/*
* @(#)Ping.java 1.2 01/12/13
* Connect to each of a list of hosts and measure the time required to complete
* the connection. This example uses a selector and two additional threads in
* order to demonstrate non-blocking connects and the multithreaded use of a
* selector.
*
* Copyright 2001-2002 Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
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*
* -Redistribution in binary form must reproduct the above copyright
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* the documentation and/or other materials provided with the
* distribution.
*
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* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any
* kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
* WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
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import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.regex.Pattern;
public class Ping {
// The default daytime port
static int DAYTIME_PORT = 13;
// The port we'll actually use
static int port = DAYTIME_PORT;
// Representation of a ping target
//
static class Target {
InetSocketAddress address;
SocketChannel channel;
Exception failure;
long connectStart;
long connectFinish = 0;
boolean shown = false;
Target(String host) {
try {
address = new InetSocketAddress(InetAddress.getByName(host),
port);
System.out.println(host + " : " + port + " : " + address);
} catch (IOException x) {
failure = x;
System.out.println(x.getMessage());
}
}
void show() {
String result;
System.out.println(connectFinish);
if (connectFinish != 0)
result = Long.toString(connectFinish - connectStart) + "ms";
else if (failure != null)
result = failure.toString();
else
result = "Timed out";
// System.out.println(failure.toString() + " " + result);
System.out.println(address + " : " + result);
shown = true;
}
}
// Thread for printing targets as they're heard from
//
static class Printer
extends Thread
{
LinkedList pending = new LinkedList();
Printer() {
setName("Printer");
setDaemon(true);
}
void add(Target t) {
synchronized (pending) {
pending.add(t);
pending.notify();
}
}
public void run() {
try {
for (;;) {
Target t = null;
synchronized (pending) {
while (pending.size() == 0)
pending.wait();
t = (Target)pending.removeFirst();
}
t.show();
}
} catch (InterruptedException x) {
return;
}
}
}
// Thread for connecting to all targets in parallel via a single selector
//
static class Connector
extends Thread
{
Selector sel;
Printer printer;
// List of pending targets. We use this list because if we try to
// register a channel with the selector while the connector thread is
// blocked in the selector then we will block.
//
LinkedList pending = new LinkedList();
Connector(Printer pr) throws IOException {
printer = pr;
sel = Selector.open();
setName("Connector");
}
// Initiate a connection sequence to the given target and add the
// target to the pending-target list
//
void add(Target t) {
SocketChannel sc = null;
try {
// Open the channel, set it to non-blocking, initiate connect
sc = SocketChannel.open();
sc.configureBlocking(false);
boolean connected = sc.connect(t.address);
// Record the time we started
t.channel = sc;
t.connectStart = System.currentTimeMillis();
if (connected) {
t.connectFinish = t.connectStart;
sc.close();
printer.add(t);
} else {
// Add the new channel to the pending list
synchronized (pending) {
pending.add(t);
}
// Nudge the selector so that it will process the pending list
sel.wakeup();
}
} catch (IOException x) {
if (sc != null) {
try {
sc.close();
} catch (IOException xx) { }
}
t.failure = x;
printer.add(t);
}
}
// Process any targets in the pending list
//
void processPendingTargets() throws IOException {
synchronized (pending) {
while (pending.size() > 0) {
Target t = (Target)pending.removeFirst();
try {
// Register the channel with the selector, indicating
// interest in connection completion and attaching the
// target object so that we can get the target back
// after the key is added to the selector's
// selected-key set
t.channel.register(sel, SelectionKey.OP_CONNECT, t);
} catch (IOException x) {
// Something went wrong, so close the channel and
// record the failure
t.channel.close();
t.failure = x;
printer.add(t);
}
}
}
}
// Process keys that have become selected
//
void processSelectedKeys() throws IOException {
for (Iterator i = sel.selectedKeys().iterator(); i.hasNext();) {
// Retrieve the next key and remove it from the set
SelectionKey sk = (SelectionKey)i.next();
i.remove();
// Retrieve the target and the channel
Target t = (Target)sk.attachment();
SocketChannel sc = (SocketChannel)sk.channel();
// Attempt to complete the connection sequence
try {
if (sc.finishConnect()) {
sk.cancel();
t.connectFinish = System.currentTimeMillis();
sc.close();
printer.add(t);
}
} catch (IOException x) {
sc.close();
t.failure = x;
printer.add(t);
}
}
}
volatile boolean shutdown = false;
// Invoked by the main thread when it's time to shut down
//
void shutdown() {
shutdown = true;
sel.wakeup();
}
// Connector loop
//
public void run() {
for (;;) {
try {
int n = sel.select();
if (n > 0)
processSelectedKeys();
processPendingTargets();
if (shutdown) {
sel.close();
return;
}
} catch (IOException x) {
x.printStackTrace();
}
}
}
}
public static void main(String[] args)
throws InterruptedException, IOException
{
if (args.length < 1) {
System.err.println("Usage: java Ping [port] host...");
return;
}
int firstArg = 0;
// If the first argument is a string of digits then we take that
// to be the port number to use
if (Pattern.matches("[0-9]+", args[0])) {
port = Integer.parseInt(args[0]);
firstArg = 1;
}
// Create the threads and start them up
Printer printer = new Printer();
printer.start();
Connector connector = new Connector(printer);
connector.start();
// Create the targets and add them to the connector
LinkedList targets = new LinkedList();
for (int i = firstArg; i < args.length; i++) {
Target t = new Target(args[i]);
targets.add(t);
connector.add(t);
}
// Wait for everything to finish
Thread.sleep(2000);
connector.shutdown();
connector.join();
// Print status of targets that have not yet been shown
for (Iterator i = targets.iterator(); i.hasNext();) {
Target t = (Target)i.next();
if (!t.shown)
t.show();
}
}
}
