/*
* Copyright 2000-2004 The Apache Software Foundation
*
* 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.
*
*/
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:
* <pre>
* 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
* }
* </pre>
* @author thomas.haas@softwired-inc.com
* @author <a href="mailto:sbailliez_at_apache.org">Stephane Bailliez</a>
* @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 */
private Process process;
/** say whether or not the watchdog is currently monitoring a process */
private boolean watch = false;
/** 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 */
private boolean killedProcess = false;
/** will tell us whether timeout has occurred */
private Watchdog watchdog;
/**
* 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);
}
/**
* @see #ExecuteWatchdog(long)
* @deprecated Use constructor with a long type instead.
* (1.4.x compatibility)
*/
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.
* @param process the process to monitor. It cannot be <tt>null</tt>
* @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.
*/
public synchronized void stop() {
watchdog.stop();
watch = false;
process = null;
}
/**
* Called after watchdog has finished.
*/
public 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.
*/
protected 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.
*/
public 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.
* @return <tt>true</tt> if the process is still running, otherwise
* <tt>false</tt>.
*/
public boolean isWatching() {
return watch;
}
/**
* Indicates whether the last process run was killed on timeout or not.
* @return <tt>true</tt> if the process was killed otherwise
* <tt>false</tt>.
*/
public boolean killedProcess() {
return killedProcess;
}
}