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.http.ProcessorTask;
import com.sun.grizzly.util.ExtendedThreadPool;
import com.sun.grizzly.util.LinkedTransferQueue;
import com.sun.grizzly.util.SelectorFactory;
import com.sun.grizzly.util.WorkerThreadImpl;
import java.io.IOException;
import java.nio.channels.SelectionKey;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.sun.grizzly.util.FixedThreadPool;
/**
* 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 {
// Disable suspended connection time out for a {@link CometContext#setExpirationDelay}
public final static int DISABLE_SUSPEND_TIMEOUT = -1;
// Disable client detection close for a {@link CometContext#setExpirationDelay}
public final static int DISABLE_CLIENT_DISCONNECTION_DETECTION = 0;
/**
* 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
*/
protected final static Logger logger = SelectorThread.logger();
/**
*
*/
private final static IllegalStateException ISE = new IllegalStateException("Invalid state");
/**
* The {@link ExecutorService} used to execute {@link CometTask}
*/
protected ExtendedThreadPool threadPool;
/**
* The single instance of this class.
*/
protected final static CometEngine cometEngine = new CometEngine();
/**
* The current active {@link CometContext} keyed by context path.
*/
protected final ConcurrentHashMap activeContexts;
/**
* 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();
/**
* Creat a singleton and initialize all lists required.
*/
protected CometEngine() {
cometContextCache = new LinkedTransferQueue();
activeContexts = new ConcurrentHashMap(16,0.75f,64);
ExtendedThreadPool tpe = new FixedThreadPool(Runtime.getRuntime().availableProcessors(),"CometWorker");
setThreadPool(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.
* shuttdownnow is called on the existing threadpool.
* does notupdate existing notificationhandlers.
*/
public void setThreadPool(ExtendedThreadPool threadPool) {
if (threadPool != null){
int oldsize = 0;
if (this.threadPool != null){
oldsize = this.threadPool.getMaximumPoolSize();
this.threadPool.shutdownNow();
}
this.threadPool = threadPool;
int delta = threadPool.getMaximumPoolSize() - oldsize;
try {
SelectorFactory.changeSelectorsBy(delta);
} catch (IOException ex) {
logger.log(Level.WARNING, "comet failed to resize Selector cache", ex);
}
}
}
/**
* returns the threadpool comet is using
* @return ExtendedThreadPool
*/
public ExtendedThreadPool getThreadPool() {
return 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){
cometContext.recycle();
}
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;
}else{
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.setNotificationHandler(notificationHandler);
if (notificationHandler != null && (notificationHandler
instanceof DefaultNotificationHandler)){
((DefaultNotificationHandler)notificationHandler)
.setThreadPool(threadPool);
}
activeContexts.put(topic,cometContext);
}
}
}
cometContext.continuationType = type;
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) {
//need to impl tlocal that gets and sets null in one efficent operation
updatedContexts.set(null);
cometContext = cometTask.getCometContext();
if (cometTask.upcoming_op_isread){ //alreadySuspended
cometTask.upcoming_op_isread = false;
//need to set dumykey in cometTask ?
cometContext.addActiveHandler(cometTask);
return false;
}
cometTask.setAsyncProcessorTask(apt);
if (cometContext.getExpirationDelay() != -1){
cometTask.setTimeout(System.currentTimeMillis());
}
SelectionKey mainKey = apt.getAsyncExecutor().getProcessorTask().getSelectionKey();
if (mainKey.isValid() && cometContext.getExpirationDelay()
!= DISABLE_CLIENT_DISCONNECTION_DETECTION){
try{
mainKey.interestOps(SelectionKey.OP_READ);
mainKey.attach(cometTask);
cometContext.initialize(cometTask.getCometHandler());
}catch(Exception e){
mainKey.attach(Long.MIN_VALUE);
return false;
}
cometContext.addActiveHandler(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);
}
/**
* Interrupt a {@link CometHandler} by invoking {@link CometHandler#onInterrupt}
* @param task. The {@link CometTask} encapsulating the suspended connection.
* @param finishExecution Finish the current execution.
*/
protected boolean interrupt(final CometTask task, final boolean finishExecution) {
if (task != null && task.getCometContext().handlers().remove(task.cometHandler) != null){
final SelectionKey key = task.getSelectionKey();
// setting attachment non asynced to ensure grizzly dont keep calling us
key.attach(System.currentTimeMillis());
if (finishExecution){
key.cancel();
task.callInterrupt = true;
((WorkerThreadImpl)Thread.currentThread()).
getPendingIOhandler().addPendingIO(task);
}else{
interrupt0(task, finishExecution);
}
return true;
}
return false;
}
/**
* Interrupt logic in its own method, so it can be executed either async or sync.
* cometHandler.onInterrupt is performed async due to its functionality is unknown,
* hence not safe to run in the performance critical selector thread.
* @param task. The {@link CometTask} encapsulating the suspended connection.
* @param finishExecution Finish the current execution.
*/
protected void interrupt0(CometTask task, boolean finishExecution){
if (finishExecution){
try{
task.cometHandler.onInterrupt(task.getCometContext().eventInterrupt);
}catch(IOException e) { }
}
flushPostExecute(task,finishExecution);
}
/**
* Ensures {@link ProcessorTask} is recycled and that {@link Selectionkey} is canceled when needed.
*
* @param task
* @param cancelkey
*/
protected void flushPostExecute(final CometTask task,boolean cancelkey) {
AsyncProcessorTask apt = task.getAsyncProcessorTask();
ProcessorTask p = task.getAsyncProcessorTask().getAsyncExecutor().getProcessorTask();
p.setReRegisterSelectionKey(false);
p.setAptCancelKey(cancelkey);
if (apt.getStage() == AsyncTask.POST_EXECUTE){
try{
//All comet IO operations sync on handler except close
synchronized(task.cometHandler){
apt.doTask();
}
} catch (IllegalStateException ex){
if (logger.isLoggable(Level.FINEST)){
logger.log(Level.FINEST,"Resuming Response failed at aptflush",ex);
}
} catch (Throwable ex) {
logger.log(Level.SEVERE,"Resuming failed at aptflush",ex);
}
}else{
logger.warning("APTflush called at wrong stage");
}
}
/**
* 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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