+
+/* =========================== Software Watchdog ============================ */
+#include <sys/time.h>
+
+void watchdogSignalHandler(int sig, siginfo_t *info, void *secret) {
+ ucontext_t *uc = (ucontext_t*) secret;
+ REDIS_NOTUSED(info);
+ REDIS_NOTUSED(sig);
+ sds st, log;
+
+ log = sdsnew("\n--- WATCHDOG TIMER EXPIRED ---\n");
+#ifdef HAVE_BACKTRACE
+ st = getStackTrace(uc);
+#else
+ st = sdsnew("Sorry: no support for backtrace().\n");
+#endif
+ log = sdscatsds(log,st);
+ log = sdscat(log,"------\n");
+ redisLogFromHandler(REDIS_WARNING,log);
+ sdsfree(st);
+ sdsfree(log);
+}
+
+/* Schedule a SIGALRM delivery after the specified period in milliseconds.
+ * If a timer is already scheduled, this function will re-schedule it to the
+ * specified time. If period is 0 the current timer is disabled. */
+void watchdogScheduleSignal(int period) {
+ struct itimerval it;
+
+ /* Will stop the timer if period is 0. */
+ it.it_value.tv_sec = period/1000;
+ it.it_value.tv_usec = (period%1000)*1000;
+ /* Don't automatically restart. */
+ it.it_interval.tv_sec = 0;
+ it.it_interval.tv_usec = 0;
+ setitimer(ITIMER_REAL, &it, NULL);
+}
+
+/* Enable the software watchdong with the specified period in milliseconds. */
+void enableWatchdog(int period) {
+ if (server.watchdog_period == 0) {
+ struct sigaction act;
+
+ /* Watchdog was actually disabled, so we have to setup the signal
+ * handler. */
+ sigemptyset(&act.sa_mask);
+ act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_SIGINFO;
+ act.sa_sigaction = watchdogSignalHandler;
+ sigaction(SIGALRM, &act, NULL);
+ }
+ if (period < 200) period = 200; /* We don't accept periods < 200 ms. */
+ watchdogScheduleSignal(period); /* Adjust the current timer. */
+ server.watchdog_period = period;
+}
+
+/* Disable the software watchdog. */
+void disableWatchdog(void) {
+ struct sigaction act;
+ if (server.watchdog_period == 0) return; /* Already disabled. */
+ watchdogScheduleSignal(0); /* Stop the current timer. */
+
+ /* Set the signal handler to SIG_IGN, this will also remove pending
+ * signals from the queue. */
+ sigemptyset(&act.sa_mask);
+ act.sa_flags = 0;
+ act.sa_handler = SIG_IGN;
+ sigaction(SIGALRM, &act, NULL);
+ server.watchdog_period = 0;
+}