/*
* The Sun Project JXTA(TM) Software License
*
* Copyright (c) 2001-2007 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The end-user documentation included with the redistribution, if any, must
* include the following acknowledgment: "This product includes software
* developed by Sun Microsystems, Inc. for JXTA(TM) technology."
* Alternately, this acknowledgment may appear in the software itself, if
* and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
* not be used to endorse or promote products derived from this software
* without prior written permission. For written permission, please contact
* Project JXTA at http://www.jxta.org.
*
* 5. Products derived from this software may not be called "JXTA", nor may
* "JXTA" appear in their name, without prior written permission of Sun.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SUN
* MICROSYSTEMS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* JXTA is a registered trademark of Sun Microsystems, Inc. in the United
* States and other countries.
*
* Please see the license information page at :
* <http://www.jxta.org/project/www/license.html> for instructions on use of
* the license in source files.
*
* ====================================================================
* This software consists of voluntary contributions made by many individuals
* on behalf of Project JXTA. For more information on Project JXTA, please see
* http://www.jxta.org.
*
* This license is based on the BSD license adopted by the Apache Foundation.
*/
package net.jxta.impl.content.defprovider;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.jxta.logging.Logging;
import net.jxta.peergroup.PeerGroup;
import net.jxta.protocol.PipeAdvertisement;
/**
* This class provides a somewhat efficient mechanism for tracking active
* transfers and providing a cache for information related to those transfers.
* As an example, Contents currently only have streamed data accessors. Requests
* for data will typically come in a linear fashion, so it makes good
* sense from a performance perspective to leave the stream open for a period
* of time. Additionally, this tracker class puts some absolute limits in
* place as to how many concurrent clients will be served, giving preference
* to transfers already in progress.
*/
public class ActiveTransferTracker {
/**
* Logger.
*/
private static final Logger LOG =
Logger.getLogger(ActiveTransferTracker.class.getName());
/**
* Maximum number of clients to serve concurrently.
*/
private static final int MAX_CLIENTS =
Integer.getInteger(ActiveTransferTracker.class.getName()
+ ".maxClients", 5).intValue();
/**
* Garbage collection interval, in seconds.
*/
private static final long GC_INTERVAL =
Long.getLong(ActiveTransferTracker.class.getName()
+ ".gcInterval", 5).intValue();
/**
*
*/
private final List<ActiveTransferTrackerListener> listeners =
new CopyOnWriteArrayList<ActiveTransferTrackerListener>();
/**
* PeerGroup to use to resolve pipes.
*/
private final PeerGroup group;
/**
* Timer to use when scheduling tasks.
*/
private final ScheduledExecutorService schedExec;
/**
* Garbage collection task;
*/
private ScheduledFuture gcTask;
/**
* Map of clients being served, keyed off the destination pipe ID.
*/
private Map<Object, ActiveTransfer> clients =
new HashMap<Object, ActiveTransfer>();
/**
* Constructor.
*
* @param peerGroup PeerGroup to use to resolve pipes
* @param executor executor to submit garbage collection tasks to
*/
public ActiveTransferTracker(
PeerGroup peerGroup,
ScheduledExecutorService executor) {
group = peerGroup;
schedExec = executor;
}
//////////////////////////////////////////////////////////////////////////
// Public methods:
/**
* Adds an tracker listener to notify of interesting events.
*
* @param listener listener to add
*/
public void addActiveTransferListener(
ActiveTransferTrackerListener listener) {
listeners.add(listener);
}
/**
* Removes a transfer listener, preventin further event
* notifications.
*
* @param listener listener to add
*/
public void removeActiveTransferListener(
ActiveTransferTrackerListener listener) {
listeners.remove(listener);
}
/**
* Creates and/or retrieves the active transfer session for the
* provided combination of share and destination.
*
* @param share content share to serve to the destination
* @param destination pipe to send data to
* @return trnsfer session object
*/
public ActiveTransfer getSession(
DefaultContentShare share, PipeAdvertisement destination)
throws TooManyClientsException, IOException {
Object key = destination.getPipeID().getUniqueValue();
ActiveTransfer result;
boolean newSession = false;
synchronized(this) {
result = clients.get(key);
if (result == null) {
if (clients.size() < MAX_CLIENTS) {
result = new ActiveTransfer(group, share, destination);
newSession = true;
clients.put(key, result);
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Added client node: " + key);
}
}
}
}
// Too many clients to serve this request.
if (result == null) {
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Cound not add client node. Too many clients.");
}
throw(new TooManyClientsException());
}
// Notify listners
if (newSession) {
fireSessionCreated(result);
}
return result;
}
/**
* Start tracking and serving.
*/
public synchronized void start() {
if (gcTask == null || gcTask.isDone()) {
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Starting GC task");
}
gcTask = schedExec.scheduleAtFixedRate(new Runnable() {
public void run() {
clientGC();
}
}, 0, GC_INTERVAL, TimeUnit.SECONDS);
}
}
/**
* Stop tracking and serving, freeing any resources held.
*/
public void stop() {
List<ActiveTransfer> toNotify = new ArrayList<ActiveTransfer>();
synchronized(this) {
for (Map.Entry<Object, ActiveTransfer> entry : clients.entrySet()) {
ActiveTransfer session = entry.getValue();
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Closing client session: " + entry.getKey());
}
try {
session.close();
} catch (IOException iox) {
LOG.log(Level.FINEST, "Ignoring exception", iox);
}
toNotify.add(session);
}
clients.clear();
try {
if (gcTask != null) {
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Stopping GC task");
}
gcTask.cancel(false);
}
} catch (IllegalStateException isx) {
if (Logging.SHOW_FINEST && LOG.isLoggable(Level.FINEST)) {
LOG.log(Level.FINEST, "Ignoring exception", isx);
}
} finally {
gcTask = null;
}
}
// Notify listeners
for (ActiveTransfer transfer : toNotify) {
fireSessionCollected(transfer);
}
}
//////////////////////////////////////////////////////////////////////////
// Private methods:
/**
* Periodic cleanup task to remove any inactive clients.
*/
private void clientGC() {
Iterator<Map.Entry<Object, ActiveTransfer>> it;
Map.Entry<Object, ActiveTransfer> entry;
List<ActiveTransfer> toNotify = null;
ActiveTransfer session;
if (Logging.SHOW_FINEST && LOG.isLoggable(Level.FINEST)) {
LOG.finest("clientGC");
}
synchronized(this) {
it = clients.entrySet().iterator();
while (it.hasNext()) {
entry = it.next();
session = entry.getValue();
if (session.isIdle()) {
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Closing client session: " + entry.getKey());
}
try {
session.close();
} catch (IOException iox) {
if (Logging.SHOW_FINEST
&& LOG.isLoggable(Level.FINEST)) {
LOG.log(Level.FINEST, "Ignoring exception", iox);
}
}
if (toNotify == null) {
toNotify = new ArrayList<ActiveTransfer>();
toNotify.add(session);
}
it.remove();
}
}
}
// Notify listeners
if (toNotify != null) {
for (ActiveTransfer transfer : toNotify) {
fireSessionCollected(transfer);
}
}
}
/**
* Notify all listeners that a new session has been created.
*
* @param transfer the new session
*/
private void fireSessionCreated(ActiveTransfer transfer) {
for (ActiveTransferTrackerListener listener : listeners) {
listener.sessionCreated(transfer);
}
}
/**
* Notify all listeners that an idle session has been garbage
* collected.
*
* @param transfer the idle session
*/
private void fireSessionCollected(ActiveTransfer transfer) {
for (ActiveTransferTrackerListener listener : listeners) {
listener.sessionCollected(transfer);
}
}
}