event/CoarseTimerEvent: add methods SetDue(), ScheduleCurrent()

FineTimerEvent has these already.

Author: MaxKellermann

src/event/CoarseTimerEvent.cxx

@@ -5,13 +5,29 @@
 #include "CoarseTimerEvent.hxx"
 #include "Loop.hxx"
 
+void
+CoarseTimerEvent::SetDue(Event::Duration d) noexcept
+{
+	assert(!IsPending());
+
+	SetDue(loop.SteadyNow() + d);
+}
+
+void
+CoarseTimerEvent::ScheduleCurrent() noexcept
+{
+	assert(!IsPending());
+
+	loop.Insert(*this);
+}
+
 void
 CoarseTimerEvent::Schedule(Event::Duration d) noexcept
 {
 	Cancel();
 
-	due = loop.SteadyNow() + d;
-	loop.Insert(*this);
+	SetDue(d);
+	ScheduleCurrent();
 }
 
 void
@@ -26,6 +42,7 @@ CoarseTimerEvent::ScheduleEarlier(Event::Duration d) noexcept
 		Cancel();
 	}
 
-	due = new_due;
-	loop.Insert(*this);
+	SetDue(new_due);
+	ScheduleCurrent();
+
 }

src/event/CoarseTimerEvent.hxx

@@ -51,13 +51,38 @@ public:
 		return due;
 	}
 
+	/**
+	 * Set the due time as an absolute time point.  This can be
+	 * done to prepare an eventual ScheduleCurrent() call.  Must
+	 * not be called while the timer is already scheduled.
+	 */
+	void SetDue(Event::TimePoint _due) noexcept {
+		assert(!IsPending());
+
+		due = _due;
+	}
+
+	/**
+	 * Set the due time as a duration relative to now.  This can
+	 * done to prepare an eventual ScheduleCurrent() call.  Must
+	 * not be called while the timer is already scheduled.
+	 */
+	void SetDue(Event::Duration d) noexcept;
+
 	/**
 	 * Was this timer scheduled?
 	 */
 	bool IsPending() const noexcept {
 		return is_linked();
 	}
 
+	/**
+	 * Schedule the timer at the due time that was already set;
+	 * either by SetDue() or by a Schedule() call that was already
+	 * canceled.
+	 */
+	void ScheduleCurrent() noexcept;
+
 	void Schedule(Event::Duration d) noexcept;
 
 	/**