src/Pure/System/isabelle_process.scala

slightly more robust Isabelle_Process startup -- NB: openening fifo streams synchronizes with other end, which may fail to reach that point;

/*  Title:      Pure/System/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.concurrent.LinkedBlockingQueue
import java.io.{BufferedReader, BufferedWriter, InputStreamReader, OutputStreamWriter,
  InputStream, OutputStream, BufferedOutputStream, IOException}

import scala.actors.Actor
import Actor._


object Isabelle_Process
{
  /* results */

  object Kind {
    // message markup
    val markup = Map(
      ('A' : Int) -> Markup.INIT,
      ('B' : Int) -> Markup.STATUS,
      ('C' : Int) -> Markup.REPORT,
      ('D' : Int) -> Markup.WRITELN,
      ('E' : Int) -> Markup.TRACING,
      ('F' : Int) -> Markup.WARNING,
      ('G' : Int) -> Markup.ERROR)
    def is_raw(kind: String) =
      kind == Markup.STDOUT
    def is_control(kind: String) =
      kind == Markup.SYSTEM ||
      kind == Markup.SIGNAL ||
      kind == Markup.EXIT
    def is_system(kind: String) =
      kind == Markup.SYSTEM ||
      kind == Markup.INPUT ||
      kind == Markup.STDIN ||
      kind == Markup.SIGNAL ||
      kind == Markup.EXIT ||
      kind == Markup.STATUS
  }

  class Result(val message: XML.Elem)
  {
    def kind = message.markup.name
    def properties = message.markup.properties
    def body = message.body

    def is_raw = Kind.is_raw(kind)
    def is_control = Kind.is_control(kind)
    def is_system = Kind.is_system(kind)
    def is_status = kind == Markup.STATUS
    def is_report = kind == Markup.REPORT
    def is_ready = is_status && body == List(XML.Elem(Markup.Ready, Nil))

    override def toString: String =
    {
      val res =
        if (is_status || is_report) message.body.map(_.toString).mkString
        else Pretty.string_of(message.body)
      if (properties.isEmpty)
        kind.toString + " [[" + res + "]]"
      else
        kind.toString + " " +
          (for ((x, y) <- properties) yield x + "=" + y).mkString("{", ",", "}") + " [[" + res + "]]"
    }
  }
}


class Isabelle_Process(system: Isabelle_System, receiver: Actor, args: String*)
{
  import Isabelle_Process._


  /* demo constructor */

  def this(args: String*) =
    this(new Isabelle_System,
      actor { loop { react { case res => Console.println(res) } } }, args: _*)


  /* process information */

  @volatile private var proc: Option[Process] = None
  @volatile private var pid: Option[String] = None


  /* results */

  private val xml_cache = new XML.Cache(131071)

  private def put_result(kind: String, props: List[(String, String)], body: XML.Body)
  {
    if (pid.isEmpty && kind == Markup.INIT)
      pid = props.find(_._1 == Markup.PID).map(_._1)

    val msg = XML.Elem(Markup(kind, props), Isar_Document.clean_message(body))
    xml_cache.cache_tree(msg)((message: XML.Tree) =>
      receiver ! new Result(message.asInstanceOf[XML.Elem]))
  }

  private def put_result(kind: String, text: String)
  {
    put_result(kind, Nil, List(XML.Text(system.symbols.decode(text))))
  }


  /* signals */

  def interrupt()
  {
    if (proc.isEmpty) put_result(Markup.SYSTEM, "Cannot interrupt Isabelle: no process")
    else
      pid match {
        case None => put_result(Markup.SYSTEM, "Cannot interrupt Isabelle: unknowd pid")
        case Some(i) =>
          try {
            if (system.execute(true, "kill", "-INT", i).waitFor == 0)
              put_result(Markup.SIGNAL, "INT")
            else
              put_result(Markup.SYSTEM, "Cannot interrupt Isabelle: kill command failed")
          }
          catch { case e: IOException => error("Cannot interrupt Isabelle: " + e.getMessage) }
      }
  }

  def kill()
  {
    proc match {
      case None => put_result(Markup.SYSTEM, "Cannot kill Isabelle: no process")
      case Some(p) =>
        close()
        Thread.sleep(500)  // FIXME !?
        put_result(Markup.SIGNAL, "KILL")
        p.destroy
        proc = None
        pid = None
    }
  }



  /** stream actors **/

  private val in_fifo = system.mk_fifo()
  private val out_fifo = system.mk_fifo()
  private def rm_fifos() = { system.rm_fifo(in_fifo); system.rm_fifo(out_fifo) }

  private case class Input_Text(text: String)
  private case class Input_Chunks(chunks: List[Array[Byte]])
  private case object Close


  /* raw stdin */

  private def stdin_actor(name: String, stream: OutputStream): Actor =
    Simple_Thread.actor(name) {
      val writer = new BufferedWriter(new OutputStreamWriter(stream, Standard_System.charset))
      var finished = false
      while (!finished) {
        try {
          //{{{
          receive {
            case Input_Text(text) =>
              // FIXME echo input?!
              writer.write(text)
              writer.flush
            case Close =>
              writer.close
              finished = true
            case bad => System.err.println(name + ": ignoring bad message " + bad)
          }
          //}}}
        }
        catch {
          case e: IOException => put_result(Markup.SYSTEM, name + ": " + e.getMessage)
        }
      }
      put_result(Markup.SYSTEM, name + " terminated")
    }


  /* raw stdout */

  private def stdout_actor(name: String, stream: InputStream): Actor =
    Simple_Thread.actor(name) {
      val reader = new BufferedReader(new InputStreamReader(stream, Standard_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(Markup.STDOUT, result.toString)
            result.length = 0
          }
          else {
            reader.close
            finished = true
            close()
          }
          //}}}
        }
        catch {
          case e: IOException => put_result(Markup.SYSTEM, name + ": " + e.getMessage)
        }
      }
      put_result(Markup.SYSTEM, name + " terminated")
    }


  /* command input */

  private def input_actor(name: String): Actor =
    Simple_Thread.actor(name) {
      val stream = new BufferedOutputStream(system.fifo_output_stream(in_fifo))  // FIXME potentially blocking forever
      var finished = false
      while (!finished) {
        try {
          //{{{
          receive {
            case Input_Chunks(chunks) =>
              stream.write(Standard_System.string_bytes(
                  chunks.map(_.length).mkString("", ",", "\n")));
              chunks.foreach(stream.write(_));
              stream.flush
            case Close =>
              stream.close
              finished = true
            case bad => System.err.println(name + ": ignoring bad message " + bad)
          }
          //}}}
        }
        catch {
          case e: IOException => put_result(Markup.SYSTEM, name + ": " + e.getMessage)
        }
      }
      put_result(Markup.SYSTEM, name + " terminated")
    }


  /* message output */

  private class Protocol_Error(msg: String) extends Exception(msg)

  private def message_actor(name: String): Actor =
    Simple_Thread.actor(name) {
      val stream = system.fifo_input_stream(out_fifo)  // FIXME potentially blocking forever
      val default_buffer = new Array[Byte](65536)
      var c = -1

      def read_chunk(): XML.Body =
      {
        //{{{
        // chunk size
        var n = 0
        c = stream.read
        while (48 <= c && c <= 57) {
          n = 10 * n + (c - 48)
          c = stream.read
        }
        if (c != 10) throw new Protocol_Error("bad message chunk header")

        // chunk content
        val buf =
          if (n <= default_buffer.size) default_buffer
          else new Array[Byte](n)

        var i = 0
        var m = 0
        do {
          m = stream.read(buf, i, n - i)
          i += m
        } while (m > 0 && n > i)

        if (i != n) throw new Protocol_Error("bad message chunk content")

        YXML.parse_body_failsafe(YXML.decode_chars(system.symbols.decode, buf, 0, n))
        //}}}
      }

      do {
        try {
          val header = read_chunk()
          val body = read_chunk()
          header match {
            case List(XML.Elem(Markup(name, props), Nil))
                if name.size == 1 && Kind.markup.isDefinedAt(name(0)) =>
              put_result(Kind.markup(name(0)), props, body)
            case _ => throw new Protocol_Error("bad header: " + header.toString)
          }
        }
        catch {
          case e: IOException =>
            put_result(Markup.SYSTEM, "Cannot read message:\n" + e.getMessage)
          case e: Protocol_Error =>
            put_result(Markup.SYSTEM, "Malformed message:\n" + e.getMessage)
        }
      } while (c != -1)
      stream.close
      close()

      put_result(Markup.SYSTEM, name + " terminated")
    }



  /** init **/

  /* exec process */

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


  /* I/O actors */

  private val command_input = input_actor("command_input")
  message_actor("message_output")

  private val standard_input = stdin_actor("standard_input", proc.get.getOutputStream)
  stdout_actor("standard_output", proc.get.getInputStream)


  /* exit process */

  Simple_Thread.actor("process_exit") {
    proc match {
      case None =>
      case Some(p) =>
        val rc = p.waitFor()
        Thread.sleep(300)  // FIXME property!?
        put_result(Markup.SYSTEM, "process_exit terminated")
        put_result(Markup.EXIT, rc.toString)
    }
    rm_fifos()
  }



  /** main methods **/

  def input_raw(text: String): Unit = standard_input ! Input_Text(text)

  def input_bytes(name: String, args: Array[Byte]*): Unit =
    command_input ! Input_Chunks(Standard_System.string_bytes(name) :: args.toList)

  def input(name: String, args: String*): Unit =
    input_bytes(name, args.map(Standard_System.string_bytes): _*)

  def close(): Unit = command_input ! Close
}