src/Pure/Tools/isabelle_process.scala

refined execute, which replaces exec/exec2;

/*  Title:      Pure/Tools/isabelle_process.ML
    Author:     Makarius
    Options:    :folding=explicit:collapseFolds=1:

Isabelle process management -- always reactive due to multi-threaded I/O.
*/

package isabelle

import java.util.Properties
import java.util.concurrent.LinkedBlockingQueue
import java.io.{BufferedReader, BufferedWriter, InputStreamReader, OutputStreamWriter,
  InputStream, OutputStream, IOException}


object IsabelleProcess {

  /* results */

  object Kind extends Enumeration {
    //{{{ values and codes
    // internal system notification
    val SYSTEM = Value("SYSTEM")
    // Posix channels/events
    val STDIN = Value("STDIN")
    val STDOUT = Value("STDOUT")
    val SIGNAL = Value("SIGNAL")
    val EXIT = Value("EXIT")
    // Isabelle messages
    val INIT = Value("INIT")
    val STATUS = Value("STATUS")
    val WRITELN = Value("WRITELN")
    val PRIORITY = Value("PRIORITY")
    val TRACING = Value("TRACING")
    val WARNING = Value("WARNING")
    val ERROR = Value("ERROR")
    val DEBUG = Value("DEBUG")
    // messages codes
    val code = Map(
      ('A' : Int) -> Kind.INIT,
      ('B' : Int) -> Kind.STATUS,
      ('C' : Int) -> Kind.WRITELN,
      ('D' : Int) -> Kind.PRIORITY,
      ('E' : Int) -> Kind.TRACING,
      ('F' : Int) -> Kind.WARNING,
      ('G' : Int) -> Kind.ERROR,
      ('H' : Int) -> Kind.DEBUG,
      ('0' : Int) -> Kind.SYSTEM,
      ('1' : Int) -> Kind.STDIN,
      ('2' : Int) -> Kind.STDOUT,
      ('3' : Int) -> Kind.SIGNAL,
      ('4' : Int) -> Kind.EXIT)
    //}}}
    def is_raw(kind: Value) =
      kind == STDOUT
    def is_control(kind: Value) =
      kind == SYSTEM ||
      kind == SIGNAL ||
      kind == EXIT
    def is_system(kind: Value) =
      kind == SYSTEM ||
      kind == STDIN ||
      kind == SIGNAL ||
      kind == EXIT ||
      kind == STATUS
  }

  class Result(val kind: Kind.Value, val props: Properties, val result: String) {
    override def toString = {
      val res = XML.content(YXML.parse_failsafe(result)).mkString
      if (props == null) kind.toString + " [[" + res + "]]"
      else kind.toString + " " + props.toString + " [[" + res + "]]"
    }
    def is_raw() = Kind.is_raw(kind)
    def is_control() = Kind.is_control(kind)
    def is_system() = Kind.is_system(kind)
  }

}


class IsabelleProcess(isabelle_system: IsabelleSystem, args: String*) {

  import IsabelleProcess._


  /* alternative constructors */

  def this(args: String*) = this(new IsabelleSystem, args: _*)


  /* process information */

  private var proc: Process = null
  private var closing = false
  private var pid: String = null
  private var the_session: String = null
  def session() = the_session


  /* results */

  private val results = new LinkedBlockingQueue[Result]

  private def put_result(kind: Kind.Value, props: Properties, result: String) {
    if (kind == Kind.INIT && props != null) {
      pid = props.getProperty(Markup.PID)
      the_session = props.getProperty(Markup.SESSION)
    }
    results.put(new Result(kind, props, result))
  }

  def get_result() = results.take

  def try_result() = {
    val res = results.poll
    if (res != null) Some(res) else None
  }


  /* signals */

  def interrupt() = synchronized {
    if (proc == null) error("Cannot interrupt Isabelle: no process")
    if (pid == null) put_result(Kind.SYSTEM, null, "Cannot interrupt: unknown pid")
    else {
      try {
        if (isabelle_system.execute(true, "kill", "-INT", pid).waitFor == 0)
          put_result(Kind.SIGNAL, null, "INT")
        else
          put_result(Kind.SYSTEM, null, "Cannot interrupt: kill command failed")
      }
      catch { case e: IOException => error("Cannot interrupt Isabelle: " + e.getMessage) }
    }
  }

  def kill() = synchronized {
    if (proc == 0) error("Cannot kill Isabelle: no process")
    else {
      try_close()
      Thread.sleep(500)
      put_result(Kind.SIGNAL, null, "KILL")
      proc.destroy
      proc = null
      pid = null
    }
  }


  /* output being piped into the process */

  private val output = new LinkedBlockingQueue[String]

  private def output_raw(text: String) = synchronized {
    if (proc == null) error("Cannot output to Isabelle: no process")
    if (closing) error("Cannot output to Isabelle: already closing")
    output.put(text)
  }

  def output_sync(text: String) =
    output_raw(" \\<^sync>\n; " + text + " \\<^sync>;\n")


  def command(text: String) =
    output_sync("Isabelle.command " + IsabelleSyntax.encode_string(text))

  def command(props: Properties, text: String) =
    output_sync("Isabelle.command " + IsabelleSyntax.encode_properties(props) + " " +
      IsabelleSyntax.encode_string(text))

  def ML(text: String) =
    output_sync("ML_val " + IsabelleSyntax.encode_string(text))

  def close() = synchronized {    // FIXME watchdog/timeout
    output_raw("\u0000")
    closing = true
  }

  def try_close() = synchronized {
    if (proc != null && !closing) {
      try { close() }
      catch { case _: RuntimeException => }
    }
  }


  /* stdin */

  private class StdinThread(out_stream: OutputStream) extends Thread("isabelle: stdin") {
    override def run() = {
      val writer = new BufferedWriter(new OutputStreamWriter(out_stream, isabelle_system.charset))
      var finished = false
      while (!finished) {
        try {
          //{{{
          val s = output.take
          if (s == "\u0000") {
            writer.close
            finished = true
          }
          else {
            put_result(Kind.STDIN, null, s)
            writer.write(s)
            writer.flush
          }
          //}}}
        }
        catch {
          case e: IOException => put_result(Kind.SYSTEM, null, "Stdin thread: " + e.getMessage)
        }
      }
      put_result(Kind.SYSTEM, null, "Stdin thread terminated")
    }
  }


  /* stdout */

  private class StdoutThread(in_stream: InputStream) extends Thread("isabelle: stdout") {
    override def run() = {
      val reader = new BufferedReader(new InputStreamReader(in_stream, isabelle_system.charset))
      var result = new StringBuilder(100)

      var finished = false
      while (!finished) {
        try {
          //{{{
          var c = -1
          var done = false
          while (!done && (result.length == 0 || reader.ready)) {
            c = reader.read
            if (c >= 0) result.append(c.asInstanceOf[Char])
            else done = true
          }
          if (result.length > 0) {
            put_result(Kind.STDOUT, null, result.toString)
            result.length = 0
          }
          else {
            reader.close
            finished = true
            try_close()
          }
          //}}}
        }
        catch {
          case e: IOException => put_result(Kind.SYSTEM, null, "Stdout thread: " + e.getMessage)
        }
      }
      put_result(Kind.SYSTEM, null, "Stdout thread terminated")
    }
  }


  /* messages */

  private class MessageThread(fifo: String) extends Thread("isabelle: messages") {
    override def run() = {
      val reader = isabelle_system.fifo_reader(fifo)
      var kind: Kind.Value = null
      var props: Properties = null
      var result = new StringBuilder

      var finished = false
      while (!finished) {
        try {
          if (kind == null) {
            //{{{ Char mode -- resync
            var c = -1
            do {
              c = reader.read
              if (c >= 0 && c != 2) result.append(c.asInstanceOf[Char])
            } while (c >= 0 && c != 2)

            if (result.length > 0) {
              put_result(Kind.SYSTEM, null, "Malformed message:\n" + result.toString)
              result.length = 0
            }
            if (c < 0) {
              reader.close
              finished = true
              try_close()
            }
            else {
              c = reader.read
              if (Kind.code.isDefinedAt(c)) kind = Kind.code(c)
              else kind = null
              props = null
            }
            //}}}
          }
          else {
            //{{{ Line mode
            val line = reader.readLine
            if (line == null) {
              reader.close
              finished = true
              try_close()
            }
            else {
              val len = line.length
              // property
              if (line.endsWith("\u0002,")) {
                val i = line.indexOf('=')
                if (i > 0) {
                  val name = line.substring(0, i)
                  val value = line.substring(i + 1, len - 2)
                  if (props == null) props = new Properties
                  if (!props.containsKey(name)) props.setProperty(name, value)
                }
              }
              // last text line
              else if (line.endsWith("\u0002.")) {
                result.append(line.substring(0, len - 2))
                put_result(kind, props, result.toString)
                result.length = 0
                kind = null
              }
              // text line
              else {
                result.append(line)
                result.append('\n')
              }
            }
            //}}}
          }
        }
        catch {
          case e: IOException => put_result(Kind.SYSTEM, null, "Message thread: " + e.getMessage)
        }
      }
      put_result(Kind.SYSTEM, null, "Message thread terminated")
    }
  }


  /** main **/

  {
    /* isabelle version */

    {
      val (msg, rc) = isabelle_system.isabelle_tool("version")
      if (rc != 0) error("Version check failed -- bad Isabelle installation:\n" + msg)
      put_result(Kind.SYSTEM, null, msg)
    }


    /* message fifo */

    val message_fifo = isabelle_system.mk_fifo()
    def rm_fifo() = isabelle_system.rm_fifo(message_fifo)

    val message_thread = new MessageThread(message_fifo)
    message_thread.start


    /* exec process */

    try {
      val cmdline =
        List(isabelle_system.getenv_strict("ISABELLE_PROCESS"), "-W", message_fifo) ++ args
      proc = isabelle_system.execute(true, cmdline: _*)
    }
    catch {
      case e: IOException =>
        rm_fifo()
        error("Failed to execute Isabelle process: " + e.getMessage)
    }


    /* stdin/stdout */

    new StdinThread(proc.getOutputStream).start
    new StdoutThread(proc.getInputStream).start


    /* exit */

    new Thread("isabelle: exit") {
      override def run() = {
        val rc = proc.waitFor()
        Thread.sleep(300)
        put_result(Kind.SYSTEM, null, "Exit thread terminated")
        put_result(Kind.EXIT, null, Integer.toString(rc))
        rm_fifo()
      }
    }.start

  }

}