Attachment 13362 Details for Bug 25951 – Demonstator source file using seperate reaper/coordinator

Demonstator source file using seperate reaper/coordinator

pipes.c (text/x-csrc), 2.79 KB, created by Tom de Vries on 2021-04-12 08:22:20 UTC

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Filename:

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Creator: Tom de Vries

Created: 2021-04-12 08:22:20 UTC

Size: 2.79 KB

patch

obsolete

>#include <unistd.h>
>#include <assert.h>
>#include <stdlib.h>
>#include <stdio.h>
>#include <sys/types.h>
>#include <sys/wait.h>
>
>#define N 5
>
>#define READ_FD 0
>#define WRITE_FD 1
>#define FDS_PER_PIPE 2
>
>#define PARENT_TO_CHILD 0
>#define CHILD_TO_PARENT 1
>#define PIPES_PER_CHILD 2
>
>int pipes[N][PIPES_PER_CHILD][FDS_PER_PIPE];
>
>/* Get token.  */
>static char
>get_token (int n, int m, const char *msg)
>{
>  int readfd = pipes[n][m][READ_FD];
>  int writefd = pipes[n][m][WRITE_FD];
>  //close (writefd);
>  char buf;
>  fprintf (stderr, "%s: READING TOKEN for child %d direction %s\n", msg, n,
>	   m == PARENT_TO_CHILD ? "P2C" : "C2P");
>  read (readfd, &buf, 1);
>  fprintf (stderr, "%s: READ TOKEN for child %d direction %s: '%c'\n", msg, n,
>	   m == PARENT_TO_CHILD ? "P2C" : "C2P", buf);
>  //close (readfd);
>  return buf;
>}
>
>/* Pass token to child N.  */
>static void
>pass_token (int n, int m, char buf, char *msg)
>{
>  int readfd = pipes[n][m][READ_FD];
>  int writefd = pipes[n][m][WRITE_FD];
>  //close (readfd);
>  fprintf (stderr, "%s: WRITING TOKEN for child %d direction %s: '%c'\n", msg, n,
>	   m == PARENT_TO_CHILD ? "P2C" : "C2P", buf);
>  write (writefd, &buf, 1);
>  fprintf (stderr, "%s: WROTE TOKEN for child %d direction %s\n", msg, n,
>	   m == PARENT_TO_CHILD ? "P2C" : "C2P");
>  //close (writefd);
>}
>
>
>int
>main (void)
>{
>
>  int i;
>  pid_t pids[N];
>
>  for (i = 0; i < N; i++)
>    {
>      int j;
>      for (j = 0; j < PIPES_PER_CHILD; ++j)
>	{
>	  int fds[FDS_PER_PIPE];
>	  if (pipe (fds) != 0)
>	    abort ();
>	  pipes[i][j][READ_FD] = fds[READ_FD];
>	  pipes[i][j][WRITE_FD] = fds[WRITE_FD];
>	}
>    }
>
>  for (i = 0; i < N; ++i)
>    {
>      pid_t fork_res = fork ();
>      assert (fork_res != -1);
>      if (fork_res == 0)
>	{
>	  int child_id = i;
>	  sleep (1);
>
>	  /* Let's have one of the children not pass a token.  */
>	  if (child_id == 3)
>	    return 0;
>
>	  pass_token (child_id, CHILD_TO_PARENT, '0', "Child");
>	  char c = get_token (child_id, PARENT_TO_CHILD, "Child");
>	  assert (c == '1');
>	  return 0;
>	}
>      else
>	{
>	  pids[i] = fork_res;
>	}
>    }
>
>  pid_t coordinator_pid = 0;
>  pid_t fork_res = fork ();
>  assert (fork_res != -1);
>  if (fork_res == 0)
>    {
>      /* Coordinator.  */
>      for (i = 0; i < N; ++i)
>	{
>	  int state;
>	  char c = get_token (i, CHILD_TO_PARENT, "Coordinator");
>	  if (c == '0')
>	    {
>	      pass_token (i, PARENT_TO_CHILD, '1', "Coordinator");
>	    }
>	  else if (c == '2')
>	    {
>	      /* Child terminated.  */
>	    }
>	  else
>	    abort ();
>	}
>
>      return 0;
>    }
>  else
>    {
>      coordinator_pid = fork_res;      
>    }
>
>  for (i = 0; i < N; ++i)
>    {
>      int state;
>      waitpid (pids[i], &state, 0);
>      fprintf (stderr, "Parent: CHILD TERMINATED: %d\n", i);
>      pass_token (i, CHILD_TO_PARENT, '2', "Parent");
>    }
>
>  {
>    int state;
>    waitpid (coordinator_pid, &state, 0);
>  }
>
>  return 0;
>}

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Attachments on bug 25951: 13297 | 13362