/* | |
* 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.commons.testing.net; | |
import java.io.IOException; | |
import java.net.DatagramSocket; | |
import java.net.ServerSocket; | |
import java.util.NoSuchElementException; | |
import java.util.concurrent.atomic.AtomicInteger; | |
import org.apache.commons.testing.Closer; | |
/** | |
* Finds currently available server ports. | |
*/ | |
public final class AvailableServerPortFinder { | |
/** | |
* The minimum server currentMinPort number for IPv4. | |
* Set at 1100 to avoid returning privileged currentMinPort numbers. | |
*/ | |
public static final int MIN_PORT_NUMBER = 1100; | |
/** | |
* Incremented to the next lowest available port when getNextAvailable() is called. | |
*/ | |
private static AtomicInteger currentMinPort = new AtomicInteger(MIN_PORT_NUMBER); | |
/** | |
* We'll hold open the lowest port in this process | |
* so parallel processes won't use the same block | |
* of ports. They'll go up to the next block. | |
*/ | |
private static final ServerSocket LOCK; | |
/** | |
* The maximum server currentMinPort number for IPv4. | |
*/ | |
public static final int MAX_PORT_NUMBER = 65535; | |
static { | |
int port = MIN_PORT_NUMBER; | |
ServerSocket ss = null; | |
while (ss == null) { | |
try { | |
ss = new ServerSocket(port); | |
} catch (final Exception e) { | |
ss = null; | |
port += 200; | |
} | |
} | |
LOCK = ss; | |
Runtime.getRuntime().addShutdownHook(new Thread() { | |
@Override | |
public void run() { | |
close(); | |
} | |
}); | |
currentMinPort.set(port + 1); | |
} | |
/** | |
* Checks to see if a specific port is available. | |
* | |
* @param port the port number to check for availability | |
* @return {@code true} if the port is available, or {@code false} if not | |
* @throws IllegalArgumentException is thrown if the port number is out of range | |
*/ | |
public static synchronized boolean available(final int port) throws IllegalArgumentException { | |
if (port < currentMinPort.get() || port > MAX_PORT_NUMBER) { | |
throw new IllegalArgumentException("Invalid start currentMinPort: " + port); | |
} | |
ServerSocket ss = null; | |
DatagramSocket ds = null; | |
try { | |
ss = new ServerSocket(port); | |
ss.setReuseAddress(true); | |
ds = new DatagramSocket(port); | |
ds.setReuseAddress(true); | |
return true; | |
} catch (final IOException e) { | |
// Do nothing | |
} finally { | |
Closer.closeSilently(ds); | |
Closer.closeSilently(ss); | |
} | |
return false; | |
} | |
public static void close() { | |
Closer.closeSilently(LOCK); | |
} | |
/** | |
* Gets the next available port starting at the lowest number. This is the preferred | |
* method to use. The port return is immediately marked in use and doesn't rely on the caller actually opening | |
* the port. | |
* | |
* @throws IllegalArgumentException is thrown if the port number is out of range | |
* @throws NoSuchElementException if there are no ports available | |
* @return the available port | |
*/ | |
public static synchronized int getNextAvailable() { | |
final int next = getNextAvailable(currentMinPort.get()); | |
currentMinPort.set(next + 1); | |
return next; | |
} | |
/** | |
* Gets the next available port starting at a given from port. | |
* | |
* @param fromPort the from port to scan for availability | |
* @throws IllegalArgumentException is thrown if the port number is out of range | |
* @throws NoSuchElementException if there are no ports available | |
* @return the available port | |
*/ | |
public static synchronized int getNextAvailable(final int fromPort) { | |
if (fromPort < currentMinPort.get() || fromPort > MAX_PORT_NUMBER) { | |
throw new IllegalArgumentException("From port number not in valid range: " + fromPort); | |
} | |
for (int i = fromPort; i <= MAX_PORT_NUMBER; i++) { | |
if (available(i)) { | |
return i; | |
} | |
} | |
throw new NoSuchElementException("Could not find an available port above " + fromPort); | |
} | |
/** | |
* Creates a new instance. | |
*/ | |
private AvailableServerPortFinder() { | |
// Do nothing | |
} | |
} |