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/*
* Copyright (c) 2007, 2020 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package org.glassfish.grizzly.comet;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.grizzly.localization.LogMessages;
/**
* 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 {@link 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}
@Deprecated
public final static int DISABLE_SUSPEND_TIMEOUT = -1;
// Disable client detection close for a {@link CometContext#setExpirationDelay}
@Deprecated
public final static int DISABLE_CLIENT_DISCONNECTION_DETECTION = 0;
/**
* The token used to support BEFORE_REQUEST_PROCESSING polling.
*/
@Deprecated
public final static int BEFORE_REQUEST_PROCESSING = 0;
/**
* The token used to support AFTER_SERVLET_PROCESSING polling.
*/
@Deprecated
public final static int AFTER_SERVLET_PROCESSING = 1;
/**
* The token used to support BEFORE_RESPONSE_PROCESSING polling.
*/
@Deprecated
public final static int AFTER_RESPONSE_PROCESSING = 2;
/**
* Main logger
*/
protected final static Logger logger = Logger.getLogger(CometEngine.class.getName());
/**
* The {@link ExecutorService} used to execute
*/
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 Map activeContexts;
/**
* Is Grizzly ARP enabled? By default we set it to false.
*/
private boolean isCometSupported;
/**
* Create a singleton and initialize all lists required.
*/
protected CometEngine() {
activeContexts = new ConcurrentHashMap<>(16, 0.75f, 64);
}
/**
* Return true if comet is enabled.
*/
protected boolean isCometEnabled() {
return isCometSupported;
}
public void setCometSupported(boolean supported) {
isCometSupported = supported;
}
/**
* Return a singleton of this Class.
*
* @return CometEngine the singleton.
*/
public static CometEngine getEngine() {
return cometEngine;
}
/**
* Calls through to {@link #deregister(String)}.
*
* @deprecated
*/
@Deprecated
public CometContext unregister(String topic) {
return deregister(topic);
}
/**
* Deregister 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 deregister(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
* type.
*
* @param topic the context path used to create the {@link CometContext}
* @param type when the request will be suspended
*
* @return CometContext a configured {@link CometContext}.
* @deprecated Use {@link #register(String)} instead
*/
@Deprecated
public CometContext register(String topic, int type) {
return register(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, DefaultNotificationHandler.class);
}
/**
* Instantiate a new {@link CometContext}.
*
* @param topic the topic the new {@link CometContext} will represent.
* @return a new {@link CometContext} if not already created, or the existing one.
*/
@SuppressWarnings({ "unchecked" })
public CometContext register(String topic, 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 = new CometContext<>(topic);
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);
}
}
}
return cometContext;
}
/**
* Return the {@link CometContext} associated with the topic.
*
* @param topic the topic used to creates the {@link CometContext}
*/
@SuppressWarnings({ "unchecked" })
public CometContext getCometContext(String topic) {
return activeContexts.get(topic);
}
/**
* Interrupt a {@link CometHandler} by invoking {@link CometHandler#onInterrupt}
*
* @param handler The {@link CometHandler} encapsulating the suspended connection.
* @param finishExecution Finish the current execution.
*
* @see CometContext#interrupt(CometHandler, boolean)
* @deprecated use the CometContext version
*/
@Deprecated
@SuppressWarnings({ "deprecation" })
protected boolean interrupt(CometHandler handler, boolean finishExecution) throws IOException {
final CometContext cometContext = handler.getCometContext();
final boolean removed = cometContext.removeCometHandler(handler, finishExecution);
if (removed && !finishExecution) {
interrupt0(handler, finishExecution);
}
return removed;
}
/**
* 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 handler The {@link CometHandler} encapsulating the suspended connection.
* @param finishExecution Finish the current execution.
*
* @see CometContext#interrupt0(CometHandler, boolean)
* @deprecated use the CometContext version
*/
@Deprecated
protected void interrupt0(CometHandler handler, boolean finishExecution) throws IOException {
if (finishExecution) {
try {
handler.onInterrupt(handler.getCometContext().eventInterrupt);
} catch (IOException e) {
}
}
handler.getResponse().finish();
}
/**
* Return the current logger.
*/
public static Logger logger() {
return logger;
}
}
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