dk.netarkivet.common.utils
Class ProcessUtils

java.lang.Object
  dk.netarkivet.common.utils.ProcessUtils

public class ProcessUtils
extends java.lang.Object

Various utilities for running processes -- not exactly Java's forte.

Constructor Summary

ProcessUtils()

Method Summary

static java.lang.Object	collectProcessOutput(java.io.InputStream inputStream, int maxCollect, java.util.Set<java.lang.Thread> collectionThreads) Collect all output from an inputstream, up to maxCollect bytes, in an output object.
static void	discardProcessOutput(java.io.InputStream inputStream) Read the output from a process.
static int	runProcess(java.lang.String... programAndArgs) Runs an external process that takes no input, discarding its output.
static int	runProcess(java.lang.String[] environment, java.lang.String... programAndArgs) Runs an external process that takes no input, discarding its output.
static java.lang.Integer	waitFor(java.lang.Process p, long maxWait) Wait for the end of a process, but only for a limited time.
static void	writeProcessOutput(java.io.InputStream inputStream, java.io.File outputFile, java.util.Set<java.lang.Thread> collectionThreads) Collect all output from an inputstream, appending it to a file.

Methods inherited from class java.lang.Object

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

Constructor Detail

ProcessUtils

public ProcessUtils()

Method Detail

runProcess

public static int runProcess(java.lang.String[] environment,
                             java.lang.String... programAndArgs)

Runs an external process that takes no input, discarding its output.

Parameters:

environment - An environment to run the process in (may be null)

programAndArgs - The program and its arguments.

Returns:

The return code of the process.

runProcess

public static int runProcess(java.lang.String... programAndArgs)

Runs an external process that takes no input, discarding its output. This is a convenience wrapper for runProcess(environment, programAndArgs)

Parameters:

programAndArgs - The program to run and its arguments

Returns:

The return code of the process.

discardProcessOutput

public static void discardProcessOutput(java.io.InputStream inputStream)

Read the output from a process. Due to oddities in the Process handling, this has to be done char by char. This method just implements a consumer thread to eat the output of a process and so prevent blocking.

Parameters:

inputStream - A stream to read up to end of file. This stream is closed at some point in the future, but not necessarily before this method returns.

collectProcessOutput

public static java.lang.Object collectProcessOutput(java.io.InputStream inputStream,
                                                    int maxCollect,
                                                    java.util.Set<java.lang.Thread> collectionThreads)

Collect all output from an inputstream, up to maxCollect bytes, in an output object. This will eventually close the given InputStream, but not necessarily before the method returns. The thread created is placed in a thread set, and should be removed once all output has been collected. While only a limited amount may be written to the output object, the entire output will be read from the inputStream unless the thread or the inputStream is destroyed first.

Parameters:

inputStream - The inputstream to read contents from

maxCollect - The maximum number of bytes to collect, or -1 for no limit

collectionThreads - Set of threads that concurrently collect output

Returns:

An object that collects the output. Once the thread returned is finished, the object will no longer be written to. The collected output can be retrieved with the toString method.

writeProcessOutput

public static void writeProcessOutput(java.io.InputStream inputStream,
                                      java.io.File outputFile,
                                      java.util.Set<java.lang.Thread> collectionThreads)

Collect all output from an inputstream, appending it to a file. This will eventually close the given InputStream, but not necessarily before the method returns. The thread created is placed in a thread set, and should be removed once all output has been collected.

Parameters:

inputStream - The inputstream to read contents from

outputFile - The file that output should be appended to.

collectionThreads - Set of threads that concurrently collect output

waitFor

public static java.lang.Integer waitFor(java.lang.Process p,
                                        long maxWait)

Wait for the end of a process, but only for a limited time. This method takes care of the ways waitFor can get interrupted.

Parameters:

p - Process to wait for

maxWait - The maximum number of milliseconds to wait for the process to exit.

Returns:

Exit value for process, or null if the process didn't exit within the expected time.