org.miv.mbox.net.SenderPool Maven / Gradle / Ivy

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The message box acts as a buffer for incoming messages. Its major property is to be usable from any thread. This allows any external source to post any message at any time without having to wonder about synchronisation.
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package org.miv.mbox.net;

import java.io.*;
import java.net.*;
import java.util.*;

/**
 * Create and cache senders automatically.
 *
 * 
 * A sender pool allows to avoid creating a {@link org.miv.mbox.net.Sender} for
 * each remote object we want to send message to, since one can use the same
 * sender for the same host. The sender pool remembers hosts and ports and their
 * associated sender. It can also create senders automatically for a given
 * {@link org.miv.mbox.net.MBoxLocator}.
 * 
 * 
 * @see org.miv.mbox.net.Sender
 * @see org.miv.mbox.net.Receiver
 * @author Antoine Dutot
 * @since 20040624
 */
public class SenderPool
{
// Attributes

	/**
	 * Map of senders. Each item is a pair (key,value) where the key is the
	 * sender locator host id ({@link org.miv.mbox.net.MBoxLocator#getHostId()})
	 * as a string and the value is the Sender instance.
	 */
	protected HashMap senders = new HashMap();

	protected boolean debug;
	
// Constructors

	/**
	 * Empty sender pool.
	 */
	public
	SenderPool()
	{
	}
	
	/**
	 * Empty sender pool.
	 * @param debug Activate debugging in all senders created.
	 */
	public
	SenderPool( boolean debug )
	{
		this.debug = debug;
	}

// Accessors

	/**
	 * Is there a cached connection to the hostname and port of the given
	 * locator.
	 * @param locator The locator to check.
	 * @return True if a sender is cached for this locator.
	 */
	public boolean
	hasSender( MBoxLocator locator )
	{
		return( senders.get( locator.getHostId() ) != null );
	}

	/**
	 * Get the sender for the host given by the given locator. Only the hostname
	 * and port of the locator are considered.
	 * @param locator The locator of the host to search.
	 * @return A sender to this host if cached, else null.
	 */
	public Sender
	getSender( MBoxLocator locator )
	{
		return( senders.get( locator.getHostId() ) );
	}

	/**
	 * Get the sender for the host given by the given hostname and port.
	 * @param hostname The hostname of the host to connect to.
	 * @param port The port to connect to.
	 * @return A sender to this host if cached, else null.
	 */
	public Sender
	getSender( String hostname, int port )
	{
		String id = "//" + hostname + ":" + port;
		return senders.get( id );
	}

// Commands

	/**
	 * Create a new sender to "//hostname:port" and cache it. If  a sender
	 * already exists it is used.
	 * @param hostname The hostname of the host to connect to.
	 * @param port The port to connect to.
	 */
	public Sender
	connect( String hostname, int port )
		throws IOException, UnknownHostException
	{
		String id     = "//" + hostname + ":" + port;
		Sender sender = senders.get( id );

		if( sender == null )
		{
			sender = new Sender( new MBoxLocator( hostname, port ), debug );
			senders.put( id, sender );
		}

		return sender;
	}

	/**
	 * Create a new sender for the host part of the given locator and cache it.
	 * If a sender already exists it is used.
	 * @param locator The locator used to create the connection.
	 */
	public Sender
	connect( MBoxLocator locator )
		throws IOException, UnknownHostException
	{
		String id     = locator.getHostId();
		Sender sender = senders.get( id );

		if( sender == null )
		{
			sender = new Sender( new MBoxLocator( locator.getHostname(), locator.getPort() ), debug );
			senders.put( id, sender );
		}

		return sender;
	}

	/**
	 * Send a message to a distant message box, first creating a sender if not
	 * already cached.
	 * @param from The sender object name.
	 * @param hostname The host name where the receiver box resides.
	 * @param port The port of the host where the receiver box resides.
	 * @param to The receiver box name.
	 * @param messages The message data.
	 */
	public void
	send( String from, String hostname, int port, String to, Object ... messages )
		throws IOException, UnknownHostException
	{
		Sender sender = connect( hostname, port );
		sender.send( from, to, messages );
	}

	/**
	 * Send a message to a distant message box, first creating a sender if not
	 * already cached.
	 * @param from The sender object name.
	 * @param to The location and name of the receiver box.
	 * @param messages The message data.
	 */
	public void
	send( String from, MBoxLocator to, Object ... messages )
		throws IOException, UnknownHostException
	{
		Sender sender = connect( to );
		sender.send( from, to.getName(), messages );
	}

	/**
	 * Send a prepacked message to a distant message box, first creating a
	 * sender if not already cached.
	 * @param to The location and name of the receiver box.
	 * @param packet The prepacket message.
	 */
	public void
	send( MBoxLocator to, Packet packet )
		throws IOException, UnknownHostException
	{
		Sender sender = connect( to );
		sender.send( packet );
	}
}