dovecot-2.0: Added signal_term_counter that keeps track of how m...

[dovecot at dovecot.org]

details:   http://hg.dovecot.org/dovecot-2.0/rev/7f364dafc675
changeset: 12117:7f364dafc675
user:      Timo Sirainen <tss at iki.fi>
date:      Tue Sep 14 17:38:08 2010 +0100
description:
Added signal_term_counter that keeps track of how many terminal signals have been received.

diffstat:

 src/lib/lib-signals.c |   8 ++++++++
 src/lib/lib-signals.h |  11 +++++++++++
 2 files changed, 19 insertions(+), 0 deletions(-)

diffs (53 lines):

diff -r 02d78c4a0a51 -r 7f364dafc675 src/lib/lib-signals.c
--- a/src/lib/lib-signals.c	Tue Sep 14 16:43:10 2010 +0100
+++ b/src/lib/lib-signals.c	Tue Sep 14 17:38:08 2010 +0100
@@ -11,6 +11,9 @@
 
 #define MAX_SIGNAL_VALUE 31
 
+#define SIGNAL_IS_TERMINAL(signo) \
+	((signo) == SIGINT || (signo) == SIGQUIT || (signo) == SIGTERM)
+
 #if !defined(SA_SIGINFO) && !defined(SI_NOINFO)
 /* without SA_SIGINFO we don't know what the real code is. we need SI_NOINFO
    to make sure lib_signal_code_to_str() returns "". */
@@ -25,6 +28,8 @@
         struct signal_handler *next;
 };
 
+volatile unsigned int signal_term_counter = 0;
+
 /* Remember that these are accessed inside signal handler which may be called
    even while we're initializing/deinitializing. Try hard to keep everything
    in consistent state. */
@@ -112,6 +117,9 @@
 	if (signo < 0 || signo > MAX_SIGNAL_VALUE)
 		return;
 
+	if (SIGNAL_IS_TERMINAL(signo))
+		signal_term_counter++;
+
 	/* remember that we're inside a signal handler which might have been
 	   called at any time. don't do anything that's unsafe. we might also
 	   get interrupted by another signal while inside this handler. */
diff -r 02d78c4a0a51 -r 7f364dafc675 src/lib/lib-signals.h
--- a/src/lib/lib-signals.h	Tue Sep 14 16:43:10 2010 +0100
+++ b/src/lib/lib-signals.h	Tue Sep 14 17:38:08 2010 +0100
@@ -5,6 +5,17 @@
 
 typedef void signal_handler_t(const siginfo_t *si, void *context);
 
+/* Number of times a "termination signal" has been received.
+   These signals are SIGINT, SIGQUIT and SIGTERM. Callers can compare this to
+   their saved previous value to see if a syscall returning EINTR should be
+   treated as someone wanting to end the process or just some internal signal
+   that should be ignored, such as SIGCHLD.
+
+   This is marked as volatile so that compiler won't optimize away its
+   comparisons. It may not work perfectly everywhere, such as when accessing it
+   isn't atomic, so you shouldn't heavily rely on its actual value. */
+extern volatile unsigned int signal_term_counter;
+
 /* Convert si_code to string */
 const char *lib_signal_code_to_str(int signo, int sicode);