event/SocketMonitor: Schedule() returns bool

2 files changed, 19 insertions, 11 deletions

diff --git a/src/event/SocketMonitor.cxx b/src/event/SocketMonitor.cxx
index 64cc42820..f335c8fdc 100644
--- a/src/event/SocketMonitor.cxx
+++ b/src/event/SocketMonitor.cxx
@@ -68,20 +68,24 @@ SocketMonitor::Close() noexcept
 	Steal().Close();
 }
 
-void
+bool
 SocketMonitor::Schedule(unsigned flags) noexcept
 {
 	assert(IsDefined());
 
 	if (flags == GetScheduledFlags())
-		return;
+		return true;
 
+	bool success;
 	if (scheduled_flags == 0)
-		loop.AddFD(fd.Get(), flags, *this);
+		success = loop.AddFD(fd.Get(), flags, *this);
 	else if (flags == 0)
-		loop.RemoveFD(fd.Get(), *this);
+		success = loop.RemoveFD(fd.Get(), *this);
 	else
-		loop.ModifyFD(fd.Get(), flags, *this);
+		success = loop.ModifyFD(fd.Get(), flags, *this);
+
+	if (success)
+		scheduled_flags = flags;
 
-	scheduled_flags = flags;
+	return success;
 }
diff --git a/src/event/SocketMonitor.hxx b/src/event/SocketMonitor.hxx
index df80ced04..1d8814cc5 100644
--- a/src/event/SocketMonitor.hxx
+++ b/src/event/SocketMonitor.hxx
@@ -98,18 +98,22 @@ public:
 		return scheduled_flags;
 	}
 
-	void Schedule(unsigned flags) noexcept;
+	/**
+	 * @return true on success, false on error (with errno set if
+	 * USE_EPOLL is defined)
+	 */
+	bool Schedule(unsigned flags) noexcept;
 
 	void Cancel() noexcept {
 		Schedule(0);
 	}
 
-	void ScheduleRead() noexcept {
-		Schedule(GetScheduledFlags() | READ | HANGUP | ERROR);
+	bool ScheduleRead() noexcept {
+		return Schedule(GetScheduledFlags() | READ | HANGUP | ERROR);
 	}
 
-	void ScheduleWrite() noexcept {
-		Schedule(GetScheduledFlags() | WRITE);
+	bool ScheduleWrite() noexcept {
+		return Schedule(GetScheduledFlags() | WRITE);
 	}
 
 	void CancelRead() noexcept {