From eb208a6bb555a2e2de0e5f89db9beb1ce726cdcb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C3=A5rten=20Nordheim?= <marten.nordheim@qt.io>
Date: Mon, 17 Jun 2024 15:11:51 +0200
Subject: [PATCH] compressEvents: simplify TimerEvent compression

While better in some benchmarks, it turns out to be less efficient to
first find an event to the receiver, and then checking the event-ptr
and -type in other benchmarks, compared to just iterating the list and
checking these values.

Partially reverts 3e6b42ae9dbf4f90ba890d78a4c49f9936f4976b

Fixes: QTBUG-126394
Pick-to: 6.7
Change-Id: I748bda3d31350aea6e87db9bd57359ab17cf5d67
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: YAMAMOTO Atsushi - Signal Slot <atsushi.yamamoto@signal-slot.co.jp>
(cherry picked from commit b039d2251a14281947a43e226bae6c6fbae7312a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/kernel/qcoreapplication.cpp | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 4262c14405e..a18e3630b37 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -1729,18 +1729,17 @@ bool QCoreApplication::compressEvent(QEvent *event, QObject *receiver, QPostEven
     int receiverPostedEvents = receiver->d_func()->postedEvents.loadRelaxed();
     // compress posted timers to this object.
     if (event->type() == QEvent::Timer && receiverPostedEvents > 0) {
-        int timerId = static_cast<QTimerEvent *>(event)->timerId();
-        auto sameReceiver = [receiver](const QPostEvent &e) { return e.receiver == receiver; };
-        auto it = std::find_if(postedEvents->cbegin(), postedEvents->cend(), sameReceiver);
-        while (receiverPostedEvents > 0 && it != postedEvents->cend()) {
-            if (it->event && it->event->type() == QEvent::Timer
-                && static_cast<QTimerEvent *>(it->event)->timerId() == timerId) {
-                delete event;
-                return true;
+        const int timerId = static_cast<QTimerEvent *>(event)->timerId();
+        auto it = postedEvents->cbegin();
+        const auto end = postedEvents->cend();
+        while (it != end) {
+            if (it->event && it->event->type() == QEvent::Timer && it->receiver == receiver) {
+                if (static_cast<QTimerEvent *>(it->event)->timerId() == timerId) {
+                    delete event;
+                    return true;
+                }
             }
-
-            if (--receiverPostedEvents)
-                it = std::find_if(it + 1, postedEvents->cend(), sameReceiver);
+            ++it;
         }
         return false;
     }