Regularly send a notification for the systemd watchdog

src/xmpp/xmpp_component.cpp

@@ -1,3 +1,4 @@
+#include <utils/timed_events.hpp>
 #include <utils/scopeguard.hpp>
 #include <utils/tolower.hpp>
 #include <logger/logger.hpp>
@@ -273,6 +274,16 @@ void XmppComponent::handle_handshake(const Stanza& stanza)
   log_info("Authenticated with the XMPP server");
 #ifdef SYSTEMDDAEMON_FOUND
   sd_notify(0, "READY=1");
+  // Install an event that sends a keepalive to systemd.  If biboumi crashes
+  // or hangs for too long, systemd will restart it.
+  uint64_t usec;
+  if (sd_watchdog_enabled(0, &usec) > 0)
+    {
+      std::chrono::microseconds delay(usec);
+      TimedEventsManager::instance().add_event(TimedEvent(
+             std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::microseconds(usec / 2)),
+             []() { sd_notify(0, "WATCHDOG=1"); }));
+    }
 #endif
 }