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package com.sun.grizzly.comet;
import com.sun.grizzly.comet.concurrent.DefaultConcurrentCometHandler;
import com.sun.grizzly.http.SelectorThread;
import java.io.IOException;
import java.nio.channels.SelectionKey;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Logger;
/**
* The main object used by {@link CometHandler} and Servlet to push information
* amongs suspended request/response. The {@link CometContext} is always available for {@link CometHandler}
* and can be used to {@link #notify}, or share information with other
* {@link CometHandler}. This is the equivalent of server push as the CometContext
* will invoke all registered CometHandler ({@link #addCometHandler}) sequentially
* or using a thread pool when the {@link #setBlockingNotification} is set to
* <tt>false</tt>
* <p>
* A CometContext can be considered as a topic where CometHandler register for
* information. A CometContext can be shared amongs Servlet of the same application,
* or globally accros all deployed web applications. Normally, a CometContext
* is created using a topic's name like:</p><p><pre><code>
*
* CometEngine ce = CometEngine.getEngine();
* CometContext cc = ce.registerContext("MyTopic");
* cc.setBlockingNotification(false); // Use multiple thread to execute the server push
*
* and then inside a Servlet.service() method, you just need to call:
*
* cc.addCometListener(myNewCometListener());
* cc.notify("I'm pushing data to all registered CometHandler");
* </core></pre></p>
* <p>
* As soom as {@link #addCometHandler} is invoked, Grizzly will automatically
* <strong>suspend</strong> the request/response (will not commit the response).
* A response can be <strong>resumed</strong> by invoking {@link #resumeCometHandler},
* which will automatically commit the response and remove the associated
* CometHandler from the CometContext.
*
* A CometContext uses a {@link NotificationHandler} to invoke, using the calling
* thread or a Grizzly thread pool, all CometHandler than have been added using the
* {@link #addCometHandler}. A {@link NotificationHandler} can be used to filter
* or transform the content that will eventually be pushed back to all connected
* clients. You can also use a {@link NotificationHandler} to throttle push like
* invoking only a subset of the CometHandler, etc.
*
* Idle suspended connection can be timed out by configuring the {@link #setExpirationDelay(long)}.
* The value needs to be in milliseconds. If there is no I/O operations and no
* invokation of {@link #notify} during the expiration delay, Grizzly
* will resume all suspended connection. An application will have a chance to
* send back data using the connection as Grizzly will invoke the {@link CometHandler#onInterrupt}
* before resuming the connection. Note that setting the expiration delay to -1
* disable the above mechanism, e.g. idle connection will never get resumed
* by Grizzly.
*
* </p>
* <p>
* Attributes can be added/removed the same way HttpServletSession
* is doing. It is not recommended to use attributes if this
* {@link CometContext} is not shared amongst multiple
* context path (uses HttpServletSession instead).
* </p>
* @author Jeanfrancois Arcand
* @author Gustav Trede
*/
public class CometContext<E> {
/**
* Generic error message
*/
protected final static String INVALID_COMET_HANDLER = "CometHandler cannot be null. "
+ "This CometHandler was probably resumed and an invalid "
+ "reference was made to it.";
protected final static String ALREADY_REMOVED =
"CometHandler already been removed or invalid.";
private final static String COMET_NOT_ENABLED =
"Make sure you have enabled Comet "
+ "or make sure the Thread invoking that method is the same "
+ "as the Servlet.service() Thread.";
/**
* Main logger
*/
protected final static Logger logger = SelectorThread.logger();
/**
* Attributes placeholder.
*/
private final ConcurrentHashMap attributes;
/**
* The context path associated with this instance.
*/
protected String topic;
/**
* The {@link CometContext} continuationType. See {@link CometEngine}
*/
protected int continuationType = CometEngine.AFTER_SERVLET_PROCESSING;
/**
* The default delay expiration before a {@link CometContext}'s
* {@link CometHandler} are interrupted.
*/
private long expirationDelay ;
/**
* <tt>true</tt> if the caller of {@link #notify} should block when
* notifying other CometHandler.
*/
protected boolean blockingNotification;
/**
* The default NotificationHandler.
*/
protected NotificationHandler notificationHandler;
/**
* time stamp for next idle check
* used to limit the frequency of actual performed resets.
*/
private volatile long nextIdleClear;
/**
* The list of registered {@link CometHandler}
*/
protected final ConcurrentHashMap<CometHandler,CometTask> handlers;
protected final CometEvent eventInterrupt;
protected final CometEvent eventTerminate;
private final CometEvent eventInitialize;
/**
* Create a new instance
* @param contextTopic the context path
* @param type when the Comet processing will happen (see {@link CometEngine}).
*/
public CometContext(String contextTopic, int type) {
topic = contextTopic;
continuationType = type;
attributes = new ConcurrentHashMap();
handlers = new ConcurrentHashMap<CometHandler,CometTask>(16,0.75f,64);
eventInterrupt = new CometEvent<CometContext>(CometEvent.INTERRUPT,this);
eventInitialize = new CometEvent<CometContext>(CometEvent.INITIALIZE,this);
eventTerminate = new CometEvent<CometContext>(CometEvent.TERMINATE,this,this);
initDefaultValues();
}
/**
* init of default values.
* used by constructor and the cache recycle mechanism
*/
private void initDefaultValues() {
blockingNotification = false;
expirationDelay = 30*1000;
nextIdleClear = 0;
}
/**
* Get the context path associated with this instance.
* @return topic the context path associated with this instance
* @deprecated - use getTopic.
*/
public String getContextPath(){
return getTopic();
}
/**
* Get the topic representing this instance with this instance. This is
* the value to uses when invoking {@link CometEngine#getCometContext}
* @return topic the topic associated with this instance
*/
public String getTopic(){
return topic;
}
/**
* Add an attibute.
* @param key the key
* @param value the value
*/
public void addAttribute(Object key, Object value){
attributes.put(key,value);
}
/**
* Retrieve an attribute.
* @param key the key
* @return Object the value.
*/
public Object getAttribute(Object key){
return attributes.get(key);
}
/**
* Remove an attribute.
* @param key the key
* @return Object the value
*/
public Object removeAttribute(Object key){
return attributes.remove(key);
}
/**
* Add a {@link CometHandler}. The underlying HttpServletResponse will
* not get commited until {@link CometContext#resumeCometHandler(CometHandler)}
* is invoked, unless the {@link CometContext#setExpirationDelay(long)} expires.
* If set to alreadySuspended is set to true, no I/O operations are allowed
* inside the {@link CometHandler} as the underlying HttpServletResponse
* has not been suspended. Adding such {@link CometHandler} is usefull only when
* no I/O operations on the HttpServletResponse are required. Examples
* include calling a remote EJB when a push operations happens, storing
* data inside a database, etc.
*
* @param handler a new {@link CometHandler}
* @param alreadySuspended Add the Comethandler but don't suspend
* the HttpServletResponse. If set to true, no
* I/O operations are allowed inside the {@link CometHandler} as the
* underlying HttpServletResponse has not been suspended, unless
* the {@link CometHandler} is shared amongs more than one {@link CometContext}
*
* @return The {@link CometHandler#hashCode} value.
*/
public int addCometHandler(CometHandler handler, boolean alreadySuspended){
if (handler == null){
throw new IllegalStateException(INVALID_COMET_HANDLER);
}
if (!CometEngine.getEngine().isCometEnabled()){
throw new IllegalStateException(COMET_NOT_ENABLED);
}
// is it ok that we only manage one addcomethandler call per thread ?
// else we can use a list of handlers to add inside tlocal
CometTask cometTask = new CometTask(this,handler);
cometTask.upcoming_op_isread = alreadySuspended;
CometEngine.updatedContexts.set(cometTask);
return handler.hashCode();
}
/**
* Add a {@link CometHandler} which will starts the process of suspending
* the underlying response. The underlying HttpServletResponse will
* not get committed until {@link CometContext#resumeCometHandler(CometHandler)}
* is invoked, unless the {@link CometContext#setExpirationDelay(long)} expires.
* @param handler a new {@link CometHandler}
*/
public int addCometHandler(CometHandler handler){
return addCometHandler(handler,false);
}
/**
* Retrieve a {@link CometHandler} using its based on its {@link CometHandler#hashCode};
*/
@Deprecated
public CometHandler getCometHandler(int hashCode){
for (CometHandler handler:handlers.keySet()){
if (handler.hashCode() == hashCode )
return handler;
}
return null;
}
/**
* Recycle this object.
*/
public void recycle(){
try{
notify(this,CometEvent.TERMINATE);
} catch (IOException ex) {
}
handlers.clear();
attributes.clear();
topic = null;
notificationHandler = null;
initDefaultValues();
// add check for datastructure size, if cometcontext had large
// datastructes its probably not optimal to waste RAM with caching it
CometEngine.cometEngine.cometContextCache.offer(this);
}
/**
* adds a {@link CometTask} to the active set
* @param cometTask {@link CometTask}
*/
protected void addActiveHandler(CometTask cometTask){
handlers.put(cometTask.cometHandler, cometTask);
}
/**
* Invoke a {@link CometHandler} using the {@link CometEvent}
* @param event - {@link CometEvent}
* @param cometHandler - {@link CometHandler}
* @throws IOException
*/
protected void invokeCometHandler(CometEvent event, CometHandler cometHandler) throws IOException{
if (cometHandler == null){
throw new IllegalStateException(INVALID_COMET_HANDLER);
}
event.setCometContext(this);
if (cometHandler instanceof DefaultConcurrentCometHandler){
((DefaultConcurrentCometHandler)cometHandler).enqueueEvent(event);
}else{
synchronized(cometHandler){
cometHandler.onEvent(event);
}
}
}
/**
* Remove a {@link CometHandler}. If the continuation (connection)
* associated with this {@link CometHandler} no longer have
* {@link CometHandler} associated to it, it will be resumed by Grizzly
* by calling {@link CometContext#resumeCometHandler(CometHandler)}
* @return <tt>true</tt> if the operation succeeded.
*/
public boolean removeCometHandler(CometHandler handler){
return removeCometHandler(handler,true);
}
/**
* Remove a {@link CometHandler}. If the continuation (connection)
* associated with this {@link CometHandler} no longer have
* {@link CometHandler} associated to it, it will be resumed.
* @param handler The CometHandler to remove.
* @param resume True is the connection can be resumed if no CometHandler
* are associated with the underlying SelectionKey.
* @return <tt>true</tt> if the operation succeeded.
*/
public boolean removeCometHandler(CometHandler handler,boolean resume){
CometTask task = handlers.remove(handler);
if (task != null){
if (resume){
CometEngine.getEngine().flushPostExecute(task,false);
}
return true;
}
return false;
}
/**
* Remove a {@link CometHandler} based on its hashcode. Return <tt>true</tt>
* if the operation was sucessfull.
* O(n) performance.
* @param hashCode The hashcode of the CometHandler to remove.
* @return <tt>true</tt> if the operation succeeded.
*/
@Deprecated
public boolean removeCometHandler(int hashCode){
CometHandler handler_ = null;
for (CometHandler handler:handlers.keySet()){
if (handler.hashCode() == hashCode){
handler_ = handler;
break;
}
}
return handler_ != null && handlers.remove(handler_) != null;
}
/**
* Resume the Comet request and remove it from the active {@link CometHandler} list. Once resumed,
* a CometHandler must never manipulate the HttpServletRequest or HttpServletResponse as
* those object will be recycled and may be re-used to serve another request.
*
* If you cache them for later reuse by another thread there is a
* possibility to introduce corrupted responses next time a request is made.
* @param handler The CometHandler to resume.
* @return <tt>true</tt> if the operation succeeded.
*/
public boolean resumeCometHandler(CometHandler handler){
return CometEngine.getEngine().interrupt(handlers.get(handler),false);
}
/**
* Return true if this {@link CometHandler} is still active, e.g. there is
* still a suspended connection associated with it.
*
* @return true
*/
public boolean isActive(CometHandler handler){
return handlers.containsKey(handler);
}
/**
* Return the internal list of active {@link CometHandler}
* @return Return the internal list of active {@link CometHandler}
*/
protected ConcurrentHashMap<CometHandler,CometTask> handlers(){
return handlers;
}
/**
* Notify all {@link CometHandler}. All
* {@link CometHandler#onEvent} will be invoked with a {@link CometEvent}
* of type NOTIFY.
* @param attachment An object shared amongst {@link CometHandler}.
*/
public void notify(final Object attachment) throws IOException{
notify(attachment, CometEvent.NOTIFY);
}
/**
* Notify a single {@link CometHandler}. The {@link CometEvent#getType()}
* will determine which {@link CometHandler} method will be invoked:
* <pre><code>
* CometEvent.INTERRUPT -> {@link CometHandler#onInterrupt}
* CometEvent.NOTIFY -> {@link CometHandler#onEvent}
* CometEvent.INITIALIZE -> {@link CometHandler#onInitialize}
* CometEvent.TERMINATE -> {@link CometHandler#onTerminate}
* CometEvent.READ -> {@link CometHandler#onEvent}
* </code></pre>
* @param attachment An object shared amongst {@link CometHandler}.
* @param eventType The type of notification.
* @param cometHandlerID Notify a single CometHandler.
* @deprecated - use notify(attachment,eventType,CometHandler;
*/
public void notify(final Object attachment,final int eventType,final int cometHandlerID)
throws IOException{
notify(attachment,eventType, getCometHandler(cometHandlerID));
}
/**
* Notify a single {@link CometHandler#onEvent(CometEvent}.
* @param attachment An object shared amongst {@link CometHandler}.
* @param {@link CometHandler} to notify.
*/
public void notify(final Object attachment,final CometHandler cometHandler)
throws IOException{
notify(attachment,CometEvent.NOTIFY,cometHandler);
}
/**
* Notify a single {@link CometHandler}. The {@link CometEvent#getType()}
* will determine which {@link CometHandler} method will be invoked:
* <pre><code>
* CometEvent.INTERRUPT -> {@link CometHandler#onInterrupt}
* CometEvent.NOTIFY -> {@link CometHandler#onEvent}
* CometEvent.INITIALIZE -> {@link CometHandler#onInitialize}
* CometEvent.TERMINATE -> {@link CometHandler#onTerminate}
* CometEvent.READ -> {@link CometHandler#onEvent}
* </code></pre>
* @param attachment An object shared amongst {@link CometHandler}.
* @param eventType The type of notification.
* @param {@link CometHandler} to notify.
*/
public void notify(final Object attachment,final int eventType,final CometHandler cometHandler)
throws IOException{
if (cometHandler == null){
throw new IllegalStateException(INVALID_COMET_HANDLER);
}
CometEvent event = new CometEvent(eventType,this,attachment);
notificationHandler.setBlockingNotification(blockingNotification);
notificationHandler.notify(event,cometHandler);
if (event.getType() != CometEvent.TERMINATE
&& event.getType() != CometEvent.INTERRUPT) {
resetSuspendIdleTimeout();
}
}
/**
* Notify all {@link CometHandler}. The {@link CometEvent#getType()}
* will determine which {@link CometHandler}
* method will be invoked:
* <pre><code>
* CometEvent.INTERRUPT -> {@link CometHandler#onInterrupt}
* CometEvent.NOTIFY -> {@link CometHandler#onEvent}
* CometEvent.INITIALIZE -> {@link CometHandler#onInitialize}
* CometEvent.TERMINATE -> {@link CometHandler#onTerminate}
* CometEvent.READ -> {@link CometHandler#onEvent}
* </code></pre>
* @param attachment An object shared amongst {@link CometHandler}.
* @param eventType The type of notification.
*/
public void notify(Object attachment,int eventType)throws IOException {
CometEvent event = new CometEvent(eventType,this,attachment);
Iterator<CometHandler> iterator = handlers.keySet().iterator();
notificationHandler.setBlockingNotification(blockingNotification);
notificationHandler.notify(event,iterator);
if (event.getType() != CometEvent.TERMINATE
&& event.getType() != CometEvent.INTERRUPT) {
resetSuspendIdleTimeout();
}
}
/**
* Initialize the newly added {@link CometHandler}.
*/
protected void initialize(CometHandler handler) throws IOException {
handler.onInitialize(eventInitialize);
}
/**
* Reset the current timestamp on a suspended connection.
*/
protected void resetSuspendIdleTimeout(){
if (expirationDelay != -1){
long timestamp = System.currentTimeMillis();
if (timestamp > nextIdleClear){
boolean update=false;
synchronized(handlers){
if (timestamp > nextIdleClear){
nextIdleClear = timestamp+1000;
update = true;
}
}
if (update){
for (CometTask cometTask:handlers.values()){
cometTask.setTimeout(timestamp);
}
}
}
}
}
/**
* Register for asynchronous read event (CometEvent#READ}. As soon as Grizzly detects
* there is some bytes available for read, your {@link CometHandler#onEvent(CometEvent)} will be invoked.
* {@link CometEvent#attachment()} will return an instance of {@link CometReader}
* that can be used to asynchronously read the available bytes.
*
* If your client supports http pipelining,
* invoking this method might result in a state where your CometHandler
* is invoked with a {@link CometReader} that will read the next http request. In that
* case, it is strongly recommended to not use that method unless your
* CometHandler can handle the http request.
*
* @param handler The CometHandler that will be invoked.
*/
public boolean registerAsyncRead(CometHandler handler){
return doAsyncRegister(handler, SelectionKey.OP_READ);
}
/**
* Register for asynchronous write event (CometEvent#WRITE} .As soon as Grizzly detects
* there is some OS buffer available for write operations, your
* {@link CometHandler#onEvent(CometEvent)} will be invoked.
* {@link CometEvent#attachment()} will return an instance of {@link CometWriter}
* that can be used to asynchronously write the available bytes.
* @param handler The CometHandler that will be invoked.
*/
public boolean registerAsyncWrite(CometHandler handler){
return doAsyncRegister(handler, SelectionKey.OP_WRITE);
}
/**
* Register for asynchronous read or write I/O operations.
* @param handler the CometHandler that will be invoked
* @param interest The read or write interest.
* @return true if the operation worked.
*/
private boolean doAsyncRegister(CometHandler handler, int interest){
if (handler != null) {
CometTask task = handlers.get(handler);
if (task != null) {
SelectionKey mainKey = task.getSelectionKey();
if (mainKey != null){
mainKey.interestOps(mainKey.interestOps() | interest);
task.setComethandlerIsAsyncRegistered(true);
return true;
}
}
}
throw new IllegalStateException(INVALID_COMET_HANDLER);
}
/**
* Helper.
*/
@Override
public String toString(){
return topic;
}
/**
* Return the {@link long} delay, in millisecond, before a request is resumed.
* @return long the {@link long} delay, in millisecond, before a request is resumed.
*/
public long getExpirationDelay() {
return expirationDelay;
}
/**
* Set the {@link long} delay before a request is resumed.
* @param expirationDelay the {@link long} delay before a request is resumed.
* Value is in milliseconds.
*/
public void setExpirationDelay(long expirationDelay) {
this.expirationDelay = expirationDelay;
}
/**
* Return the current list of active {@link CometHandler}
* @return the current list of active {@link CometHandler}
*/
public Set<CometHandler> getCometHandlers(){
return handlers.keySet();
}
/**
* Return <tt>true</tt> if the invoker of {@link #notify} should block when
* notifying Comet Handlers.
*/
public boolean isBlockingNotification() {
return blockingNotification;
}
/**
* Set to <tt>true</tt> if the invoker of {@link #notify} should block when
* notifying Comet Handlers.
*/
public void setBlockingNotification(boolean blockingNotification) {
this.blockingNotification = blockingNotification;
}
/**
* Set the current {@link NotificationHandler}
* @param notificationHandler
*/
public void setNotificationHandler(NotificationHandler notificationHandler){
this.notificationHandler = notificationHandler;
}
/**
* Return the associated {@link NotificationHandler}
* @return
*/
public NotificationHandler getNotificationHandler(){
return notificationHandler;
}
}