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package org.glassfish.jersey.server;
import java.io.IOException;
import java.util.Iterator;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.jersey.server.internal.LocalizationMessages;
/**
* Used for broadcasting response chunks to multiple {@link ChunkedOutput} instances.
*
* @param broadcast type.
* @author Pavel Bucek (pavel.bucek at oracle.com)
* @author Martin Matula (martin.matula at oracle.com)
*/
public class Broadcaster implements BroadcasterListener {
// We do not expect large amounts of broadcaster listeners additions/removals, but large amounts of traversals.
private final CopyOnWriteArrayList> listeners =
new CopyOnWriteArrayList>();
private final ConcurrentLinkedQueue> chunkedOutputs =
new ConcurrentLinkedQueue>();
/**
* Creates a new instance.
* If this constructor is called by a subclass, it assumes the the reason for the subclass to exist is to implement
* {@link #onClose(ChunkedOutput)} and {@link #onException(ChunkedOutput, Exception)} methods, so it adds
* the newly created instance as the listener. To avoid this, subclasses may call {@link #Broadcaster(Class)}
* passing their class as an argument.
*/
public Broadcaster() {
this(Broadcaster.class);
}
/**
* Can be used by subclasses to override the default functionality of adding self to the set of
* {@link BroadcasterListener listeners}. If creating a direct instance of a subclass passed in the parameter,
* the broadcaster will not register itself as a listener.
*
* @param subclass subclass of Broadcaster that should not be registered as a listener - if creating a direct instance
* of this subclass, this constructor will not register the new instance as a listener.
* @see #Broadcaster()
*/
protected Broadcaster(final Class subclass) {
if (subclass != getClass()) {
listeners.add(this);
}
}
/**
* Register {@link ChunkedOutput} to this {@code Broadcaster} instance.
*
* @param chunkedOutput {@link ChunkedOutput} to register.
* @return {@code true} if the instance was successfully registered, {@code false} otherwise.
*/
public > boolean add(final OUT chunkedOutput) {
return chunkedOutputs.offer(chunkedOutput);
}
/**
* Un-register {@link ChunkedOutput} from this {@code Broadcaster} instance.
*
* This method does not close the {@link ChunkedOutput} being unregistered.
*
* @param chunkedOutput {@link ChunkedOutput} instance to un-register from this broadcaster.
* @return {@code true} if the instance was unregistered, {@code false} otherwise.
*/
public > boolean remove(final OUT chunkedOutput) {
return chunkedOutputs.remove(chunkedOutput);
}
/**
* Register {@link BroadcasterListener} for {@code Broadcaster} events listening.
*
* This operation is potentially slow, especially if large number of listeners get registered in the broadcaster.
* The {@code Broadcaster} implementation is optimized to efficiently handle small amounts of
* concurrent listener registrations and removals and large amounts of registered listener notifications.
*
*
* @param listener listener to be registered.
* @return {@code true} if registered, {@code false} otherwise.
*/
public boolean add(final BroadcasterListener listener) {
return listeners.add(listener);
}
/**
* Un-register {@link BroadcasterListener}.
*
* This operation is potentially slow, especially if large number of listeners get registered in the broadcaster.
* The {@code Broadcaster} implementation is optimized to efficiently handle small amounts of
* concurrent listener registrations and removals and large amounts of registered listener notifications.
*
*
* @param listener listener to be unregistered.
* @return {@code true} if unregistered, {@code false} otherwise.
*/
public boolean remove(final BroadcasterListener listener) {
return listeners.remove(listener);
}
/**
* Broadcast a chunk to all registered {@link ChunkedOutput} instances.
*
* @param chunk chunk to be sent.
*/
public void broadcast(final T chunk) {
forEachOutput(new Task>() {
@Override
public void run(final ChunkedOutput cr) throws IOException {
cr.write(chunk);
}
});
}
/**
* Close all registered {@link ChunkedOutput} instances.
*/
public void closeAll() {
forEachOutput(new Task>() {
@Override
public void run(final ChunkedOutput cr) throws IOException {
cr.close();
}
});
}
/**
* {@inheritDoc}
*
* Can be implemented by subclasses to handle the event of exception thrown from a particular {@link ChunkedOutput}
* instance when trying to write to it or close it.
*
* @param chunkedOutput instance that threw exception.
* @param exception exception that was thrown.
*/
@Override
public void onException(final ChunkedOutput chunkedOutput, final Exception exception) {
}
/**
* {@inheritDoc}
*
* Can be implemented by subclasses to handle the event of {@link ChunkedOutput} being closed.
*
* @param chunkedOutput instance that was closed.
*/
@Override
public void onClose(final ChunkedOutput chunkedOutput) {
}
private static interface Task {
void run(T parameter) throws IOException;
}
private void forEachOutput(final Task> t) {
for (Iterator> iterator = chunkedOutputs.iterator(); iterator.hasNext(); ) {
ChunkedOutput chunkedOutput = iterator.next();
if (!chunkedOutput.isClosed()) {
try {
t.run(chunkedOutput);
} catch (Exception e) {
fireOnException(chunkedOutput, e);
}
}
if (chunkedOutput.isClosed()) {
iterator.remove();
fireOnClose(chunkedOutput);
}
}
}
private void forEachListener(final Task> t) {
for (BroadcasterListener listener : listeners) {
try {
t.run(listener);
} catch (Exception e) {
// log, but don't break
Logger.getLogger(Broadcaster.class.getName()).log(Level.WARNING,
LocalizationMessages.BROADCASTER_LISTENER_EXCEPTION(e.getClass().getSimpleName()), e);
}
}
}
private void fireOnException(final ChunkedOutput chunkedOutput, final Exception exception) {
forEachListener(new Task>() {
@Override
public void run(BroadcasterListener parameter) throws IOException {
parameter.onException(chunkedOutput, exception);
}
});
}
private void fireOnClose(final ChunkedOutput chunkedOutput) {
forEachListener(new Task>() {
@Override
public void run(BroadcasterListener parameter) throws IOException {
parameter.onClose(chunkedOutput);
}
});
}
}