//
// ========================================================================
// 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.util.concurrent.atomic.AtomicReference;
import com.facebook.presto.jdbc.internal.jetty.client.api.Connection;
import com.facebook.presto.jdbc.internal.jetty.client.api.Request;
import com.facebook.presto.jdbc.internal.jetty.util.Promise;
public abstract class MultiplexHttpDestination<C extends Connection> extends HttpDestination implements Promise<Connection>
{
private final AtomicReference<ConnectState> connect = new AtomicReference<>(ConnectState.DISCONNECTED);
private C connection;
protected MultiplexHttpDestination(HttpClient client, Origin origin)
{
super(client, origin);
}
@Override
protected void send()
{
while (true)
{
ConnectState current = connect.get();
switch (current)
{
case DISCONNECTED:
{
if (!connect.compareAndSet(current, ConnectState.CONNECTING))
break;
newConnection(this);
return;
}
case CONNECTING:
{
// Waiting to connect, just return
return;
}
case CONNECTED:
{
if (process(connection, false))
break;
return;
}
default:
{
throw new IllegalStateException();
}
}
}
}
@Override
@SuppressWarnings("unchecked")
public void succeeded(Connection result)
{
C connection = this.connection = (C)result;
if (connect.compareAndSet(ConnectState.CONNECTING, ConnectState.CONNECTED))
{
process(connection, true);
}
else
{
connection.close();
failed(new IllegalStateException());
}
}
@Override
public void failed(Throwable x)
{
connect.set(ConnectState.DISCONNECTED);
}
protected boolean process(final C connection, boolean dispatch)
{
HttpClient client = getHttpClient();
final HttpExchange exchange = getHttpExchanges().poll();
LOG.debug("Processing {} on {}", exchange, connection);
if (exchange == null)
return false;
final Request request = exchange.getRequest();
Throwable cause = request.getAbortCause();
if (cause != null)
{
LOG.debug("Aborted before processing {}: {}", exchange, cause);
// It may happen that the request is aborted before the exchange
// is created. Aborting the exchange a second time will result in
// a no-operation, so we just abort here to cover that edge case.
exchange.abort(cause);
}
else
{
if (dispatch)
{
client.getExecutor().execute(new Runnable()
{
@Override
public void run()
{
send(connection, exchange);
}
});
}
else
{
send(connection, exchange);
}
}
return true;
}
@Override
public void close(Connection connection)
{
super.close(connection);
while (true)
{
ConnectState current = connect.get();
if (connect.compareAndSet(current, ConnectState.DISCONNECTED))
break;
}
}
protected abstract void send(C connection, HttpExchange exchange);
private enum ConnectState
{
DISCONNECTED, CONNECTING, CONNECTED
}
}