From 07f1c9665827bf9bc7dc70154fdee168c8118aaa Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@qt.io>
Date: Fri, 12 Jan 2018 16:43:48 +0100
Subject: Improve performance of QResource::load()

Avoid creating a QDateTime in the resource that will almost
never get used. Constructing the date time is expensive as we
convert the time stamp to local time.

Task-number: QTBUG-65713
Change-Id: I3638e108a8fbd237cd93e98aa2adc0ca2127822c
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Tuukka Turunen <tuukka.turunen@qt.io>
---
 src/corelib/io/qresource.cpp | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/src/corelib/io/qresource.cpp b/src/corelib/io/qresource.cpp
index 35a0de4fb7..7502fb57a3 100644
--- a/src/corelib/io/qresource.cpp
+++ b/src/corelib/io/qresource.cpp
@@ -116,7 +116,7 @@ public:
     inline bool isContainer(int node) const { return flags(node) & Directory; }
     inline bool isCompressed(int node) const { return flags(node) & Compressed; }
     const uchar *data(int node, qint64 *size) const;
-    QDateTime lastModified(int node) const;
+    quint64 lastModified(int node) const;
     QStringList children(int node) const;
     virtual QString mappingRoot() const { return QString(); }
     bool mappingRootSubdir(const QString &path, QString *match=0) const;
@@ -245,7 +245,7 @@ public:
     mutable qint64 size;
     mutable const uchar *data;
     mutable QStringList children;
-    mutable QDateTime lastModified;
+    mutable quint64 lastModified;
 
     QResource *q_ptr;
     Q_DECLARE_PUBLIC(QResource)
@@ -259,7 +259,7 @@ QResourcePrivate::clear()
     data = 0;
     size = 0;
     children.clear();
-    lastModified = QDateTime();
+    lastModified = 0;
     container = 0;
     for(int i = 0; i < related.size(); ++i) {
         QResourceRoot *root = related.at(i);
@@ -301,7 +301,7 @@ QResourcePrivate::load(const QString &file)
             data = 0;
             size = 0;
             compressed = 0;
-            lastModified = QDateTime();
+            lastModified = 0;
             res->ref.ref();
             related.append(res);
         }
@@ -539,7 +539,7 @@ QDateTime QResource::lastModified() const
 {
     Q_D(const QResource);
     d->ensureInitialized();
-    return d->lastModified;
+    return d->lastModified ? QDateTime::fromMSecsSinceEpoch(d->lastModified) : QDateTime();
 }
 
 /*!
@@ -797,18 +797,14 @@ const uchar *QResourceRoot::data(int node, qint64 *size) const
     return 0;
 }
 
-QDateTime QResourceRoot::lastModified(int node) const
+quint64 QResourceRoot::lastModified(int node) const
 {
     if (node == -1 || version < 0x02)
-        return QDateTime();
+        return 0;
 
     const int offset = findOffset(node) + 14;
 
-    const quint64 timeStamp = qFromBigEndian<quint64>(tree + offset);
-    if (timeStamp == 0)
-        return QDateTime();
-
-    return QDateTime::fromMSecsSinceEpoch(timeStamp);
+    return qFromBigEndian<quint64>(tree + offset);
 }
 
 QStringList QResourceRoot::children(int node) const
-- 
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