source: trunk/athena/bin/discuss/libds/conv_mgr.c @ 22404

/*
 *
 *      Copyright (C) 1988, 1989 by the Massachusetts Institute of Technology
 *      Developed by the MIT Student Information Processing Board (SIPB).
 *      For copying information, see the file mit-copyright.h in this release.
 *
 */
/*
 *
 *      $Id: conv_mgr.c,v 1.14 2006-03-10 07:11:38 ghudson Exp $
 *
 * conv_mgr () -- File that contains procedure to handle conversations.  This
 *                allows multiplexing of RPC stream, setting up the correct
 *                stream for the given module.
 *
 */

#ifndef __STDC__
#define const
#endif

#ifndef lint
static const char rcsid_conv_mgr_c[] =
    "$Id: conv_mgr.c,v 1.14 2006-03-10 07:11:38 ghudson Exp $";
#endif /* lint */

#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include "rpc.h"


/* conversation structure */
struct conv {
     char *module;
     int port;
     char *hostname;
     char *service_id;
     rpc_conversation rc;
     int server_version;
     int result;
};

/* variables for managing conversation table */
static struct conv *conv_base;
static int num_convs;
static int max_convs;

static int cur_conv = -1;

/*
 *
 * get_module () -- Procedure to return the current module.  Returns a
 *                  character string (static storage)
 *
 */
char *
get_module ()
{
     if (conv_base == NULL || cur_conv == -1)
          return (NULL);

     return (conv_base [cur_conv].module);
}

/*
 *
 * set_module () -- Procedure to bind the set of procedure calls with a
 *                  module.  Binds them for all remote procedure calls in
 *                  the current process.  Thus people who want to do this
 *                  temporarily should do a "get_module" to restore it back.
 *
 *
 */
void set_module (module,fatal_error,result)
    char *module;
    int *fatal_error,*result;
{
     char *hostname, *service_id;
     int port,i;
     rpc_conversation rc;
     struct conv *convp;

     *fatal_error = 0;
     *result = 0;

     /* check to see if we've set up the module table */
     if (conv_base == NULL) {
          conv_base = (struct conv *) malloc (5 * sizeof (struct conv));
          max_convs = 5;
     }

     /* see if there's a real module there */
     if (!module) {
             cur_conv = -1;
             return;
     }

     /* check if we're setting our current module */
     if (cur_conv != -1) {
          if (!strcmp (module, conv_base[cur_conv].module)) {
               set_rpc (conv_base[cur_conv].rc);
               return;
          }
     }

     /* Now loop through all, looking for module names for comparison */
     for (i = 0; i < num_convs; i++) {
          if (!strcmp (module, conv_base[i].module)) { /* match */
               if (conv_base[i].result != 0) { /* errored out before */
                    *result = conv_base[i].result;
                    *fatal_error = 1;
                    return;
               }
               set_rpc (conv_base[i].rc);
               cur_conv = i;
               return;
          }
     }

     /* not found -- we're going to have to resolve the module name. */
     resolve_module (module, &port, &hostname, &service_id, result);
     if (*result) {
          *fatal_error = 1;
          return;
     }

     /* Check through conversations, looking for resolved module */
     for (i = 0; i < num_convs; i++) {
          convp = &conv_base [i];
          if (convp -> port == port && !namcmp (hostname, convp -> hostname)
              && !strcmp (service_id, convp -> service_id)) {
              /* found match, record */
              if (conv_base[i].result != 0) {           /* errored out */
                  *result = conv_base[i].result;
                  *fatal_error = 1;
                  return;
              }
              rc = convp -> rc;
              set_rpc (rc);
              goto create_entry;
          }
     }

     /* Not found.  Create the rpc conversation */
     rc = open_rpc (hostname, port, service_id, result);
     if (rc == NULL) {
          *fatal_error = 1;
          if (*result == EINTR) {               /* control-C: don't create conversation */
               return;
          }
     }

create_entry:
     if (num_convs == max_convs) {
         max_convs += 2;
         conv_base = (struct conv *) realloc (conv_base,
                                              max_convs*sizeof (struct conv));
     }

     cur_conv = num_convs++;
     convp = &conv_base [cur_conv];
     convp -> rc = rc;
     convp -> result = 0;
     if (rc == NULL) {                  /* error opening, but 'remember' it */
          convp -> result = *result;
          cur_conv = -1;
     }
     convp -> hostname = malloc (strlen (hostname)+1);
     strcpy (convp -> hostname, hostname);
     convp -> service_id = malloc (strlen (service_id)+1);
     strcpy (convp -> service_id, service_id);
     convp -> module = malloc (strlen (module)+1);
     strcpy (convp -> module, module);
     convp -> port = port;

     convp -> server_version = get_server_version();
     return;
}

/*
 *
 * flush_convs () -- Routine to flush all conversations.
 *
 */
void flush_convs ()
{
     int i,j;
     struct conv *convp;

     if (conv_base == NULL)
          return;

     for (i = 0; i < num_convs; i++) {
          convp = &conv_base[i];

          if (convp -> rc)
               close_rpc (convp -> rc);
          free(convp -> module);
          free(convp -> hostname);
          free(convp -> service_id);
        
          /* tromp on future conversations */
          for (j = i+1; j < num_convs; j++) {
               if (convp -> rc == conv_base[j].rc)
                    conv_base[j].rc = NULL;
          }
          convp -> rc = 0;
     }
     
     free (conv_base);
     conv_base = NULL;
     num_convs = 0;
     max_convs = 0;
     cur_conv = -1;
}

get_conv_server_version()
{
     if (cur_conv == -1)
          return(SERVER_0);

     return (conv_base[cur_conv].server_version);
}