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*
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*
* Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved.
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* and Distribution License("CDDL") (collectively, the "License"). You
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package com.sun.grizzly.comet;
import com.sun.grizzly.arp.AsyncHandler;
import com.sun.grizzly.arp.AsyncTask;
import com.sun.grizzly.Pipeline;
import com.sun.grizzly.http.SelectorThread;
import com.sun.grizzly.arp.AsyncProcessorTask;
import java.io.IOException;
import java.nio.channels.SelectionKey;
import java.util.Iterator;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.locks.ReentrantLock;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Main class allowing Comet support on top of Grizzly Asynchronous
* Request Processing mechanism. This class is the entry point to any
* component interested to execute Comet request style. Components can be
* Servlets, JSP, JSF or pure Java class. A component interested to support
* Comet request must do:
*
* (1) First, register the topic on which Comet support will be applied:
* CometEngine cometEngine = CometEngine.getEngine()
* CometContext cometContext = cometEngine.register(topic)
* (2) Second, add an instance of {@link CometHandler} to the
* {@link CometContext} returned by the register method:
* {@link CometContext#addCometHandler}. Executing this operation
* will tells Grizzly to suspend the response.
* (3) Finally, you can {@link CometContext#notify} other {@link CometHandler}
* to share information between {@ CometHandler}. When notified,
* {@link CometHandler} can decides to push back the data, resume the
* response, or simply ignore the content of the notification.
*
* You can also select the stage where the suspension of the response happens when
* registering the {@link CometContext}'s topic (see {@link #register}), which can be
* before, during or after invoking a {@link Servlet}
*
* @author Jeanfrancois Arcand
*/
public class CometEngine {
/**
* The token used to support BEFORE_REQUEST_PROCESSING polling.
*/
public final static int BEFORE_REQUEST_PROCESSING = 0;
/**
* The token used to support AFTER_SERVLET_PROCESSING polling.
*/
public final static int AFTER_SERVLET_PROCESSING = 1;
/**
* The token used to support BEFORE_RESPONSE_PROCESSING polling.
*/
public final static int AFTER_RESPONSE_PROCESSING = 2;
/**
* Main logger
*/
private final static Logger logger = SelectorThread.logger();
/**
* The {@link Pipeline} used to execute {@link CometTask}
*/
protected Pipeline pipeline;
/**
* The single instance of this class.
*/
private static CometEngine cometEngine;
/**
* The current active {@link CometContext} keyed by context path.
*/
protected ConcurrentHashMap activeContexts;
/**
* Cache of {@link CometTask} instance
*/
protected ConcurrentLinkedQueue cometTasks;
/**
* Cache of {@link CometContext} instance.
*/
protected ConcurrentLinkedQueue cometContexts;
/**
* The {@link CometSelector} used to poll requests.
*/
protected CometSelector cometSelector;
/**
* The default class to use when deciding which NotificationHandler
* to use. The default is DefaultNotificationHandler.
*/
protected static String notificationHandlerClassName =
DefaultNotificationHandler.class.getName();
/**
* Temporary repository that associate a Thread ID with a Key.
* NOTE: A ThreadLocal might be more efficient.
*/
protected ConcurrentHashMap threadsId;
/**
* Store modified CometContext.
*/
protected ConcurrentHashMap updatedCometContexts;
/**
* The list of registered {@link AsyncProcessorTask}. This object
* are mainly keeping the state of the Comet request.
*/
private ConcurrentLinkedQueue asyncTasks;
// Simple lock.
private ReentrantLock lock = new ReentrantLock();
// --------------------------------------------------------------------- //
/**
* Creat a singleton and initialize all lists required. Also create and
* start the {@link CometSelector}
*/
protected CometEngine() {
activeContexts = new ConcurrentHashMap();
cometTasks = new ConcurrentLinkedQueue();
cometContexts = new ConcurrentLinkedQueue();
cometSelector = new CometSelector(this);
try{
cometSelector.start();
} catch(InterruptedException ex){
logger.log(Level.SEVERE,"Unable to start CometSelector",ex);
}
threadsId = new ConcurrentHashMap();
updatedCometContexts = new ConcurrentHashMap();
asyncTasks = new ConcurrentLinkedQueue();
}
/**
* Return a singleton of this Class.
* @return CometEngine the singleton.
*/
public synchronized static CometEngine getEngine(){
if (cometEngine == null) {
cometEngine = new CometEngine();
}
return cometEngine;
}
/**
* Unregister the {@link CometHandler} to the list of the
* {@link CometContext}.
*/
public synchronized CometContext unregister(String topic){
CometContext cometContext = activeContexts.get(topic);
try{
cometContext.notify(cometContext,CometEvent.TERMINATE);
} catch (IOException ex){
logger.log(Level.WARNING,"unregister",ex);
}
finalizeContext(cometContext);
return activeContexts.remove(topic);
}
/**
* Register a context path with this {@link CometEngine}. The
* {@link CometContext} returned will be of type
* AFTER_SERVLET_PROCESSING, which means the request target (most probably
* a Servlet) will be executed first and then polled.
* @param topic the context path used to create the
* {@link CometContext}
* @return CometContext a configured {@link CometContext}.
*/
public CometContext register(String topic){
return register(topic,AFTER_SERVLET_PROCESSING);
}
/**
* Register a context path with this {@link CometEngine}. The
* {@link CometContext} returned will be of type
* type.
* @param topic the context path used to create the
* {@link CometContext}
* @return CometContext a configured {@link CometContext}.
*/
public synchronized CometContext register(String topic, int type){
CometContext cometContext = activeContexts.get(topic);
if (cometContext == null){
cometContext = cometContexts.poll();
if (cometContext == null){
cometContext = new CometContext(topic,type);
cometContext.setCometSelector(cometSelector);
NotificationHandler notificationHandler
= loadNotificationHandlerInstance
(notificationHandlerClassName);
cometContext.setNotificationHandler(notificationHandler);
if (notificationHandler != null && (notificationHandler
instanceof DefaultNotificationHandler)){
((DefaultNotificationHandler)notificationHandler)
.setPipeline(pipeline);
}
}
activeContexts.put(topic,cometContext);
}
return cometContext;
}
/**
* Handle an interrupted(or polled) request by matching the current context
* path with the registered one.
* If required, the bring the target component (Servlet) to the proper
* execution stage and then {@link CometContext#notify} the {@link CometHandler}
* @param apt the current apt representing the request.
* @return boolean true if the request can be polled.
*/
protected boolean handle(AsyncProcessorTask apt) throws IOException{
if (pipeline == null){
pipeline = apt.getPipeline();
}
String topic = apt.getAsyncExecutor().getProcessorTask().getRequestURI();
CometContext cometContext = null;
if (topic != null){
cometContext = activeContexts.get(topic);
try{
lock.lock();
if (cometContext != null){
NotificationHandler notificationHandler =
cometContext.getNotificationHandler();
if (notificationHandler instanceof DefaultNotificationHandler){
((DefaultNotificationHandler)notificationHandler)
.setPipeline(pipeline);
}
}
} finally {
lock.unlock();
}
}
/*
* If the cometContext is null, it means the context has never
* been registered. The registration might happens during the
* Servlet.service() execution so we need to keep a reference
* to the current thread so we can later retrieve the associated
* SelectionKey. The SelectionKey is required in order to park the
* request.
*/
boolean activateContinuation = true;
SelectionKey key = apt.getAsyncExecutor().getProcessorTask().getSelectionKey();
threadsId.put(Thread.currentThread().getId(),key);
int continuationType = (cometContext == null)?
AFTER_SERVLET_PROCESSING:cometContext.continuationType;
/*
* Execute the Servlet.service method. CometEngine.register() or
* CometContext.addCometHandler() might be invoked during the
* execution.
*/
executeServlet(continuationType,apt);
/*
* Will return a CometContext instance if and only if the
* Servlet.service() have invoked CometContext.addCometHandler().
* If the returned CometContext is null, it means we need to
* execute a synchronous request.
*/
cometContext = updatedCometContexts.remove(Thread.currentThread().getId());
if (cometContext == null){
activateContinuation = false;
}
boolean parkRequest = true;
if (activateContinuation) {
// Prevent the Servlet to suspend/resume the request in a single
// transaction
CometContext.addInProgressSelectionKey(key);
// Disable keep-alive
key.attach(null);
boolean isBlocking = cometContext.isBlockingNotification();
// We must initialize in blocking mode in case the connection is resumed
// during the invocation of that method. If non blocking, there is a possible
// thread race.
cometContext.setBlockingNotification(true);
cometContext.initialize(key);
cometContext.setBlockingNotification(isBlocking);
/**
* The CometHandler has been resumed during the onIntialize method
* call if getCometHandler return null.
*/
if (cometContext.getCometHandler(key) != null){
asyncTasks.offer(apt);
CometTask cometTask = getCometTask(cometContext,key,
apt.getPipeline());
cometTask.setSelectorThread(apt.getSelectorThread());
cometTask.setExpirationDelay(cometContext.getExpirationDelay());
cometTask.setSelectorThread(apt.getSelectorThread());
cometContext.addActiveCometTask(cometTask);
cometSelector.registerKey(key,cometTask);
} else{
parkRequest = false;
}
// Now we can allow full control
CometContext.removeInProgressSelectionKey(key);
} else {
parkRequest = false;
}
return parkRequest;
}
/**
* Tell the CometEngine to activate Grizzly ARP on that CometContext.
* This method is called when CometContext.addCometHandler() is
* invoked.
* @param threadId the Thread.getId().
* @param cometContext An instance of CometContext.
* @return key The SelectionKey associated with the current request.
*/
protected SelectionKey activateContinuation(Long threadId,
CometContext cometContext, boolean continueExecution){
if (!continueExecution){
updatedCometContexts.put(threadId,cometContext);
}
return threadsId.remove(threadId);
}
/**
* Return a clean and configured {@link CometTask}
* @param cometContext the CometContext to clean
* @param key The current {@link SelectionKey}
* @return a new CometContext
*/
protected CometTask getCometTask(CometContext cometContext,SelectionKey key,
Pipeline ctxPipeline){
if (ctxPipeline == null){
ctxPipeline = pipeline;
}
CometTask cometTask = cometTasks.poll();
if (cometTask == null){
cometTask = new CometTask();
}
cometTask.setCometContext(cometContext);
cometTask.setSelectionKey(key);
cometTask.setCometSelector(cometSelector);
cometTask.setPipeline(ctxPipeline);
return cometTask;
}
/**
* Cleanup the {@link CometContext}
* @param cometContext the CometContext to clean
*/
private void finalizeContext(CometContext cometContext) {
Iterator iterator = activeContexts.keySet().iterator();
String topic;
while(iterator.hasNext()){
topic = iterator.next();
if ( activeContexts.get(topic).equals(cometContext) ){
activeContexts.remove(topic);
break;
}
}
for (AsyncProcessorTask apt: asyncTasks){
flushResponse(apt);
}
cometContext.recycle();
cometContexts.offer(cometContext);
}
/**
* Return the {@link CometContext} associated with the topic.
* @param topic the topic used to creates the {@link CometContext}
*/
public CometContext getCometContext(String topic){
return activeContexts.get(topic);
}
/**
* The {@link CometSelector} is expiring idle {@link SelectionKey},
* hence we need to resume the current request.
* @param key the expired SelectionKey
*/
protected void interrupt(SelectionKey key) {
CometTask cometTask = (CometTask)key.attachment();
key.attach(null);
if (cometTask == null)
throw new IllegalStateException("cometTask cannot be null");
SelectionKey akey = cometTask.getSelectionKey();
try{
if (akey == null || !akey.isValid()) return;
Iterator iterator = asyncTasks.iterator();
AsyncHandler ah = null;
while (iterator.hasNext()){
AsyncProcessorTask apt = iterator.next();
ah = apt.getAsyncExecutor().getAsyncHandler();
if (apt.getAsyncExecutor().getProcessorTask().getSelectionKey() == akey){
iterator.remove();
if (akey != null){
akey.attach(null);
}
/**
* The connection was parked and resumed before
* the CometEngine.handle() terminated.
*/
if (apt.getStage() != AsyncTask.POST_EXECUTE){
break;
}
flushResponse(apt);
break;
}
}
} finally {
returnTask(cometTask);
}
}
/**
* Return a {@link Task} to the pool.
*/
protected void returnTask(CometTask cometTask){
cometTask.recycle();
cometTasks.offer(cometTask);
}
/**
* Resume the long polling request by unblocking the current
* {@link SelectionKey}
*/
protected void resume(SelectionKey key) {
Iterator iterator = asyncTasks.iterator();
while (iterator.hasNext()){
AsyncProcessorTask apt = iterator.next();
if (apt.getAsyncExecutor().getProcessorTask().getSelectionKey() == key){
iterator.remove();
/**
* The connection was parked and resumed before
* the CometEngine.handle() terminated.
*/
if (apt.getStage() != AsyncTask.POST_EXECUTE){
break;
}
flushResponse(apt);
break;
}
}
}
/**
* Complete the asynchronous request.
*/
private void flushResponse(AsyncProcessorTask apt){
apt.setStage(AsyncTask.POST_EXECUTE);
try{
apt.doTask();
} catch (IllegalStateException ex){
if (logger.isLoggable(Level.FINEST)){
logger.log(Level.FINEST,"flushResponse failed",ex);
}
} catch (IOException ex) {
logger.log(Level.SEVERE,"flushResponse failed",ex);
}
}
/**
* Bring the cometContext path target (most probably a Servlet) to the processing
* stage we need for Comet request processing.
* @param cometContext The CometContext associated with the Servlet
* @param apt the AsyncProcessorTask
*/
private void executeServlet(int continuationType,
AsyncProcessorTask apt){
try{
switch (continuationType){
case BEFORE_REQUEST_PROCESSING:
apt.setStage(AsyncTask.PRE_EXECUTE);
break;
case AFTER_SERVLET_PROCESSING:
apt.getAsyncExecutor().getProcessorTask().invokeAdapter();
return;
case AFTER_RESPONSE_PROCESSING:
apt.setStage(AsyncTask.POST_EXECUTE);
// Last step, execute directly from here.
apt.doTask();
break;
default:
throw new IllegalStateException("Invalid state");
}
/**
* We have finished the processing, most probably because we
* entered the {@link FileCache} or because we of
* the {@link #AFTER_RESPONSE_PROCESSING} configuration.
*/
if (apt.getStage() == AsyncTask.POST_EXECUTE){
return;
}
apt.doTask();
} catch (IOException ex){
logger.log(Level.SEVERE,"executeServlet",ex);
}
}
/**
* Return the default {@link NotificationHandler} class name.
* @return the default {@link NotificationHandler} class name.
*/
public static String getNotificationHandlerClassName() {
return notificationHandlerClassName;
}
/**
* Set the default {@link NotificationHandler} class name.
* @param the default {@link NotificationHandler} class name.
*/
public static void setNotificationHandlerClassName(String aNotificationHandlerClassName) {
notificationHandlerClassName = aNotificationHandlerClassName;
}
/**
* Util to load classes using reflection.
*/
protected final static NotificationHandler
loadNotificationHandlerInstance(String className){
Class clazz = null;
try{
clazz = Class.forName(className,true,
Thread.currentThread().getContextClassLoader());
return (NotificationHandler)clazz.newInstance();
} catch (Throwable t) {
logger.log(Level.WARNING,"Invalid NotificationHandler: ",t);
}
return new DefaultNotificationHandler();
}
/**
* Return the current logger.
*/
public final static Logger logger(){
return logger;
}
}
