EventLoop: new implementation using epoll

Implement an event loop without GLib.

src/event/SocketMonitor.cxx

@@ -32,6 +32,19 @@
 #include <sys/socket.h>
 #endif
 
+#ifdef USE_EPOLL
+
+void
+SocketMonitor::Dispatch(unsigned flags)
+{
+	flags &= GetScheduledFlags();
+
+	if (flags != 0 && !OnSocketReady(flags) && IsDefined())
+		Cancel();
+}
+
+#else
+
 /*
  * GSource methods
  *
@@ -88,6 +101,8 @@ SocketMonitor::SocketMonitor(int _fd, EventLoop &_loop)
 	Open(_fd);
 }
 
+#endif
+
 SocketMonitor::~SocketMonitor()
 {
 	if (IsDefined())
@@ -98,10 +113,14 @@ void
 SocketMonitor::Open(int _fd)
 {
 	assert(fd < 0);
+#ifndef USE_EPOLL
 	assert(source == nullptr);
+#endif
 	assert(_fd >= 0);
 
 	fd = _fd;
+
+#ifndef USE_EPOLL
 	poll = {fd, 0, 0};
 
 	source = (Source *)g_source_new(&socket_monitor_source_funcs,
@@ -110,6 +129,7 @@ SocketMonitor::Open(int _fd)
 
 	g_source_attach(&source->base, loop.GetContext());
 	g_source_add_poll(&source->base, &poll);
+#endif
 }
 
 int
@@ -122,9 +142,11 @@ SocketMonitor::Steal()
 	int result = fd;
 	fd = -1;
 
+#ifndef USE_EPOLL
 	g_source_destroy(&source->base);
 	g_source_unref(&source->base);
 	source = nullptr;
+#endif
 
 	return result;
 }
@@ -143,10 +165,21 @@ SocketMonitor::Schedule(unsigned flags)
 	if (flags == GetScheduledFlags())
 		return;
 
+#ifdef USE_EPOLL
+	if (scheduled_flags == 0)
+		loop.AddFD(fd, flags, *this);
+	else if (flags == 0)
+		loop.RemoveFD(fd, *this);
+	else
+		loop.ModifyFD(fd, flags, *this);
+
+	scheduled_flags = flags;
+#else
 	poll.events = flags;
 	poll.revents &= flags;
 
 	loop.WakeUp();
+#endif
 }
 
 SocketMonitor::ssize_t