From ee6b101adf18eaf6f2dea571787a04161d7426ed Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Wed, 28 Aug 2024 14:33:58 +0200
Subject: [PATCH] QTimer: port defaultTypeFor() helper from ms to ns resolution

This doesn't change a thing for QTimer, but is a building block for
making its singleShot() have nanosecond resolution, and allows
QChronoTimer to reuse the function.

Task-number: QTBUG-128426
Change-Id: I3d7e79972f236ca63b216a1a5a871edf5025e1b8
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 25b8d3743455bd2a4a327e1068fc83acb2f1c481)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/kernel/qchronotimer.h | 13 ++++---------
 src/corelib/kernel/qtimer.h       |  3 ++-
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/src/corelib/kernel/qchronotimer.h b/src/corelib/kernel/qchronotimer.h
index 79c475e93ce..136edb06a2e 100644
--- a/src/corelib/kernel/qchronotimer.h
+++ b/src/corelib/kernel/qchronotimer.h
@@ -10,6 +10,7 @@
 #include <QtCore/qnamespace.h>
 #include <QtCore/qobject.h>
 #include <QtCore/qproperty.h>
+#include <QtCore/qtimer.h>
 
 #include <chrono>
 
@@ -68,7 +69,7 @@ public:
     static void singleShot(std::chrono::nanoseconds interval,
                            const FunctorContext<Functor> *receiver, Functor &&slot)
     {
-        singleShot(interval, defaultTimerTypeFor(interval), receiver, std::forward<Functor>(slot));
+        singleShot(interval, QTimer::defaultTypeFor(interval), receiver, std::forward<Functor>(slot));
     }
     template <typename Functor>
     static void singleShot(std::chrono::nanoseconds interval, Qt::TimerType timerType,
@@ -88,14 +89,14 @@ public:
     template <typename Functor>
     static void singleShot(std::chrono::nanoseconds interval, Functor &&slot)
     {
-        singleShot(interval, defaultTimerTypeFor(interval), nullptr, std::forward<Functor>(slot));
+        singleShot(interval, QTimer::defaultTypeFor(interval), nullptr, std::forward<Functor>(slot));
     }
 
     static void singleShot(std::chrono::nanoseconds interval, Qt::TimerType timerType,
                            const QObject *receiver, const char *member);
     static void singleShot(std::chrono::nanoseconds interval, const QObject *receiver,
                            const char *member)
-    { singleShot(interval, defaultTimerTypeFor(interval), receiver, member); }
+    { singleShot(interval, QTimer::defaultTypeFor(interval), receiver, member); }
 
 #ifdef Q_QDOC
     template <typename Functor>
@@ -132,12 +133,6 @@ private:
     int startTimer(std::chrono::nanoseconds) = delete;
     void killTimer(int) = delete;
 
-    static constexpr Qt::TimerType defaultTimerTypeFor(std::chrono::nanoseconds interval) noexcept
-    {
-        using namespace std::chrono_literals;
-        return interval >= 2s ? Qt::CoarseTimer : Qt::PreciseTimer;
-    }
-
     static void singleShotImpl(std::chrono::nanoseconds interval, Qt::TimerType timerType,
                                const QObject *receiver, QtPrivate::QSlotObjectBase *slotObj);
 };
diff --git a/src/corelib/kernel/qtimer.h b/src/corelib/kernel/qtimer.h
index 854d9072f20..06e90ac52ef 100644
--- a/src/corelib/kernel/qtimer.h
+++ b/src/corelib/kernel/qtimer.h
@@ -142,6 +142,7 @@ protected:
 private:
     Q_DISABLE_COPY(QTimer)
     Q_DECLARE_PRIVATE(QTimer)
+    friend class QChronoTimer;
 
     inline int startTimer(int){ return -1;}
     inline void killTimer(int){}
@@ -149,7 +150,7 @@ private:
     static constexpr Qt::TimerType defaultTypeFor(int msecs) noexcept
     { return defaultTypeFor(std::chrono::milliseconds{msecs}); }
 
-    static constexpr Qt::TimerType defaultTypeFor(std::chrono::milliseconds interval) noexcept
+    static constexpr Qt::TimerType defaultTypeFor(std::chrono::nanoseconds interval) noexcept
     {
         // coarse timers are worst in their first firing
         // so we prefer a high precision timer for something that happens only once