/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.net;
import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;
import java.util.*;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.net.io.FastSerializer;
import org.apache.cassandra.net.io.ISerializer;
import org.apache.cassandra.net.io.ProtocolState;
import org.apache.cassandra.net.io.StartState;
import org.apache.cassandra.net.io.TcpReader;
import org.apache.cassandra.utils.LogUtil;
import org.apache.log4j.Logger;
/**
* Author : Avinash Lakshman ( alakshman@facebook.com) & Prashant Malik ( pmalik@facebook.com )
*/
public class TcpConnection extends SelectionKeyHandler implements Comparable
{
// logging and profiling.
private static Logger logger_ = Logger.getLogger(TcpConnection.class);
private static ISerializer serializer_ = new FastSerializer();
private SocketChannel socketChannel_;
private SelectionKey key_;
private TcpConnectionManager pool_;
private boolean isIncoming_ = false;
private TcpReader tcpReader_;
private ReadWorkItem readWork_ = new ReadWorkItem();
private Queue<ByteBuffer> pendingWrites_ = new ConcurrentLinkedQueue<ByteBuffer>();
private EndPoint localEp_;
private EndPoint remoteEp_;
boolean inUse_ = false;
/*
* Added for streaming support. We need the boolean
* to indicate that this connection is used for
* streaming. The Condition and the Lock are used
* to signal the stream() that it can continue
* streaming when the socket becomes writable.
*/
private boolean bStream_ = false;
private Lock lock_;
private Condition condition_;
// used from getConnection - outgoing
TcpConnection(TcpConnectionManager pool, EndPoint from, EndPoint to) throws IOException
{
socketChannel_ = SocketChannel.open();
socketChannel_.configureBlocking(false);
pool_ = pool;
localEp_ = from;
remoteEp_ = to;
if ( !socketChannel_.connect( remoteEp_.getInetAddress() ) )
{
key_ = SelectorManager.getSelectorManager().register(socketChannel_, this, SelectionKey.OP_CONNECT);
}
else
{
key_ = SelectorManager.getSelectorManager().register(socketChannel_, this, SelectionKey.OP_READ);
}
}
/*
* Used for streaming purposes has no pooling semantics.
*/
TcpConnection(EndPoint from, EndPoint to) throws IOException
{
socketChannel_ = SocketChannel.open();
socketChannel_.configureBlocking(false);
localEp_ = from;
remoteEp_ = to;
if ( !socketChannel_.connect( remoteEp_.getInetAddress() ) )
{
key_ = SelectorManager.getSelectorManager().register(socketChannel_, this, SelectionKey.OP_CONNECT);
}
else
{
key_ = SelectorManager.getSelectorManager().register(socketChannel_, this, SelectionKey.OP_READ);
}
bStream_ = true;
lock_ = new ReentrantLock();
condition_ = lock_.newCondition();
}
/*
* This method is invoked by the TcpConnectionHandler to accept incoming TCP connections.
* Accept the connection and then register interest for reads.
*/
static void acceptConnection(SocketChannel socketChannel, EndPoint localEp, boolean isIncoming) throws IOException
{
TcpConnection tcpConnection = new TcpConnection(socketChannel, localEp, true);
tcpConnection.registerReadInterest();
}
private void registerReadInterest() throws IOException
{
key_ = SelectorManager.getSelectorManager().register(socketChannel_, this, SelectionKey.OP_READ);
}
// used for incoming connections
TcpConnection(SocketChannel socketChannel, EndPoint localEp, boolean isIncoming) throws IOException
{
socketChannel_ = socketChannel;
socketChannel_.configureBlocking(false);
isIncoming_ = isIncoming;
localEp_ = localEp;
}
EndPoint getLocalEp()
{
return localEp_;
}
public void setLocalEp(EndPoint localEp)
{
localEp_ = localEp;
}
public EndPoint getEndPoint()
{
return remoteEp_;
}
public boolean isIncoming()
{
return isIncoming_;
}
public SocketChannel getSocketChannel()
{
return socketChannel_;
}
public void write(Message message) throws IOException
{
byte[] data = serializer_.serialize(message);
if ( data.length > 0 )
{
boolean listening = !message.getFrom().equals(EndPoint.randomLocalEndPoint_);
ByteBuffer buffer = MessagingService.packIt( data , false, false, listening);
synchronized(this)
{
if (!pendingWrites_.isEmpty() || !socketChannel_.isConnected())
{
pendingWrites_.add(buffer);
return;
}
socketChannel_.write(buffer);
if (buffer.remaining() > 0)
{
pendingWrites_.add(buffer);
turnOnInterestOps(key_, SelectionKey.OP_WRITE);
}
}
}
}
public void stream(File file, long startPosition, long endPosition) throws IOException, InterruptedException
{
if ( !bStream_ )
throw new IllegalStateException("Cannot stream since we are not set up to stream data.");
lock_.lock();
try
{
/* transfer 64MB in each attempt */
int limit = 64*1024*1024;
long total = endPosition - startPosition;
/* keeps track of total number of bytes transferred */
long bytesWritten = 0L;
RandomAccessFile raf = new RandomAccessFile(file, "r");
FileChannel fc = raf.getChannel();
/*
* If the connection is not yet established then wait for
* the timeout period of 2 seconds. Attempt to reconnect 3 times and then
* bail with an IOException.
*/
long waitTime = 2;
int retry = 0;
while (!socketChannel_.isConnected())
{
if ( retry == 3 )
throw new IOException("Unable to connect to " + remoteEp_ + " after " + retry + " attempts.");
condition_.await(waitTime, TimeUnit.SECONDS);
++retry;
}
while ( bytesWritten < total )
{
if ( startPosition == 0 )
{
ByteBuffer buffer = MessagingService.constructStreamHeader(false, true);
socketChannel_.write(buffer);
if (buffer.remaining() > 0)
{
pendingWrites_.add(buffer);
turnOnInterestOps(key_, SelectionKey.OP_WRITE);
condition_.await();
}
}
/* returns the number of bytes transferred from file to the socket */
long bytesTransferred = fc.transferTo(startPosition, limit, socketChannel_);
logger_.debug("Bytes transferred " + bytesTransferred);
bytesWritten += bytesTransferred;
startPosition += bytesTransferred;
/*
* If the number of bytes transferred is less than intended
* then we need to wait till socket becomes writeable again.
*/
if ( bytesTransferred < limit && bytesWritten != total )
{
turnOnInterestOps(key_, SelectionKey.OP_WRITE);
condition_.await();
}
}
}
finally
{
lock_.unlock();
}
}
private void resumeStreaming()
{
/* if not in streaming mode do nothing */
if ( !bStream_ )
return;
lock_.lock();
try
{
condition_.signal();
}
finally
{
lock_.unlock();
}
}
public void close()
{
inUse_ = false;
if ( pool_.contains(this) )
pool_.decUsed();
}
public boolean isConnected()
{
return socketChannel_.isConnected();
}
public boolean equals(Object o)
{
if ( !(o instanceof TcpConnection) )
return false;
TcpConnection rhs = (TcpConnection)o;
if ( localEp_.equals(rhs.localEp_) && remoteEp_.equals(rhs.remoteEp_) )
return true;
else
return false;
}
public int hashCode()
{
return (localEp_ + ":" + remoteEp_).hashCode();
}
public String toString()
{
return socketChannel_.toString();
}
void closeSocket()
{
logger_.warn("Closing down connection " + socketChannel_ + " with " + pendingWrites_.size() + " writes remaining.");
if ( pool_ != null )
{
pool_.removeConnection(this);
}
cancel(key_);
pendingWrites_.clear();
}
void errorClose()
{
logger_.warn("Closing down connection " + socketChannel_);
pendingWrites_.clear();
cancel(key_);
pendingWrites_.clear();
if ( pool_ != null )
{
pool_.removeConnection(this);
}
}
private void cancel(SelectionKey key)
{
if ( key != null )
{
key.cancel();
try
{
key.channel().close();
}
catch (IOException e) {}
}
}
// called in the selector thread
public void connect(SelectionKey key)
{
turnOffInterestOps(key, SelectionKey.OP_CONNECT);
try
{
if (socketChannel_.finishConnect())
{
turnOnInterestOps(key, SelectionKey.OP_READ);
synchronized(this)
{
// this will flush the pending
if (!pendingWrites_.isEmpty())
{
turnOnInterestOps(key_, SelectionKey.OP_WRITE);
}
}
resumeStreaming();
}
else
{
logger_.error("Closing connection because socket channel could not finishConnect.");;
errorClose();
}
}
catch(IOException e)
{
logger_.error("Encountered IOException on connection: " + socketChannel_, e);
errorClose();
}
}
// called in the selector thread
public void write(SelectionKey key)
{
turnOffInterestOps(key, SelectionKey.OP_WRITE);
doPendingWrites();
/*
* This is executed only if we are in streaming mode.
* Idea is that we read a chunk of data from a source
* and wait to read the next from the source until we
* are siganlled to do so from here.
*/
resumeStreaming();
}
void doPendingWrites()
{
synchronized(this)
{
try
{
while(!pendingWrites_.isEmpty())
{
ByteBuffer buffer = pendingWrites_.peek();
socketChannel_.write(buffer);
if (buffer.remaining() > 0)
{
break;
}
pendingWrites_.remove();
}
}
catch(IOException ex)
{
logger_.error(LogUtil.throwableToString(ex));
// This is to fix the wierd Linux bug with NIO.
errorClose();
}
finally
{
if (!pendingWrites_.isEmpty())
{
turnOnInterestOps(key_, SelectionKey.OP_WRITE);
}
}
}
}
// called in the selector thread
public void read(SelectionKey key)
{
turnOffInterestOps(key, SelectionKey.OP_READ);
// publish this event onto to the TCPReadEvent Queue.
MessagingService.getReadExecutor().execute(readWork_);
}
class ReadWorkItem implements Runnable
{
// called from the TCP READ thread pool
public void run()
{
if ( tcpReader_ == null )
{
tcpReader_ = new TcpReader(TcpConnection.this);
StartState nextState = tcpReader_.getSocketState(TcpReader.TcpReaderState.PREAMBLE);
if ( nextState == null )
{
nextState = new ProtocolState(tcpReader_);
tcpReader_.putSocketState(TcpReader.TcpReaderState.PREAMBLE, nextState);
}
tcpReader_.morphState(nextState);
}
try
{
byte[] bytes = new byte[0];
while ( (bytes = tcpReader_.read()).length > 0 )
{
ProtocolHeader pH = tcpReader_.getProtocolHeader();
if ( !pH.isStreamingMode_ )
{
/* first message received */
if (remoteEp_ == null)
{
int port = ( pH.isListening_ ) ? DatabaseDescriptor.getStoragePort() : EndPoint.randomPort_;
remoteEp_ = new EndPoint( socketChannel_.socket().getInetAddress().getHostAddress(), port );
// put connection into pool if possible
pool_ = MessagingService.getConnectionPool(localEp_, remoteEp_);
pool_.addToPool(TcpConnection.this);
}
/* Deserialize and handle the message */
MessagingService.getDeserilizationExecutor().submit( new MessageDeserializationTask(pH.serializerType_, bytes) );
tcpReader_.resetState();
}
else
{
MessagingService.setStreamingMode(false);
/* Close this socket connection used for streaming */
closeSocket();
}
}
}
catch ( IOException ex )
{
handleException(ex);
}
catch ( Throwable th )
{
handleException(th);
}
finally
{
turnOnInterestOps(key_, SelectionKey.OP_READ);
}
}
private void handleException(Throwable th)
{
logger_.warn("Problem reading from socket connected to : " + socketChannel_);
logger_.warn(LogUtil.throwableToString(th));
// This is to fix the wierd Linux bug with NIO.
errorClose();
}
}
public int pending()
{
return pendingWrites_.size();
}
public int compareTo(Object o)
{
if (o instanceof TcpConnection)
{
return pendingWrites_.size() - ((TcpConnection) o).pendingWrites_.size();
}
throw new IllegalArgumentException();
}
}