update comment (#24566)

* update comment * Update src/platform/OpenThread/GenericThreadStackManagerImpl_OpenThread.cpp Co-authored-by: Boris Zbarsky <bzbarsky@apple.com> Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>
project-chip · Oct 12, 2023 · 1171359 · 1171359
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commit 1171359
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diff --git a/src/platform/OpenThread/GenericThreadStackManagerImpl_OpenThread.cpp b/src/platform/OpenThread/GenericThreadStackManagerImpl_OpenThread.cpp
@@ -1896,6 +1896,10 @@ CHIP_ERROR GenericThreadStackManagerImpl_OpenThread<ImplClass>::_RequestSEDActiv
 
     if (!onOff && delayIdle && CHIP_DEVICE_CONFIG_SED_ACTIVE_THRESHOLD.count() != 0)
     {
+        // StartTimer will cancel a timer if the same callback & context is used.
+        // This will have the effect of canceling the previous one (if any) and starting
+        // a new timer of the same duration. This effectively prolongs the active threshold
+        // without consuming additional resources.
         err = DeviceLayer::SystemLayer().StartTimer(CHIP_DEVICE_CONFIG_SED_ACTIVE_THRESHOLD, RequestSEDModeUpdate, this);
         if (CHIP_NO_ERROR == err)
         {

diff --git a/src/system/SystemLayer.h b/src/system/SystemLayer.h
@@ -118,12 +118,8 @@ class DLL_EXPORT Layer
      *   This method cancels a one-shot timer, started earlier through @p StartTimer().
      *
      *   @note
-     *       The cancellation could fail silently in two different ways. If the timer specified by the combination of the callback
-     *       function and application state object couldn't be found, cancellation could fail. If the timer has fired, then
-     *       an event is queued and will be processed later.
-     *
-     *   WARNING: Timer handlers MUST assume that they may be hit even after CancelTimer due to cancelling an
-     *            already fired timer that is queued in the event loop already.
+     *       The cancellation could fail silently if the timer specified by the combination of the callback
+     *       function and application state object couldn't be found.
      *
      *   @param[in]  aOnComplete   A pointer to the callback function used in calling @p StartTimer().
      *   @param[in]  aAppState     A pointer to the application state object used in calling @p StartTimer().