uk.ac.ed.epcc.webapp.exec

Class ProcessHandler

java.lang.Object

java.lang.Thread

uk.ac.ed.epcc.webapp.exec.ProcessHandler

All Implemented Interfaces:

java.lang.Runnable, DeferredProcessProxy, ProcessProxy

public class ProcessHandler
extends java.lang.Thread
implements DeferredProcessProxy

Wrapper thread to wait for a process in a thread. This serves two purposes. This thread can be used to provide input to the process. and it allows a timeout that kills the process as the thread will kill the process when interrupted. Additional threads are spawned to capture any output When the process exits the thread also exits so waiting for the thread is equivalent to waiting for the process. If the thread is interrupted the process will be destroyed. Optionally input to the process can be provided. This will be provided to the process asynchronously by the ProcessHandler thread rather than using the main thread.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
ProcessHandler(byte[] input, java.lang.Process process) Create a ProcessHandler with specified input The input will be delivered to the process stdin (and the stream closed) when the handler is run
ProcessHandler(java.lang.Process process) Create a ProcessHandler No input is provided for the process.

Method Summary

Modifier and Type	Method and Description
void	complete(long timeout_millis) wait for the process to complete.
java.lang.Integer	execute(long timeout_millis) blocking call to the process.
java.lang.String	getErr() get the erro output of the process
java.lang.Integer	getExit() get the exit value of the process, This may return null if the timeout is reached.
java.io.IOException	getInputException()
java.lang.String	getOutput() get the output of the process
void	run()
void	setTimeout(long timeout) Set an automatic timeout for the ProcessHandler implemented by a thread.
void	start() Start the deferred process
boolean	wasTerminated() did the process time-out or killed via interrupt

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Constructor Detail

ProcessHandler

public ProcessHandler(java.lang.Process process)

Create a ProcessHandler No input is provided for the process. If any is required this must be provided by a different thread.

Parameters:

process -

ProcessHandler

public ProcessHandler(byte[] input,
                      java.lang.Process process)

Create a ProcessHandler with specified input The input will be delivered to the process stdin (and the stream closed) when the handler is run

Parameters:

input -

process -

Method Detail

run

public void run()

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

setTimeout

public void setTimeout(long timeout)

Set an automatic timeout for the ProcessHandler implemented by a thread. This can be used if the spawning thread is not going to wait for completion.

Specified by:

setTimeout in interface DeferredProcessProxy

Parameters:

timeout -

getExit

public java.lang.Integer getExit()

get the exit value of the process, This may return null if the timeout is reached.

Specified by:

getExit in interface ProcessProxy

Returns:

getInputException

public java.io.IOException getInputException()

start

public void start()

Description copied from interface: DeferredProcessProxy

Start the deferred process

Specified by:

start in interface DeferredProcessProxy

Overrides:

start in class java.lang.Thread

execute

public java.lang.Integer execute(long timeout_millis)
                          throws java.lang.Exception

blocking call to the process. The process will be destoyed if the timeout is exceeded.

Specified by:

execute in interface DeferredProcessProxy

Parameters:

timeout_millis -

Returns:

exit code

Throws:

java.lang.Exception

complete

public void complete(long timeout_millis)
              throws java.lang.InterruptedException

wait for the process to complete. If the timeout is exceeded the process is forcebly destroyed.

Specified by:

complete in interface DeferredProcessProxy

Parameters:

timeout_millis -

Throws:

java.lang.InterruptedException

getOutput

public java.lang.String getOutput()

Description copied from interface: ProcessProxy

get the output of the process

Specified by:

getOutput in interface ProcessProxy

Returns:

String

getErr

public java.lang.String getErr()

Description copied from interface: ProcessProxy

get the erro output of the process

Specified by:

getErr in interface ProcessProxy

Returns:

wasTerminated

public boolean wasTerminated()

Description copied from interface: ProcessProxy

did the process time-out or killed via interrupt

Specified by:

wasTerminated in interface ProcessProxy

Returns: