minix/servers/ds/main.c
Ben Gras 3512a86b44 . DS understands publishing and subscribing where keys are in string
form. Subscriptions are regular expressions.
 . different types are stored per key; currently u32 and/or string.
   the same key can be referenced (publish, subscribe, check) as any type.
 . notify()s are sent when subscriptions are triggered (publishing or
   updating of matching keys); optionally, a subscribe flag sends
   updates for all matching keys at subscription time, instead of only
   after updates after subscribing
 . all interfacing to ds is in /usr/src/lib/syslib/ds.c.
 . subscribe is ds_subscribe
   publish functions are ds_publish_<type>
   retrieve functions are ds_retrieve_<type> (one-time retrieval of a value)
   check functions are ds_check_<type> (check for updated key caller
      subscribes to not yet checked for, or ESRCH for none)
 . ramdisk driver updated with new ds interface
2006-07-13 14:50:23 +00:00

157 lines
4.9 KiB
C

/* Data Store Server.
* This service implements a little publish/subscribe data store that is
* crucial for the system's fault tolerance. Components that require state
* can store it here, for later retrieval, e.g., after a crash and subsequent
* restart by the reincarnation server.
*
* Created:
* Oct 19, 2005 by Jorrit N. Herder
*/
#include "inc.h" /* include master header file */
/* Allocate space for the global variables. */
int who_e; /* caller's proc number */
int callnr; /* system call number */
int sys_panic; /* flag to indicate system-wide panic */
extern int errno; /* error number set by system library */
/* Declare some local functions. */
FORWARD _PROTOTYPE(void init_server, (int argc, char **argv) );
FORWARD _PROTOTYPE(void exit_server, (void) );
FORWARD _PROTOTYPE(void sig_handler, (void) );
FORWARD _PROTOTYPE(void get_work, (message *m_ptr) );
FORWARD _PROTOTYPE(void reply, (int whom, message *m_ptr) );
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC int main(int argc, char **argv)
{
/* This is the main routine of this service. The main loop consists of
* three major activities: getting new work, processing the work, and
* sending the reply. The loop never terminates, unless a panic occurs.
*/
message m;
int result;
sigset_t sigset;
/* Initialize the server, then go to work. */
init_server(argc, argv);
/* Main loop - get work and do it, forever. */
while (TRUE) {
/* Wait for incoming message, sets 'callnr' and 'who'. */
get_work(&m);
switch (callnr) {
case PROC_EVENT:
sig_handler();
continue;
case DS_PUBLISH:
result = do_publish(&m);
break;
case DS_RETRIEVE:
result = do_retrieve(&m);
break;
case DS_SUBSCRIBE:
result = do_subscribe(&m);
break;
case DS_CHECK:
result = do_check(&m);
break;
case GETSYSINFO:
result = do_getsysinfo(&m);
break;
default:
report("DS","warning, got illegal request from:", m.m_source);
result = EINVAL;
}
/* Finally send reply message, unless disabled. */
if (result != EDONTREPLY) {
m.m_type = result; /* build reply message */
reply(who_e, &m); /* send it away */
}
}
return(OK); /* shouldn't come here */
}
/*===========================================================================*
* init_server *
*===========================================================================*/
PRIVATE void init_server(int argc, char **argv)
{
/* Initialize the data store server. */
int i, s;
struct sigaction sigact;
/* Install signal handler. Ask PM to transform signal into message. */
sigact.sa_handler = SIG_MESS;
sigact.sa_mask = ~0; /* block all other signals */
sigact.sa_flags = 0; /* default behaviour */
if (sigaction(SIGTERM, &sigact, NULL) < 0)
report("DS","warning, sigaction() failed", errno);
/* Initialize DS. */
ds_init();
}
/*===========================================================================*
* sig_handler *
*===========================================================================*/
PRIVATE void sig_handler()
{
/* Signal handler. */
sigset_t sigset;
int sig;
/* Try to obtain signal set from PM. */
if (getsigset(&sigset) != 0) return;
/* Check for known signals. */
if (sigismember(&sigset, SIGTERM)) {
exit_server();
}
}
/*===========================================================================*
* exit_server *
*===========================================================================*/
PRIVATE void exit_server()
{
/* Shut down the information service. */
/* Done. Now exit. */
exit(0);
}
/*===========================================================================*
* get_work *
*===========================================================================*/
PRIVATE void get_work(m_ptr)
message *m_ptr; /* message buffer */
{
int status = 0;
status = receive(ANY, m_ptr); /* this blocks until message arrives */
if (OK != status)
panic("DS","failed to receive message!", status);
who_e = m_ptr->m_source; /* message arrived! set sender */
callnr = m_ptr->m_type; /* set function call number */
}
/*===========================================================================*
* reply *
*===========================================================================*/
PRIVATE void reply(who_e, m_ptr)
int who_e; /* destination */
message *m_ptr; /* message buffer */
{
int s;
s = send(who_e, m_ptr); /* send the message */
if (OK != s)
panic("DS", "unable to send reply!", s);
}