From b9daeef524f71f880fd232812fc559e263b20e98 Mon Sep 17 00:00:00 2001
From: Max Kellermann <mk@cm4all.com>
Date: Fri, 10 Nov 2023 12:27:51 +0100
Subject: [PATCH] event/FineTimerEvent: add SetDue(), ScheduleCurrent()

---
 src/event/FineTimerEvent.cxx | 24 ++++++++++++++++++++----
 src/event/FineTimerEvent.hxx | 27 +++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/src/event/FineTimerEvent.cxx b/src/event/FineTimerEvent.cxx
index 0a092019d..a32be763d 100644
--- a/src/event/FineTimerEvent.cxx
+++ b/src/event/FineTimerEvent.cxx
@@ -5,13 +5,29 @@
 #include "FineTimerEvent.hxx"
 #include "Loop.hxx"
 
+void
+FineTimerEvent::SetDue(Event::Duration d) noexcept
+{
+	assert(!IsPending());
+
+	SetDue(loop.SteadyNow() + d);
+}
+
+void
+FineTimerEvent::ScheduleCurrent() noexcept
+{
+	assert(!IsPending());
+
+	loop.Insert(*this);
+}
+
 void
 FineTimerEvent::Schedule(Event::Duration d) noexcept
 {
 	Cancel();
 
-	due = loop.SteadyNow() + d;
-	loop.Insert(*this);
+	SetDue(d);
+	ScheduleCurrent();
 }
 
 void
@@ -26,6 +42,6 @@ FineTimerEvent::ScheduleEarlier(Event::Duration d) noexcept
 		Cancel();
 	}
 
-	due = new_due;
-	loop.Insert(*this);
+	SetDue(due);
+	ScheduleCurrent();
 }
diff --git a/src/event/FineTimerEvent.hxx b/src/event/FineTimerEvent.hxx
index bd30c6cb5..e0cd15d94 100644
--- a/src/event/FineTimerEvent.hxx
+++ b/src/event/FineTimerEvent.hxx
@@ -14,6 +14,8 @@
 #include <boost/intrusive/set_hook.hpp>
 #endif
 
+#include <cassert>
+
 class EventLoop;
 
 /**
@@ -62,6 +64,24 @@ 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?
 	 */
@@ -69,6 +89,13 @@ public:
 		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;
 
 	/**