org.apache.nifi.io.nio

Class ChannelListener

java.lang.Object

org.apache.nifi.io.nio.ChannelListener

public final class ChannelListener
extends Object

This class provides the entry point to NIO based socket listeners for NiFi processors and services. There are 2 supported types of Listeners, Datagram (UDP based transmissions) and ServerSocket (TCP based transmissions). This will create the ChannelDispatcher, which is a Runnable and is controlled via the ScheduledExecutorService, which is also created by this class. The ChannelDispatcher handles connections to the ServerSocketChannels and creates the readers associated with the resulting SocketChannels. Additionally, this creates and manages two Selectors, one for ServerSocketChannels and another for SocketChannels and DatagramChannels. The threading model for this consists of one thread for the ChannelDispatcher, one thread per added SocketChannel reader, one thread per added DatagramChannel reader. The ChannelDispatcher is not scheduled with fixed delay as the others are. It is throttled by the provided timeout value. Within the ChannelDispatcher there are two blocking operations which will block for the given timeout each time through the enclosing loop. All channels are cached in one of the two Selectors via their SelectionKey. The serverSocketSelector maintains all the added ServerSocketChannels; the socketChannelSelector maintains the all the add DatagramChannels and the created SocketChannels. Further, the SelectionKey of the DatagramChannel and the SocketChannel is injected with the channel's associated reader. All ChannelReaders will get throttled by the unavailability of buffers in the provided BufferPool. This is designed to create back pressure.

Field Summary

Fields

Modifier and Type	Field and Description
private BufferPool	bufferPool
private ChannelDispatcher	channelDispatcher
private long	channelReaderFrequencyMSecs
private ScheduledExecutorService	executor
private int	initialBufferPoolSize
private static org.slf4j.Logger	LOGGER
private Selector	serverSocketSelector
private Selector	socketChannelSelector

Constructor Summary

Constructors

Constructor and Description
ChannelListener(int threadPoolSize, StreamConsumerFactory consumerFactory, BufferPool bufferPool, int timeout, TimeUnit unit, boolean readSingleDatagram)

Method Summary

Methods

Modifier and Type	Method and Description
void	addDatagramChannel(InetAddress nicIPAddress, int port, int receiveBufferSize) Binds to listen for data grams on the given local IPAddress/port
void	addDatagramChannel(InetAddress nicIPAddress, int port, int receiveBufferSize, String sendingHost, Integer sendingPort) Binds to listen for data grams on the given local IPAddress/port and restricts receipt of datagrams to those from the provided host and port, must specify both.
void	addServerSocket(InetAddress nicIPAddress, int port, int receiveBufferSize) Adds a server socket channel for listening to connections.
private DatagramChannel	createAndBindDatagramChannel(InetAddress nicIPAddress, int port, int receiveBufferSize)
void	setChannelReaderSchedulingPeriod(long period, TimeUnit unit)
void	shutdown(long period, TimeUnit timeUnit)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOGGER

private static final org.slf4j.Logger LOGGER

executor

private final ScheduledExecutorService executor

serverSocketSelector

private final Selector serverSocketSelector

socketChannelSelector

private final Selector socketChannelSelector

channelDispatcher

private final ChannelDispatcher channelDispatcher

bufferPool

private final BufferPool bufferPool

initialBufferPoolSize

private final int initialBufferPoolSize

channelReaderFrequencyMSecs

private volatile long channelReaderFrequencyMSecs

Constructor Detail

ChannelListener

public ChannelListener(int threadPoolSize,
               StreamConsumerFactory consumerFactory,
               BufferPool bufferPool,
               int timeout,
               TimeUnit unit,
               boolean readSingleDatagram)
                throws IOException

Throws:

IOException

Method Detail

setChannelReaderSchedulingPeriod

public void setChannelReaderSchedulingPeriod(long period,
                                    TimeUnit unit)

addServerSocket

public void addServerSocket(InetAddress nicIPAddress,
                   int port,
                   int receiveBufferSize)
                     throws IOException

Adds a server socket channel for listening to connections.

Parameters:

nicIPAddress - - if null binds to wildcard address

port - - port to bind to

receiveBufferSize - - size of OS receive buffer to request. If less than 0 then will not be set and OS default will win.

Throws:

IOException - if unable to add socket

addDatagramChannel

public void addDatagramChannel(InetAddress nicIPAddress,
                      int port,
                      int receiveBufferSize)
                        throws IOException

Binds to listen for data grams on the given local IPAddress/port

Parameters:

nicIPAddress - - if null will listen on wildcard address, which means datagrams will be received on all local network interfaces. Otherwise, will bind to the provided IP address associated with some NIC.

port - - the port to listen on

receiveBufferSize - - the number of bytes to request for a receive buffer from OS

Throws:

IOException - if unable to add channel

addDatagramChannel

public void addDatagramChannel(InetAddress nicIPAddress,
                      int port,
                      int receiveBufferSize,
                      String sendingHost,
                      Integer sendingPort)
                        throws IOException

Binds to listen for data grams on the given local IPAddress/port and restricts receipt of datagrams to those from the provided host and port, must specify both. This improves performance for datagrams coming from a sender that is known a-priori.

Parameters:

nicIPAddress - - if null will listen on wildcard address, which means datagrams will be received on all local network interfaces. Otherwise, will bind to the provided IP address associated with some NIC.

port - - the port to listen on. This is used to provide a well-known destination for a sender.

receiveBufferSize - - the number of bytes to request for a receive buffer from OS

sendingHost - - the hostname, or IP address, of the sender of datagrams. Only datagrams from this host will be received. If this is null the wildcard ip is used, which means datagrams may be received from any network interface on the local host.

sendingPort - - the port used by the sender of datagrams. Only datagrams from this port will be received.

Throws:

IOException - if unable to add channel

createAndBindDatagramChannel

private DatagramChannel createAndBindDatagramChannel(InetAddress nicIPAddress,
                                           int port,
                                           int receiveBufferSize)
                                              throws IOException

Throws:

IOException

shutdown

public void shutdown(long period,
            TimeUnit timeUnit)