From: Ian Jackson <ian@liberator.relativity.greenend.org.uk>
Date: Sat, 1 May 2010 01:32:54 +0000 (+0100)
Subject: signal handling
X-Git-Tag: innduct-0.1~83
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=innduct.git;a=commitdiff_plain;h=f3a845d82cf46aed625bced7f0551ac436b50241

signal handling
---

diff --git a/backends/innduct.c b/backends/innduct.c
index c518fd0..b02e9d1 100644
--- a/backends/innduct.c
+++ b/backends/innduct.c
@@ -1,11 +1,11 @@
 /*
  * todo
- *  - inotify not working ?
  *  - some per-conn info thing for control
  *  - manpage: document control master stuff
+ *  - admin-initiated flush
  *
  * debugging rune:
- *      build-lfs/backends/innduct --no-daemon -f `pwd`/fee sit dom
+ *  build-lfs/backends/innduct --no-daemon -C ../inn.conf -f `pwd`/fee sit localhost
  */
 
 /*
@@ -303,6 +303,8 @@ static void period(void);
 static void open_defer(void);
 static void close_defer(void);
 static void search_backlog_file(void);
+static void preterminate(void);
+static void defraise(int signo);
 
 static void inputfile_reading_start(InputFile *ipf);
 static void inputfile_reading_stop(InputFile *ipf);
@@ -490,7 +492,7 @@ static int sm_period_counter;
 /* initialisation to 0 is good */
 static int until_connect, until_backlog_nextscan;
 static double accept_proportion;
-static int nocheck, nocheck_reported;
+static int nocheck, nocheck_reported, in_child;
 
 /* for simulation, debugging, etc. */
 int simulate_flush= -1;
@@ -530,6 +532,7 @@ static void logv(int sysloglevel, const char *pfx, int errnoval,
 #define diewrap(fn, pfx, sysloglevel, err, estatus)		\
   static void fn(const char *fmt, ...) NORET_PRINTF(1,2);	\
   static void fn(const char *fmt, ...) {			\
+    preterminate();						\
     VA;								\
     logv(sysloglevel, pfx, err, fmt, al);			\
     exit(estatus);						\
@@ -654,6 +657,11 @@ static time_t xtime(void) {
   return now;
 }
 
+static void xsigaction(int s, const struct sigaction *sa) {
+  int r= sigaction(s,sa,0);
+  if (r) sysdie("sigaction failed for \"%s\"", strsignal(s));
+}
+
 static void xgettimeofday(struct timeval *tv_r) {
   int r= gettimeofday(tv_r,0);
   if (r) sysdie("gettimeofday(2) failed");
@@ -789,10 +797,17 @@ CCMD(setintarg) { *(int*)c->xdata= atoi(arg); }
 CCMD(setint) { *(int*)c->xdata= c->xval; }
 CCMD(setint_period) { *(int*)c->xdata= c->xval; period(); }
 
+CCMD(stop) {
+  preterminate();
+  notice("terminating (CTRL%d)",cc->fd);
+  defraise(SIGTERM);
+  abort();
+}
+
 static const ControlCommand control_commands[]= {
   { "h",             ccmd_help },
   { "p",             ccmd_period },
-  { "pretend flush", ccmd_setintarg, &simulate_flush             },
+  { "stop",          ccmd_stop },
 
 #define POKES(cmd,func)							\
   { cmd "sm",        func,           &sm_period_counter,       1 },	\
@@ -801,6 +816,7 @@ static const ControlCommand control_commands[]= {
 POKES("prod ", ccmd_setint_period)
 POKES("next ", ccmd_setint)
 
+  { "pretend flush", ccmd_setintarg, &simulate_flush             },
   { "wedge blscan",  ccmd_setint,    &until_backlog_nextscan, -1 },
   { 0 }
 };
@@ -2414,20 +2430,26 @@ static int inputfile_is_done(InputFile *ipf) {
   return 1;
 }
 
-static void notice_processed(InputFile *ipf, const char *what,
-			     const char *spec) {
+static void notice_processed(InputFile *ipf, int completed,
+			     const char *what, const char *spec) {
+  if (!ipf) return; /* allows preterminate to be lazy */
+
 #define RCI_NOTHING(x) /* nothing */
 #define RCI_TRIPLE_FMT(x) " " #x "=" RCI_TRIPLE_FMT_BASE
 #define RCI_TRIPLE_VALS(x) , RCI_TRIPLE_VALS_BASE(ipf->counts, [RC_##x])
 
 #define CNT(art,rc) (ipf->counts[art_##art][RC_##rc])
 
-  info("processed %s%s read=%d (+bl=%d,+err=%d)"
+  char *inprog= completed
+    ? xasprintf("%s","") /* GCC produces a stupid warning for printf("") ! */
+    : xasprintf(" inprogress=%ld", ipf->inprogress);
+
+  info("%s %s%s read=%d (+bl=%d,+err=%d)%s"
        " offered=%d (ch=%d,nc=%d) accepted=%d (ch=%d,nc=%d)"
        RESULT_COUNTS(RCI_NOTHING, RCI_TRIPLE_FMT)
        ,
-       what, spec,
-       ipf->readcount_ok, ipf->readcount_blank, ipf->readcount_err,
+       completed?"completed":"processed", what, spec,
+       ipf->readcount_ok, ipf->readcount_blank, ipf->readcount_err, inprog,
        CNT(Unchecked,sent) + CNT(Unsolicited,sent)
        , CNT(Unchecked,sent), CNT(Unsolicited,sent),
        CNT(Wanted,accepted) + CNT(Unsolicited,accepted)
@@ -2435,6 +2457,8 @@ static void notice_processed(InputFile *ipf, const char *what,
        RESULT_COUNTS(RCI_NOTHING,  RCI_TRIPLE_VALS)
        );
 
+  free(inprog);
+
 #undef CNT
 }
 
@@ -2447,7 +2471,7 @@ static void statemc_check_backlog_done(void) {
   const char *under= strchr(slash, '_');
   const char *rest= under ? under+1 : leaf;
   if (!strncmp(rest,"backlog",7)) rest += 7;
-  notice_processed(ipf,"backlog ",rest);
+  notice_processed(ipf,1,"backlog ",rest);
 
   close_input_file(ipf);
   if (unlink(ipf->path)) {
@@ -2469,7 +2493,7 @@ static void statemc_check_flushing_done(void) {
 
   assert(sms==sm_SEPARATED || sms==sm_DROPPING);
 
-  notice_processed(ipf,"feedfile","");
+  notice_processed(ipf,1,"feedfile","");
 
   close_defer();
 
@@ -2670,6 +2694,7 @@ static void search_backlog_file(void) {
     debug("backlog scan: none");
 
     if (sms==sm_DROPPED) {
+      preterminate();
       notice("feed dropped and our work is complete");
 
       int r= unlink(path_control);
@@ -2716,6 +2741,74 @@ static void search_backlog_file(void) {
   return;
 }
 
+/*---------- shutdown and signal handling ----------*/
+
+static void preterminate(void) {
+  if (in_child) return;
+  notice_processed(main_input_file,0,"feedfile","");
+  notice_processed(flushing_input_file,0,"flushing file","");
+  if (backlog_input_file)
+    notice_processed(backlog_input_file,0, "backlog file ",
+		     backlog_input_file->path);
+}
+
+static int signal_self_pipe[2];
+static sig_atomic_t terminate_sig_flag;
+
+static void defraise(int signo) {
+  struct sigaction sa;
+  memset(&sa,0,sizeof(sa));
+  sa.sa_handler= SIG_DFL;
+  xsigaction(signo,&sa);
+  raise(signo);
+}
+
+static void *sigarrived_event(oop_source *lp, int fd, oop_event e, void *u) {
+  assert(fd=signal_self_pipe[0]);
+  char buf[PIPE_BUF];
+  int r= read(signal_self_pipe[0], buf, sizeof(buf));
+  if (r<0 && !isewouldblock(errno)) sysdie("failed to read signal self pipe");
+  if (r==0) die("eof on signal self pipe");
+  if (terminate_sig_flag) {
+    preterminate();
+    notice("terminating (%s)", strsignal(terminate_sig_flag));
+    defraise(terminate_sig_flag);
+    abort();
+  }
+  return OOP_CONTINUE;
+}
+
+static void sigarrived_handler(int signum) {
+  static char x;
+  switch (signum) {
+  case SIGINT: case SIGTERM:
+    if (!terminate_sig_flag) terminate_sig_flag= signum;
+    break;
+  default:
+    abort();
+  }
+  write(signal_self_pipe[1],&x,1);
+}
+
+static void init_signals(void) {
+  if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
+    sysdie("could not ignore SIGPIPE");
+
+  if (pipe(signal_self_pipe)) sysfatal("create self-pipe for signals");
+
+  xsetnonblock(signal_self_pipe[0],1);
+  xsetnonblock(signal_self_pipe[1],1);
+
+  struct sigaction sa;
+  memset(&sa,0,sizeof(sa));
+  sa.sa_handler= sigarrived_handler;
+  sa.sa_flags= SA_RESTART;
+  xsigaction(SIGTERM,&sa);
+  xsigaction(SIGINT,&sa);
+
+  on_fd_read_except(signal_self_pipe[0], sigarrived_event);
+}
+
 /*========== flushing the feed ==========*/
 
 static pid_t inndcomm_child;
@@ -2858,6 +2951,8 @@ static void postfork_stdio(FILE *f, const char *what, const char *what2) {
 }
 
 static void postfork(void) {
+  in_child= 1;
+
   if (signal(SIGPIPE, SIG_DFL) == SIG_ERR)
     sysdie("(in child) failed to reset SIGPIPE");
 
@@ -3240,9 +3335,6 @@ int main(int argc, char **argv) {
   if (!sysloop) sysdie("could not create liboop event loop");
   loop= (oop_source*)sysloop;
 
-  if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
-    sysdie("could not ignore SIGPIPE");
-
   LIST_INIT(conns);
   LIST_INIT(queue);
 
@@ -3275,6 +3367,8 @@ int main(int argc, char **argv) {
 
   statemc_lock();
 
+  init_signals();
+
   notice("starting");
 
   if (!become_daemon)
diff --git a/doc/man/innduct.8 b/doc/man/innduct.8
index 83aeade..c3beb92 100644
--- a/doc/man/innduct.8
+++ b/doc/man/innduct.8
@@ -307,13 +307,10 @@ articles it has in hand now, and then exit.  It is harmless to cause
 innd to flush the feed (but innduct won't notice and flushing won't
 start a new feedfile; you have to leave that to innduct).
 .LP
-There are no signals that can usefully be sent to innduct to give it
-complicated instructions.  If you need to kill innduct, feel free to
-send it a
-.B SIGTERM
-or
-.B SIGKILL
-and nothing will be broken or corrupted.
+If you want to stop innduct you can send it SIGTERM or SIGINT, in
+which case it will report statistics so far and quickly exit.
+If innduct receives SIGKILL nothing will be broken or corrupted; you
+just won't see some of the article stats.
 .SH EXIT STATUS
 .TP
 .B 0