svn commit: samba r20938 - in branches/SAMBA_4_0/source/lib/events:
.
tridge at samba.org
tridge at samba.org
Sun Jan 21 21:02:24 GMT 2007
Author: tridge
Date: 2007-01-21 21:02:24 +0000 (Sun, 21 Jan 2007)
New Revision: 20938
WebSVN: http://websvn.samba.org/cgi-bin/viewcvs.cgi?view=rev&root=samba&rev=20938
Log:
use a double counter trick to avoid the need for atomic increment
Modified:
branches/SAMBA_4_0/source/lib/events/events_signal.c
Changeset:
Modified: branches/SAMBA_4_0/source/lib/events/events_signal.c
===================================================================
--- branches/SAMBA_4_0/source/lib/events/events_signal.c 2007-01-21 20:15:06 UTC (rev 20937)
+++ branches/SAMBA_4_0/source/lib/events/events_signal.c 2007-01-21 21:02:24 UTC (rev 20938)
@@ -32,14 +32,24 @@
/* maximum number of SA_SIGINFO signals to hold in the queue */
#define SA_INFO_QUEUE_COUNT 10
+struct sigcounter {
+ uint32_t count;
+ uint32_t seen;
+};
+
+#define SIG_INCREMENT(s) (s).count++
+#define SIG_SEEN(s, n) (s).seen += (n)
+#define SIG_PENDING(s) ((s).seen != (s).count)
+
+
/*
the poor design of signals means that this table must be static global
*/
static struct {
struct signal_event *sig_handlers[NUM_SIGNALS];
struct sigaction oldact[NUM_SIGNALS];
- uint32_t signal_count[NUM_SIGNALS];
- uint32_t got_signal;
+ struct sigcounter signal_count[NUM_SIGNALS];
+ struct sigcounter got_signal;
int pipe_hack[2];
#ifdef SA_SIGINFO
/* with SA_SIGINFO we get quite a lot of info per signal */
@@ -47,6 +57,16 @@
#endif
} sig_state;
+/*
+ return number of sigcounter events not processed yet
+*/
+static uint32_t sig_count(struct sigcounter s)
+{
+ if (s.count >= s.seen) {
+ return s.count - s.seen;
+ }
+ return 1 + (0xFFFFFFFF & ~(s.seen - s.count));
+}
/*
signal handler - redirects to registered signals
@@ -54,8 +74,8 @@
static void signal_handler(int signum)
{
char c = 0;
- sig_state.signal_count[signum]++;
- sig_state.got_signal++;
+ SIG_INCREMENT(sig_state.signal_count[signum]);
+ SIG_INCREMENT(sig_state.got_signal);
/* doesn't matter if this pipe overflows */
write(sig_state.pipe_hack[1], &c, 1);
}
@@ -66,12 +86,13 @@
*/
static void signal_handler_info(int signum, siginfo_t *info, void *uctx)
{
- sig_state.sig_info[signum][sig_state.signal_count[signum]] = *info;
+ uint32_t count = sig_count(sig_state.signal_count[signum]);
+ sig_state.sig_info[signum][count] = *info;
signal_handler(signum);
/* handle SA_SIGINFO */
- if (sig_state.signal_count[signum] == SA_INFO_QUEUE_COUNT) {
+ if (count+1 == SA_INFO_QUEUE_COUNT) {
/* we've filled the info array - block this signal until
these ones are delivered */
sigset_t set;
@@ -180,13 +201,13 @@
int common_event_check_signal(struct event_context *ev)
{
int i;
- if (sig_state.got_signal == 0) {
+ if (!SIG_PENDING(sig_state.got_signal)) {
return 0;
}
for (i=0;i<NUM_SIGNALS+1;i++) {
struct signal_event *se, *next;
- uint32_t count = sig_state.signal_count[i];
+ uint32_t count = sig_count(sig_state.signal_count[i]);
if (count == 0) {
continue;
@@ -217,8 +238,8 @@
talloc_free(se);
}
}
- sig_state.signal_count[i] -= count;
- sig_state.got_signal -= count;
+ SIG_SEEN(sig_state.signal_count[i], count);
+ SIG_SEEN(sig_state.got_signal, count);
}
return 1;
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