minix/servers/is/main.c
Cristiano Giuffrida 1f5841c8ed Basic System Event Framework (SEF) with ping and live update.
SYSLIB CHANGES:
- SEF must be used by every system process and is thereby part of the system
library.
- The framework provides a receive() interface (sef_receive) for system
processes to automatically catch known system even messages and process them.
- SEF provides a default behavior for each type of system event, but allows
system processes to register callbacks to override the default behavior.
- Custom (local to the process) or predefined (provided by SEF) callback
implementations can be registered to SEF.
- SEF currently includes support for 2 types of system events:
  1. SEF Ping. The event occurs every time RS sends a ping to figure out
  whether a system process is still alive. The default callback implementation
  provided by SEF is to notify RS back to let it know the process is alive
  and kicking.
  2. SEF Live update. The event occurs every time RS sends a prepare to update
  message to let a system process know an update is available and to prepare
  for it. The live update support is very basic for now. SEF only deals with
  verifying if the prepare state can be supported by the process, dumping the
  state for debugging purposes, and providing an event-driven programming
  model to the process to react to state changes check-in when ready to update.
- SEF should be extended in the future to integrate support for more types of
system events. Ideally, all the cross-cutting concerns should be integrated into
SEF to avoid duplicating code and ease extensibility. Examples include:
  * PM notify messages primarily used at shutdown.
  * SYSTEM notify messages primarily used for signals.
  * CLOCK notify messages used for system alarms.
  * Debug messages. IS could still be in charge of fkey handling but would
  forward the debug message to the target process (e.g. PM, if the user
  requested debug information about PM). SEF would then catch the message and
  do nothing unless the process has registered an appropriate callback to
  deal with the event. This simplifies the programming model to print debug
  information, avoids duplicating code, and reduces the effort to print
  debug information.

SYSTEM PROCESSES CHANGES:
- Every system process registers SEF callbacks it needs to override the default
system behavior and calls sef_startup() right after being started.
- sef_startup() does almost nothing now, but will be extended in the future to
support callbacks of its own to let RS control and synchronize with every
system process at initialization time.
- Every system process calls sef_receive() now rather than receive() directly,
to let SEF handle predefined system events.

RS CHANGES:
- RS supports a basic single-component live update protocol now, as follows:
  * When an update command is issued (via "service update *"), RS notifies the
  target system process to prepare for a specific update state.
  * If the process doesn't respond back in time, the update is aborted.
  * When the process responds back, RS kills it and marks it for refreshing.
  * The process is then automatically restarted as for a buggy process and can
  start running again.
  * Live update is currently prototyped as a controlled failure.
2009-12-21 14:12:21 +00:00

163 lines
5.3 KiB
C

/* System Information Service.
* This service handles the various debugging dumps, such as the process
* table, so that these no longer directly touch kernel memory. Instead, the
* system task is asked to copy some table in local memory.
*
* Created:
* Apr 29, 2004 by Jorrit N. Herder
*/
#include "inc.h"
#include <minix/endpoint.h>
/* Allocate space for the global variables. */
message m_in; /* the input message itself */
message m_out; /* the output message used for reply */
int who_e; /* caller's proc number */
int callnr; /* system call number */
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 sig_handler, (void) );
FORWARD _PROTOTYPE(void get_work, (void) );
FORWARD _PROTOTYPE(void reply, (int whom, int result) );
/* SEF functions and variables. */
FORWARD _PROTOTYPE( void sef_local_startup, (void) );
/*===========================================================================*
* 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.
*/
int result;
sigset_t sigset;
/* SEF local startup. */
sef_local_startup();
/* 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();
if (is_notify(callnr)) {
switch (_ENDPOINT_P(who_e)) {
case SYSTEM:
printf("got message from SYSTEM\n");
sigset = m_in.NOTIFY_ARG;
for ( result=0; result< _NSIG; result++) {
if (sigismember(&sigset, result))
printf("signal %d found\n", result);
}
continue;
case PM_PROC_NR:
sig_handler();
continue;
case TTY_PROC_NR:
result = do_fkey_pressed(&m_in);
break;
}
}
else {
printf("IS: warning, got illegal request %d from %d\n",
callnr, m_in.m_source);
result = EDONTREPLY;
}
/* Finally send reply message, unless disabled. */
if (result != EDONTREPLY) {
reply(who_e, result);
}
}
return(OK); /* shouldn't come here */
}
/*===========================================================================*
* sef_local_startup *
*===========================================================================*/
PRIVATE void sef_local_startup()
{
/* Register live update callbacks. */
sef_setcb_lu_prepare(sef_cb_lu_prepare_always_ready);
sef_setcb_lu_state_isvalid(sef_cb_lu_state_isvalid_standard);
/* Let SEF perform startup. */
sef_startup();
}
/*===========================================================================*
* init_server *
*===========================================================================*/
PRIVATE void init_server(int argc, char **argv)
{
/* Initialize the information service. */
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("IS","warning, sigaction() failed", errno);
/* Set key mappings. */
map_unmap_fkeys(TRUE /*map*/);
}
/*===========================================================================*
* sig_handler *
*===========================================================================*/
PRIVATE void sig_handler()
{
sigset_t sigset;
/* Try to obtain signal set from PM. */
if (getsigset(&sigset) != 0) return;
/* Only check for termination signal. */
if (!sigismember(&sigset, SIGTERM)) return;
/* Shutting down. Unset key mappings, and quit. */
map_unmap_fkeys(FALSE /*map*/);
exit(0);
}
/*===========================================================================*
* get_work *
*===========================================================================*/
PRIVATE void get_work()
{
int status = 0;
status = sef_receive(ANY, &m_in); /* this blocks until message arrives */
if (OK != status)
panic("IS","sef_receive failed!", status);
who_e = m_in.m_source; /* message arrived! set sender */
callnr = m_in.m_type; /* set function call number */
}
/*===========================================================================*
* reply *
*===========================================================================*/
PRIVATE void reply(who, result)
int who; /* destination */
int result; /* report result to replyee */
{
int send_status;
m_out.m_type = result; /* build reply message */
send_status = send(who, &m_out); /* send the message */
if (OK != send_status)
panic("IS", "unable to send reply!", send_status);
}