ProcessClosure.java

/*
  ProcessClosure.java

  (c) 2006-2009 IBM and others (from CDT)

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package ejs.base.launch;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;

/**
 * Bundled state of a launched process including the threads linking the process
 * in/output to console documents.
 */
public class ProcessClosure {

	/**
	 * Thread which continuously reads from a input stream and pushes the read
	 * data to an output stream which is immediately flushed afterwards.
	 */
	protected static class ReaderThread extends Thread {

		private InputStream fInputStream;
		private OutputStream fOutputStream;
		private boolean fFinished = false;
		private String lineSeparator;
		/*
		 * outputStream can be null
		 */
		public ReaderThread(ThreadGroup group, String name, InputStream in, OutputStream out) {
			super(group, name);
			fOutputStream = out;
			fInputStream = in;
			setDaemon(true);
			lineSeparator = System.getProperty("line.separator"); //$NON-NLS-1$
		}

		@Override
		public void run() {
			try {
				try {
					BufferedReader reader = new BufferedReader(new InputStreamReader(fInputStream));
					String line;
					while ((line = reader.readLine()) != null) {
						line += lineSeparator;
						fOutputStream.write(line.getBytes());
					}
				} catch (IOException x) {
					// ignore
				} finally {
					try {
						//					writer.flush();
						fOutputStream.flush();
					} catch (IOException e) {
						// ignore
					}
					try {
						fInputStream.close();
					} catch (IOException e) {
						// ignore
					}
				}
			} finally {
				complete();
			}
		}

		public synchronized boolean finished() {
			return fFinished;
		}

		public synchronized void waitFor() {
			while (!fFinished) {
				try {
					wait();
				} catch (InterruptedException e) {
				}
			}
		}

		public synchronized void complete() {
			fFinished = true;
			notify();
		}

		public void close() {
			try {
				fOutputStream.close();
			} catch (IOException e) {
				// ignore
			}
		}
	}

	protected static int fCounter = 0;

	protected Process fProcess;

	protected OutputStream fOutput;
	protected OutputStream fError;

	protected ReaderThread fOutputReader;
	protected ReaderThread fErrorReader;

	/**
	 * Creates a process closure and connects the launched process with a
	 * console document.
	 * 
	 * @param outputStream
	 *            prcess stdout is written to this stream. Can be
	 *            <code>null</code>, if not interested in reading the output
	 * @param errorStream
	 *            prcess stderr is written to this stream. Can be
	 *            <code>null</code>, if not interested in reading the output
	 */
	public ProcessClosure(Process process, OutputStream outputStream, OutputStream errorStream) {
		fProcess = process;
		fOutput = outputStream;
		fError = errorStream;
	}

	/**
	 * Live links the launched process with the configured in/out streams using
	 * reader threads.
	 */
	public void runNonBlocking() {
		ThreadGroup group = new ThreadGroup("CBuilder" + fCounter++); //$NON-NLS-1$

		InputStream stdin = fProcess.getInputStream();
		InputStream stderr = fProcess.getErrorStream();

		fOutputReader = new ReaderThread(group, "OutputReader", stdin, fOutput); //$NON-NLS-1$
		fErrorReader = new ReaderThread(group, "ErrorReader", stderr, fError); //$NON-NLS-1$

		fOutputReader.start();
		fErrorReader.start();
	}

	public void runBlocking() {
		runNonBlocking();

		boolean finished = false;
		while (!finished) {
			try {
				fProcess.waitFor();
			} catch (InterruptedException e) {
				//System.err.println("Closure exception " +e);
			}
			try {
				fProcess.exitValue();
				finished = true;
			} catch (IllegalThreadStateException e) {
				//System.err.println("Closure exception " +e);
			}
		}

		// @@@FIXME: Windows 2000 is screwed; double-check using output threads
		if (!fOutputReader.finished()) {
			fOutputReader.waitFor();
		}

		if (!fErrorReader.finished()) {
			fErrorReader.waitFor();
		}

		fOutputReader.close();
		fErrorReader.close();
		// it seems that thread termination and stream closing is working
		// without
		// any help
		fProcess = null;
		fOutputReader = null;
		fErrorReader = null;
	}

	public boolean isAlive() {
		if (fProcess != null) {
			if (fOutputReader.isAlive() || fErrorReader.isAlive()) {
				return true;
			}
			fProcess = null;
			fOutputReader.close();
			fErrorReader.close();
			fOutputReader = null;
			fErrorReader = null;
		}
		return false;
	}

	/**
	 * The same functionality as "isAlive()"
	 * but does not affect out streams,
	 * because they can be shared among processes
	 */
	public boolean isRunning() {
		if (fProcess != null) {
			if (fOutputReader.isAlive() || fErrorReader.isAlive()) {
				return true;
			}
			fProcess = null;
		}
		return false;
	}
	/**
	 * Forces the termination the launched process
	 */
	public void terminate() {
		if (fProcess != null) {
			fProcess.destroy();
			fProcess = null;
		}
		if (!fOutputReader.finished()) {
			fOutputReader.waitFor();
		}
		if (!fErrorReader.finished()) {
			fErrorReader.waitFor();
		}
		fOutputReader.close();
		fErrorReader.close();
		fOutputReader = null;
		fErrorReader = null;
	}
}