edu.rice.cs.util
Class ProcessChain

java.lang.Object
  java.lang.Process
      edu.rice.cs.util.ProcessChain

public class ProcessChain
extends Process

This class represents a piping chain of processes, in which the output of the first process is piped into the input of the second process, and so on. The class allows the entire chain to be treated as if it were just one process. The constructor also sets up the input and output streams of the individual processes so they can function as a chain.

Nested Class Summary

protected class

ProcessChain.ProcessChainThreadGroup Thread group for all threads that deal with this process sequence.

Field Summary

protected boolean	_aborted True when execution of this chain has been aborted.
protected PipedInputStream	_combinedErrorStream The combined error stream of all processes.
protected JoinInputStream	_combinedInputJoinedWithDebugStream The combined input stream of all the processes, plus a debug stream.
protected PipedInputStream	_combinedInputStream The combined input stream of all processes.
protected PipedOutputStream	_combinedStdErrStream The stream into which all outputs to stderr are written.
protected PipedOutputStream	_combinedStdOutStream The stream into which all outputs to stdout are written.
protected ProcessCreator[]	_creators The process creators that create the processes in this process chain.
protected PipedInputStream	_debugInputStream Debug input and output stream.
protected PrintWriter	_debugOutput Debug output that gets joined with the streams from the processes.
protected PipedOutputStream	_debugOutputStream
protected Process[]	_processes The processes inside this piping chain.
protected Set<StreamRedirectThread>	_redirectors The redirector threads that move output (both stdout and stderr) from one process to the input of the next process.
static String	PIPE_SEPARATOR Separator used between processes inside the same process chain.
static char	PIPE_SEPARATOR_CHAR Separator used between processes inside the same process chain.
static String	PROCESS_SEPARATOR Separator used between different process chains.
static char	PROCESS_SEPARATOR_CHAR Separator used between different process chains.

Constructor Summary

ProcessChain(ProcessCreator[] pcs)
Constructor for a process chain consisting of the individual processes provided.

Method Summary

void	destroy() Kills all subprocesses.
int	exitValue() Returns the exit value for the subprocess.
InputStream	getErrorStream() Gets the error stream of the process sequence, i.e.
InputStream	getInputStream() Gets the input stream of the process sequence, i.e.
OutputStream	getOutputStream() Gets the output stream of the process sequence, i.e.
protected void	stopAllRedirectors() Set the stop flags for all redirector threads.
int	waitFor() Causes the current thread to wait, if necessary, until the process chain has terminated, i.e.

Methods inherited from class java.lang.Object

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

Field Detail

PROCESS_SEPARATOR_CHAR

public static final char PROCESS_SEPARATOR_CHAR

Separator used between different process chains.

See Also:

Constant Field Values

PROCESS_SEPARATOR

public static final String PROCESS_SEPARATOR

Separator used between different process chains.

PIPE_SEPARATOR_CHAR

public static final char PIPE_SEPARATOR_CHAR

Separator used between processes inside the same process chain.

See Also:

Constant Field Values

PIPE_SEPARATOR

public static final String PIPE_SEPARATOR

Separator used between processes inside the same process chain.

_creators

protected ProcessCreator[] _creators

The process creators that create the processes in this process chain.

_processes

protected Process[] _processes

The processes inside this piping chain.

_aborted

protected boolean _aborted

True when execution of this chain has been aborted.

_redirectors

protected Set<StreamRedirectThread> _redirectors

The redirector threads that move output (both stdout and stderr) from one process to the input of the next process.

_combinedInputStream

protected PipedInputStream _combinedInputStream

The combined input stream of all processes.

_combinedStdOutStream

protected PipedOutputStream _combinedStdOutStream

The stream into which all outputs to stdout are written.

_combinedInputJoinedWithDebugStream

protected JoinInputStream _combinedInputJoinedWithDebugStream

The combined input stream of all the processes, plus a debug stream.

_debugOutput

protected PrintWriter _debugOutput

Debug output that gets joined with the streams from the processes.

_debugInputStream

protected PipedInputStream _debugInputStream

Debug input and output stream.

_debugOutputStream

protected PipedOutputStream _debugOutputStream

_combinedErrorStream

protected PipedInputStream _combinedErrorStream

The combined error stream of all processes.

_combinedStdErrStream

protected PipedOutputStream _combinedStdErrStream

The stream into which all outputs to stderr are written.

Constructor Detail

ProcessChain

public ProcessChain(ProcessCreator[] pcs)

Constructor for a process chain consisting of the individual processes provided.

Parameters:

pcs - array of ProcessCreators

Method Detail

getOutputStream

public OutputStream getOutputStream()

Gets the output stream of the process sequence, i.e. the combined output stream of all the processes in the sequence.

Specified by:

getOutputStream in class Process

Returns:

the output stream of the process sequence.

getErrorStream

public InputStream getErrorStream()

Gets the error stream of the process sequence, i.e. the combined error stream of all the processes in the sequence.

Specified by:

getErrorStream in class Process

Returns:

the error stream of the process sequence.

getInputStream

public InputStream getInputStream()

Gets the input stream of the process sequence, i.e. the combined input stream of all the processes in the sequence.

Specified by:

getInputStream in class Process

Returns:

the input stream of the process chain

waitFor

public int waitFor()
            throws InterruptedException

Causes the current thread to wait, if necessary, until the process chain has terminated, i.e. until all processes in the chain have terminated. This method returns immediately if all subprocesses have already terminated. If any of the subprocess has not yet terminated, the calling thread will be blocked until all subprocesses exit.

Specified by:

waitFor in class Process

Returns:

the exit value of the process chain, i.e. the exit code of the last process in the chain.

Throws:

InterruptedException - if the current thread is interrupted by another thread while it is waiting, then the wait is ended and an InterruptedException is thrown.

exitValue

public int exitValue()

Returns the exit value for the subprocess.

Specified by:

exitValue in class Process

Returns:

the exit value of the subprocess represented by this Process object. by convention, the value 0 indicates normal termination.

Throws:

IllegalThreadStateException - if the subprocess represented by this Process object has not yet terminated.

destroy

public void destroy()

Kills all subprocesses. The subprocesses represented by this ProcessChain object is forcibly terminated.

Specified by:

destroy in class Process

stopAllRedirectors

protected void stopAllRedirectors()

Set the stop flags for all redirector threads.