Execution.java [src/csip/utils] Revision: default  Date:
/*
 * $Id$
 *
 * This file is part of the Cloud Services Integration Platform (CSIP),
 * a Model-as-a-Service framework, API and application suite.
 *
 * 2012-2022, Olaf David and others, OMSLab, Colorado State University.
 *
 * OMSLab licenses this file to you under the MIT license.
 * See the LICENSE file in the project root for more information.
 */
package csip.utils;

import csip.api.server.Executable.StdHandler;
import static csip.api.server.Executable.TIMED_OUT;
import csip.SessionLogger;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;

/**
 * Executable. Helper class to execute external programs.
 *
 * @author od
 */
class Execution {

  final ProcessBuilder pb = new ProcessBuilder();
  final File executable;
  Object[] args = new Object[]{};
  SessionLogger logger;
  long time = 3600 * 24;
  TimeUnit unit = TimeUnit.SECONDS;

  //
  Writer stderr = new OutputStreamWriter(System.err) {
    @Override
    public void close() throws IOException {
      System.err.flush();
      stderr_closed = -1;
    }
  };
  //
  Writer stdout = new OutputStreamWriter(System.out) {
    @Override
    public void close() throws IOException {
      System.out.flush();
      stdout_closed = -1;
    }
  };

  StdHandler stdout_handler;
  StdHandler stderr_handler;

  // Do nothing.
  private static class NOPWriter extends Writer {

    @Override
    public void write(char[] cbuf, int off, int len) throws IOException {
    }


    @Override
    public void flush() throws IOException {
    }


    @Override
    public void close() throws IOException {
    }
  }


  /**
   * Create a new ProcessExecution.
   *
   * @param executable the executable file.
   */
  Execution(File executable) {
    this.executable = executable;
  }


  File getFile() {
    return executable;
  }


  /**
   * Set the execution arguments.
   *
   * @param args the command line arguments
   */
  void setArguments(Object... args) {
    this.args = args;
  }


  /**
   * Set the timeout.
   *
   * @param time the amount of the time unit.
   * @param unit the TimeUnit
   */
  void setTimeout(long time, TimeUnit unit) {
    if (time < 1) 
      throw new IllegalArgumentException("time: " + time);
    if (unit == null) 
      throw new IllegalArgumentException("time unit is null");
    this.time = time;
    this.unit = unit;
  }


  /**
   * Set the execution arguments.
   *
   * @param args the command line arguments
   */
  void setArguments(String... args) {
    this.args = args;
  }


  /**
   * Set the execution arguments.
   *
   * @param args the program arguments.
   */
  void setArguments(List<Object> args) {
    this.args = args.toArray(new Object[args.size()]);
  }


  /**
   * Get the arguments
   *
   * @return
   */
  Object[] getArguments() {
    Object[] ar = new Object[args.length];
    System.arraycopy(args, 0, ar, 0, ar.length);
    return ar;
  }


  /**
   * Set the working directory where the handle get executed.
   *
   * @param dir the directory in which the executable will be started
   */
  void setWorkingDirectory(File dir) {
    if (!dir.exists() || dir.isFile()) 
      throw new IllegalArgumentException("directory " + dir + " doesn't exist.");
    pb.directory(dir);
  }


  /**
   * get the execution environment. Use the returned map to customize the
   * environment variables.
   *
   * @return the handle environment.
   */
  Map<String, String> environment() {
    return pb.environment();
  }


  /**
   * Set the logger. This is optional.
   *
   * @param log the logger
   */
  void setLogger(SessionLogger log) {
    this.logger = log;
  }

  /**
   * Output handler for stdout/stderr
   */
  private static class OutputHandler extends Thread {

    Writer w;
    Reader r;
    CountDownLatch l;
    StdHandler handler;
    String remainder = "";


    OutputHandler(CountDownLatch l, InputStream is, Writer w, StdHandler handler) {
      r = new InputStreamReader(is);
      this.w = w;
      this.l = l;
      this.handler = handler;
      setPriority(Thread.MIN_PRIORITY);
    }


    @Override
    public void run() {
      try {
        char[] b = new char[2048];
        int n = r.read(b);
        while (n != -1) {
          w.write(b, 0, n);
          w.flush();
          if (handler != null) {
            handle(new String(b, 0, n));
          }
          n = r.read(b);
        }
        if (handler != null) {
          handleRemainder();
        }
      } catch (IOException ex) {
        if (ex.getMessage().equals("Stream closed.")) {
          return;
        }
        ex.printStackTrace(System.err);
      } finally {
        try {
          w.flush();
          w.close();
          r.close();
        } catch (IOException ex) {
          ex.printStackTrace(System.err);
        }
        l.countDown();
      }
    }


    void handle(String out) {
      int last = out.lastIndexOf('\n') + 1;
      if (last > 0) {
        String chunk = out.substring(0, last);
        handler.handle(remainder + chunk);
        remainder = out.substring(last);
      } else {
        handler.handle(remainder + out);
        remainder = "";
      }
    }


    void handleRemainder() {
      if (!remainder.isEmpty()) {
        handler.handle(remainder);
      }
    }
  }

  int stderr_closed = 0;
  int stdout_closed = 0;


  /**
   * Process execution. This call blocks until the handle is done.
   *
   * @return the exit status of the handle. 0 = all good
   * @throws java.io.IOException
   */
  int exec() throws IOException {
    if (stdout_closed == stdout.hashCode()) {
      throw new IOException("stdout for " + getFile() + " already closed. invoke redirectDefaults() or create new instance.");
    }
    if (stderr_closed == stderr.hashCode()) {
      throw new IOException("stderr for " + getFile() + " already closed. invoke redirectDefaults() or create new instance.");
    }
    List<String> cmd = new ArrayList<>();
    cmd.add(executable.toString());
    for (Object arg : args) {
      if (arg != null) {
        if (arg.getClass() == String[].class) {
          for (String s : (String[]) arg) {
            if (s != null && !s.isEmpty()) 
              cmd.add(s);
          }
        } else {
          String a = arg.toString();
          if (!a.isEmpty()) 
            cmd.add(a);
        }
      }
    }
    pb.command(cmd);

    if (logger != null && logger.isLoggable(Level.INFO)) {
      logger.info("Cmd:   " + pb.command().toString());
      logger.info("  Env: " + pb.environment().toString());
      logger.info("  Cwd: " + pb.directory().toString());
    }

    CountDownLatch l = new CountDownLatch(2);

    Process p = pb.start();

    new OutputHandler(l, p.getInputStream(), stdout, stdout_handler).start();
    new OutputHandler(l, p.getErrorStream(), stderr, stderr_handler).start();

    int exitValue = 0;
    try {
      boolean finnished = p.waitFor(time, unit);
      l.await();
      exitValue = finnished ? p.exitValue() : TIMED_OUT;
    } catch (InterruptedException E) {
      // do nothing
    } finally {
      if (stdout_closed != -1) 
        stdout_closed = stdout.hashCode();
      if (stderr_closed != -1) 
        stderr_closed = stderr.hashCode();
      p.getOutputStream().close();
      p.destroy();
    }
    return exitValue;
  }


  /**
   * Redirect the output stream
   *
   * @param w the stream handler
   */
  void redirectOutput(Writer w) {
    if (w == null) 
      throw new NullPointerException("w");
    stdout = w;
  }


  /**
   * Redirect the error stream
   *
   * @param w the new handler.
   */
  void redirectError(Writer w) {
    if (w == null) 
      throw new NullPointerException("w");
    stderr = w;
  }


  /**
   * Redirect stdout to null
   *
   */
  void redirectOutputNull() {
    stdout = new NOPWriter();
    stdout_closed = -1;
  }


  /**
   * Redirect stderr to null
   *
   */
  void redirectErrorNull() {
    stderr = new NOPWriter();
    stderr_closed = -1;
  }


  /**
   * Receive the current output from stdout.
   *
   * @param handler
   */
  void setStdoutHandler(StdHandler handler) {
    stdout_handler = handler;
  }


  /**
   * Receive the current output from stderr.
   *
   * @param handler
   */
  void setStderrHandler(StdHandler handler) {
    stderr_handler = handler;
  }


  @Override
  public String toString() {
    return "Executable: " + executable.toString();
  }

}