Usenet 1994 January/usenetsourcesnewsgroupsinfomagicjanuary1994.iso/sources/unix/volume24/lb/rsdclnt.c

C/C++ Source or Header | 1991-06-05 | 5.5 KB | 203 lines

/*
 * Copyright (c) 1989,1990,1991 University of Rochester
 * Department of Electrical Engineering
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * at the University of Rochester.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 * rsdclnt.c  for the 'lb' load balancer
 *   -Deke Kassabian, University of Rochester EE Department
 *   ( [e-mail] )  [phone]
 *
 * $Revision: 1.2 $
 * $Author: deke $
 * $Date: 91/03/03 17:52:36 $
 * $Log:    rsdclnt.c,v $
 * Revision 1.2  91/03/03  17:52:36  deke
 * changed stats to lstats to avoid name clash: required by change in rstat.h
 *
 */

#include <stdio.h>
#include <rpc/rpc.h>
#include <rpcsvc/rstat.h>
#include "config.h"

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

struct statstime lstats;
FILE *fd,*fopen();
char *fgets();
int getstats();

int start,             /* where in the argv the command begins */
    ppgrp,            /* parent process group            */
    command,            /* whether there is a command         */
    verbose_mode,         /* all possible output            */
    quiet_mode;            /* no output                */

char *path=RSH;

char *dir,*pname;
char *cmd_exec[MAXSHBUF],    /* command to execute (local)        */
     *rcmd_exec[MAXSHBUF],    /* command to execute (remote)        */
     dbuf[MAXSHBUF],        /* working directory placeholder    */
     host[MAXHOST],        /* hostname placeholder            */
     best_host[MAXHOST],    /* hostname placeholder            */
     fentry[MAXLINE];        /* file buffer */

float my_sfactor,
      best_sfactor,
      factor, limit,        /* file variables            */
      load;

    pname = *argv;            /* Name of this program  */
    verbose_mode=0,quiet_mode=0;    /* Default is neither    */
    best_sfactor=MAXFLOAT;         /* Practically infinity! */
     command=1;            /* There is a command     */

 /* Check arguments.
  *
  * if argc=1 then verbose=Y and command=NULL
  * if argc>=2 check for flags:
  *    -v=verbose (full output),  -q=quiet (don't output machine selection)
  *    with no flags, only machine selection will be output
  *    The above flags are mutually exclusive.  v overrides q
  *
  *    Additional arguments are taken to be a command.  No sanity checking
  *    will be done.  When a machine is selected, the command will be sent
  *    to that machine as a shell command.
  *
  */

 if (argc == 1) {
    command=0;            /* no command to execute */
    verbose_mode=1;            /* verbose mode         */
 }
 else {
     start=1;
     if(!strcmp(argv[1],"-q")){
      quiet_mode=1;            /* quiet mode - no output */
      start=2;
      if(argc == 2) exit(0);        /* No command, no output! */
     }
     if(!strcmp(argv[1],"-v")){
      verbose_mode=1;            /* verbose mode         */
      start=2;
      if(argc == 2) command=0;        /* No command - verbose   */
     }
 }
 if(command){
    for( ; start<argc ; start++){
        strcat(cmd_exec," "); strcat(cmd_exec,argv[start]);
    }
 }


 if((fd=fopen(CONFIGFILE,"r"))==0){
     fprintf(stderr,"Error opening configuration file\n");
     exit(1);
 }

    while((fgets(fentry,MAXLINE,fd))!=NULL){
       sscanf(fentry,"%s %f %f",host,&factor,&limit);
       if(fentry[0]=='#') continue;     /*ignore comments*/

       if(verbose_mode)
          printf("\nHOST=%s\tFACTOR=%.2f\tLIMIT=%.2f\n",host,factor,limit);

       if(getstats(host,&lstats) !=0){
        load=MAXFLOAT;            /* skip this one */
       }
       else {
        load=loadavg(&lstats,0);
       }

       if( load > limit){
          if(verbose_mode) printf("Host %s is over defined limit\n",host);
          continue;
          }

       my_sfactor=100*(load/factor);

       if(verbose_mode)
        printf("Load avg=%.3f\tSelection factor=%.3f\n",
            load,my_sfactor);

       if(best_sfactor>my_sfactor){
        best_sfactor=my_sfactor;
        strcpy(best_host,host);
       }
    } /*endwhile */

    if(verbose_mode)
       printf("Selected host: <%s> factor=<%.3f>\n",best_host,best_sfactor);

    if(command){
        sprintf(rcmd_exec,"(cd %s;%s)",getwd(dbuf),cmd_exec);
        if(!quiet_mode){ /* print if not quiet_mode */
           printf("\nrsh %s %s &\n",best_host,rcmd_exec);
        }
        ppgrp = getpgrp(getppid());
        if (fork())
        exit(0);
        if(setpgrp(getpid(), ppgrp))
        perror("stepgrp");
        execle(path,path,best_host,rcmd_exec,(char *)0,envp); exit(0);
        perror("");
    }
exit(0);
}

getstats(hostname,lstats)
char *hostname;
struct statstime *lstats;
{
int c;
    c=rstat(hostname,lstats);    /* rstat seems to return:        */
                /*    0  on success            */
                /*    13 on hostname lookup fail  */
                /*    14 on connection timeout    */
                /*    15 on "rstat not supported" */
    /*  I chose to generate my own error messages.  perror() didn't */
    /*    give error messages I liked.  Switch back to perror if you  */
    /*    care to.                            */

    switch(c){
    case 0:
        break;
    case 13:
        fprintf(stderr,"rstat error (%d): ",c);
        fprintf(stderr,"host %s is unknown.\n",hostname);
        break;
    case 14:
        fprintf(stderr,"rstat error (%d): ",c);
        fprintf(stderr,"host %s is down or unreachable.\n",hostname);
        break;
    case 15:
        fprintf(stderr,"rstat error (%d): ",c);
        fprintf(stderr,"host %s does not support protocol.\n",hostname);
        break;
    default:
        fprintf(stderr,"rstat error (%d): ",c);
            fprintf(stderr,"unknown error\n");
        break;
    }
    return(c);
}