main.c

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    1 /* Data Store Server. 
    2  * This service implements a little publish/subscribe data store that is 
    3  * crucial for the system's fault tolerance. Components that require state
    4  * can store it here, for later retrieval, e.g., after a crash and subsequent
    5  * restart by the reincarnation server. 
    6  * 
    7  * Created:
    8  *   Oct 19, 2005       by Jorrit N. Herder
    9  */
   10 
   11 #include "inc.h"        /* include master header file */
   12 
   13 /* Allocate space for the global variables. */
   14 int who;                /* caller's proc number */
   15 int callnr;             /* system call number */
   16 int sys_panic;          /* flag to indicate system-wide panic */
   17 
   18 extern int errno;       /* error number set by system library */
   19 
   20 /* Declare some local functions. */
   21 FORWARD _PROTOTYPE(void init_server, (int argc, char **argv)            );
   22 FORWARD _PROTOTYPE(void exit_server, (void)                             );
   23 FORWARD _PROTOTYPE(void get_work, (message *m_ptr)                      );
   24 FORWARD _PROTOTYPE(void reply, (int whom, message *m_ptr)               );
   25 
   26 /*===========================================================================*
   27  *                              main                                         *
   28  *===========================================================================*/
   29 PUBLIC int main(int argc, char **argv)
   30 {
   31 /* This is the main routine of this service. The main loop consists of 
   32  * three major activities: getting new work, processing the work, and
   33  * sending the reply. The loop never terminates, unless a panic occurs.
   34  */
   35   message m;
   36   int result;                 
   37   sigset_t sigset;
   38 
   39   /* Initialize the server, then go to work. */
   40   init_server(argc, argv);
   41 
   42   /* Main loop - get work and do it, forever. */         
   43   while (TRUE) {              
   44 
   45       /* Wait for incoming message, sets 'callnr' and 'who'. */
   46       get_work(&m);
   47 
   48       switch (callnr) {
   49       case SYS_SIG:
   50           sigset = (sigset_t) m.NOTIFY_ARG;
   51           if (sigismember(&sigset,SIGTERM) || sigismember(&sigset,SIGKSTOP)) {
   52               exit_server();
   53           }
   54           continue;
   55       case DS_PUBLISH:
   56           result = do_publish(&m);
   57           break;
   58       case DS_RETRIEVE:
   59           result = do_retrieve(&m);
   60           break;
   61       case DS_SUBSCRIBE:
   62           result = do_subscribe(&m);
   63           break;
   64       case GETSYSINFO:
   65           result = do_getsysinfo(&m);
   66           break;
   67       default: 
   68           report("DS","warning, got illegal request from:", m.m_source);
   69           result = EINVAL;
   70       }
   71 
   72       /* Finally send reply message, unless disabled. */
   73       if (result != EDONTREPLY) {
   74           m.m_type = result;            /* build reply message */
   75           reply(who, &m);               /* send it away */
   76       }
   77   }
   78   return(OK);                           /* shouldn't come here */
   79 }
   80 
   81 /*===========================================================================*
   82  *                               init_server                                 *
   83  *===========================================================================*/
   84 PRIVATE void init_server(int argc, char **argv)
   85 {
   86 /* Initialize the data store server. */
   87   int i, s;
   88   struct sigaction sigact;
   89 
   90   /* Install signal handler. Ask PM to transform signal into message. */
   91   sigact.sa_handler = SIG_MESS;
   92   sigact.sa_mask = ~0;                  /* block all other signals */
   93   sigact.sa_flags = 0;                  /* default behaviour */
   94   if (sigaction(SIGTERM, &sigact, NULL) < 0) 
   95       report("DS","warning, sigaction() failed", errno);
   96 }
   97 
   98 /*===========================================================================*
   99  *                              exit_server                                  *
  100  *===========================================================================*/
  101 PRIVATE void exit_server()
  102 {
  103 /* Shut down the information service. */
  104 
  105   /* Done. Now exit. */
  106   exit(0);
  107 }
  108 
  109 /*===========================================================================*
  110  *                              get_work                                     *
  111  *===========================================================================*/
  112 PRIVATE void get_work(m_ptr)
  113 message *m_ptr;                         /* message buffer */
  114 {
  115     int status = 0;
  116     status = receive(ANY, m_ptr);   /* this blocks until message arrives */
  117     if (OK != status)
  118         panic("DS","failed to receive message!", status);
  119     who = m_ptr->m_source;        /* message arrived! set sender */
  120     callnr = m_ptr->m_type;       /* set function call number */
  121 }
  122 
  123 /*===========================================================================*
  124  *                              reply                                        *
  125  *===========================================================================*/
  126 PRIVATE void reply(who, m_ptr)
  127 int who;                                /* destination */
  128 message *m_ptr;                         /* message buffer */
  129 {
  130     int s;
  131     s = send(who, m_ptr);    /* send the message */
  132     if (OK != s)
  133         panic("DS", "unable to send reply!", s);
  134 }
  135

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FreeBSD/Linux Kernel Cross Reference sys/servers/ds/main.c

FreeBSD/Linux Kernel Cross Reference
sys/servers/ds/main.c