/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.nifi.io.socket;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Implements a listener for TCP/IP messages sent over unicast socket.
*
*/
public abstract class SocketListener {
private static final int DEFAULT_SHUTDOWN_LISTENER_SECONDS = 5;
private static final Logger logger = LoggerFactory.getLogger(SocketListener.class);
private volatile ExecutorService executorService; // volatile to guarantee most current value is visible
private volatile ServerSocket serverSocket; // volatile to guarantee most current value is visible
private final int numThreads;
private final int port;
private final ServerSocketConfiguration configuration;
private final AtomicInteger shutdownListenerSeconds = new AtomicInteger(DEFAULT_SHUTDOWN_LISTENER_SECONDS);
public SocketListener(
final int numThreads,
final int port,
final ServerSocketConfiguration configuration) {
if (numThreads <= 0) {
throw new IllegalArgumentException("Number of threads may not be less than or equal to zero.");
} else if (configuration == null) {
throw new IllegalArgumentException("Server socket configuration may not be null.");
}
this.numThreads = numThreads;
this.port = port;
this.configuration = configuration;
}
/**
* Implements the action to perform when a new socket request is received.
* This class will close the socket.
*
* @param socket the socket
*/
public abstract void dispatchRequest(final Socket socket);
public void start() throws IOException {
if (isRunning()) {
return;
}
try {
serverSocket = SocketUtils.createServerSocket(port, configuration);
} catch (KeyManagementException | UnrecoverableKeyException | NoSuchAlgorithmException | KeyStoreException | CertificateException e) {
throw new IOException(e);
}
final ThreadFactory defaultThreadFactory = Executors.defaultThreadFactory();
executorService = Executors.newFixedThreadPool(numThreads, new ThreadFactory() {
private final AtomicLong threadCounter = new AtomicLong(0L);
@Override
public Thread newThread(final Runnable r) {
final Thread newThread = defaultThreadFactory.newThread(r);
newThread.setName("Process Cluster Protocol Request-" + threadCounter.incrementAndGet());
return newThread;
}
});
final ExecutorService runnableExecServiceRef = executorService;
final ServerSocket runnableServerSocketRef = serverSocket;
final Thread t = new Thread(new Runnable() {
@Override
public void run() {
while (runnableExecServiceRef.isShutdown() == false) {
Socket socket = null;
try {
try {
socket = runnableServerSocketRef.accept();
if (configuration.getSocketTimeout() != null) {
socket.setSoTimeout(configuration.getSocketTimeout());
}
} catch (final SocketTimeoutException ste) {
// nobody connected to us. Go ahead and call closeQuietly just to make sure we don't leave
// any sockets lingering
SocketUtils.closeQuietly(socket);
continue;
} catch (final SocketException se) {
logger.warn("Failed to communicate with " + (socket == null ? "Unknown Host" : socket.getInetAddress().getHostName()) + " due to " + se, se);
SocketUtils.closeQuietly(socket);
continue;
} catch (final Throwable t) {
logger.warn("Socket Listener encountered exception: " + t, t);
SocketUtils.closeQuietly(socket);
continue;
}
final Socket finalSocket = socket;
runnableExecServiceRef.execute(new Runnable() {
@Override
public void run() {
try {
dispatchRequest(finalSocket);
} catch (final Throwable t) {
logger.warn("Dispatching socket request encountered exception due to: " + t, t);
} finally {
SocketUtils.closeQuietly(finalSocket);
}
}
});
} catch (final Throwable t) {
logger.error("Socket Listener encountered exception: " + t, t);
SocketUtils.closeQuietly(socket);
}
}
}
});
t.setName("Cluster Socket Listener");
t.start();
logger.info("Now listening for connections from nodes on port " + port);
}
public boolean isRunning() {
return (executorService != null && executorService.isShutdown() == false);
}
public void stop() throws IOException {
if (isRunning() == false) {
return;
}
// shutdown executor service
try {
if (getShutdownListenerSeconds() <= 0) {
executorService.shutdownNow();
} else {
executorService.shutdown();
}
executorService.awaitTermination(getShutdownListenerSeconds(), TimeUnit.SECONDS);
} catch (final InterruptedException ex) {
Thread.currentThread().interrupt();
} finally {
if (executorService.isTerminated()) {
logger.info("Socket Listener has been terminated successfully.");
} else {
logger.warn("Socket Listener has not terminated properly. There exists an uninterruptable thread that will take an indeterminate amount of time to stop.");
}
}
// shutdown server socket
SocketUtils.closeQuietly(serverSocket);
}
public int getShutdownListenerSeconds() {
return shutdownListenerSeconds.get();
}
public void setShutdownListenerSeconds(final int shutdownListenerSeconds) {
this.shutdownListenerSeconds.set(shutdownListenerSeconds);
}
public ServerSocketConfiguration getConfiguration() {
return configuration;
}
public int getPort() {
if (isRunning()) {
return serverSocket.getLocalPort();
} else {
return port;
}
}
}