com.sun.grizzly.comet.CometEngine Maven / Gradle / Ivy
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package com.sun.grizzly.comet;
import com.sun.grizzly.arp.AsyncTask;
import com.sun.grizzly.http.SelectorThread;
import com.sun.grizzly.arp.AsyncProcessorTask;
import com.sun.grizzly.util.LinkedTransferQueue;
import java.io.IOException;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
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
* @author Gustav Trede
*/
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();
/**
*
*/
private final static IllegalStateException ISE = new IllegalStateException("Invalid state");
/**
* The {@link ExecutorService} used to execute {@link CometTask}
*/
protected ExecutorService threadPool;
/**
* The single instance of this class.
*/
private final static CometEngine cometEngine = new CometEngine();
/**
* The current active {@link CometContext} keyed by context path.
*/
protected final ConcurrentHashMap activeContexts;
/**
* The {@link CometSelector} used to poll requests.
*/
protected final CometSelector cometSelector;
/**
* cached CometContexts
*/
protected final LinkedTransferQueue cometContextCache;
/**
* Is Grizzly ARP enabled? By default we set it to false.
*/
private static volatile boolean isCometSupported;
/**
* Store updatedCometContextCometContext.
*/
protected final static ThreadLocal updatedContexts = new ThreadLocal();
protected static final SelectionKey dumykey = new SelectionKey() {
public SelectableChannel channel() {throw ISE;}
public int interestOps() {throw ISE;}
public SelectionKey interestOps(int ops) {throw ISE;}
public int readyOps() {throw ISE;}
public Selector selector() {throw ISE;}
public boolean isValid() {return true;}
public void cancel() { }
};
/**
* Creat a singleton and initialize all lists required. Also create and
* start the {@link CometSelector}
*/
protected CometEngine() {
cometSelector = new CometSelector(this);
try{
cometSelector.start();
} catch(InterruptedException ex){
logger.log(Level.SEVERE,"Unable to start CometSelector",ex);
}
cometContextCache = new LinkedTransferQueue();
activeContexts = new ConcurrentHashMap(16,0.75f,64);
ThreadPoolExecutor tpe = new ThreadPoolExecutor(
8,
64,
30L,
TimeUnit.SECONDS,
new LinkedBlockingQueue(),
new ThreadFactory() {
private final AtomicInteger counter = new AtomicInteger();
public Thread newThread(Runnable r) {
return new Thread(r, "CometWorker-"+counter.incrementAndGet());
}
});
//tpe.allowCoreThreadTimeOut(true);
threadPool = tpe;
}
/**
* Return true is Comet is enabled, e.g. {@link SelectorThread.setAsyncExectution}
* has been set to true
* @return
*/
protected boolean isCometEnabled(){
return isCometSupported;
}
/**
* Return a singleton of this Class.
* @return CometEngine the singleton.
*/
public static CometEngine getEngine(){
return cometEngine;
}
/**
* sets the default threadpool that DefaultNotificationHandler use.
* does notupdate existing notificationhandlers
*/
public void setThreadPool(ExecutorService threadPool) {
if (threadPool != null){
this.threadPool.shutdownNow();
this.threadPool = threadPool;
}
}
/**
* Unregister the {@link CometHandler} to the list of the
* {@link CometContext}. Invoking this method will invoke all
* {@link CometHandler#onTerminate(com.sun.grizzly.comet.CometEvent)} before
* removing the associated {@link CometContext}. Invoking that method
* will also resume the underlying connection associated with the
* {@link CometHandler}, similar to what
* {@link CometContext#resumeCometHandler(com.sun.grizzly.comet.CometHandler)}
* do.
*/
public CometContext unregister(String topic){
CometContext cometContext = activeContexts.remove(topic);
if (cometContext != null){
try{
cometContext.notify(cometContext,CometEvent.TERMINATE);
} catch (IOException ex) {}
Set tasks = cometContext.getActiveTasks();
for (CometTask cometTask: tasks){
// does this work ? the notify above might be async.
flushResponse(cometTask.getAsyncProcessorTask());
}
//TODO: add check for datastructure size, if cometcontext had large
// datastructes its probably not optimal to waste RAM with caching it
cometContext.recycle();
cometContextCache.offer(cometContext);
}
return cometContext;
}
/**
* 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}
* @param type when the request will be suspended, e.g. {@link BEFORE_REQUEST_PROCESSING},
* {@link AFTER_SERVLET_PROCESSING} or {@link AFTER_RESPONSE_PROCESSING}
* @return CometContext a configured {@link CometContext}.
*/
public CometContext register(String topic, int type){
return register(topic, type, DefaultNotificationHandler.class);
}
/**
* Instanciate a new {@link CometContext}.
* @param topic the topic the new {@link CometContext} will represent.
* @param type when the request will be suspended, e.g. {@link BEFORE_REQUEST_PROCESSING},
* {@link AFTER_SERVLET_PROCESSING} or {@link AFTER_RESPONSE_PROCESSING}
* @return a new {@link CometContext} if not already created, or the
* existing one.
*/
public CometContext register(String topic, int type,
Class notificationClass ) {
// Double checked locking used used to prevent the otherwise static/global
// locking, cause example code does heavy usage of register calls
// for existing topics from http get calls etc.
CometContext cometContext = activeContexts.get(topic);
if (cometContext == null){
synchronized(activeContexts){
cometContext = activeContexts.get(topic);
if (cometContext == null){
cometContext = cometContextCache.poll();
if (cometContext != null)
cometContext.topic = topic;
if (cometContext == null){
cometContext = new CometContext(topic, type);
NotificationHandler notificationHandler = null;
try{
notificationHandler = notificationClass.newInstance();
} catch (Throwable t) {
logger.log(Level.SEVERE,"Invalid NotificationHandler class : "
+ notificationClass.getName() + " Using default.",t);
notificationHandler = new DefaultNotificationHandler();
}
cometContext.setCometSelector(cometSelector);
cometContext.setNotificationHandler(notificationHandler);
if (notificationHandler != null && (notificationHandler
instanceof DefaultNotificationHandler)){
((DefaultNotificationHandler)notificationHandler)
.setThreadPool(threadPool);
}
}
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{
// That means Grizzly ARP is invoking us via AsyncFilter.
if (!isCometSupported){
//volatile read is in general cheaper then a write.
isCometSupported = true;
}
String topic = apt.getAsyncExecutor().getProcessorTask().getRequestURI();
CometContext cometContext = topic==null?null:activeContexts.get(topic);
/* 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.
*/
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.
*/
CometTask cometTask = updatedContexts.get();
if (cometTask != null) {
updatedContexts.set(null);
if (cometTask.isSuspended()){ //alreadySuspended)
cometTask.setSuspended(false);
cometTask.getCometContext().addActiveHandler(cometTask.getCometHandler(), dumykey);
return false;
}
SelectionKey key = apt.getAsyncExecutor().getProcessorTask().getSelectionKey();
key.attach("comet"); // Disable keep-alive
cometTask.getCometContext().initialize(cometTask.getCometHandler());
cometTask.setAsyncProcessorTask(apt);
cometTask.setSelectionKey(key);
cometTask.setCometSelector(cometSelector);
cometTask.setSelectorThread(apt.getSelectorThread());
cometTask.setThreadPool(apt.getThreadPool());
cometSelector.registerKey(cometTask);
return true;
}
return false;
}
/**
* 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);
}
/**
* flush if AsyncTask.POST_EXECUTE
* {@link AsyncProcessorTask}
*/
protected void flushPostExecute(AsyncProcessorTask apt) {
if (apt != null && apt.getStage() == AsyncTask.POST_EXECUTE){
flushResponse(apt);
}
}
/**
* Complete the asynchronous request.
*/
protected void flushResponse(AsyncProcessorTask apt){
apt.setStage(AsyncTask.POST_EXECUTE);
try{
apt.doTask();
} catch (IllegalStateException ex){
if (logger.isLoggable(Level.FINEST)){
logger.log(Level.FINEST,"Resuming Response failed",ex);
}
} catch (Throwable ex) {
logger.log(Level.SEVERE,"Resuming 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 ISE;
}
/**
* 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){
apt.doTask();
}
} catch (IOException ex){
logger.log(Level.SEVERE,"executeServlet",ex);
}
}
/**
* Return the current logger.
*/
public final static Logger logger(){
return logger;
}
}
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