maxConnections);
}
public BlockingQueue<Connection> getIdleConnections()
{
return idleConnections;
}
public BlockingQueue<Connection> getActiveConnections()
{
return activeConnections;
}
public Connection acquire()
{
Connection connection = acquireIdleConnection();
if (connection == null)
connection = tryCreate();
return connection;
}
private Connection tryCreate()
{
while (true)
{
int current = connectionCount.get();
final int next = current + 1;
if (next > maxConnections)
{
LOG.debug("Max connections {}/{} reached", current, maxConnections);
// Try again the idle connections
return acquireIdleConnection();
}
if (connectionCount.compareAndSet(current, next))
{
LOG.debug("Connection {}/{} creation", next, maxConnections);
destination.newConnection(new Promise<Connection>()
{
@Override
public void succeeded(Connection connection)
{
LOG.debug("Connection {}/{} creation succeeded {}", next, maxConnections, connection);
if (activate(connection))
connectionPromise.succeeded(connection);
}
@Override
public void failed(Throwable x)
{
LOG.debug("Connection " + next + "/" + maxConnections + " creation failed", x);
connectionCount.decrementAndGet();
connectionPromise.failed(x);
}
});
// Try again the idle connections
return acquireIdleConnection();
}
}
}
private Connection acquireIdleConnection()
{
Connection connection = idleConnections.pollFirst();
if (connection == null)
return null;
return activate(connection) ? connection : null;
}
private boolean activate(Connection connection)
{
if (activeConnections.offer(connection))
{
LOG.debug("Connection active {}", connection);
acquired(connection);
return true;
}
else
{
LOG.debug("Connection active overflow {}", connection);
connection.close();
return false;
}
}
protected void acquired(Connection connection)
{
}
public boolean release(Connection connection)
{
released(connection);
if (activeConnections.remove(connection))
{
// Make sure we use "hot" connections first
if (idleConnections.offerFirst(connection))
{
LOG.debug("Connection idle {}", connection);
return true;
}
else
{
LOG.debug("Connection idle overflow {}", connection);
connection.close();
}
}
return false;
}
protected void released(Connection connection)
{
}
public boolean remove(Connection connection)
{
boolean activeRemoved = activeConnections.remove(connection);
boolean idleRemoved = idleConnections.remove(connection);
if (!idleRemoved)
released(connection);
boolean removed = activeRemoved || idleRemoved;
if (removed)
{
int pooled = connectionCount.decrementAndGet();
LOG.debug("Connection removed {} - pooled: {}", connection, pooled);
}
return removed;
}
public boolean isActive(Connection connection)
{
return activeConnections.contains(connection);
}
public boolean isIdle(Connection connection)
{
return idleConnections.contains(connection);
}
public void close()
{
for (Connection connection : idleConnections)
connection.close();
idleConnections.clear();
// A bit drastic, but we cannot wait for all requests to complete
for (Connection connection : activeConnections)
connection.close();
activeConnections.clear();
connectionCount.set(0);
}
@Override
public String dump()
{
return ContainerLifeCycle.dump(this);
}
@Override
public void dump(Appendable out, String indent) throws IOException
{
ContainerLifeCycle.dumpObject(out, this);
ContainerLifeCycle.dump(out, indent, activeConnections, idleConnections);
}
@Override
public String toString()
{
return String.format("%s %d/%d", getClass().getSimpleName(), connectionCount.get(), maxConnections);
}
}