https://ant.apache.org/: master POM (The Apache Software Foundation) 
/*
 *  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
 *
 *      https://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.tools.ant.taskdefs;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.util.TimeoutObserver;
import org.apache.tools.ant.util.Watchdog;


Destroys a process running for too long.
For example:

ExecuteWatchdog watchdog = new ExecuteWatchdog(30000);
Execute exec = new Execute(myloghandler, watchdog);
exec.setCommandLine(mycmdline);
int exitvalue = exec.execute();
if (Execute.isFailure(exitvalue) && watchdog.killedProcess()) {
             // it was killed on purpose by the watchdog
}



See Also:
Since:Ant 1.2
/**
 * Destroys a process running for too long.
 * For example:
 * <pre>
 * ExecuteWatchdog watchdog = new ExecuteWatchdog(30000);
 * Execute exec = new Execute(myloghandler, watchdog);
 * exec.setCommandLine(mycmdline);
 * int exitvalue = exec.execute();
 * if (Execute.isFailure(exitvalue) &amp;&amp; watchdog.killedProcess()) {
 *              // it was killed on purpose by the watchdog
 * }
 * </pre>

 * @see Execute
 * @see org.apache.tools.ant.util.Watchdog
 * @since Ant 1.2
 */
public class ExecuteWatchdog implements TimeoutObserver {

    
the process to execute and watch for duration 
/** the process to execute and watch for duration */
    private Process process;

    
say whether or not the watchdog is currently monitoring a process 
/** say whether or not the watchdog is currently monitoring a process */
    private volatile boolean watch = false;

    
exception that might be thrown during the process execution 
/** exception that might be thrown during the process execution */
    private Exception caught = null;

    
say whether or not the process was killed due to running overtime 
/** say whether or not the process was killed due to running overtime */
    private volatile boolean killedProcess = false;

    
will tell us whether timeout has occurred 
/** will tell us whether timeout has occurred */
    private Watchdog watchdog;

    
Creates a new watchdog with a given timeout.

Params:
  • timeout – the timeout for the process in milliseconds.
It must be greater than 0.
/**
     * Creates a new watchdog with a given timeout.
     *
     * @param timeout the timeout for the process in milliseconds.
     * It must be greater than 0.
     */
    public ExecuteWatchdog(long timeout) {
        watchdog = new Watchdog(timeout);
        watchdog.addTimeoutObserver(this);
    }

    
Params:
  • timeout – the timeout value to use in milliseconds.
See Also:
Deprecated:since 1.5.x.
            Use constructor with a long type instead.
(1.4.x compatibility)
/**
     * @param timeout the timeout value to use in milliseconds.
     * @see #ExecuteWatchdog(long)
     * @deprecated since 1.5.x.
     *             Use constructor with a long type instead.
     * (1.4.x compatibility)
     */
    @Deprecated
    public ExecuteWatchdog(int timeout) {
        this((long) timeout);
    }

    
Watches the given process and terminates it, if it runs for too long.
All information from the previous run are reset.

Params:
  • process – the process to monitor. It cannot be null
Throws:
/**
     * Watches the given process and terminates it, if it runs for too long.
     * All information from the previous run are reset.
     * @param process the process to monitor. It cannot be <code>null</code>
     * @throws IllegalStateException if a process is still being monitored.
     */
    public synchronized void start(Process process) {
        if (process == null) {
            throw new NullPointerException("process is null.");
        }
        if (this.process != null) {
            throw new IllegalStateException("Already running.");
        }
        this.caught = null;
        this.killedProcess = false;
        this.watch = true;
        this.process = process;
        watchdog.start();
    }

    
Stops the watcher. It will notify all threads possibly waiting
on this object.

/**
     * Stops the watcher. It will notify all threads possibly waiting
     * on this object.
     */
    public synchronized void stop() {
        watchdog.stop();
        cleanUp();
    }

    
Called after watchdog has finished.
This can be called in the watchdog thread

Params:
  • w – the watchdog
/**
     * Called after watchdog has finished.
     * This can be called in the watchdog thread
     * @param w the watchdog
     */
    @Override
    public synchronized void timeoutOccured(Watchdog w) {
        try {
            try {
                // We must check if the process was not stopped
                // before being here
                process.exitValue();
            } catch (IllegalThreadStateException itse) {
                // the process is not terminated, if this is really
                // a timeout and not a manual stop then kill it.
                if (watch) {
                    killedProcess = true;
                    process.destroy();
                }
            }
        } catch (Exception e) {
            caught = e;
        } finally {
            cleanUp();
        }
    }

    
reset the monitor flag and the process.

/**
     * reset the monitor flag and the process.
     */
    protected synchronized void cleanUp() {
        watch = false;
        process = null;
    }

    
This method will rethrow the exception that was possibly caught during
the run of the process. It will only remains valid once the process has
been terminated either by 'error', timeout or manual intervention.
Information will be discarded once a new process is ran.

Throws:
  • BuildException –  a wrapped exception over the one that was
silently swallowed and stored during the process run.
/**
     * This method will rethrow the exception that was possibly caught during
     * the run of the process. It will only remains valid once the process has
     * been terminated either by 'error', timeout or manual intervention.
     * Information will be discarded once a new process is ran.
     * @throws  BuildException  a wrapped exception over the one that was
     * silently swallowed and stored during the process run.
     */
    public synchronized void checkException() throws BuildException {
        if (caught != null) {
            throw new BuildException("Exception in ExecuteWatchdog.run: "
                                     + caught.getMessage(), caught);
        }
    }

    
Indicates whether or not the watchdog is still monitoring the process.

Returns: true if the process is still running, otherwise
         false.
/**
     * Indicates whether or not the watchdog is still monitoring the process.
     * @return  <code>true</code> if the process is still running, otherwise
     *          <code>false</code>.
     */
    public boolean isWatching() {
        return watch;
    }

    
Indicates whether the last process run was killed on timeout or not.

Returns: true if the process was killed otherwise
         false.
/**
     * Indicates whether the last process run was killed on timeout or not.
     * @return  <code>true</code> if the process was killed otherwise
     *          <code>false</code>.
     */
    public boolean killedProcess() {
        return killedProcess;
    }
}