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 fd_set wait_for, are_ready;
  25 fd_set write_on, can_write;
  26 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