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