org.jppf.process
Class ProcessLauncher

java.lang.Object
  org.jppf.utils.ThreadSynchronization
      org.jppf.process.ProcessLauncher

All Implemented Interfaces:

Runnable, EventListener, IdleStateListener, ProcessWrapperEventListener

public class ProcessLauncher
extends ThreadSynchronization
implements Runnable, ProcessWrapperEventListener, IdleStateListener

This class is intended as a controller for a subprocess, to enable stopping and restarting it when requested.

It performs the following operations:

• open a server socket the driver will listen to (port number is dynamically attributed)
• Start the subprocess, sending the server socket port number as an argument
• Wait for the subprocess to exit
• If the subprocess exit code is equal to 2, the subprocess is restarted, otherwise this process exits as well

Author:

Laurent Cohen

Field Summary

Fields inherited from class org.jppf.utils.ThreadSynchronization

stopped

Constructor Summary

ProcessLauncher(String mainClass)
Initialize this process launcher.

Method Summary

Process	buildProcess() Start the JPPF driver subprocess.
protected void	createShutdownHook() Create a shutdown hook that is run when this JVM terminates.
void	errorStreamAltered(ProcessWrapperEvent event) Notification that the process has written to its error stream.
String	getOutput(Process process, String streamType) Get the output of the driver process.
void	idleStateChanged(IdleStateEvent event) Called when the idle state of the system has changed.
void	outputStreamAltered(ProcessWrapperEvent event) Notification that the process has written to its output stream.
void	run() Start the socket listener and the subprocess.
protected int	startDriverSocket() Start a server socket that will accept one connection at a time with the JPPF driver, so the server can shtutdown properly, when this driver is killed, by a way other than the API (ie CTRL-C or killing the process through the OS shell).
void	startProcess() Start the sub-process.

Methods inherited from class org.jppf.utils.ThreadSynchronization

goToSleep, goToSleep, goToSleep, isStopped, setStopped, wakeUp

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ProcessLauncher

public ProcessLauncher(String mainClass)

Initialize this process launcher.

Parameters:

mainClass - the fully qualified name of the main class of the sub process to launch.

Method Detail

run

public void run()

Start the socket listener and the subprocess.

Specified by:

run in interface Runnable

startProcess

public void startProcess()
                  throws Exception

Start the sub-process.

Throws:

Exception - if any error occurs.

buildProcess

public Process buildProcess()
                     throws Exception

Start the JPPF driver subprocess.

Returns:

A reference to the Process object representing the JPPF driver suprocess.

Throws:

Exception - if the process failed to start.

createShutdownHook

protected void createShutdownHook()

Create a shutdown hook that is run when this JVM terminates.
This is normally used to ensure the subprocess is terminated as well.

startDriverSocket

protected int startDriverSocket()

Start a server socket that will accept one connection at a time with the JPPF driver, so the server can shtutdown properly, when this driver is killed, by a way other than the API (ie CTRL-C or killing the process through the OS shell).
The port the server socket listens to is dynamically attributed, which is obtained by using the constructor new ServerSocket(0).
The driver will connect and listen to this port, and exit when the connection is broken.
The single connection at a time is obtained by doing the ServerSocket.accept() and the Socket.getInputStream().read() in the same thread.

Returns:

the port number on which the server socket is listening.

getOutput

public String getOutput(Process process,
                        String streamType)

Get the output of the driver process.

Parameters:

process - the process to get the standard or error output from.

streamType - detrmines whether to obtain the standard or error output.

Returns:

the output as a string.

errorStreamAltered

public void errorStreamAltered(ProcessWrapperEvent event)

Notification that the process has written to its error stream.

Specified by:

errorStreamAltered in interface ProcessWrapperEventListener

Parameters:

event - encapsulate the error stream's content.

See Also:

ProcessWrapperEventListener.errorStreamAltered(org.jppf.process.event.ProcessWrapperEvent)

outputStreamAltered

public void outputStreamAltered(ProcessWrapperEvent event)

Notification that the process has written to its output stream.

Specified by:

outputStreamAltered in interface ProcessWrapperEventListener

Parameters:

event - encapsulate the output stream's content.

See Also:

ProcessWrapperEventListener.outputStreamAltered(org.jppf.process.event.ProcessWrapperEvent)

idleStateChanged

public void idleStateChanged(IdleStateEvent event)

Called when the idle state of the system has changed.

Specified by:

idleStateChanged in interface IdleStateListener

Parameters:

event - the event encapsulating the state change.