com.sun.grizzly.comet.CometEngine Maven / Gradle / Ivy
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package com.sun.grizzly.comet;
import com.sun.grizzly.util.LogMessages;
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.http.StatsThreadPool;
import com.sun.grizzly.util.DataStructures;
import com.sun.grizzly.util.ExtendedThreadPool;
import com.sun.grizzly.util.SelectorFactory;
import java.io.IOException;
import java.nio.channels.SelectionKey;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.Queue;
import java.util.concurrent.TimeUnit;
/**
* 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 Servlet
*
* There is known limitation related to HTTP pipelining, it can't work
* properly when {@link CometContext#isDetectClosedConnections()} is enabled.
* So if you want to support HTTP pipelining, the closed connection
* detection mechanism should be disabled via {@link CometContext#setDetectClosedConnections(boolean)}.
*
* @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 Queue cometContextCache;
/**
* Is Grizzly ARP enabled? By default we set it to false.
*/
private static volatile boolean isCometSupported;
/**
* Store updatedCometContext.
*/
protected final static ThreadLocal updatedContexts = new ThreadLocal();
/**
* Creat a singleton and initialize all lists required.
*/
protected CometEngine() {
cometContextCache = DataStructures.getCLQinstance(CometContext.class);
activeContexts = new ConcurrentHashMap(16, 0.75f, 64);
final int poolSize = Runtime.getRuntime().availableProcessors();
ExtendedThreadPool tpe = new StatsThreadPool("CometWorker",
poolSize, poolSize, -1, -1, TimeUnit.MILLISECONDS);
setThreadPool(tpe);
}
/**
* Return true is Comet is enabled, e.g. {@link SelectorThread#setEnableAsyncExecution(boolean)}
* 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.
* shutdownNow is called on the existing ThreadPool.
* does not update existing notification handlers.
*/
public final void setThreadPool(ExtendedThreadPool pool) {
if (pool != null) {
if (threadPool != null) {
threadPool.shutdownNow();
}
threadPool = pool;
SelectorFactory.setMaxSelectors(pool.getMaximumPoolSize());
}
}
/**
* returns the thread pool 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(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(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 CometEngine#BEFORE_REQUEST_PROCESSING},
* {@link CometEngine#AFTER_SERVLET_PROCESSING} or {@link CometEngine#AFTER_RESPONSE_PROCESSING}
* @return CometContext a configured {@link CometContext}.
*/
public CometContext register(String topic, int type) {
return register(topic, type, DefaultNotificationHandler.class);
}
/**
* Instantiate 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 CometEngine#BEFORE_REQUEST_PROCESSING},
* {@link CometEngine#AFTER_SERVLET_PROCESSING} or {@link CometEngine#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;
try {
notificationHandler = notificationClass.newInstance();
} catch (Throwable t) {
if (logger.isLoggable(Level.SEVERE)) {
logger.log(Level.SEVERE,
LogMessages.SEVERE_GRIZZLY_COMET_ENGINE_INVALID_NOTIFICATION_HANDLER_ERROR(notificationClass.getName()),
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;
}
final ProcessorTask processorTask = apt.getAsyncExecutor().getProcessorTask();
String topic = processorTask.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() ork
* 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 thread local that gets and sets null in one efficient operation
updatedContexts.set(null);
cometContext = cometTask.getCometContext();
if (cometTask.upcoming_op_isread) { //alreadySuspended
cometTask.upcoming_op_isread = false;
//need to set dummy key in cometTask ?
cometContext.addActiveHandler(cometTask);
return false;
}
cometTask.setAsyncProcessorTask(apt);
if (cometContext.getExpirationDelay() > 0) {
cometTask.setTimeout(System.currentTimeMillis());
}
SelectionKey mainKey = processorTask.getSelectionKey();
if (mainKey.isValid() && cometTask.isDetectConnectionClose()) {
// If Detect connection close mode is on - disable keep-alive for this connection
processorTask.getRequest().getResponse().addHeader("Connection", "close");
try {
mainKey.interestOps(SelectionKey.OP_READ);
} catch (Exception e) {
mainKey.attach(Long.MIN_VALUE);
return false;
}
}
mainKey.attach(cometTask);
cometContext.initialize(cometTask.getCometHandler());
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();
AsyncProcessorTask apt = task.getAsyncProcessorTask();
ProcessorTask p = apt.getAsyncExecutor().getProcessorTask();
p.setAptCancelKey(true);
task.callInterrupt = true;
task.run();
} 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 = apt.getAsyncExecutor().getProcessorTask();
p.setReRegisterSelectionKey(!task.isDetectConnectionClose());
// 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) {
if (logger.isLoggable(Level.SEVERE)) {
logger.log(Level.SEVERE,
LogMessages.SEVERE_GRIZZLY_COMET_ENGINE_FLUSH_ERROR(),
ex);
}
}
} else {
if (logger.isLoggable(Level.WARNING)) {
logger.warning(LogMessages.WARNING_GRIZZLY_COMET_ENGINE_FLUSH_INVALID_STAGE_ERROR());
}
}
}
/**
* Bring the cometContext path target (most probably a Servlet) to the processing
* stage we need for Comet request processing.
* @param continuationType the continuation type
* @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) {
if (logger.isLoggable(Level.SEVERE)) {
logger.log(Level.SEVERE,
LogMessages.SEVERE_GRIZZLY_COMET_IO_ERROR("CometEngine.executeServlet()"),
ex);
}
}
}
/**
* Return the current logger.
*/
public static Logger logger() {
return logger;
}
}
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