mainloop.c

   1
   2
   3 #include        "metad.h"
   4 #include        <signal.h>
   5 #include        "skip.h"
   6 #include        <sys/time.h>
   7
   8 /*
   9  * main loop of metad
  10  * wait for read-select on some sockets, or for time to pass
  11  * or for a process to exit.
  12  * when one of these happens, we check with each service to see
  13  * if it wants to do something.
  14  *
  15  * services ask to do something with
  16  *  listenon(socket)
  17  *  waituntil(time)
  18  * and can check is a socket is read with
  19  *  readyon(socket)
  20  *
  21  */
  22
  23
  24 static fd_set wait_for, are_ready;
  25 static fd_set write_on, can_write;
  26 static time_t when_wake;
  27
  28 void listenon(int socket)
  29 {
  30         FD_SET(socket, &wait_for);
  31 }
  32
  33 int readyon(int socket)
  34 {
  35         return FD_ISSET(socket, &are_ready);
  36 }
  37
  38 void writeon(int socket)
  39 {
  40         FD_SET(socket, &write_on);
  41 }
  42
  43
  44
  45 int canwrite(int socket)
  46 {
  47         return FD_ISSET(socket, &can_write);
  48 }
  49
  50 void waituntil(time_t when)
  51 {
  52         if (when_wake == 0 || when_wake > when) when_wake = when;
  53 }
  54
  55 static struct
  56 {
  57         pid_t pid;
  58         int status;
  59         time_t time;
  60 } saved_pids[20] = { { 0 } };
  61
  62 static struct timeval select_tv;
  63 static void collectchild()
  64 {
  65         pid_t pid;
  66         int status;
  67
  68         if ((pid = waitpid(-1, &status, WNOHANG)) > 0)
  69         {
  70                 int i;
  71                 for (i=0; i<20 ; i++)
  72                         if (saved_pids[i].pid == 0)
  73                         {
  74                                 saved_pids[i].pid = pid;
  75                                 saved_pids[i].status = status;
  76                                 time(&saved_pids[i].time);
  77                                 break;
  78                         }
  79         }
  80         select_tv.tv_usec = 0;
  81         select_tv.tv_sec = 0;
  82 }
  83
  84 int is_saved_pid(pid_t pid)
  85 {
  86         int i;
  87         for (i=0; i<20; i++)
  88                 if (saved_pids[i].pid == pid)
  89                         return 1;
  90         return 0;
  91 }
  92
  93 void main_loop()
  94 {
  95         struct sigaction sa;
  96         sigset_t ss;
  97         sa.sa_handler = collectchild;
  98         sa.sa_flags = 0;
  99         sigemptyset(&ss);
 100         sigaddset(&ss, SIGCLD);
 101         sa.sa_mask = ss;
 102         sigaction(SIGCLD, &sa, NULL);
 103
 104         FD_ZERO(&are_ready);
 105         FD_ZERO(&can_write);
 106         while (1)
 107         {
 108                 service_t *svp;
 109                 int i;
 110                 FD_ZERO(&wait_for);
 111                 FD_ZERO(&write_on);
 112                 when_wake = time(0)+5*60; /* always wakeup every 5minutes to look around... */
 113                 collectchild(); /* incase signal was missed */
 114
 115                 for (i=0 ; i<20 ; i++)
 116                         if (saved_pids[i].pid)
 117                         {
 118                                 proc_t *pp;
 119                                 pp = skip_search(allprocs, &saved_pids[i].pid);
 120                                 if (pp)
 121                                 {
 122                                         (*pp)->status = saved_pids[i].status;
 123                                         (*pp)->exit_time = saved_pids[i].time;;
 124                                         select_tv.tv_sec = 0;
 125                                         logmsg(LOG_INFO, "process %d (%s) exited - status 0x%04x", saved_pids[i].pid, (*pp)->service->service, (*pp)->status);
 126                                 } else
 127                                         logmsg(LOG_INFO, "process %d exited - status 0x%04x", saved_pids[i].pid, saved_pids[i].status);
 128                                 saved_pids[i].pid = 0;
 129
 130                         }
 131
 132                 for (svp = skip_first(services) ; svp ; svp = skip_next(svp))
 133                         check_service(*svp);
 134                 check_control();
 135                 are_ready = wait_for;
 136                 can_write = write_on;
 137
 138                 if (when_wake)
 139                 {
 140                         time_t now;
 141                         time(&now);
 142                         select_tv.tv_sec = when_wake - now;
 143                         select_tv.tv_usec = 0;
 144                         if (when_wake < now) select_tv.tv_sec = 0;
 145                 }
 146                 else
 147                 {
 148                         select_tv.tv_sec = 100000;
 149                         select_tv.tv_usec = 0;
 150                 }
 151                 if (select(FD_SETSIZE, &are_ready, &can_write, NULL, &select_tv) <= 0)
 152                 {
 153                         FD_ZERO(&are_ready);
 154                         FD_ZERO(&can_write);
 155                 }
 156         }
 157 }
 158