ProcessManager.java

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/*
 * ProcessManager.java
 * Use this class for painless process spawning.
 * This class was specifically written to be compatable with 1.4
 * @since JDK 1.4
 * @author bnevins
 * Created on October 28, 2005, 10:08 PM
 */
package com.sun.enterprise.universal.process;

import java.io.*;
import java.util.*;

/**
 *
 */
public class ProcessManager {
    public ProcessManager(String... cmds) {
        cmdline = cmds;
        sb_out = new StringBuffer();
        sb_err = new StringBuffer();
    }

    ////////////////////////////////////////////////////////////////////////////
    public ProcessManager(List<String> Cmdline) {
        cmdline = new String[Cmdline.size()];
        cmdline = (String[]) Cmdline.toArray(cmdline);
        sb_out = new StringBuffer();
        sb_err = new StringBuffer();
    }

    ////////////////////////////////////////////////////////////////////////////
    public final void setTimeoutMsec(int num) {
        if (num > 0) {
            timeout = num;
        }
    }
    
    public final void setEnvironment(String[] env) {
        this.env = env;
    }

    ////////////////////////////////////////////////////////////////////////////
    public final void setStdinLines(List<String> list) {
        if (list != null && list.size() > 0) {
            stdinLines = new String[list.size()];
            stdinLines = (String[]) list.toArray(stdinLines);
        }
    }

    public final void waitForReaderThreads(boolean b) {
        waitForReaderThreads = b;
    }

    ////////////////////////////////////////////////////////////////////////////
    /** Should the output of the process be echoed to stdout?
     *
     * @param newEcho
     */
    public final void setEcho(boolean newEcho) {
        echo = newEcho;
    }

    ////////////////////////////////////////////////////////////////////////////
    public final int execute() throws ProcessManagerException {
        try {
            Runtime rt = Runtime.getRuntime();
            process = rt.exec(cmdline, env);
            readStream("stderr", process.getErrorStream(), sb_err);
            readStream("stdout", process.getInputStream(), sb_out);
            writeStdin();
            await();

            try {
                exit = process.exitValue();
            }
            catch (IllegalThreadStateException tse) {
                // this means that the process is still running...
                process.destroy();
                throw new ProcessManagerTimeoutException(tse);
            }
        }
        catch (ProcessManagerException pme) {
            throw pme;
        }
        catch (Exception e) {
            if (process != null) {
                process.destroy();
            }

            throw new ProcessManagerException(e);
        }
        finally {
            // Always wait for reader threads -- unless the boolean flag is false.
            // note that this won't block when there was a timeout because the process
            // has been forcibly destroyed above.
            doWaitForReaderThreads();
        }

        return exit;
    }

    ////////////////////////////////////////////////////////////////////////////
    public final String getStdout() {
        return sb_out.toString();
    }

    ////////////////////////////////////////////////////////////////////////////
    public final String getStderr() {
        return sb_err.toString();
    }

    ////////////////////////////////////////////////////////////////////////////
    public final int getExitValue() {
        return exit;
    }

    ////////////////////////////////////////////////////////////////////////////
    @Override
    public String toString() {
        return Arrays.toString(cmdline);
    }

    ////////////////////////////////////////////////////////////////////////////
    private void writeStdin() throws ProcessManagerException {
        if (stdinLines == null || stdinLines.length <= 0) {
            return;
        }

        PrintWriter pipe = null;

        if(process == null) {
            throw new ProcessManagerException(Strings.get("null.process"));
        }

        try {
            pipe = new PrintWriter(new BufferedWriter(new OutputStreamWriter(process.getOutputStream())));

            for (int i = 0; i < stdinLines.length; i++) {
                debug("InputLine ->" + stdinLines[i] + "<-");
                pipe.println(stdinLines[i]);
            }
            pipe.flush();
        }
        catch (Exception e) {
            throw new ProcessManagerException(e);
        }
        finally {
            try {
                pipe.close();
            }
            catch (Throwable t) {
            }
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    private void readStream(String name, InputStream stream, StringBuffer sb) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
        Thread thread = new Thread(new ReaderThread(reader, sb, echo), name);
        threads.add(thread);
        thread.start();
    }

    ////////////////////////////////////////////////////////////////////////////
    private void await() throws InterruptedException, ProcessManagerException {
        if (timeout <= 0) {
            waitForever();
        }
        else {
            waitAwhile();
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    private void waitForever() throws InterruptedException, ProcessManagerException {
        if(process == null) {
            throw new ProcessManagerException(Strings.get("null.process"));
        }

        process.waitFor();
    }

    ////////////////////////////////////////////////////////////////////////////
    private void waitAwhile() throws InterruptedException {
        {
            Thread processWaiter = new Thread(new TimeoutThread(process));
            processWaiter.start();
            processWaiter.join(timeout);
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    private void doWaitForReaderThreads() {
        if (waitForReaderThreads) {
            // wait for stdin and stderr to finish up
            for (Thread t : threads) {
                try {
                    t.join();
                }
                catch (InterruptedException ex) {
                    // nothing to do
                }
            }
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    private static void debug(String s) {
        if (debugOn) {
            System.out.println(s);
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    public static void main(String[] args) {
        try {
            if (args.length <= 0) {
                System.out.println("Usage: ProcessManager cmd arg1 arg2 ... argn");
                System.exit(1);
            }

            List<String> cmds = new ArrayList<String>();
            cmds.addAll(Arrays.asList(args));

            ProcessManager pm = new ProcessManager(cmds);
            pm.execute();

            System.out.println("*********** STDOUT ***********\n" + pm.getStdout());
            System.out.println("*********** STDERR ***********\n" + pm.getStderr());
            System.out.println("*********** EXIT VALUE: " + pm.getExitValue());
        }
        catch (ProcessManagerException pme) {
            pme.printStackTrace();
        }
    }
    ////////////////////////////////////////////////////////////////////////////
    private String[] cmdline;
    private String[] env = null;
    private StringBuffer sb_out;
    private StringBuffer sb_err;
    private int exit = -1;
    private int timeout;
    private Process process;
    private boolean echo = true;
    private static final boolean debugOn = false;
    private String[] stdinLines;
    private List<Thread> threads = new ArrayList<Thread>(2);
    private boolean waitForReaderThreads = true;
    ////////////////////////////////////////////////////////////////////////////

    static class ReaderThread implements Runnable {
        ReaderThread(BufferedReader Reader, StringBuffer SB, boolean echo) {
            reader = Reader;
            sb = SB;
            this.echo = echo;
        }

        @Override
        public void run
                () {
            try {
                for (String line = reader.readLine(); line != null; line = reader.readLine()) {
                    sb.append(line).append('\n');

                    if (echo) {
                        System.out.println(line);
                    }
                }
            }
            catch (Exception e) {
            }
            ProcessManager.debug("ReaderThread exiting...");
        }
        private BufferedReader reader;
        private StringBuffer sb;
        private boolean echo;
    }

    static class TimeoutThread implements Runnable {
        TimeoutThread(Process p) {
            process = p;
        }

        @Override
        public void run() {
            try {
                process.waitFor();
            }
            catch (Exception e) {
            }
            ProcessManager.debug("TimeoutThread exiting...");
        }
        private Process process;
    }
}