event/SignalMonitor: use BoundMethod instead of raw function pointer

src/event/SignalMonitor.cxx

@@ -158,7 +158,7 @@ SignalMonitorFinish()
 	sa.sa_handler = SIG_DFL;
 
 	for (unsigned i = 0; i < MAX_SIGNAL; ++i) {
-		if (signal_handlers[i] != nullptr) {
+		if (signal_handlers[i]) {
 			x_sigaction(i, sa);
 			signal_handlers[i] = nullptr;
 		}
@@ -179,7 +179,7 @@ SignalMonitorGetEventLoop()
 void
 SignalMonitorRegister(int signo, SignalHandler handler)
 {
-	assert(signal_handlers[signo] == nullptr);
+	assert(!signal_handlers[signo]);
 #ifndef USE_SIGNALFD
 	assert(!signal_pending[signo]);
 #endif
@@ -209,7 +209,7 @@ SignalMonitor::OnSocketReady(unsigned)
 	int signo;
 	while ((signo = fd.Read()) >= 0) {
 		assert(unsigned(signo) < MAX_SIGNAL);
-		assert(signal_handlers[signo] != nullptr);
+		assert(signal_handlers[signo]);
 
 		signal_handlers[signo]();
 	}

src/event/SignalMonitor.hxx

@@ -26,7 +26,9 @@ class EventLoop;
 
 #ifndef WIN32
 
-typedef void (*SignalHandler)();
+#include "util/BindMethod.hxx"
+
+typedef BoundMethod<void()> SignalHandler;
 
 /**
  * Initialise the signal monitor subsystem.

src/unix/SignalHandlers.cxx

@@ -34,9 +34,10 @@
 static constexpr Domain signal_handlers_domain("signal_handlers");
 
 static void
-HandleShutdownSignal()
+HandleShutdownSignal(void *ctx)
 {
-	SignalMonitorGetEventLoop().Break();
+	auto &loop = *(EventLoop *)ctx;
+	loop.Break();
 }
 
 static void
@@ -47,7 +48,7 @@ x_sigaction(int signum, const struct sigaction *act)
 }
 
 static void
-handle_reload_event(void)
+handle_reload_event(void *)
 {
 	LogDebug(signal_handlers_domain, "got SIGHUP, reopening log files");
 	cycle_log_files();
@@ -68,10 +69,10 @@ SignalHandlersInit(EventLoop &loop)
 	sa.sa_handler = SIG_IGN;
 	x_sigaction(SIGPIPE, &sa);
 
-	SignalMonitorRegister(SIGINT, HandleShutdownSignal);
-	SignalMonitorRegister(SIGTERM, HandleShutdownSignal);
+	SignalMonitorRegister(SIGINT, {&loop, HandleShutdownSignal});
+	SignalMonitorRegister(SIGTERM, {&loop, HandleShutdownSignal});
 
-	SignalMonitorRegister(SIGHUP, handle_reload_event);
+	SignalMonitorRegister(SIGHUP, {nullptr, handle_reload_event});
 #endif
 }
 

test/ShutdownHandler.cxx

@@ -27,17 +27,18 @@
 #include <signal.h>
 
 static void
-HandleShutdownSignal()
+HandleShutdownSignal(void *ctx)
 {
-	SignalMonitorGetEventLoop().Break();
+	auto &loop = *(EventLoop *)ctx;
+	loop.Break();
 }
 
 ShutdownHandler::ShutdownHandler(EventLoop &loop)
 {
 	SignalMonitorInit(loop);
 
-	SignalMonitorRegister(SIGINT, HandleShutdownSignal);
-	SignalMonitorRegister(SIGTERM, HandleShutdownSignal);
+	SignalMonitorRegister(SIGINT, {&loop, HandleShutdownSignal});
+	SignalMonitorRegister(SIGTERM, {&loop, HandleShutdownSignal});
 }
 
 ShutdownHandler::~ShutdownHandler()