custom guile stdin port for MPI users

* custom guile stdin port for MPI users
@ 2006-11-28 18:52 Alexander Shirokov
  2006-12-01 12:59 ` Mario Storti
  0 siblings, 1 reply; 4+ messages in thread
From: Alexander Shirokov @ 2006-11-28 18:52 UTC (permalink / raw)

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[please disregard my prev message - the misprint in the subject line is 
now fixed]
---

Dear GUILE Developers

I would like to embed guile interpreter into my application - a
parallel program using MPI (message passing interface) and operating
massive data and computations. I would like that program to be able to
process standard input in order to be able to have a live interactive
session with my application. Below I describe the problem i
encountered.

I am currently using Tcl as an embedded
interpreter but looking for a possibility of other alternatives.

Since Tcl does not take over the control of stdin, I am currently just
reading stdin on the MPI process zero until the Tcl command is complete
(checking with Tcl_CommandComplete after each line of stdin) and when
the command is complete i stop reading stdin, copy the string to all
the other MPI processes using MPI_Bcast and process (with Tcl_Eval)
them on worker processes.

With guile however, I am limited to using

    scm_shell(argc, argv);

which is supposed to do the stdin processing itself, - I hoped it would
even in the parallel environment. I inserted

    MPI_Init(&argc,&argv);
    MPI_Finalize()

into the tortoise.c program of the guile tutorial (the complete copy of
the program is attached) and compiled it with 'mpicc', but I do not get
the expected behavior, for example when i run on 4 processes:

mpirun -np 4 ./tortoise2
guile> (tortoise-move 100)

the next guile prompt does not appear after the entered command has
completed.

I looked into the guile archieves using search "MPI" and found
that another person was having the same problem one year ago.
That user has recieved a very informative message :
http://lists.gnu.org/archive/html/guile-user/2005-02/msg00018.html
but unfortunately, the thread stops there.
I did some followup and found nice documentation on setting custom
ports on stdin at
http://www.gnu.org/software/guile/docs/docs-1.8/guile-ref/Port-Types.html#Port-Types
but the resources of my expertise in scheme and setting custom
ports have exhausted there.

There are many people using MPI, I think a solution very be greatly
appreciated by a sizable community of MPI users.

Thank you.

Regards,
Alexander Shirokov

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/* Be-Guiled version of the program */
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

#include <X11/Xlib.h>
#define WINDOW_SIZE 500
#include <guile/gh.h>

#include <mpi.h>
int myid, serv, nproc;

Display *theDisplay;
Window theWindow;
Screen *theScreen;
GC theGC;
double currentX;
double currentY;
double currentDirection;
int penDown;

#include <math.h>
#define DEGREES_TO_RADIANS  (3.1415926535897932384626433832795029L/180.0)

SCM tortoise_reset() 
{
    currentX = currentY = WINDOW_SIZE/2;
    currentDirection = 0;
    penDown = 1;
    return SCM_EOL;
}
SCM tortoise_pendown()
{
    penDown = 1;
    return SCM_EOL;
}
SCM tortoise_penup()
{
    penDown = 0;
    return SCM_EOL;
}
SCM tortoise_turn(SCM s_degrees)
{
    int degrees = SCM_INUM(s_degrees);
    currentDirection += (double)degrees;
    return SCM_EOL;
}
SCM tortoise_move(SCM s_steps)
{
    double newX, newY;
    int steps = SCM_INUM(s_steps);
    /* first work out the new endpoint */
    newX = currentX + sin(currentDirection*DEGREES_TO_RADIANS)*(double)steps;
    newY = currentY - cos(currentDirection*DEGREES_TO_RADIANS)*(double)steps;
    /* if the pen is down, draw a line */
    if (penDown) XDrawLine(theDisplay, theWindow, theGC, 
                           (int)currentX, (int)currentY, (int)newX, (int)newY);
    /* in either case, move the tortoise */
    currentX = newX;
    currentY = newY;
    return SCM_EOL;
}

void register_procs(void)
{
    gh_new_procedure("tortoise-reset",   tortoise_reset,   0, 0, 0);
    gh_new_procedure("tortoise-pendown", tortoise_pendown, 0, 0, 0);
    gh_new_procedure("tortoise-penup",   tortoise_penup,   0, 0, 0);
    gh_new_procedure("tortoise-turn",    tortoise_turn,    1, 0, 0);
    gh_new_procedure("tortoise-move",    tortoise_move,    1, 0, 0);
}
void inner_main(int argc, char **argv)
{
  register_procs();

  scm_shell(argc, argv);

  MPI_Finalize();
}

int main(int argc, char *argv[])
{

  char pname[256];
  char fname[256];
  int reslen;

  MPI_Comm world;
  serv = 0;
  world = MPI_COMM_WORLD;

  MPI_Init(&argc,&argv);

  MPI_Comm_rank     (world,  &myid);
  MPI_Comm_size     (world,  &nproc);

  if(myid != 0){
    char *name;
    asprintf(&name, "so-%d", myid);
    stdout =  freopen(name, "w", stdout);
    if(!stdout){
      printf("Error: can not reopen stdout (%s:%d)\n", __FILE__, __LINE__);
      exit(2);
    }
    free(name);
  }

  theDisplay = XOpenDisplay(NULL);
  XSynchronize(theDisplay, True);
  theScreen = DefaultScreenOfDisplay(theDisplay);
  theWindow = XCreateSimpleWindow(theDisplay, RootWindowOfScreen(theScreen), 
				  0, 0, 
				  WINDOW_SIZE, WINDOW_SIZE, 0, 
				  BlackPixelOfScreen(theScreen), 
				  WhitePixelOfScreen(theScreen));
  theGC = XCreateGC(theDisplay, theWindow, 0L, NULL);
  XSetForeground(theDisplay, theGC, BlackPixelOfScreen(theScreen));
  XMapWindow(theDisplay,theWindow);  

  /* more stuff to come here . . */
  tortoise_reset();
  gh_enter(argc, argv, inner_main);

  return(0);			/* never reached */
  return 0;
}

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