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/*-
* ============LICENSE_START=======================================================
* Copyright (C) 2016-2018 Ericsson. All rights reserved.
* ================================================================================
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* SPDX-License-Identifier: Apache-2.0
* ============LICENSE_END=========================================================
*/
package org.onap.policy.apex.core.infrastructure.messaging.impl.ws;
import com.google.common.eventbus.Subscribe;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.TimeUnit;
import org.onap.policy.apex.core.infrastructure.messaging.MessageHolder;
import org.onap.policy.apex.core.infrastructure.messaging.MessageListener;
import org.onap.policy.apex.core.infrastructure.messaging.impl.ws.messageblock.MessageBlock;
import org.onap.policy.apex.core.infrastructure.messaging.impl.ws.messageblock.MessageBlockHandler;
import org.onap.policy.apex.core.infrastructure.messaging.impl.ws.messageblock.RawMessageBlock;
import org.onap.policy.apex.core.infrastructure.threading.ThreadUtilities;
import org.slf4j.ext.XLogger;
import org.slf4j.ext.XLoggerFactory;
/**
* The Class RawMessageHandler handles raw messages being received on a Java web socket and forwards
* the messages to the DataHandler instance that has subscribed to the RawMessageHandler instance.
*
* @author Sajeevan Achuthan (sajeevan.achuthan@ericsson.com)
* @param <MESSAGE> the generic type of message being received
*/
public class RawMessageHandler<MESSAGE> implements WebSocketMessageListener<MESSAGE>, Runnable {
// The logger for this class
private static final XLogger LOGGER = XLoggerFactory.getXLogger(RawMessageHandler.class);
// The amount of time to sleep during shutdown for the thread of this message handler to stop
private static final int SHUTDOWN_WAIT_TIME = 10;
// The timeout to wait between queue poll timeouts in milliseconds
private static final long QUEUE_POLL_TIMEOUT = 50;
// A queue that temporarily holds message blocks
private final BlockingQueue<MessageBlock<MESSAGE>> messageBlockQueue = new LinkedBlockingDeque<>();
// A queue that temporarily holds message blocks
private final BlockingQueue<String> stringMessageQueue = new LinkedBlockingDeque<>();
// Client applications that have subscribed for messages
private final MessageBlockHandler<MESSAGE> dataHandler = new MessageBlockHandler<MESSAGE>("data-processor");
// The thread that the raw message handler is receiving messages on
private Thread thisThread = null;
/**
* This method is called by the class with which this message listener has been registered.
*
* @param incomingData the data forwarded by the message reception class
*/
@Override
@Subscribe
public void onMessage(final RawMessageBlock incomingData) {
// Sanity check and get incoming data
ByteBuffer dataByteBuffer = null;
if (incomingData != null && incomingData.getMessage() != null) {
dataByteBuffer = incomingData.getMessage();
} else {
return;
}
// Read the messages from the web socket and place them on the message queue for handling by
// the queue
// processing thread
ObjectInputStream ois = null;
try {
ois = new ObjectInputStream(new ByteArrayInputStream(dataByteBuffer.array()));
@SuppressWarnings("unchecked")
final MessageHolder<MESSAGE> messageHolder = (MessageHolder<MESSAGE>) ois.readObject();
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("message {} recieved from the client {} ", messageHolder,
messageHolder == null ? "Apex Engine " : messageHolder.getSenderHostAddress());
}
final List<MESSAGE> messages = messageHolder.getMessages();
if (messages != null) {
messageBlockQueue.add(new MessageBlock<MESSAGE>(messages, incomingData.getConn()));
}
} catch (IOException | ClassNotFoundException e) {
LOGGER.error("Failed to process message received");
LOGGER.catching(e);
} finally {
closeObjectStream(ois);
}
}
/**
* This method is called when a string message is received on a web socket and is to be
* forwarded to a listener.
*
* @param messageString the message string
*/
@Override
@Subscribe
public void onMessage(final String messageString) {
if (messageString == null) {
return;
}
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("message {} recieved from the client {} ", messageString);
}
stringMessageQueue.add(messageString);
}
/**
* Close the {@link ObjectInputStream} stream.
*
* @param ois is an instance of {@link ObjectInputStream}
*/
private void closeObjectStream(final ObjectInputStream ois) {
if (ois != null) {
try {
ois.close();
} catch (final IOException e) {
LOGGER.catching(e);
}
}
}
/**
* This thread monitors the message queue and processes messages as they appear on the queue.
*
* @see java.lang.Runnable#run()
*/
@Override
public void run() {
LOGGER.debug("raw message listening started");
thisThread = Thread.currentThread();
// Run until termination
while (thisThread.isAlive() && !thisThread.isInterrupted()) {
try {
// Read message block messages from the queue and pass it to the data handler
MessageBlock<MESSAGE> messageBlock = null;
while ((messageBlock = messageBlockQueue.poll(1, TimeUnit.MILLISECONDS)) != null) {
dataHandler.post(messageBlock);
}
} catch (final InterruptedException e) {
// restore the interrupt status
Thread.currentThread().interrupt();
LOGGER.debug("raw message listening has been interrupted");
break;
}
try {
// Read string messages from the queue and pass it to the data handler
String stringMessage = null;
while ((stringMessage = stringMessageQueue.poll(1, TimeUnit.MILLISECONDS)) != null) {
dataHandler.post(stringMessage);
}
} catch (final InterruptedException e) {
// restore the interrupt status
Thread.currentThread().interrupt();
LOGGER.debug("raw message listening has been interrupted");
break;
}
// Wait for new messages
try {
Thread.sleep(QUEUE_POLL_TIMEOUT);
} catch (final InterruptedException e) {
// restore the interrupt status
Thread.currentThread().interrupt();
LOGGER.debug("raw message listening has been interrupted");
break;
}
}
LOGGER.debug("raw message listening stopped");
}
/**
* Shutdown the message handler.
*/
public void shutdown() {
LOGGER.entry("shutting down raw message listening . . .");
// Interrupt the message handling thread
thisThread.interrupt();
// Wait for thread shutdown
while (thisThread.isAlive()) {
ThreadUtilities.sleep(SHUTDOWN_WAIT_TIME);
}
LOGGER.exit("shut down raw message listening");
}
/**
* This method is called when a message is received on a web socket and is to be forwarded to a
* listener.
*
* @param data the message data containing a message
*/
@Override
public void onMessage(final MessageBlock<MESSAGE> data) {
throw new UnsupportedOperationException("this operation is not supported");
}
/**
* Register a data forwarder to which messages coming in on the web socket will be forwarded.
*
* @param listener The listener to register
*/
@Override
public void registerDataForwarder(final MessageListener<MESSAGE> listener) {
stateCheck(listener);
dataHandler.registerMessageHandler(listener);
}
/**
* Unregister a data forwarder that was previously registered on the web socket listener.
*
* @param listener The listener to unregister
*/
@Override
public void unRegisterDataForwarder(final MessageListener<MESSAGE> listener) {
stateCheck(listener);
dataHandler.unRegisterMessageHandler(listener);
}
/**
* Sanity check for the listener and data handler.
*
* @param listener the listener to check
*/
private void stateCheck(final MessageListener<MESSAGE> listener) {
if (listener == null) {
throw new IllegalArgumentException("The listener object cannot be null");
}
}
}
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