dim_fork.cxx

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#include <cerrno>
#include <cstdio>
#include <unistd.h>
#include <sys/wait.h>
extern "C" {
#include "dis.hxx"
}

static int id, id_cmd, run = 0;
static int doForkNow = 0;

void handle_cmd(void *tag, void *data, int *size)
{
  doForkNow = 1;
}

static pid_t fork_em() {
  //  ::dis_remove_service(id);
  ::dis_stop_serving();
  ::printf("Sleep a bit to see task disappear in did\n");
  //::sleep(3);
  pid_t pid = ::fork();
  if ( pid == 0 ) {
    ::dim_init();
    ::printf("PID:%d Register Child service Child/run to DNS....\n",::getpid());
    id = ::dis_add_service((char*)"Child/run",(char*)"I",&run,sizeof(run),0,0);
    ::dis_start_serving((char*)"Child");
  }
  else if ( pid > 0 ) {
    ::dim_init();
    //::sleep(3);
    ::printf("PID:%d RE-Register Parent to DNS....\n",::getpid());
    id = ::dis_add_service((char*)"Parent/run",(char*)"I",&run,sizeof(run),0,0);
    //    id_cmd = :: dis_add_cmnd((char *)"Parent/cmd",(char*)"C",handle_cmd,0);
    ::dis_start_serving((char*)"Parent");
  }      
  else {
    ::printf("ERROR in fork!!!!  %s\n",strerror(errno));
    ::exit(0);
  }
  return pid;
}

int main(int /* argc */, char** /* argv */) {
  id = ::dis_add_service((char*)"Parent/run",(char*)"I",&run,sizeof(run),0,0);
  //  id_cmd = :: dis_add_cmnd((char *)"Parent/cmd",(char*)"C",handle_cmd,0);
  ::dis_start_serving((char*)"Parent");
  ::sleep(5);
  pid_t child = 0;

 Again:
  child = fork_em();
  if ( child > 0 ) {
    int status;
    sleep(5);
    kill(child,SIGTERM);
    wait(&status);
    sleep(1);
    goto Again;
  }
 
  while(1)
  {
    /*
    if(doForkNow)
    {
      int status;
      doForkNow = 0;
      if(child > 0)
      {
        kill(child,SIGTERM);
        wait(&status);
        sleep(1);
      }
      child = fork_em();
    }
    */
    ::sleep(1);
  }
  return 1;
}


/*

g++ -o dim_fork -I../../DIM/dim -ldim -lrt -pthread ../test/dim_fork.cpp

[frankm@plus04 cmt]$ ./dim_fork
PID:20407 Register Child to DNS....
PID 20407 - Fri Dec  3 22:01:57 2010 - (FATAL) Child: Some Services already known to DNS
PID:20404 RE-Register Parent to DNS....

*/