From b4114589ffbfb9ca5091fdacc5c98f4d3daaf10d Mon Sep 17 00:00:00 2001
From: Chris Johns <chrisj@rtems.org>
Date: Wed, 3 Dec 2025 14:45:55 +1100
Subject: [PATCH] Skip any missed timer events updating the timer to now

This stops a timer calling the callback for every missed event if the
time jumps forward when corrected or moved.
---
 src/misc/timer.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/misc/timer.cpp b/src/misc/timer.cpp
index e3239eb..1dda328 100644
--- a/src/misc/timer.cpp
+++ b/src/misc/timer.cpp
@@ -118,6 +118,18 @@ void Timer::run()
             work->processing = true;
             queue.pop_front();
 
+            if(work->period > 0.0 && alive && !work->cancelled) {
+                /*
+                 * If the distance between the time now and the time
+                 * the timer was to run is more than the period move
+                 * the timer's run time to now and avoid the timer
+                 * spinning issuing callbacks for missed timer events
+                 */
+                if ((now - work->timeToRun) > work->period) {
+                    work->timeToRun = now;
+                }
+            }
+
             {
                 epicsGuardRelease<epicsMutex> U(G);