Example program: failure.c

/* 
    Failure notification example
    Demonstrates how to tell when a task exits
*/

/* defines and prototypes for the PVM library */
#include <pvm3.h>

/* Maximum number of children this program will spawn */
#define MAXNCHILD   20
/* Tag to use for the task done message */
#define TASKDIED        11

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

    /* number of tasks to spawn, use 3 as the default */
    int ntask = 3;
    /* return code from pvm calls */
    int info;
    /* my task id */
    int mytid;
    /* my parents task id */
    int myparent;
    /* children task id array */
    int child[MAXNCHILD];
    int i, deadtid;
    int tid;
    char *argv[5];

    /* find out my task id number */
    mytid = pvm_mytid();

    /* check for error */
    if (mytid < 0) { 
        /* print out the error */
        pvm_perror(argv[0]); 
        /* exit the program */ 
        return -1;
        }
    /* find my parent's task id number */
    myparent = pvm_parent();

    /* exit if there is some error other than PvmNoParent */
    if ((myparent < 0) && (myparent != PvmNoParent)) {
        pvm_perror(argv[0]);
        pvm_exit();
        return -1;
        }

    /* if i don't have a parent then i am the parent */
    if (myparent == PvmNoParent) {
        /* find out how many tasks to spawn */
        if (argc == 2) ntask = atoi(argv[1]);
        /* make sure ntask is legal */
        if ((ntask < 1) || (ntask > MAXNCHILD)) { pvm_exit(); return 0; }

        /* spawn the child tasks */
        info = pvm_spawn(argv[0], (char**)0, PvmTaskDebug, (char*)0,
            ntask, child);

        /* make sure spawn succeeded */
        if (info != ntask) { pvm_exit(); return -1; }

        /* print the tids */
        for (i = 0; i < ntask; i++) printf("t%x\t",child[i]); putchar('\n');

        /* ask for notification when child exits */
        info = pvm_notify(PvmTaskExit, TASKDIED, ntask, child);
        if (info < 0) { pvm_perror("notify"); pvm_exit(); return -1; }

        /* reap the middle child */
        info = pvm_kill(child[ntask/2]);
        if (info < 0) { pvm_perror("kill"); pvm_exit(); return -1; }

        /* wait for the notification */
        info = pvm_recv(-1, TASKDIED);
        if (info < 0) { pvm_perror("recv"); pvm_exit(); return -1; }
        info = pvm_upkint(&deadtid, 1, 1);
        if (info < 0) pvm_perror("calling pvm_upkint");

        /* should be the middle child */
        printf("Task t%x has exited.\n", deadtid);
        printf("Task t%x is middle child.\n", child[ntask/2]);
        pvm_exit();
        return 0;
        }

    /* i'm a child */
    sleep(63);
    pvm_exit();
    return 0;
}