Improve use of QHash to minimize double hashing

Avoid looking up by key twice in a row in various locations, but instead
using iterators and index lookup.

Change-Id: I61a079115199ab9c041ad3a26d36b45ee3f775e0
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/gui/image/qiconloader.cpp

@@ -383,13 +383,11 @@ QThemeIconInfo QIconLoader::findIconHelper(const QString &themeName,
     // Used to protect against potential recursions
     visited << themeName;
 
-    QIconTheme theme = themeList.value(themeName);
+    QIconTheme &theme = themeList[themeName];
     if (!theme.isValid()) {
         theme = QIconTheme(themeName);
         if (!theme.isValid())
             theme = QIconTheme(fallbackTheme());
-
-        themeList.insert(themeName, theme);
     }
 
     const QStringList contentDirs = theme.contentDirs();

src/gui/image/qpixmapcache.cpp

@@ -324,26 +324,23 @@ QPixmap *QPMCache::object(const QPixmapCache::Key &key) const
 
 bool QPMCache::insert(const QString& key, const QPixmap &pixmap, int cost)
 {
-    QPixmapCache::Key cacheKey;
-    QPixmapCache::Key oldCacheKey = cacheKeys.value(key);
+    QPixmapCache::Key &cacheKey = cacheKeys[key];
     //If for the same key we add already a pixmap we should delete it
-    if (oldCacheKey.d) {
-        QCache<QPixmapCache::Key, QPixmapCacheEntry>::remove(oldCacheKey);
-        cacheKeys.remove(key);
-    }
+    if (cacheKey.d)
+        QCache<QPixmapCache::Key, QPixmapCacheEntry>::remove(cacheKey);
 
     //we create a new key the old one has been removed
     cacheKey = createKey();
 
     bool success = QCache<QPixmapCache::Key, QPixmapCacheEntry>::insert(cacheKey, new QPixmapCacheEntry(cacheKey, pixmap), cost);
     if (success) {
-        cacheKeys.insert(key, cacheKey);
         if (!theid) {
             theid = startTimer(flush_time);
             t = false;
         }
     } else {
         //Insertion failed we released the new allocated key
+        cacheKeys.remove(key);
         releaseKey(cacheKey);
     }
     return success;
@@ -389,12 +386,12 @@ bool QPMCache::replace(const QPixmapCache::Key &key, const QPixmap &pixmap, int
 
 bool QPMCache::remove(const QString &key)
 {
-    QPixmapCache::Key cacheKey = cacheKeys.value(key);
+    auto cacheKey = cacheKeys.constFind(key);
     //The key was not in the cache
-    if (!cacheKey.d)
+    if (cacheKey == cacheKeys.constEnd())
         return false;
-    cacheKeys.remove(key);
-    return QCache<QPixmapCache::Key, QPixmapCacheEntry>::remove(cacheKey);
+    cacheKeys.erase(cacheKey);
+    return QCache<QPixmapCache::Key, QPixmapCacheEntry>::remove(cacheKey.value());
 }
 
 bool QPMCache::remove(const QPixmapCache::Key &key)

src/gui/kernel/qopenglcontext.cpp

@@ -848,14 +848,15 @@ QAbstractOpenGLFunctions *QOpenGLContext::versionFunctions(const QOpenGLVersionP
 
     // Create object if suitable one not cached
     QAbstractOpenGLFunctions* funcs = 0;
-    if (!d->versionFunctions.contains(vp)) {
+    auto it = d->versionFunctions.constFind(vp);
+    if (it == d->versionFunctions.constEnd()) {
         funcs = QOpenGLVersionFunctionsFactory::create(vp);
         if (funcs) {
             funcs->setOwningContext(this);
             d->versionFunctions.insert(vp, funcs);
         }
     } else {
-        funcs = d->versionFunctions.value(vp);
+        funcs = it.value();
     }
 
     if (funcs && QOpenGLContext::currentContext() == this)

src/gui/text/qfontengine_ft.cpp

@@ -320,8 +320,9 @@ void QFreetypeFace::release(const QFontEngine::FaceId &face_id)
 
             cleanup();
 
-            if (freetypeData->faces.contains(face_id))
-                freetypeData->faces.take(face_id);
+            auto it = freetypeData->faces.constFind(face_id);
+            if (it != freetypeData->faces.constEnd())
+                freetypeData->faces.erase(it);
 
             if (freetypeData->faces.isEmpty()) {
                 FT_Done_FreeType(freetypeData->library);

src/gui/text/qtextformat.cpp

@@ -3409,8 +3409,7 @@ int QTextFormatCollection::indexForFormat(const QTextFormat &format)
             f.d = new QTextFormatPrivate;
         f.d->resolveFont(defaultFnt);
 
-        if (!hashes.contains(hash, idx))
-            hashes.insert(hash, idx);
+        hashes.insert(hash, idx);
 
     } QT_CATCH(...) {
         formats.pop_back();

src/gui/text/qtextlayout.cpp

@@ -1059,9 +1059,10 @@ QList<QGlyphRun> QTextLayout::glyphRuns(int from, int length) const
                 QGlyphRun::GlyphRunFlags flags = glyphRun.flags();
                 QPair<QFontEngine *, int> key(fontEngine, int(flags));
                 // merge the glyph runs using the same font
-                if (glyphRunHash.contains(key)) {
-                    QGlyphRun &oldGlyphRun = glyphRunHash[key];
-
+                QGlyphRun &oldGlyphRun = glyphRunHash[key];
+                if (oldGlyphRun.isEmpty()) {
+                    oldGlyphRun = glyphRun;
+                } else {
                     QVector<quint32> indexes = oldGlyphRun.glyphIndexes();
                     QVector<QPointF> positions = oldGlyphRun.positions();
                     QRectF boundingRect = oldGlyphRun.boundingRect();
@@ -1073,8 +1074,6 @@ QList<QGlyphRun> QTextLayout::glyphRuns(int from, int length) const
                     oldGlyphRun.setGlyphIndexes(indexes);
                     oldGlyphRun.setPositions(positions);
                     oldGlyphRun.setBoundingRect(boundingRect);
-                } else {
-                    glyphRunHash[key] = glyphRun;
                 }
             }
         }

src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp

@@ -524,10 +524,11 @@ namespace {
 
         const void *key = *reinterpret_cast<void * const *>(fontFileReferenceKey);
         *fontFileStream = NULL;
-        if (!m_fontDatas.contains(key))
+        auto it = m_fontDatas.constFind(key);
+        if (it == m_fontDatas.constEnd())
             return E_FAIL;
 
-        QByteArray fontData = m_fontDatas.value(key);
+        QByteArray fontData = it.value();
         DirectWriteFontFileStream *stream = new DirectWriteFontFileStream(fontData);
         stream->AddRef();
         *fontFileStream = stream;

src/widgets/accessible/itemviews.cpp

@@ -486,10 +486,9 @@ QAccessibleInterface *QAccessibleTable::child(int logicalIndex) const
     if (!view()->model())
         return 0;
 
-    if (childToId.contains(logicalIndex)) {
-        QAccessible::Id id = childToId.value(logicalIndex);
-        return QAccessible::accessibleInterface(id);
-    }
+    auto id = childToId.constFind(logicalIndex);
+    if (id != childToId.constEnd())
+        return QAccessible::accessibleInterface(id.value());
 
     int vHeader = verticalHeader() ? 1 : 0;
     int hHeader = horizontalHeader() ? 1 : 0;

src/widgets/styles/qpixmapstyle.cpp

@@ -628,10 +628,10 @@ void QPixmapStyle::drawCachedPixmap(QPixmapStyle::ControlDescriptor control, con
                                     QPainter *p) const
 {
     Q_D(const QPixmapStyle);
-    if (!d->descriptors.contains(control))
+    auto descriptor = d->descriptors.constFind(control);
+    if (descriptor == d->descriptors.constEnd())
         return;
-    const QPixmapStyleDescriptor &desc = d->descriptors.value(control);
-    const QPixmap pix = d->getCachedPixmap(control, desc, rect.size());
+    const QPixmap pix = d->getCachedPixmap(control, descriptor.value(), rect.size());
     Q_ASSERT(!pix.isNull());
     p->drawPixmap(rect, pix);
 }